subject:(quorum sensing)

Oregon State University

1. Gupta, Rashmi. Quorum sensing gene regulation in Pseudomonas aeruginosa.

Degree: PhD, Microbiology, 2012, Oregon State University

URL: http://hdl.handle.net/1957/29021

► Pseudomonas aeruginosa is an opportunistic human pathogen that infects immunocompromised individuals such as those suffering from burns or the genetic disorder cystic fibrosis. This organism… (more)

Subjects/Keywords: Quorum-sensing; Quorum sensing (Microbiology)

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APA (6^th Edition):

Gupta, R. (2012). Quorum sensing gene regulation in Pseudomonas aeruginosa. (Doctoral Dissertation). Oregon State University. Retrieved from http://hdl.handle.net/1957/29021

Chicago Manual of Style (16^th Edition):

Gupta, Rashmi. “Quorum sensing gene regulation in Pseudomonas aeruginosa.” 2012. Doctoral Dissertation, Oregon State University. Accessed March 01, 2021. http://hdl.handle.net/1957/29021.

MLA Handbook (7^th Edition):

Gupta, Rashmi. “Quorum sensing gene regulation in Pseudomonas aeruginosa.” 2012. Web. 01 Mar 2021.

Vancouver:

Gupta R. Quorum sensing gene regulation in Pseudomonas aeruginosa. [Internet] [Doctoral dissertation]. Oregon State University; 2012. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/1957/29021.

Council of Science Editors:

Gupta R. Quorum sensing gene regulation in Pseudomonas aeruginosa. [Doctoral Dissertation]. Oregon State University; 2012. Available from: http://hdl.handle.net/1957/29021

2. Bergonzi, Céline. Étude, caractérisation et ingénierie de lactonases pour l'inhibition de la virulence et des biofilms bactériens : Studies, characterization and engineering of lactonases for the inhibition of bacterial virulence and biofilm formation.

Degree: Docteur es, Biologie. Biochimie structurale, 2018, Aix Marseille Université

URL: http://www.theses.fr/2018AIXM0241

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Certains microorganismes sont capables de communiquer en utilisant des molécules et d’utiliser ce système pour réguler des comportements en fonction de la densité cellulaire. Ce… (more)

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Certains microorganismes sont capables de communiquer en utilisant des molécules et d’utiliser ce système pour réguler des comportements en fonction de la densité cellulaire. Ce système de communication, appelé quorum sensing (QS), régule des comportements bactériens, tels que la virulence et la formation de biofilm. Les molécules signal les plus étudiées sont les acyle-homosérine lactones (AHLs). Les enzymes qui sont capables de dégrader ces molécules peuvent couper la communication bactérienne, et se comportent ainsi comme des inhibiteurs de virulence et de biofilm. Ce phénomène, appelé quorum quenching (QQ), est une approche prometteuse pour le contrôle bactérien sans les tuer, ainsi que pour le développement de nouvelles thérapies contre les bactéries résistantes aux antibiotiques. Les travaux menés durant ma thèse ont permis d’isoler et de caractériser biochimiquement, enzymatiquement et structuralement de nouvelles lactonases provenant d’organismes thermophiles, capables d’inhiber le QS. J’ai résolu les structures de trois lactonases et en complexe avec différents types de lactones. Ces données ont révélées l’extrême polyvalence des sites actifs de ces enzymes, et ont permis d’identifier les résidus potentiellement impliqués dans la spécificité de substrat de ces enzymes. Ces résultats serviront de bases aux futurs projets d’ingénierie visant à changer la spécificité de ces enzymes. Enfin, mes travaux de caractérisation sur ces lactonases très stables ont permis de les utiliser hors du laboratoire et de démontrer l’importance de la signalisation bactérienne dans des processus biologiques complexes tels que la formation de biofilm et la bio-corrosion.

Numerous microorganisms are able to communicate using molecules and use this signaling system to coordinate behaviors in a cell-density-dependent manner. This communication system, dubbed quorum sensing (QS), regulates bacterial behaviors such as biofilm formation. The most popular system utilizes acyl homoserine lactones (AHLs) as signals. Enzymes that can degrade these signaling molecules can effectively disrupt bacterial signaling, and thereby behave as potent biofilm and virulence inhibitors. Therefore, the inhibition of QS, termed quorum quenching (QQ) by these enzymes is a promising approach to control microbes without killing them and develop therapies on multidrugs resistant strains. During this thesis, I have isolated and characterized biochemically, enzymatically and structurally novel lactonases from thermophilic sources. I have determined the structures of three lactonases in complex with different types of lactones. This enabled me to elucidate their catalytic mechanisms, as well as the unique binding modes of structurally different lactones. These data revealed the extreme catalytic versatility of the active sites of these enzymes, and allowed for the determination of residues possibly involved in substrate specificity. These data, in combination with structural data obtained on improved lactonase mutants, will serve as a foundation to guide future…

Advisors/Committee Members: Chabrière, Eric (thesis director), Elias, Mikael (thesis director).

Subjects/Keywords: Quorum sensing; Quorum sensing

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Bergonzi, C. (2018). Étude, caractérisation et ingénierie de lactonases pour l'inhibition de la virulence et des biofilms bactériens : Studies, characterization and engineering of lactonases for the inhibition of bacterial virulence and biofilm formation. (Doctoral Dissertation). Aix Marseille Université. Retrieved from http://www.theses.fr/2018AIXM0241

Chicago Manual of Style (16^th Edition):

Bergonzi, Céline. “Étude, caractérisation et ingénierie de lactonases pour l'inhibition de la virulence et des biofilms bactériens : Studies, characterization and engineering of lactonases for the inhibition of bacterial virulence and biofilm formation.” 2018. Doctoral Dissertation, Aix Marseille Université. Accessed March 01, 2021. http://www.theses.fr/2018AIXM0241.

MLA Handbook (7^th Edition):

Bergonzi, Céline. “Étude, caractérisation et ingénierie de lactonases pour l'inhibition de la virulence et des biofilms bactériens : Studies, characterization and engineering of lactonases for the inhibition of bacterial virulence and biofilm formation.” 2018. Web. 01 Mar 2021.

Vancouver:

Bergonzi C. Étude, caractérisation et ingénierie de lactonases pour l'inhibition de la virulence et des biofilms bactériens : Studies, characterization and engineering of lactonases for the inhibition of bacterial virulence and biofilm formation. [Internet] [Doctoral dissertation]. Aix Marseille Université 2018. [cited 2021 Mar 01]. Available from: http://www.theses.fr/2018AIXM0241.

Council of Science Editors:

Bergonzi C. Étude, caractérisation et ingénierie de lactonases pour l'inhibition de la virulence et des biofilms bactériens : Studies, characterization and engineering of lactonases for the inhibition of bacterial virulence and biofilm formation. [Doctoral Dissertation]. Aix Marseille Université 2018. Available from: http://www.theses.fr/2018AIXM0241

3. Rémy, Benjamin. Développement d'une nouvelle génération de pansements antimicrobiens à base d'enzyme à activité lactonase : Development of a new generation of antimicrobial bandages containing lactonases.

Degree: Docteur es, Biologie. Biochimie structurale, 2018, Aix Marseille Université

URL: http://www.theses.fr/2018AIXM0391

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Des bactéries utilisent un système de communication, quorum sensing (QS), qui leur permet de synchroniser leur comportement proportionnellement à la densité de population. Des bactéries… (more)

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Des bactéries utilisent un système de communication, quorum sensing (QS), qui leur permet de synchroniser leur comportement proportionnellement à la densité de population. Des bactéries pathogènes utilisent le QS pour coordonner leur virulence et la formation de biofilm. Bloquer le QS, quorum quenching (QQ), constitue donc une piste pour étendre l'arsenal thérapeutique antibactérien. Durant cette thèse, SsoPox, une lactonase hyperstable hydrolysant les acyl homosérine lactones (AHL) impliquées dans le QS de bactéries à Gram négative pathogènes comme P. aeruginosa, a été étudiée. Son utilisation dans des pansements contre les infections à P. aeruginosa a été évaluée. La résistance aux contraintes industrielles liées aux procédés de fabrication des pansements a été évaluée. SsoPox s'est montrée résistante à la chaleur, aux solvants organiques, au stockage à température ambiante et à la stérilisation. L’efficacité de l’enzyme a été montrée sur 2 souches modèles et 51 isolats cliniques de P. aeruginosa. SsoPox a été plus efficace que 2 inhibiteurs du QS. L’efficacité de l’enzyme est aussi conservée après immobilisation. Une étude phénotypique et moléculaire du QQ enzymatique de P. aeruginosa a été réalisée entre SsoPox et une autre lactonase GcL ayant un spectre d'action distinct sur les AHL. In vitro, il a été mis en évidence des impacts différents entre les 2 enzymes sur les facteurs de virulence et le biofilm. In vivo, il a été montré que seul SsoPox réduit la virulence de P. aeruginosa. L’expression des gènes du QS et le protéome ont confirmé des différences entre GcL et SsoPox. Ainsi SsoPox semble constituer un bon candidat pour le développement de pansements innovants.

Bacteria use a communication system, or quorum sensing (QS), to synchronize group behaviors according to population density. Some pathogens use QS to coordinate virulence and biofilm formation. Interfering with QS, or quorum quenching, represents a target to extent antibacterial drug resources. Along this PhD project, SsoPox, a hyperstable lactonase, hydrolyzing acyl homoserine lactones (AHL) involved in the QS of Gram-negative pathogen bacteria like Pseudomonas aeruginosa was studied. SsoPox was studied and characterized for its use in wound dressing against P. aeruginosa infection. The enzyme resistance to industrial constraints encountered during wound dressings manufacturing processes was estimated. SsoPox demonstrated a high tolerance to heat, organic solvents, ambient temperature storage and to sterilization processes. The enzyme efficiency was shown on 2 model strains and 51 clinical isolates of P. aeruginosa. SsoPox was also more efficient than 2 well characterized QS inhibitors. The enzyme kept its efficiency even when immobilized. A last part was dedicated to phenotypical and molecular study of enzymatic QQ of P. aeruginosa. SsoPox and another lactonase GcL, having distinct AHL specificities, were compared. In vitro experiments highlighted different impacts between the enzymes on virulence factors and biofilm. An in vivo study showed…

Advisors/Committee Members: Chabrière, Eric (thesis director), Daude, David (thesis director).

Subjects/Keywords: Quorum sensing; Quorum sensing

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Rémy, B. (2018). Développement d'une nouvelle génération de pansements antimicrobiens à base d'enzyme à activité lactonase : Development of a new generation of antimicrobial bandages containing lactonases. (Doctoral Dissertation). Aix Marseille Université. Retrieved from http://www.theses.fr/2018AIXM0391

Chicago Manual of Style (16^th Edition):

Rémy, Benjamin. “Développement d'une nouvelle génération de pansements antimicrobiens à base d'enzyme à activité lactonase : Development of a new generation of antimicrobial bandages containing lactonases.” 2018. Doctoral Dissertation, Aix Marseille Université. Accessed March 01, 2021. http://www.theses.fr/2018AIXM0391.

MLA Handbook (7^th Edition):

Rémy, Benjamin. “Développement d'une nouvelle génération de pansements antimicrobiens à base d'enzyme à activité lactonase : Development of a new generation of antimicrobial bandages containing lactonases.” 2018. Web. 01 Mar 2021.

Vancouver:

Rémy B. Développement d'une nouvelle génération de pansements antimicrobiens à base d'enzyme à activité lactonase : Development of a new generation of antimicrobial bandages containing lactonases. [Internet] [Doctoral dissertation]. Aix Marseille Université 2018. [cited 2021 Mar 01]. Available from: http://www.theses.fr/2018AIXM0391.

Council of Science Editors:

Rémy B. Développement d'une nouvelle génération de pansements antimicrobiens à base d'enzyme à activité lactonase : Development of a new generation of antimicrobial bandages containing lactonases. [Doctoral Dissertation]. Aix Marseille Université 2018. Available from: http://www.theses.fr/2018AIXM0391

Oregon State University

4. Asfahl, Kyle. Social Evolution and Regulatory Architecture of Pseudomonas aeruginosa Quorum Sensing.

Degree: PhD, 2017, Oregon State University

URL: http://hdl.handle.net/1957/61582

► Cell-cell communication in bacteria is understood to facilitate the coordination of population-wide cooperative behavior in the form of concerted gene expression. The opportunistic pathogen Pseudomonas… (more)

▼ Cell-cell communication in bacteria is understood to facilitate the coordination of population-wide cooperative behavior in the form of concerted gene expression. The opportunistic pathogen Pseudomonas aeruginosa uses such a communication mechanism to regulate a large group of genes important to virulence strategies in this bacterium. This general mechanism of communication is termed quorum sensing (QS) and restricts activation of target genes to high cell density when cooperation is beneficial. QS in P. aeruginosa, like many Gram-negative Proteobacteria, is mediated through the synthesis of diffusible N-acyl-homoserine lactone (AHL) signals by LuxI-type synthases, and recognition by LuxR-type receptors that function as transcriptional regulators. P. aeruginosa harbors two complete AHL QS synthase/receptor pairs termed LasI/R and RhlI/R. Here we use P. aeruginosa QS as a model system to investigate mechanisms that help maintain cooperative, QS-dependent secretion in the face of non-cooperating cheater mutants, and that define the cell density threshold that triggers the activation of QS target gene expression. We begin with analysis of an in vitro evolution system in which P. aeruginosa must express QS-controlled extracellular proteases in order to grow. In this system, QS-deficient cheater mutants evolve over time. They take advantage of protease production by the QS-proficient wild-type. Curiously, QS-deficient cheaters only reach a frequency of about 25% during the duration of the experiment. They do not enrich to levels that would cause a collapse of the population, generally referred to as a “tragedy of the commons”. Genomic sequence analysis revealed a previously unknown mutation in this system in the transcriptional regulator PsdR. Mutations in the gene coding for PsdR derepress growth rate limiting nutrient uptake and metabolism, a non-social adaptation. Combining mutational analysis with phenotypic assays and measurements of relative fitness, we show that rapid fixation of PsdR mutation in evolving populations serves to preserve cooperation and prevent a tragedy of the commons. Next, we focus on the mechanisms that determine the threshold of QS induction in P. aeruginosa. We constructed a set of isogenic mutant strains deficient in one, two, or three anti-activator proteins that serve to delay QS activation: QteE, QscR, and QslA. While these anti-activator proteins are understood to bind LasR and RhlR QS receptors, it is yet unclear why multiple anti-activators are needed, and how they work in concert to achieve the QS threshold. Using phenotypic assays, QS gene activation kinetics, and transcriptomic profiling, we found additive effects in the deletion of multiple anti-activator genes with largely overlapping sets of anti-activator-affected genes. Progressive deletion of anti-activators advances the induction threshold and increases expression levels. Our results suggest some anti-activators may even co-associate with R-proteins in exerting their effect. Together, these studies contribute new… Advisors/Committee Members: Schuster, Martin (advisor), Rockey, Dan (committee member).

Subjects/Keywords: quorum sensing

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Asfahl, K. (2017). Social Evolution and Regulatory Architecture of Pseudomonas aeruginosa Quorum Sensing. (Doctoral Dissertation). Oregon State University. Retrieved from http://hdl.handle.net/1957/61582

Chicago Manual of Style (16^th Edition):

Asfahl, Kyle. “Social Evolution and Regulatory Architecture of Pseudomonas aeruginosa Quorum Sensing.” 2017. Doctoral Dissertation, Oregon State University. Accessed March 01, 2021. http://hdl.handle.net/1957/61582.

MLA Handbook (7^th Edition):

Asfahl, Kyle. “Social Evolution and Regulatory Architecture of Pseudomonas aeruginosa Quorum Sensing.” 2017. Web. 01 Mar 2021.

Vancouver:

Asfahl K. Social Evolution and Regulatory Architecture of Pseudomonas aeruginosa Quorum Sensing. [Internet] [Doctoral dissertation]. Oregon State University; 2017. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/1957/61582.

Council of Science Editors:

Asfahl K. Social Evolution and Regulatory Architecture of Pseudomonas aeruginosa Quorum Sensing. [Doctoral Dissertation]. Oregon State University; 2017. Available from: http://hdl.handle.net/1957/61582

University of Otago

5. Wilson, Charlotte Mary. Lactobacillus dialogues: the impact of cell signalling on gene expression and ecological behaviour of a gut commensal .

Degree: 2011, University of Otago

URL: http://hdl.handle.net/10523/1754

► Quorum-sensing is a system where genes are regulated in response to changing cell density by the synthesis, release and detection of a signalling molecule to… (more)

▼ Quorum-sensing is a system where genes are regulated in response to changing cell density by the synthesis, release and detection of a signalling molecule to facilitate the coordination of group behaviour such as in the development of a biofilm. Studies in Vibrio, Salmonella and Escherichia identified the autoinducer-2 (AI-2) signalling molecule produced by LuxS, an enzyme widely distributed among bacterial species. The extensive taxonomic distribution of luxS suggested a universal signalling role for AI-2 with potential for interspecies microbial communication. The identification of loss of quorum-sensing phenotypes when luxS is mutated is complicated however by the dual role of LuxS in both the production of AI-2 and catalysis of a reaction in the activated methyl cycle (AMC). Previously a luxS mutant strain of Lactobacillus reuteri 100-23, an autochthonous inhabitant of the mouse gastrointestinal (GI) tract, was developed and found to have altered biofilm formation, lower cellular ATP and a reduced ability to compete with a closely related species in the GI tract of mice. It was hypothesised that loss of quorum-sensing ability affected the phenotype of L. reuteri 100-23. Cells of wild type and luxS mutant L. reuteri 100-23 were harvested from log phase and stationary growth phases, when extracellular amounts of AI-2 were highest and near baseline, respectively. Transcriptome analysis, using a microarray representing the genome of strain 100-23, identified altered gene regulation in the metabolic pathways of methionine biosynthesis, cysteine biosynthesis, and pyrimidine biosynthesis when luxS was mutated. Two prophage regions were down-regulated in the mutant relative to the wild type and circularised phage DNA could be detected in the wild type. The regulation of two genes encoding proteins with LPXTG motifs was affected by luxS mutation during growth in laboratory culture. The expression pattern of one of these genes was similarly affected when the mutant formed in vitro biofilms in a bioreactor and during colonisation of the mouse stomach. Stress response genes were induced in all conditions analysed when luxS was mutated. The metabolite profile measured by GC-MS supported the cellular stress response induced by luxS mutation, and an accumulation of amino acids in the mutant relative to the wild type suggested a redirection of metabolic pathways to compensate for loss of LuxS. Further studies investigated important colonisation features of L. reuteri 100-23 by transcriptome comparison of L. reuteri 100-23 harvested from the mouse stomach to L. reuteri 100-23 harvested from broth culture. Genes involved in the acid tolerance response including glutamate decarboxylase and the urease enzyme were substantially up-regulated during gut colonisation. The urease enzyme was functional and a knockout of the main subunit of the enzyme, UreC, resulted in a strain unable to use urea and with a reduced tolerance to acid. This strain was severely compromised during colonisation of the mouse and constituted less than 1%… Advisors/Committee Members: Tannock, Gerald (advisor).

Subjects/Keywords: Lactobacillus; Quorum sensing

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Wilson, C. M. (2011). Lactobacillus dialogues: the impact of cell signalling on gene expression and ecological behaviour of a gut commensal . (Doctoral Dissertation). University of Otago. Retrieved from http://hdl.handle.net/10523/1754

Chicago Manual of Style (16^th Edition):

Wilson, Charlotte Mary. “Lactobacillus dialogues: the impact of cell signalling on gene expression and ecological behaviour of a gut commensal .” 2011. Doctoral Dissertation, University of Otago. Accessed March 01, 2021. http://hdl.handle.net/10523/1754.

MLA Handbook (7^th Edition):

Wilson, Charlotte Mary. “Lactobacillus dialogues: the impact of cell signalling on gene expression and ecological behaviour of a gut commensal .” 2011. Web. 01 Mar 2021.

Vancouver:

Wilson CM. Lactobacillus dialogues: the impact of cell signalling on gene expression and ecological behaviour of a gut commensal . [Internet] [Doctoral dissertation]. University of Otago; 2011. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/10523/1754.

Council of Science Editors:

Wilson CM. Lactobacillus dialogues: the impact of cell signalling on gene expression and ecological behaviour of a gut commensal . [Doctoral Dissertation]. University of Otago; 2011. Available from: http://hdl.handle.net/10523/1754

Texas State University – San Marcos

6. Hidalgo Romano, Benjamin. Indole Inhibition of AHL-Mediated Quorum Signaling is Widespread in Gram-Negative.

Degree: MS, Biology, 2014, Texas State University – San Marcos

URL: https://digital.library.txstate.edu/handle/10877/5808

► The luxI/R quorum-sensing system and associated N-acylated homoserine lactone (AHL) signals is a widespread mechanism of gene regulation in gram negative bacteria. Quorum inhibition can… (more)

Subjects/Keywords: Quorum sensing; Indole

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Hidalgo Romano, B. (2014). Indole Inhibition of AHL-Mediated Quorum Signaling is Widespread in Gram-Negative. (Masters Thesis). Texas State University – San Marcos. Retrieved from https://digital.library.txstate.edu/handle/10877/5808

Chicago Manual of Style (16^th Edition):

Hidalgo Romano, Benjamin. “Indole Inhibition of AHL-Mediated Quorum Signaling is Widespread in Gram-Negative.” 2014. Masters Thesis, Texas State University – San Marcos. Accessed March 01, 2021. https://digital.library.txstate.edu/handle/10877/5808.

MLA Handbook (7^th Edition):

Hidalgo Romano, Benjamin. “Indole Inhibition of AHL-Mediated Quorum Signaling is Widespread in Gram-Negative.” 2014. Web. 01 Mar 2021.

Vancouver:

Hidalgo Romano B. Indole Inhibition of AHL-Mediated Quorum Signaling is Widespread in Gram-Negative. [Internet] [Masters thesis]. Texas State University – San Marcos; 2014. [cited 2021 Mar 01]. Available from: https://digital.library.txstate.edu/handle/10877/5808.

Council of Science Editors:

Hidalgo Romano B. Indole Inhibition of AHL-Mediated Quorum Signaling is Widespread in Gram-Negative. [Masters Thesis]. Texas State University – San Marcos; 2014. Available from: https://digital.library.txstate.edu/handle/10877/5808

Oregon State University

7. Huie, Jessica L. Evolution of a streamlined cooperator in Pseudomonas aeruginosa quorum sensing.

Degree: MS, Microbiology, 2011, Oregon State University

URL: http://hdl.handle.net/1957/23591

► Social behavior leading to the production of common goods is prone to exploitation. One such behavior in Pseudomonas aeruginosa is quorum sensing (QS), by which… (more)

Subjects/Keywords: Social evolution; Quorum sensing (Microbiology)

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Huie, J. L. (2011). Evolution of a streamlined cooperator in Pseudomonas aeruginosa quorum sensing. (Masters Thesis). Oregon State University. Retrieved from http://hdl.handle.net/1957/23591

Chicago Manual of Style (16^th Edition):

Huie, Jessica L. “Evolution of a streamlined cooperator in Pseudomonas aeruginosa quorum sensing.” 2011. Masters Thesis, Oregon State University. Accessed March 01, 2021. http://hdl.handle.net/1957/23591.

MLA Handbook (7^th Edition):

Huie, Jessica L. “Evolution of a streamlined cooperator in Pseudomonas aeruginosa quorum sensing.” 2011. Web. 01 Mar 2021.

Vancouver:

Huie JL. Evolution of a streamlined cooperator in Pseudomonas aeruginosa quorum sensing. [Internet] [Masters thesis]. Oregon State University; 2011. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/1957/23591.

Council of Science Editors:

Huie JL. Evolution of a streamlined cooperator in Pseudomonas aeruginosa quorum sensing. [Masters Thesis]. Oregon State University; 2011. Available from: http://hdl.handle.net/1957/23591

Cornell University

8. Pinto, Uelinton. Quorum Sensing, Entry Exclusion And Replication Of The Ti Plasmid Of Agrobacterium Tumefaciens.

Degree: PhD, Microbiology, 2011, Cornell University

URL: http://hdl.handle.net/1813/33639

► Agrobacterium tumefaciens contains the tumor inducing (Ti) plasmid that stimulates tumor formation in wounded plant tissues. Replication, partitioning, conjugation and entry exclusion of this plasmid… (more)

▼ Agrobacterium tumefaciens contains the tumor inducing (Ti) plasmid that stimulates tumor formation in wounded plant tissues. Replication, partitioning, conjugation and entry exclusion of this plasmid are under strict cellular control, and are regulated by quorum sensing. In Gram-negative bacteria, the quorum sensing circuitry is usually mediated by small diffusible signal molecules produced by LuxI homologues and signal receptor proteins homologous to LuxR. In A. tumefaciens, TraR is the LuxR-type quorum sensing receptor that is activated by the signal molecule N-3-oxooctanoyl-L-homoserine lactone (OOHL). We studied the TraR dimerization properties, the involvement of quorum sensing on entry exclusion, and replication of the Ti-plasmid. First we wanted to know whether TraR dimerization is required for protein stability. It is well established that transcriptional activation by TraR depends on the presence of the signal molecule OOHL, which is required for protein folding, protease resistance, and dimerization. My results suggest that dimerization of TraR enhances resistance to cellular proteases, further contributing to protein stability and function. In a second study it is shown that the Ti plasmid encodes for robust entry exclusion, which prevents conjugation between donor cells containing Ti plasmids. Entry exclusion of the Ti plasmid is tightly regulated by TraR and mediated by TrbK and TrbJ proteins. In the absence of OOHL, the Trb proteins are not expressed, and Agrobacterium cells harboring a Ti plasmid are efficient recipients. However, in the presence of OOHL, cells block the entry of Ti plasmids and instead become efficient conjugal donors. Finally, the replication properties of the Ti plasmid were analyzed and I show that the origin of replication resides within the repC gene. I also show that RepC protein binds to a site located at an AT-rich region within its own gene. The DNA binding domain of RepC was localized to a region at the N-terminus of the protein. RepC functions in cis to initiate replication, and this mode of action may have important implications for plasmid compatibility. Advisors/Committee Members: Winans, Stephen C (chair), Helmann, John D (committee member), Alani, Eric E (committee member).

Subjects/Keywords: quorum sensing; entry exclusion; replication

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Pinto, U. (2011). Quorum Sensing, Entry Exclusion And Replication Of The Ti Plasmid Of Agrobacterium Tumefaciens. (Doctoral Dissertation). Cornell University. Retrieved from http://hdl.handle.net/1813/33639

Chicago Manual of Style (16^th Edition):

Pinto, Uelinton. “Quorum Sensing, Entry Exclusion And Replication Of The Ti Plasmid Of Agrobacterium Tumefaciens.” 2011. Doctoral Dissertation, Cornell University. Accessed March 01, 2021. http://hdl.handle.net/1813/33639.

MLA Handbook (7^th Edition):

Pinto, Uelinton. “Quorum Sensing, Entry Exclusion And Replication Of The Ti Plasmid Of Agrobacterium Tumefaciens.” 2011. Web. 01 Mar 2021.

Vancouver:

Pinto U. Quorum Sensing, Entry Exclusion And Replication Of The Ti Plasmid Of Agrobacterium Tumefaciens. [Internet] [Doctoral dissertation]. Cornell University; 2011. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/1813/33639.

Council of Science Editors:

Pinto U. Quorum Sensing, Entry Exclusion And Replication Of The Ti Plasmid Of Agrobacterium Tumefaciens. [Doctoral Dissertation]. Cornell University; 2011. Available from: http://hdl.handle.net/1813/33639

Royal Holloway, University of London

9. Zhou, Liqin. The evolutionary ecology of the PlcR-PapR quorum sensing system in Bacillus thuringiensis.

Degree: PhD, 2014, Royal Holloway, University of London

URL: https://pure.royalholloway.ac.uk/portal/en/publications/the-evolutionary-ecology-of-the-plcrpapr-quorum-sensing-system-in-bacillus-thuringiensis(5276e721-cc0d-4b69-b05b-c162eee45dc0).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.792253

► Bacteria can engage in multicellular behaviour via a process called quorum sensing (QS), whereby bacteria monitor population density through the secretion of small, diffusible signal… (more)

▼ Bacteria can engage in multicellular behaviour via a process called quorum sensing (QS), whereby bacteria monitor population density through the secretion of small, diffusible signal molecules. However, the evolutionary forces that maintain QS have rarely been investigated in naturally co-evolved host-pathogen systems. This thesis investigated the evolutionary ecology of the PlcR-PapR QS system in Bacillus thuringiensis, in which the PlcR regulon controls the production of various extracellular proteins, often involved in virulence, in response to an autoinduced heptapeptide signal PapR. The thesis tested the hypothesis that both signal production and PlcR regulated gene expression are social traits, and measured the invasion of isogenic mutants at varying pathogen doses and mutant frequencies. Productivity in host and infection success was positively correlated with the abundance of wild type in inocula. However, mutants could not outcompete wild type bacteria in vivo. Experiments with homogenized insects indicate that mutants can outcompete wild type bacteria in homogeneous environment. Microscopic observation of insect sections with fluorescent QS cells showed that, in the midgut, bacteria population was founded on isolated patches of 1 to 3 individual cells 24 hours post infection. However, a mixed population consisted of wild type and mutants was evident 48 hours post infection. The results suggested that spatial heterogeneity and population bottleneck imposed by the midgut barriers limited invasion of QS mutants. A polymorphism comprising four distinct communication groups (pherotypes) of the PlcR-PapR QS system was found in the B. cereus group. Strains from the same pherotype exchange information efficiently while strains from different pherotypes communicate far less effectively. Recent theory has suggested that social interactions may account for the within-species diversity of QS systems. Pairwise competition between pherotypes of the studied QS system in vivo revealed fitness to be positively frequency dependent. However, when challenged with a competitive gut bacterium, Enterobacter cloacae, each pherotype exhibited different fitness benefits when competing with other pherotypes in the presence of competitors. The results suggested that environmental dependent fitness has the potential to maintain a stable polymorphism. The results of this thesis confirm that clinical interventions to prevent QS might be beneficial, as diverse virulence factors are often regulated by QS. If QS regulated virulence factors are required for an essential part of infection, inhibiting these behaviours can be helpful.

Subjects/Keywords: Quorum sensing; evolutionary ecology

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APA (6^th Edition):

Zhou, L. (2014). The evolutionary ecology of the PlcR-PapR quorum sensing system in Bacillus thuringiensis. (Doctoral Dissertation). Royal Holloway, University of London. Retrieved from https://pure.royalholloway.ac.uk/portal/en/publications/the-evolutionary-ecology-of-the-plcrpapr-quorum-sensing-system-in-bacillus-thuringiensis(5276e721-cc0d-4b69-b05b-c162eee45dc0).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.792253

Chicago Manual of Style (16^th Edition):

Zhou, Liqin. “The evolutionary ecology of the PlcR-PapR quorum sensing system in Bacillus thuringiensis.” 2014. Doctoral Dissertation, Royal Holloway, University of London. Accessed March 01, 2021. https://pure.royalholloway.ac.uk/portal/en/publications/the-evolutionary-ecology-of-the-plcrpapr-quorum-sensing-system-in-bacillus-thuringiensis(5276e721-cc0d-4b69-b05b-c162eee45dc0).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.792253.

MLA Handbook (7^th Edition):

Zhou, Liqin. “The evolutionary ecology of the PlcR-PapR quorum sensing system in Bacillus thuringiensis.” 2014. Web. 01 Mar 2021.

Vancouver:

Zhou L. The evolutionary ecology of the PlcR-PapR quorum sensing system in Bacillus thuringiensis. [Internet] [Doctoral dissertation]. Royal Holloway, University of London; 2014. [cited 2021 Mar 01]. Available from: https://pure.royalholloway.ac.uk/portal/en/publications/the-evolutionary-ecology-of-the-plcrpapr-quorum-sensing-system-in-bacillus-thuringiensis(5276e721-cc0d-4b69-b05b-c162eee45dc0).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.792253.

Council of Science Editors:

Zhou L. The evolutionary ecology of the PlcR-PapR quorum sensing system in Bacillus thuringiensis. [Doctoral Dissertation]. Royal Holloway, University of London; 2014. Available from: https://pure.royalholloway.ac.uk/portal/en/publications/the-evolutionary-ecology-of-the-plcrpapr-quorum-sensing-system-in-bacillus-thuringiensis(5276e721-cc0d-4b69-b05b-c162eee45dc0).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.792253

University of Texas Southwestern Medical Center

10. Zhang, Fang. A Synthetic Quorum Sensing System Reveals Interaction Between Extracellular Matrix and Quorum Sensing Molecules.

Degree: 2015, University of Texas Southwestern Medical Center

URL: http://hdl.handle.net/2152.5/4453

► Even though bacteria are unicellular organisms, they commonly reside in structured communities known as biofilms. One of the defining characteristics of biofilms is the presence… (more)

Subjects/Keywords: Bacillus subtilis; Biofilms; Quorum Sensing

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APA (6^th Edition):

Zhang, F. (2015). A Synthetic Quorum Sensing System Reveals Interaction Between Extracellular Matrix and Quorum Sensing Molecules. (Thesis). University of Texas Southwestern Medical Center. Retrieved from http://hdl.handle.net/2152.5/4453

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Zhang, Fang. “A Synthetic Quorum Sensing System Reveals Interaction Between Extracellular Matrix and Quorum Sensing Molecules.” 2015. Thesis, University of Texas Southwestern Medical Center. Accessed March 01, 2021. http://hdl.handle.net/2152.5/4453.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Zhang, Fang. “A Synthetic Quorum Sensing System Reveals Interaction Between Extracellular Matrix and Quorum Sensing Molecules.” 2015. Web. 01 Mar 2021.

Vancouver:

Zhang F. A Synthetic Quorum Sensing System Reveals Interaction Between Extracellular Matrix and Quorum Sensing Molecules. [Internet] [Thesis]. University of Texas Southwestern Medical Center; 2015. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/2152.5/4453.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Zhang F. A Synthetic Quorum Sensing System Reveals Interaction Between Extracellular Matrix and Quorum Sensing Molecules. [Thesis]. University of Texas Southwestern Medical Center; 2015. Available from: http://hdl.handle.net/2152.5/4453

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Manitoba

11. Hernandez-Doria, Juan David. Biofilm formation in Escherichia coli and regulatory gene expression via quorum sensing systems.

Degree: Animal Science, 2011, University of Manitoba

URL: http://hdl.handle.net/1993/4995

► Bacterial biofilms are microbial communities that adhere to abiotic or biotic surfaces. Biofilm formation (BF) studies in E. coli have primarily concentrated on uropathogenic E.… (more)

▼ Bacterial biofilms are microbial communities that adhere to abiotic or biotic surfaces. Biofilm formation (BF) studies in E. coli have primarily concentrated on uropathogenic E. coli, commensal K-12 and enterohemorrhagic E. coli O157:H7. This does not include the vast diversity of environmental strains. Quorum sensing (QS) is a means by which bacteria can communication with one another through the production of signalling molecules. The autoinducer 2 (AI-2) QS system is utilized by E. coli and several other bacterial species for controlling gene expression. The role of AI-2 in E. coli BF varies among different strains. For example in the K-12 strain, AI-2 regulates motility, and thus can affect BF; whereas in O157:H7, AI-2 has a more metabolic role. Interestingly, in strain O157:H7, motility is controlled by a newly discovered QS system regulated by the autoinducer 3 (AI-3) molecule plus the mammalian hormones epinephrine (Epi) and norepinephrine (Ne). The purpose of this study was to investigate the ability of a panel of environmental E. coli strains to form biofilms and to determine whether QS is involved in the process. A new pathotype of E. coli, adherent invasive E. coli (AIEC) which is associated with Crohn’s disease was included in the investigation. Study 1 sought to determine whether BF under different media conditions correlated with the presence of genes involved in the AI-2 QS system or adhesin factors. Media conditions were the principal variable affecting the BF. Study 2 examined the role of the AI-2 and AI-3/Epi/Ne QS systems in motility and BF by the AIEC strain. It was discovered that the AI-3 system is involved in motility; whereas the AI-2 system had no effect on BF or motility. In Study 3, microarray gene expression analysis and invasion assays were performed using qseB or qseC mutants. These genes encode the two-component regulatory system recognizing AI-3 or its cognate, epinephrine. Our findings indicate that alternative pathways likely account for the BF observed for the qseB and qseC mutants. It was concluded that the AI-3/Epi/Ne QS system partially controls AIEC motility and the invasion of epithelial cells. Advisors/Committee Members: Krause, Denis (Animal Science) (supervisor), DeKievit, Teresa (Microbiology) Ominski, Kim (Animal Science) Plaizier, Kees J.C (Animal Science) Gray-Owen, Scott D. (Molecular Genetics, University of Toronto) (examiningcommittee).

Subjects/Keywords: biofilm; quorum sensing; E. coli

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APA (6^th Edition):

Hernandez-Doria, J. D. (2011). Biofilm formation in Escherichia coli and regulatory gene expression via quorum sensing systems. (Thesis). University of Manitoba. Retrieved from http://hdl.handle.net/1993/4995

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Hernandez-Doria, Juan David. “Biofilm formation in Escherichia coli and regulatory gene expression via quorum sensing systems.” 2011. Thesis, University of Manitoba. Accessed March 01, 2021. http://hdl.handle.net/1993/4995.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Hernandez-Doria, Juan David. “Biofilm formation in Escherichia coli and regulatory gene expression via quorum sensing systems.” 2011. Web. 01 Mar 2021.

Vancouver:

Hernandez-Doria JD. Biofilm formation in Escherichia coli and regulatory gene expression via quorum sensing systems. [Internet] [Thesis]. University of Manitoba; 2011. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/1993/4995.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Hernandez-Doria JD. Biofilm formation in Escherichia coli and regulatory gene expression via quorum sensing systems. [Thesis]. University of Manitoba; 2011. Available from: http://hdl.handle.net/1993/4995

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Harvard University

12. Kim, Suhyun. Quorum sensing can be repurposed to promote information transfer between bacteria in the mammalian gut.

Degree: PhD, 2019, Harvard University

URL: http://nrs.harvard.edu/urn-3:HUL.InstRepos:42029725

►

The gut microbiome is intricately involved with establishing and maintaining the health of the host. Engineering of gut microbes aims to add new functions and… (more)

Subjects/Keywords: Microbiome engineering; quorum sensing

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APA (6^th Edition):

Kim, S. (2019). Quorum sensing can be repurposed to promote information transfer between bacteria in the mammalian gut. (Doctoral Dissertation). Harvard University. Retrieved from http://nrs.harvard.edu/urn-3:HUL.InstRepos:42029725

Chicago Manual of Style (16^th Edition):

Kim, Suhyun. “Quorum sensing can be repurposed to promote information transfer between bacteria in the mammalian gut.” 2019. Doctoral Dissertation, Harvard University. Accessed March 01, 2021. http://nrs.harvard.edu/urn-3:HUL.InstRepos:42029725.

MLA Handbook (7^th Edition):

Kim, Suhyun. “Quorum sensing can be repurposed to promote information transfer between bacteria in the mammalian gut.” 2019. Web. 01 Mar 2021.

Vancouver:

Kim S. Quorum sensing can be repurposed to promote information transfer between bacteria in the mammalian gut. [Internet] [Doctoral dissertation]. Harvard University; 2019. [cited 2021 Mar 01]. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:42029725.

Council of Science Editors:

Kim S. Quorum sensing can be repurposed to promote information transfer between bacteria in the mammalian gut. [Doctoral Dissertation]. Harvard University; 2019. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:42029725

Princeton University

13. Silpe, Justin Ezekiel. A Quorum-Sensing Autoinducer that Controls Bacterial Group Behaviors and a Phage Lysis-Lysogeny Decision .

Degree: PhD, 2020, Princeton University

URL: http://arks.princeton.edu/ark:/88435/dsp01hx11xj16g

► Bacterial collective behaviors are regulated by the cell-cell communication process called quorum sensing. Quorum sensing relies on the production, release, and group-wide detection of extracellular… (more)

▼ Bacterial collective behaviors are regulated by the cell-cell communication process called quorum sensing. Quorum sensing relies on the production, release, and group-wide detection of extracellular signal molecules called autoinducers. Quorum sensing is well established in the Vibrio genus, for which Vibrio cholerae is a particularly compelling model as it causes the globally-important human disease cholera and quorum sensing controls pathogenicity. This thesis describes the discovery of a new quorum-sensing system in V. cholerae and other Vibrios consisting of a receptor-transcription factor called VqmA and an autoinducer called DPO. Upon binding DPO, VqmA activates transcription of a gene encoding a small RNA (sRNA), called VqmR, and VqmR represses genes involved in biofilm formation and virulence factor production. Repression of these traits is crucial for V. cholerae to disperse from its human host and disseminate to new victims. The second part of this thesis describes phage-encoded quorum-sensing-like systems. One such system is employed by the phage VP882, which infects and kills Vibrios including V. cholerae. VP882 encodes a VqmA homolog, which I named VqmAPhage. Analogous to bacterial VqmA, VqmAPhage binds to DPO produced by its host bacterium. However, unlike bacterial quorum sensing, which benefits the bacterial population, activation of the VP882 phage-based quorum-sensing system benefits the phage at the expense of the host bacteria by promoting the spread of the phage infection and bacterial-cell killing. Specifically, in V. cholerae infected with the VP882 quorum-sensing phage, DPO, via VqmAPhage, activates expression of a gene encoding an antirepressor called Qtip, which inactivates the phage master regulator, leading to phage replication and lytic development. Additional chapters of this thesis are devoted to characterizing the mechanism by which the VP882 quorum-sensing pathway functions with a focus on Qtip and the discovery that other phage-based quorum-sensing-like pathways exist. Finally, I used genetic engineering to reprogram phages to be responsive to user-defined cues. These recombinant phages have the potential to be developed into therapies for environmental, industrial, and medical applications. Advisors/Committee Members: Bassler, Bonnie L (advisor).

Subjects/Keywords: Autoinducer; Phage; Quorum Sensing

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APA (6^th Edition):

Silpe, J. E. (2020). A Quorum-Sensing Autoinducer that Controls Bacterial Group Behaviors and a Phage Lysis-Lysogeny Decision . (Doctoral Dissertation). Princeton University. Retrieved from http://arks.princeton.edu/ark:/88435/dsp01hx11xj16g

Chicago Manual of Style (16^th Edition):

Silpe, Justin Ezekiel. “A Quorum-Sensing Autoinducer that Controls Bacterial Group Behaviors and a Phage Lysis-Lysogeny Decision .” 2020. Doctoral Dissertation, Princeton University. Accessed March 01, 2021. http://arks.princeton.edu/ark:/88435/dsp01hx11xj16g.

MLA Handbook (7^th Edition):

Silpe, Justin Ezekiel. “A Quorum-Sensing Autoinducer that Controls Bacterial Group Behaviors and a Phage Lysis-Lysogeny Decision .” 2020. Web. 01 Mar 2021.

Vancouver:

Silpe JE. A Quorum-Sensing Autoinducer that Controls Bacterial Group Behaviors and a Phage Lysis-Lysogeny Decision . [Internet] [Doctoral dissertation]. Princeton University; 2020. [cited 2021 Mar 01]. Available from: http://arks.princeton.edu/ark:/88435/dsp01hx11xj16g.

Council of Science Editors:

Silpe JE. A Quorum-Sensing Autoinducer that Controls Bacterial Group Behaviors and a Phage Lysis-Lysogeny Decision . [Doctoral Dissertation]. Princeton University; 2020. Available from: http://arks.princeton.edu/ark:/88435/dsp01hx11xj16g

University of Georgia

14. Bose, Jeffrey L. ArcA and FNR regulate bioluminescence in the light-organ symbiont Vibrio fischeri.

Degree: 2014, University of Georgia

URL: http://hdl.handle.net/10724/24076

► Despite years of intense study of bioluminescence in Vibrio fischeri, much remains unanswered regarding its benefit to the cell and the environmental factors affecting its… (more)

▼ Despite years of intense study of bioluminescence in Vibrio fischeri, much remains unanswered regarding its benefit to the cell and the environmental factors affecting its regulation. In this dissertation, I show that bioluminescence leads to a growth rate reduction under some culture conditions, yet it contributes to this bacterium’s ability to colonize one of its symbiotic hosts, the squid Euprymna scolopes. Based on the reaction catalyzed by the light-producing enzyme luciferase, two conflicting hypotheses have been suggested to explain the benefit that bioluminescence provides symbiotic V. fischeri. One proposal is that luminescence provides an advantage by consuming oxygen and thus serving as an antioxidant to protect the cell from toxic oxygen radicals. Conversely, a second proposal suggests that by consuming excess reductant luminescence acts as an electron sink. I examined the regulation of luminescence to help distinguish between these two hypotheses, assuming that luminescence would be maximally expressed when it is most beneficial. I examined luminescence of mutants lacking the redox-responsive and oxygen-sensitive regulators ArcA and FNR, respectively. This was performed in the well-studied and naturally visibly luminescent strain MJ1 as well as in the relatively dim strain ES114, which is a natural symbiont of E. scolopes. ArcA is most active under reducing conditions, and I found that it represses luminescence in both strains due to a conserved ArcA binding site in the PluxI promoter, which controls the expression of the proteins necessary for light production. Similar to ArcA, FNR is active under anaerobic conditions and represses luminescence in MJ1, although no such effect is apparent in ES114. These results demonstrate that luminescence is repressed under reduced conditions and therefore my data is consistent with the antioxidant model explaining the benefits of luminescence, but are inconsistent with the electron sink model. This work is the first to use defined mutants in V. fischeri to elucidate a mechanism by which specific environmental factors alter the regulation of luminescence.

Subjects/Keywords: Photobacterium; Symbiosis; Quorum sensing; Lux

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APA (6^th Edition):

Bose, J. L. (2014). ArcA and FNR regulate bioluminescence in the light-organ symbiont Vibrio fischeri. (Thesis). University of Georgia. Retrieved from http://hdl.handle.net/10724/24076

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Bose, Jeffrey L. “ArcA and FNR regulate bioluminescence in the light-organ symbiont Vibrio fischeri.” 2014. Thesis, University of Georgia. Accessed March 01, 2021. http://hdl.handle.net/10724/24076.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Bose, Jeffrey L. “ArcA and FNR regulate bioluminescence in the light-organ symbiont Vibrio fischeri.” 2014. Web. 01 Mar 2021.

Vancouver:

Bose JL. ArcA and FNR regulate bioluminescence in the light-organ symbiont Vibrio fischeri. [Internet] [Thesis]. University of Georgia; 2014. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/10724/24076.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Bose JL. ArcA and FNR regulate bioluminescence in the light-organ symbiont Vibrio fischeri. [Thesis]. University of Georgia; 2014. Available from: http://hdl.handle.net/10724/24076

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Georgia

15. Kimbrough, John Henry. Control of the AinS/AinR pheromone-signaling system in Vibrio fischeri ES114.

Degree: 2016, University of Georgia

URL: http://hdl.handle.net/10724/36215

► Many bacteria use small pheromone molecules to regulate group behaviors. The marine bacterium Vibrio fischeri uses two distinct but integrated acyl-homoserine lactone (AHL) pheromone-signaling systems… (more)

▼ Many bacteria use small pheromone molecules to regulate group behaviors. The marine bacterium Vibrio fischeri uses two distinct but integrated acyl-homoserine lactone (AHL) pheromone-signaling systems (PSS) to regulate behaviors during colonization of its host squid Euprymna scolopes, including induction of symbiotic bioluminescence. One V. fischeri PSS, consisting of LuxI and LuxR, was the first AHL-based system discovered and remains the archetype for similar AHL signaling found broadly throughout the phylum Proteobacteria. However, LuxI/LuxR itself is regulated along with several other genes by a second structurally unrelated AHL-based PSS that is specific to the Vibrionaceae family. This PSS, which is underpinned by AinS and AinR, is responsible for regulating behaviors associated with initiating the symbiosis with E. scolopes, and it represents part of a conserved “core” PSS within the Vibrionaceae. Despite its importance in V. fischeri, many aspects of AinS function are not well-understood. In this dissertation, I describe aspects of AinS regulation, AinR’s role in signal perception, and previously unknown mechanisms of cross-talk between AinS/AinR and LuxI/LuxR. I provide evidence that AinR has high sensitivity and low selectivity for a range of AHL pheromones. Additionally, I show that the presence of ainR in cis affects regulation of ainS, which appears related to a large inverted repeat in ainR. I also describe how spontaneous mutations affecting a PSS regulator downstream of AinS/AinR, LuxO, result in decreased ainSR expression and increased survivability when V. fischeri is grown in static culture. Finally, I explore additional levels of cross-talk between the Ain and Lux PSSs. Together, these results show how previously unknown connections between AinS/AinR, LuxI/LuxR, and the core Vibrio PSS finely tune regulation of symbiotic factors in response to changing environmental conditions. This work extends our knowledge of bacterial communication and its role in host-microbe and microbe-microbe interactions.

Subjects/Keywords: Aliivibrio; Photobacterium; quorum sensing; ain

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Kimbrough, J. H. (2016). Control of the AinS/AinR pheromone-signaling system in Vibrio fischeri ES114. (Thesis). University of Georgia. Retrieved from http://hdl.handle.net/10724/36215

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Kimbrough, John Henry. “Control of the AinS/AinR pheromone-signaling system in Vibrio fischeri ES114.” 2016. Thesis, University of Georgia. Accessed March 01, 2021. http://hdl.handle.net/10724/36215.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Kimbrough, John Henry. “Control of the AinS/AinR pheromone-signaling system in Vibrio fischeri ES114.” 2016. Web. 01 Mar 2021.

Vancouver:

Kimbrough JH. Control of the AinS/AinR pheromone-signaling system in Vibrio fischeri ES114. [Internet] [Thesis]. University of Georgia; 2016. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/10724/36215.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Kimbrough JH. Control of the AinS/AinR pheromone-signaling system in Vibrio fischeri ES114. [Thesis]. University of Georgia; 2016. Available from: http://hdl.handle.net/10724/36215

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Guelph

16. Tran, Lucy. Mathematical Modeling of Quorum Sensing Inhibitors as Adjuvantsto Antimicrobials in a Chemostat Environment.

Degree: MS, Department of Mathematics and Statistics, 2021, University of Guelph

URL: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/23697

► Many bacterial cells coordinate group behaviour by a mechanism known as QuorumSensing (QS). QS involves the production and secretion of signalling molecules, called au-toinducers. When… (more)

Subjects/Keywords: Chemostat; Mathematical Modelling; Quorum Sensing

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Tran, L. (2021). Mathematical Modeling of Quorum Sensing Inhibitors as Adjuvantsto Antimicrobials in a Chemostat Environment. (Masters Thesis). University of Guelph. Retrieved from https://atrium.lib.uoguelph.ca/xmlui/handle/10214/23697

Chicago Manual of Style (16^th Edition):

Tran, Lucy. “Mathematical Modeling of Quorum Sensing Inhibitors as Adjuvantsto Antimicrobials in a Chemostat Environment.” 2021. Masters Thesis, University of Guelph. Accessed March 01, 2021. https://atrium.lib.uoguelph.ca/xmlui/handle/10214/23697.

MLA Handbook (7^th Edition):

Tran, Lucy. “Mathematical Modeling of Quorum Sensing Inhibitors as Adjuvantsto Antimicrobials in a Chemostat Environment.” 2021. Web. 01 Mar 2021.

Vancouver:

Tran L. Mathematical Modeling of Quorum Sensing Inhibitors as Adjuvantsto Antimicrobials in a Chemostat Environment. [Internet] [Masters thesis]. University of Guelph; 2021. [cited 2021 Mar 01]. Available from: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/23697.

Council of Science Editors:

Tran L. Mathematical Modeling of Quorum Sensing Inhibitors as Adjuvantsto Antimicrobials in a Chemostat Environment. [Masters Thesis]. University of Guelph; 2021. Available from: https://atrium.lib.uoguelph.ca/xmlui/handle/10214/23697

17. Koirala, Bimal. Development of Peptide-Based Probes to Target Quorum Sensing in Streptococcus pneumoniae.

Degree: 2019, University of Nevada – Reno

URL: http://hdl.handle.net/11714/5678

► The microbial world existed from the beginning of the evolution process on Earth. Only after its discovery in the 17th century did much of the… (more)

▼ The microbial world existed from the beginning of the evolution process on Earth. Only after its discovery in the 17th century did much of the unknown facts surrounding this bacterial world start to be elucidated. It took three more centuries to discover that these tiny microorganisms can actually communicate with each other. This mechanism of communication is termed quorum sensing (QS). QS has since been shown to play a crucial role in different phenotypic behaviors like competence, virulence, and biofilm formation, and these bacterial behaviors contribute to survival. In the studies composing this dissertation, we structurally evaluate and modulate the QS mechanism in Streptococcus pneumoniae in order to attenuate its pathogenicity. S. pneumoniae is a commensal bacterium that resides in the nasopharynx of humans and can be deadly if it spreads throughout the body. It can cause conditions ranging from mild respiratory disease to life threating diseases like pneumonia, bacteremia and meningitis. The main problem associated with this pathogen is that it has developed resistance to conventional antibiotic drugs, making it critical to develop alternative avenues to fight this deadly pathogen. Targeting QS could be an alternative approach because it doesn’t involve killing the bacteria, rather it is aimed at “disarming” them. QS in S. pneumoniae centers around a 17-mer signaling peptide molecule known as competence stimulating peptide (CSP). The main aim of my Ph.D. work has been to modulate the QS circuit by interfering with the interaction between the signal (CSP) and the receptor (ComD). We have designed several CSP-mimicking peptide analogs aiming to competitively inhibit the signal-receptor interaction. First, we have conducted thorough structure-activity relationship (SAR) studies of the CSP signal and identified several key residues that are critical for receptor binding, activation, and specificity. We further evaluated the secondary structures of CSPs and their analogs using circular dichroism (CD) to correlate between the structure and function of these peptides. The CD analysis results suggest that an α-helix conformation is required for effective binding to the cognate ComD receptor. Moreover, a double mutant analog, CSP2 E1Ad10, was found to effectively inhibit ComD2-mediated pneumolysin release in vitro and to attenuate pherotype-2 pneumococcus infectivity in a mouse model of acute pneumonia, as well as exhibiting high stability against enzymatic degradation, making this analog a lead scaffold for the design of potential therapeutics. Advisors/Committee Members: Tal-Gan, Yftah (advisor), Bell, Thomas W (committee member), Chalifoux, Wesley A (committee member), AuCoin, David P (committee member), Sumby, Paul (committee member).

Subjects/Keywords: Quorum sensing; Streptococcus pneumoniae

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Koirala, B. (2019). Development of Peptide-Based Probes to Target Quorum Sensing in Streptococcus pneumoniae. (Thesis). University of Nevada – Reno. Retrieved from http://hdl.handle.net/11714/5678

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Koirala, Bimal. “Development of Peptide-Based Probes to Target Quorum Sensing in Streptococcus pneumoniae.” 2019. Thesis, University of Nevada – Reno. Accessed March 01, 2021. http://hdl.handle.net/11714/5678.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Koirala, Bimal. “Development of Peptide-Based Probes to Target Quorum Sensing in Streptococcus pneumoniae.” 2019. Web. 01 Mar 2021.

Vancouver:

Koirala B. Development of Peptide-Based Probes to Target Quorum Sensing in Streptococcus pneumoniae. [Internet] [Thesis]. University of Nevada – Reno; 2019. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/11714/5678.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Koirala B. Development of Peptide-Based Probes to Target Quorum Sensing in Streptococcus pneumoniae. [Thesis]. University of Nevada – Reno; 2019. Available from: http://hdl.handle.net/11714/5678

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Universidade Federal de Viçosa

18. Adriana dos Reis Ponce. Características fenotípicas de Enterobacter cloacae controladas pelo sistema quorum sensing.

Degree: 2007, Universidade Federal de Viçosa

URL: http://www.tede.ufv.br/tedesimplificado/tde_busca/arquivo.php?codArquivo=1147

► Muitas bactérias apresentam um sistema elaborado de comunicação entre células dependente de densidade celular, denominado como quorum sensing, e o conhecimento de fenótipos controlados por… (more)

▼ Muitas bactérias apresentam um sistema elaborado de comunicação entre células dependente de densidade celular, denominado como quorum sensing, e o conhecimento de fenótipos controlados por esse mecanismo pode contribuir para a elucidação de processos importantes na microbiologia de alimentos. O objetivo deste trabalho foi determinar fenótipos regulados por quorum sensing em Enterobacter cloacae 067, isolado de leite cru refrigerado. Foram comparadas características fenotípicas da estirpe selvagem de E. cloacae 067 com uma estirpe transconjugante, que sintetiza a enzima lactonase, responsável pela hidrólise de acil homoserina lactonas (AHLs), moléculas sinal do sistema quorum sensing. Estirpes selvagem e transconjugante de E. cloacae 067 cresceram em temperaturas de 4 C a 43 C, com ótimo entre 36 C e 43 C e a população máxima foi atingida a 30 C. A densidade óptica das culturas da estirpe transconjugante foram maiores (p <0,05) do que a da selvagem, tanto em meios de cultura complexos como em meios minerais, contendo uma única fonte de carbono orgânico. A motilidade por espalhamento não foi verificada nas estirpes testadas e a motilidade por contração não foi alterada no transconjugante. Biofilmes foram formados em superfície de poliestireno e a estirpe E. cloacae 067 selvagem apresentou maior adesão que a estirpe transconjugante, quando cultivada nos meios Luria Bertani (LB), triptona, extrato de levedura e fosfato (TYEP) e meio mínimo de sais (MMS). A adição de cálcio ao meio TYEP reduziu a formação de biofilmes pela estirpe selvagem, mas não na transconjugante. Em superfície de aço inoxidável a adesão da estirpe selvagem foi cerca de um ciclo logarítmico maior do que a transconjugante, por até 48 horas de incubação. Após este período, diferenças entre as estirpes não foram detectadas, tanto na observação microscópica quanto na contagem de células viáveis aderidas. A diferença na adesão de E. cloacae 067 selvagem e transconjugante em poliestireno e em aço inoxidável sugere que o sistema quorum sensing regula a formação de biofilmes nesta estirpe. Atividades das enzimas amilases, celulases, lipases e pectinases não foram verificadas nas estirpes selvagem e transconjugante de E. cloacae 067. Entretanto, o transconjugante foi capaz de liquefazer a gelatina após 12 dias de incubação a 30 C, o que não foi observado na estirpe selvagem. O transconjugante de E. cloacae 067 também apresentou maior atividade proteolítica em ágar caseinato e em ágar LB acrescido de 2 % de leite e maior grau de proteólise do leite do que o selvagem. A coagulação do leite desnatado reconstituído a 12 % e do leite pasteurizado por E. cloacae 067 transconjugante ocorreu após 36 horas de incubação, enquanto a estirpe selvagem coagulou o leite somente após 96 horas. Estes resultados sugerem a existência de um mecanismo de regulação negativa da atividade proteolítica em E. cloacae 067 pelo sistema quorum sensing. A atividade proteolítica de ambas as estirpes avaliadas não foi detectada em zimograma contendo azocaseína como substrato. Entretanto,… Advisors/Committee Members: Elza Fernandes de Araujo, Hilário Cuquetto Mantovani, Miriam Teresinha dos Santos, Denise Mara Soares Bazzolli, Maurilio Lopes Martins, Maria Cristina Dantas Vanetti.

Subjects/Keywords: Enterobacter cloacae; Quorum sensing; Lactonase; MICROBIOLOGIA; Enterobacter cloacae; Quorum sensing; Lactonase

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Ponce, A. d. R. (2007). Características fenotípicas de Enterobacter cloacae controladas pelo sistema quorum sensing. (Thesis). Universidade Federal de Viçosa. Retrieved from http://www.tede.ufv.br/tedesimplificado/tde_busca/arquivo.php?codArquivo=1147

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Ponce, Adriana dos Reis. “Características fenotípicas de Enterobacter cloacae controladas pelo sistema quorum sensing.” 2007. Thesis, Universidade Federal de Viçosa. Accessed March 01, 2021. http://www.tede.ufv.br/tedesimplificado/tde_busca/arquivo.php?codArquivo=1147.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Ponce, Adriana dos Reis. “Características fenotípicas de Enterobacter cloacae controladas pelo sistema quorum sensing.” 2007. Web. 01 Mar 2021.

Vancouver:

Ponce AdR. Características fenotípicas de Enterobacter cloacae controladas pelo sistema quorum sensing. [Internet] [Thesis]. Universidade Federal de Viçosa; 2007. [cited 2021 Mar 01]. Available from: http://www.tede.ufv.br/tedesimplificado/tde_busca/arquivo.php?codArquivo=1147.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Ponce AdR. Características fenotípicas de Enterobacter cloacae controladas pelo sistema quorum sensing. [Thesis]. Universidade Federal de Viçosa; 2007. Available from: http://www.tede.ufv.br/tedesimplificado/tde_busca/arquivo.php?codArquivo=1147

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

19. Mamani Flores, Sigde Karina. Régulation par le quorum sensing chez la bactérie biolixiviante Acidithiobacillus ferrooxidans : Regulation by quorum sensing in the bacteria biolixiviante Acidithiobacillus ferrooxidans.

Degree: Docteur es, Biologie, 2016, Aix Marseille Université

URL: http://www.theses.fr/2016AIXM4117

►

Le Quorum sensing (QS) est un système de communication bactérienne capable de réguler divers processus cellulaires qui dépendent de la densité de la population microbienne.… (more)

▼

Le Quorum sensing (QS) est un système de communication bactérienne capable de réguler divers processus cellulaires qui dépendent de la densité de la population microbienne. Chez les bactéries à Gram négatif, cela se produit par production de molécules de signalisation auto-inductrices (AI), les acyl homosérine lactones (AHL). La libération d´AHL à l'extérieur de la cellule est détectée par la population bactérienne provoquant en réponse la régulation de l'expression de certains gènes (régulon QS).Notre laboratoire a étudié et identifié un système QS fonctionnel dans la souche Acidithiobacillus ferrooxidans ATCC 23270T. En outre, nous avons montré que des analogues synthétiques d´AHL modulent l´adhésion d´At. ferrooxidansT sur un substrat minéral, tels des coupons de soufre.Dans ce projet de recherche, nous nous proposons d'identifier les gènes qui sont régulés par le QS chez At. ferrooxidansT, en particulier ceux impliqués dans la biogénèse du biofilm. Notre hypothèse est que des analogues synthétiques d’AHL induisent le système QS. Ainsi, nous nous proposons de moduler l´adhésion sur substrat minéral grâce à l'utilisation de ces molécules. L'utilisation de ces AHL permettra de caractériser le régulon QS dans cette souche bactérienne.L'identification d'analogues synthétiques d´AHL qui favorisent l'adhésion à des coupons de soufre nous a permis d'étudier le transcriptome d´At. ferrooxidansT dans des conditions où le régulon QS est stimulé. Puces à ADN d´At. ferrooxidansT avec/sans ces analogues synthétique d´AHLs nous a permis de caractériser le régulon QS et les gènes impliqués dans la biogénèse du biofilm dans les conditions utilisées.

Quorum sensing (QS) is a bacterial communication system capable of controlling several cellular processes dependent on the density of the microbial population. In Gram-negative bacteria, it occurs mainly through the production by bacteria of small diffusible signaling molecules, termed autoinducers (AI), of the acyl homoserine lactones type (AHLs). The release of AHLs outside the cell is detected by the bacterial population generating the regulation of the expression of several genes (regulon QS).Our laboratory has studied and identified a functional QS system in the Acidithiobacillus ferrooxidans ATCC 23270T type strain. Besides, by using synthetic analogs of AHLs, we have shown that AHL-type QS molecule analogs modulate adhesion of At. ferrooxidansT to minerals, such as sulfur coupons. In this research, we propose to identify the genes that are regulated by QS in At. ferrooxidansT, particularly those that are associated with biofilm formation. For this, we propose to modulate the adhesion of At. ferrooxidansT to mineral substrate through the use of a synthetic AHL analog. Our working hypothesis postulates that AHLs molecules induce the QS system, and that their use will allow the characterization of the QS regulon of this bacterial strain by transcriptomic analysis.The identification of synthetic AHLs improving adherence of At. ferrooxidansT on sulfur coupons allowed us to study…

Advisors/Committee Members: Bonnefoy, Violaine (thesis director), Guiliani Guerin, Nicolas (thesis director).

Subjects/Keywords: Régulon; Quorum sensing; Biofilm; Regulon; Quorum sensing; Biofilm; 570

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Mamani Flores, S. K. (2016). Régulation par le quorum sensing chez la bactérie biolixiviante Acidithiobacillus ferrooxidans : Regulation by quorum sensing in the bacteria biolixiviante Acidithiobacillus ferrooxidans. (Doctoral Dissertation). Aix Marseille Université. Retrieved from http://www.theses.fr/2016AIXM4117

Chicago Manual of Style (16^th Edition):

Mamani Flores, Sigde Karina. “Régulation par le quorum sensing chez la bactérie biolixiviante Acidithiobacillus ferrooxidans : Regulation by quorum sensing in the bacteria biolixiviante Acidithiobacillus ferrooxidans.” 2016. Doctoral Dissertation, Aix Marseille Université. Accessed March 01, 2021. http://www.theses.fr/2016AIXM4117.

MLA Handbook (7^th Edition):

Mamani Flores, Sigde Karina. “Régulation par le quorum sensing chez la bactérie biolixiviante Acidithiobacillus ferrooxidans : Regulation by quorum sensing in the bacteria biolixiviante Acidithiobacillus ferrooxidans.” 2016. Web. 01 Mar 2021.

Vancouver:

Mamani Flores SK. Régulation par le quorum sensing chez la bactérie biolixiviante Acidithiobacillus ferrooxidans : Regulation by quorum sensing in the bacteria biolixiviante Acidithiobacillus ferrooxidans. [Internet] [Doctoral dissertation]. Aix Marseille Université 2016. [cited 2021 Mar 01]. Available from: http://www.theses.fr/2016AIXM4117.

Council of Science Editors:

Mamani Flores SK. Régulation par le quorum sensing chez la bactérie biolixiviante Acidithiobacillus ferrooxidans : Regulation by quorum sensing in the bacteria biolixiviante Acidithiobacillus ferrooxidans. [Doctoral Dissertation]. Aix Marseille Université 2016. Available from: http://www.theses.fr/2016AIXM4117

20. Aye, Armande Mireille. Mise en évidence du système de communication "Quorum Sensing" impliquant les AHLs chez des bactéries marines isolées de la Méditerranée : Evidence of an AHL-based communication system quorum sensing in marine bacteria isolated from the Mediterranean Sea.

Degree: Docteur es, Microbiologie, 2015, Toulon

URL: http://www.theses.fr/2015TOUL0002

►

Le contrôle du biofouling sur des surfaces inertes immergées ou en atmosphère humide est une nécessité dans le secteur marin, tant pour des raisons économiques… (more)

▼

Le contrôle du biofouling sur des surfaces inertes immergées ou en atmosphère humide est une nécessité dans le secteur marin, tant pour des raisons économiques qu’environnementales. La formation de biofilm microbien, étape préalable à la formation du biofouling, est souvent intrinsèquement liée chez les bactéries au système de communication “Quorum Sensing” (QS). Chez certaines bactéries Gram négatif, le QS est basé sur la perception de petites molécules diffusibles appelées N- Acyl Homosérine Lactones (AHLs). L’une des stratégies antifouling en voie de développement de nos jours repose sur l’inhibition du QS bactérien. L’objectif de cette thèse est d’utiliser certaines bactéries marines afin d’identifier des molécules anti-QS capables de perturber la formation de biofilm. Ce travail a donc porté sur la mise en évidence de molécules AHLs impliquées dans le QS chez certaines bactéries marines isolées de la rade de Toulon, l’étude de la modulation de certains phénotypes dont la formation du biofilm, par ces molécules et, la mise en place d’un test préliminaire d’inhibition du QS. Parmi les trois bactéries isolées de la rade de Toulon (TC8, TC14 et TC15) du genre Pseudoalteromonas, connues pour produire de nombreuses molécules actives, et testées pour leur capacité à sécréter des AHLs, seule Pseudoalteromonas sp. TC15 a produit la C12-HSL. P. ulvae TC14, capable de produire un biofilm conséquent et de la violacéine, ne produit aucune AHL. Afin d’évaluer la possibilité d’utiliser une bactérie marine comme outil de criblage anti-QS, interférant avec les AHLs et les conséquences sur son biofilm, des AHLs exogènes ont été testées sur la production de violacéine, la formation de biofilm et la mobilité de TC14. Certaines AHLs ont montré qu’elles pouvaient réguler la production de violacéine et la formation de biofilm chez TC14, suggérant l’existence d’un récepteur AHLs fonctionnel. Des tests préliminaires d’inhibition du QS ont été effectués avec des molécules commerciales et des analogues synthétiques. La 3-oxo-C6-HSL commerciale, ainsi que l’esculétine et la p- benzoquinone, connues pour interférer avec le QS bactérien, ont été capables d’inhiber la production de violacéine ainsi que la formation de biofilm de TC14 à des concentrations n’affectant pas sa croissance. Cette étude suggère donc que P. ulvae TC14 pourrait être utilisée comme un outil de recherche de molécules anti-QS en conditions proches de celles trouvées dans l’environnement marin, et ce dans le but d’être ultérieurement testées sur la formation de biofilm. L’objectif à plus long terme reste de trouver un moyen de limiter la formation du biofilm en utilisant des molécules non toxiques pour l’environnement.

The biofouling control on immersed inert surfaces or in moist atmosphere is a necessity in the marine sector for both economic and environmental reasons. Microbial biofilm formation, the initial step of biofouling development, is intrinsically linked to the communication system “Quorum sensing” (QS). In some Gram negative bacteria, QS is based on the…

Advisors/Committee Members: Blache, Yves (thesis director).

Subjects/Keywords: Inhibition du quorum sensing; AHL; Pseudoalteromonas; Quorum sensing inhibition; AHL; Pseudoalteromonas

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Aye, A. M. (2015). Mise en évidence du système de communication "Quorum Sensing" impliquant les AHLs chez des bactéries marines isolées de la Méditerranée : Evidence of an AHL-based communication system quorum sensing in marine bacteria isolated from the Mediterranean Sea. (Doctoral Dissertation). Toulon. Retrieved from http://www.theses.fr/2015TOUL0002

Chicago Manual of Style (16^th Edition):

Aye, Armande Mireille. “Mise en évidence du système de communication "Quorum Sensing" impliquant les AHLs chez des bactéries marines isolées de la Méditerranée : Evidence of an AHL-based communication system quorum sensing in marine bacteria isolated from the Mediterranean Sea.” 2015. Doctoral Dissertation, Toulon. Accessed March 01, 2021. http://www.theses.fr/2015TOUL0002.

MLA Handbook (7^th Edition):

Aye, Armande Mireille. “Mise en évidence du système de communication "Quorum Sensing" impliquant les AHLs chez des bactéries marines isolées de la Méditerranée : Evidence of an AHL-based communication system quorum sensing in marine bacteria isolated from the Mediterranean Sea.” 2015. Web. 01 Mar 2021.

Vancouver:

Aye AM. Mise en évidence du système de communication "Quorum Sensing" impliquant les AHLs chez des bactéries marines isolées de la Méditerranée : Evidence of an AHL-based communication system quorum sensing in marine bacteria isolated from the Mediterranean Sea. [Internet] [Doctoral dissertation]. Toulon; 2015. [cited 2021 Mar 01]. Available from: http://www.theses.fr/2015TOUL0002.

Council of Science Editors:

Aye AM. Mise en évidence du système de communication "Quorum Sensing" impliquant les AHLs chez des bactéries marines isolées de la Méditerranée : Evidence of an AHL-based communication system quorum sensing in marine bacteria isolated from the Mediterranean Sea. [Doctoral Dissertation]. Toulon; 2015. Available from: http://www.theses.fr/2015TOUL0002

21. Conrado, Isabel Monteiro. Bactérias e as suas redes sociais.

Degree: 2013, Universidade Fernando Pessoa

URL: http://www.rcaap.pt/detail.jsp?id=oai:bdigital.ufp.pt:10284/4168

►

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas

As bactérias são microorganismos… (more)

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Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas

As bactérias são microorganismos primitivos unicelulares que habitam em nichos ecológicos formando comunidades multiespécie e sintetizam moléculas sinalizadoras que lhes permitem comunicar entre si por um mecanismo designado de quorum sensing. O primeiro modelo experimental de quorum sensing a ser estudado foi o da bactéria de Gram-negativo bioluminescente Vibrio fischeri que sintetiza como moléculas de sinalização as N-acil-homoserina lactonas. As bactérias de Gram-negativo comunicam igualmente através de outras moléculas de sinalização nomeadamente, 2-alquil-4-quinolonas (AQs), cadeias longas de ácidos gordos e ésteres metílicos de ácidos gordos. As bactérias de Gram-positivo sintetizam auto-indutores peptídicos. Nesta revisão bibliográfica estão descritos alguns mecanismos de quorum sensing, designadamente, o sistema LuxI/LuxR pela bactéria Víbrio fischeri, sistema de quorum sensing peptídico em Staphylococcus aureus, circuitos de quorum sensing paralelos por Vibrio harveyi, circuitos de quorum sensing competitivos por Bacillus subtilis e circuitos de quorum sensing organizados em série por Pseudomonas aeruginosa. Serão igualmente abordadas novas terapêuticas antibacterianas que incluem a utilização de moléculas anti-quorum sensing. Bacteria are primitive unicellular microorganisms that inhabit ecological niches composed by multispecific communities and synthesize signal molecules that allow them to communicate between each other by quorum sensing. The first studied model of quorum sensing was of the bioluminescent Gram-negative bacteria Vibrio fischeri, which synthesize N-Acyl homoserine lactone signal molecules. Gram-negative bacteria also communicate using other signal molecules, namely 2-alkyl-4-quinolones (AQs), long-chain fatty acids and fatty acid ethyl ester. Gram-positive bacteria, however, synthesize peptide autoinducers. In this review several quorum sensing mechanisms are described, namely the LuxI/LuxR system by the bacteria Vibrio fischeri, peptide quorum sensing in Staphylococcus aureus, parallel quorum sensing circuits by Vibrio harveyi, competitive quorum sensing circuits by Bacillus subtilis and serial quorum sensing circuits by Pseudomonas aeruginosa. Novel antibacterial therapeutics that include the use of anti-quorum sensing molecules will also be approached.

Advisors/Committee Members: Castro, Anabela.

Subjects/Keywords: Bactérias; Comunicação entre as bactérias; Quorum sensing; Quorum quenching; Bacteria; Cross-talk in bacteria; Quorum sensing; Quorum quenching

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Conrado, I. M. (2013). Bactérias e as suas redes sociais. (Thesis). Universidade Fernando Pessoa. Retrieved from http://www.rcaap.pt/detail.jsp?id=oai:bdigital.ufp.pt:10284/4168

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Conrado, Isabel Monteiro. “Bactérias e as suas redes sociais.” 2013. Thesis, Universidade Fernando Pessoa. Accessed March 01, 2021. http://www.rcaap.pt/detail.jsp?id=oai:bdigital.ufp.pt:10284/4168.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Conrado, Isabel Monteiro. “Bactérias e as suas redes sociais.” 2013. Web. 01 Mar 2021.

Vancouver:

Conrado IM. Bactérias e as suas redes sociais. [Internet] [Thesis]. Universidade Fernando Pessoa; 2013. [cited 2021 Mar 01]. Available from: http://www.rcaap.pt/detail.jsp?id=oai:bdigital.ufp.pt:10284/4168.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Conrado IM. Bactérias e as suas redes sociais. [Thesis]. Universidade Fernando Pessoa; 2013. Available from: http://www.rcaap.pt/detail.jsp?id=oai:bdigital.ufp.pt:10284/4168

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Université Paris-Sud – Paris XI

22. Tannières, Mélanie. Interruption de la communication bactérienne dans la rhizosphère par la dégradation enzymatique des signaux quorum sensing : Disruption of bacterial communication in rhizosphere by enzymatic degradation of quorum sensing signals.

Degree: Docteur es, Biologie, 2012, Université Paris-Sud – Paris XI

URL: http://www.theses.fr/2012PA112050

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L’identification, chez divers organismes, d’enzymes de dégradation des N-acyl homosérineslactones (NAHLs) impliquées dans la signalisation QS pose la question de leurs rôles dans lesinteractions bactéries-eucaryotes.… (more)

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L’identification, chez divers organismes, d’enzymes de dégradation des N-acyl homosérineslactones (NAHLs) impliquées dans la signalisation QS pose la question de leurs rôles dans lesinteractions bactéries-eucaryotes. Dans une première partie, une synthèse bibliographique analyse lesconnaissances acquises sur ces enzymes dégradant les NAHLs. Dans une seconde partie, la croissancedes bactéries dégradant les signaux NAHLs a été stimulée par l’application de g-caprolactone (GCL)dans la rhizosphère de plants de pommes de terre à des fins de phytoprotection. L’effet de cetraitement sur la diversité des communautés bactériennes rhizosphériques a été évalué en combinantdifférentes approches d’écologie microbienne moléculaire comme la DGGE, le pyroséquençaged’amplicons rrs, et la métagénomique fonctionnelle. Cette dernière approche appliquée à une banquede 30 000 clones environ a conduit à l’identification d’un gène qsdB codant la dégradation des signauxNAHL. Ce travail révèle ainsi l’existence d’une nouvelle classe d’enzymes de dégradation des NAHLsappartenant à la famille des enzymes possédant une signature amidase (AS) dont des membres sontpar ailleurs impliqués dans la dégradation de composés xénobiotiques. Dans une troisième partie, unsystème expérimental a été développé afin de mesurer le transfert conjugatif du plasmide de virulenceTi (tumor inducing) chez des dérivés du pathogène Agrobacterium tumefaciens, appelés «tricheurs»,incapables de produire des signaux NAHLs mais utilisateurs de ceux produits par les autres bactéries.Ce modèle a permis de montrer l’effet modérateur de lactonases dégradant les NAHLs exprimées chezdes agrobactéries produisant les NAHLs, chez des bactéries réceptrices du plasmide Ti, ou des planteshôtes des agrobactéries sur le transfert conjugatif initié par les tricheurs. L’ensemble de ce travailrévèle à la fois une nouvelle famille d’enzymes impliquées dans la dégradation des NAHLs, ainsiqu’un nouveau rôle de ces enzymes dans la modulation des flux de gènes entre bactériesphytopathogènes en interaction avec une plante hôte.

Identification of bacterial and eukaryotic enzymes that degrade N-acyl homoserine lactones(NAHLs) involved in QS signaling raises the question of their roles in bacteria-eucaryotesinteractions. In a first part of this study, a bibliographic report analyzes the current data on thoseNAHL-degrading enzymes. In a second part, the growth of NAHL-degrading bacteria was stimulatedby g-caprolactone (GCL) amendment in potato rhizosphere to protect this plant against the soft-rotpathogen Pectobacterium. The effect of the GCL treatment on rhizospheric bacterial communities wasevaluated by a combination of different molecular microbial ecology techniques such as DGGE,pyrosequencing and functional metagenomic. This last approach was applied to generate ametagenomic library of ca. 30,000 clones and lead to the identification of the qsdB gene that encodesNAHL degradation, This work revealed the occurrence of a novel class of NAHL-degrading enzymesthat belong to the amidase signature…

Advisors/Committee Members: Faure, Denis (thesis director).

Subjects/Keywords: Quorum sensing; Quorum quenching; Métagénomique; AS family; Tricheur; Agrobacterium; Quorum sensing; Quorum quenching; Metagenomics; AS family; Cheaters; Agrobacterium

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Tannières, M. (2012). Interruption de la communication bactérienne dans la rhizosphère par la dégradation enzymatique des signaux quorum sensing : Disruption of bacterial communication in rhizosphere by enzymatic degradation of quorum sensing signals. (Doctoral Dissertation). Université Paris-Sud – Paris XI. Retrieved from http://www.theses.fr/2012PA112050

Chicago Manual of Style (16^th Edition):

Tannières, Mélanie. “Interruption de la communication bactérienne dans la rhizosphère par la dégradation enzymatique des signaux quorum sensing : Disruption of bacterial communication in rhizosphere by enzymatic degradation of quorum sensing signals.” 2012. Doctoral Dissertation, Université Paris-Sud – Paris XI. Accessed March 01, 2021. http://www.theses.fr/2012PA112050.

MLA Handbook (7^th Edition):

Tannières, Mélanie. “Interruption de la communication bactérienne dans la rhizosphère par la dégradation enzymatique des signaux quorum sensing : Disruption of bacterial communication in rhizosphere by enzymatic degradation of quorum sensing signals.” 2012. Web. 01 Mar 2021.

Vancouver:

Tannières M. Interruption de la communication bactérienne dans la rhizosphère par la dégradation enzymatique des signaux quorum sensing : Disruption of bacterial communication in rhizosphere by enzymatic degradation of quorum sensing signals. [Internet] [Doctoral dissertation]. Université Paris-Sud – Paris XI; 2012. [cited 2021 Mar 01]. Available from: http://www.theses.fr/2012PA112050.

Council of Science Editors:

Tannières M. Interruption de la communication bactérienne dans la rhizosphère par la dégradation enzymatique des signaux quorum sensing : Disruption of bacterial communication in rhizosphere by enzymatic degradation of quorum sensing signals. [Doctoral Dissertation]. Université Paris-Sud – Paris XI; 2012. Available from: http://www.theses.fr/2012PA112050

23. Bzdrenga, Janek. De la promiscuité des enzymes : cas des PLLs et de leur implication dans l'anti virulence bactérienne et la décontamination des organophosphorés : Enzymatic promiscuity : the case of PLLs and their implication in bacterial anti virulence and organophosphate decontamination.

Degree: Docteur es, Pathologie humaine. Maladies infectieuses, 2016, Aix Marseille Université

URL: http://www.theses.fr/2016AIXM5018

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Les PLLs sont une famille d’enzyme dont l’activité catalytique est double. L’activité lactonase permet entre autre de détruire les AHLs, molécules médiatrices de la communication… (more)

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Les PLLs sont une famille d’enzyme dont l’activité catalytique est double. L’activité lactonase permet entre autre de détruire les AHLs, molécules médiatrices de la communication chez les bactéries Gram négatives, empêchant ainsi la synchronisation à l’échelle de la population de la sécrétion de facteurs de virulence ou la formation de biofilm. Elles sont non seulement capables d’hydrolyser les molécules possédant un noyau lactone, mais aussi les phosphotriésters par promiscuité de substrat. L’activité phosphotriestérase permet de dégrader les composés organophosphorés (OPs) hautement toxiques, que ce soit les insecticides (Paraoxon) ou les agents neurotoxiques de guerre (Sarin, VX). Les travaux effectués ont consisté à évaluer l’efficacité de la PLL SsoPox, provenant de l’archée extrêmophile Sulfolobus solfataricus, pour empêcher la mise en place de la virulence et du biofilm chez Pseudomonas aeruginosa PAO1. Cette évaluation a été effectuée in vitro et in vivo via un modèle d’infection pulmonaire chez le rat. D’autre part, une étude in vitro a été réalisée sur 73 souches cliniques de P. aeruginosa isolés sur des patients atteints de pied diabétique, en évaluant la quantité de pyocyanine et l’activité protéolytique. Enfin, une phase prospective pour identifier de nouvelles PLLs a permis la caractérisation enzymatique et structurale de 2 nouvelles enzymes, SacPox et VmoLac, contribuant ainsi à affiner la connaissance sur cette famille et leur potentiel d’amélioration par ingénierie protéique. Au final, les PLLs offrent un intérêt biotechnologique majeur et peuvent mener à une valorisation concrète pour la santé humaine mais également pour la bioremédiation des OPs.

Phosphotriesterase-Like Lactonases (PLLs) are a family of enzyme displaying a dual catalytic activity. Lactonase activity allows for, among others, the destruction of Acyl Homoserine Lactones (AHLs). These molecules mediate the communication in Gram negative bacteria, allowing them to synchronize group behavior like virulence factor secretion or biofilm formation. Beside their ability to hydrolyze molecules with a lactones moiety, PLL also show substrate promiscuity for hydrolyzing highly toxic organophosphate compounds (OPs), such as pesticides (i.e. Paraoxon) or Chemical Warfare Nerve Agents (CWNAs) (e.g. Sarin & VX). The work described here consisted in evaluating the efficacy of the PLL SsoPox, originating from the extremophile Archaea Sulfolobus solfataricus, to prevent virulence and biofilm formation on the model strain Pseudomonas aeruginosa PAO1. This evaluation was performed both in vitro and in vivo, by using a rat pulmonary infection model. A study has been performed on a strain collection of 73 clinical strains of P. aeruginosa isolated from diabetic foot, to assess the enzyme effects on pyocyanin secretion and protease activity. Finally, a prospective phase to identify new PLLs allowed for the enzymatic and structural characterization of two new enzymes, SacPox and VmoLac, thus contributing to refine the knowledge about this enzyme family…

Advisors/Committee Members: Chabrière, Eric (thesis director).

Subjects/Keywords: Quorum sensing; Quorum quenching; Virulence; Lactonase; Biofilm; Enzyme; Quorum sensing; Quorum quenching; Virulence; Lactonase; Biofilm; Enzyme

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Bzdrenga, J. (2016). De la promiscuité des enzymes : cas des PLLs et de leur implication dans l'anti virulence bactérienne et la décontamination des organophosphorés : Enzymatic promiscuity : the case of PLLs and their implication in bacterial anti virulence and organophosphate decontamination. (Doctoral Dissertation). Aix Marseille Université. Retrieved from http://www.theses.fr/2016AIXM5018

Chicago Manual of Style (16^th Edition):

Bzdrenga, Janek. “De la promiscuité des enzymes : cas des PLLs et de leur implication dans l'anti virulence bactérienne et la décontamination des organophosphorés : Enzymatic promiscuity : the case of PLLs and their implication in bacterial anti virulence and organophosphate decontamination.” 2016. Doctoral Dissertation, Aix Marseille Université. Accessed March 01, 2021. http://www.theses.fr/2016AIXM5018.

MLA Handbook (7^th Edition):

Bzdrenga, Janek. “De la promiscuité des enzymes : cas des PLLs et de leur implication dans l'anti virulence bactérienne et la décontamination des organophosphorés : Enzymatic promiscuity : the case of PLLs and their implication in bacterial anti virulence and organophosphate decontamination.” 2016. Web. 01 Mar 2021.

Vancouver:

Bzdrenga J. De la promiscuité des enzymes : cas des PLLs et de leur implication dans l'anti virulence bactérienne et la décontamination des organophosphorés : Enzymatic promiscuity : the case of PLLs and their implication in bacterial anti virulence and organophosphate decontamination. [Internet] [Doctoral dissertation]. Aix Marseille Université 2016. [cited 2021 Mar 01]. Available from: http://www.theses.fr/2016AIXM5018.

Council of Science Editors:

Bzdrenga J. De la promiscuité des enzymes : cas des PLLs et de leur implication dans l'anti virulence bactérienne et la décontamination des organophosphorés : Enzymatic promiscuity : the case of PLLs and their implication in bacterial anti virulence and organophosphate decontamination. [Doctoral Dissertation]. Aix Marseille Université 2016. Available from: http://www.theses.fr/2016AIXM5018

Virginia Tech

24. Leaman, Eric Joshua. An Experimentally-validated Agent-based Model to Study the Emergent Behavior of Bacterial Communities.

Degree: MS, Mechanical Engineering, 2016, Virginia Tech

URL: http://hdl.handle.net/10919/78072

► Swimming bacteria are ubiquitous in aqueous environments ranging from oceans to fluidic environments within a living host. Furthermore, engineered bacteria are being increasingly utilized for… (more)

Subjects/Keywords: quorum sensing; computational biology; flagellated bacteria; quorum quenching; chemotaxis

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Leaman, E. J. (2016). An Experimentally-validated Agent-based Model to Study the Emergent Behavior of Bacterial Communities. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/78072

Chicago Manual of Style (16^th Edition):

Leaman, Eric Joshua. “An Experimentally-validated Agent-based Model to Study the Emergent Behavior of Bacterial Communities.” 2016. Masters Thesis, Virginia Tech. Accessed March 01, 2021. http://hdl.handle.net/10919/78072.

MLA Handbook (7^th Edition):

Leaman, Eric Joshua. “An Experimentally-validated Agent-based Model to Study the Emergent Behavior of Bacterial Communities.” 2016. Web. 01 Mar 2021.

Vancouver:

Leaman EJ. An Experimentally-validated Agent-based Model to Study the Emergent Behavior of Bacterial Communities. [Internet] [Masters thesis]. Virginia Tech; 2016. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/10919/78072.

Council of Science Editors:

Leaman EJ. An Experimentally-validated Agent-based Model to Study the Emergent Behavior of Bacterial Communities. [Masters Thesis]. Virginia Tech; 2016. Available from: http://hdl.handle.net/10919/78072

25. Christiaen, Steven. Exploring the role of quorum sensing and quorum sensing inhibition in the biotherapeutic potential of bacteria.

Degree: 2014, Ghent University

URL: http://hdl.handle.net/1854/LU-4232258

► The involvement of quorum sensing (QS) in several pathogenic bacteria to control biofilm formation and the expression of their virulence factors makes interfering with QS… (more)

Subjects/Keywords: Medicine and Health Sciences; quorum sensing; biotherapeutics; quorum quenching; probiotics

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APA (6^th Edition):

Christiaen, S. (2014). Exploring the role of quorum sensing and quorum sensing inhibition in the biotherapeutic potential of bacteria. (Thesis). Ghent University. Retrieved from http://hdl.handle.net/1854/LU-4232258

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Christiaen, Steven. “Exploring the role of quorum sensing and quorum sensing inhibition in the biotherapeutic potential of bacteria.” 2014. Thesis, Ghent University. Accessed March 01, 2021. http://hdl.handle.net/1854/LU-4232258.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Christiaen, Steven. “Exploring the role of quorum sensing and quorum sensing inhibition in the biotherapeutic potential of bacteria.” 2014. Web. 01 Mar 2021.

Vancouver:

Christiaen S. Exploring the role of quorum sensing and quorum sensing inhibition in the biotherapeutic potential of bacteria. [Internet] [Thesis]. Ghent University; 2014. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/1854/LU-4232258.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Christiaen S. Exploring the role of quorum sensing and quorum sensing inhibition in the biotherapeutic potential of bacteria. [Thesis]. Ghent University; 2014. Available from: http://hdl.handle.net/1854/LU-4232258

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Cornell University

26. Tsai, Ching-Sung. Detection Of Diffusible Chemical Signals By Two Species Of Proteobacteria.

Degree: PhD, Microbiology, 2011, Cornell University

URL: http://hdl.handle.net/1813/33503

► This dissertation focuses on how two different species of Proteobacteria, Yersinia enterocolitica and Agrobacterium tumefaciens, detect chemical signals that are synthesized by the same species… (more)

▼ This dissertation focuses on how two different species of Proteobacteria, Yersinia enterocolitica and Agrobacterium tumefaciens, detect chemical signals that are synthesized by the same species or by other organisms. Y. enterocolitica encodes proteins YenR and YenI, that resemble the LuxR and LuxI proteins of Vibrio fischeri. YenI synthesizes mainly 3-oxohexanoylhomoserine lactone (OHHL), while YenR is thought to be an OHHL-dependent transcriptional activator. Chromatin immunoprecipitation assays suggested that YenR might bind to a region upstream of the yenR gene. This was confirmed using purified YenR in electrophoretic mobility shift assays. Bound YenR activated a gene divergent from yenR, designated yenS, and did so only in the absence of OHHL. The yenS gene encodes two overlapping non-translated RNAs that share the same promoter. In cells expressing yenI, the yenS promoter was expressed preferentially at low cell densities. A bioinformatic analysis showed that a portion of YenS was complementary to the ribosome binding site and start codon of the yenI mRNA. The activity of yenI-lacZ translational fusions was inhibited by YenS. Earlier studies of the YenR/YenI system suggested a role in swimming and swarming motility. A yenI mutant was strongly motile on semisolid agar, while the wild type strain, the yenR mutant, and the yenS mutant were nonmotile. A yenI, yenR double mutant and a yenI, yenS double mutant were nonmotile, suggesting a direct positive role for YenR and YenS. A separate study focused on the OccR protein, which is encoded by the tumor inducing (Ti) plasmid of A. tumefaciens. OccR activates an operon that directs the uptake and catabolism of a tumor-released nutrient called octopine. In the absence of octopine, OccR binds to its operator and causes a high angle DNA bend. In contrast, OccR-octopine complexes bind DNA and cause a low angle DNA bend. mutagenesis. Eight positive control mutants were identified by random Of these, six mutants showed the same high angle bend as wild type in the absence of octopine, but retained this bend in the presence of octopine. These data support the idea that relaxation of the DNA bend by the inducing ligand is critical for transcriptional activation. Advisors/Committee Members: Winans, Stephen C (chair), Roberts, Jeffrey Warren (committee member), Marquis, Helene (committee member).

Subjects/Keywords: Yersinia enterocolitica; Quorum sensing; LysR protein

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Tsai, C. (2011). Detection Of Diffusible Chemical Signals By Two Species Of Proteobacteria. (Doctoral Dissertation). Cornell University. Retrieved from http://hdl.handle.net/1813/33503

Chicago Manual of Style (16^th Edition):

Tsai, Ching-Sung. “Detection Of Diffusible Chemical Signals By Two Species Of Proteobacteria.” 2011. Doctoral Dissertation, Cornell University. Accessed March 01, 2021. http://hdl.handle.net/1813/33503.

MLA Handbook (7^th Edition):

Tsai, Ching-Sung. “Detection Of Diffusible Chemical Signals By Two Species Of Proteobacteria.” 2011. Web. 01 Mar 2021.

Vancouver:

Tsai C. Detection Of Diffusible Chemical Signals By Two Species Of Proteobacteria. [Internet] [Doctoral dissertation]. Cornell University; 2011. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/1813/33503.

Council of Science Editors:

Tsai C. Detection Of Diffusible Chemical Signals By Two Species Of Proteobacteria. [Doctoral Dissertation]. Cornell University; 2011. Available from: http://hdl.handle.net/1813/33503

University of Georgia

27. Septer, Alecia Noelle. The effects of environmental cues on luminescence regulation in Vibrio fischeri.

Degree: 2014, University of Georgia

URL: http://hdl.handle.net/10724/28104

► Bacteria use diffusible chemical signals to communicate within and between species and to coordinate certain group behaviors, including expression of host colonization factors. For Vibrio… (more)

▼ Bacteria use diffusible chemical signals to communicate within and between species and to coordinate certain group behaviors, including expression of host colonization factors. For Vibrio fischeri, a bioluminescent bacterium that colonizes the Hawaiian bobtail squid Euprymna scolopes, bioluminescence is required to colonize the host fully, and it is controlled in part by the pheromone-dependent LuxR-LuxI regulatory system. While pheromone-dependent luminescence induction is influenced by cell density, V. fischeri cells in culture are ~1000 times less luminescent and produce less pheromone than symbiotic cells, despite being at similar high cell densities. These observations and others suggest that density-independent factors also govern LuxR-LuxI mediated pheromone signaling. In this dissertation I describe how certain environmental cues regulate the LuxR-LuxI regulatory system to control both pheromone production and bioluminescence in V. fischeri. I show evidence that the squid light organ is a low iron environment and that low iron stimulates early induction and overall brighter luminescence in V. fischeri ES114 in culture. Moreover I demonstrate that inactivation of the redox-responsive ArcA/ArcB two-component regulatory system derepresses pheromone production, initiating a positive feedback loop wherein pheromone can diffuse into surrounding cells to stimulate more pheromone synthesis and induce bright luminescence. I also describe how oxygen levels influence luminescence through the oxygen-sensitive transcriptional regulator FNR, which regulates anaerobic respiration in V. fischeri in addition to bioluminescence. Finally, I show that citrate, a primary metabolite, regulates luminescence and this pathway requires the Gac/Csr regulatory cascade, which is conserved throughout γ–proteobacteria and is a known regulator of both central carbon metabolism and host colonization factors. These findings show in greater detail how pheromone-mediated regulation in V. fischeri is governed by more than cell density alone, and they suggest that pheromones can convey information about specific conditions, such as changes in redox or carbon flow, in addition to population size. This dissertation broadens our perspective of bacterial pheromone-mediated communication and bacterial gene regulation in natural infections.

Subjects/Keywords: Photobacterium; Aliivibrio; autodinducer; quorum sensing; lux

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Septer, A. N. (2014). The effects of environmental cues on luminescence regulation in Vibrio fischeri. (Thesis). University of Georgia. Retrieved from http://hdl.handle.net/10724/28104

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Septer, Alecia Noelle. “The effects of environmental cues on luminescence regulation in Vibrio fischeri.” 2014. Thesis, University of Georgia. Accessed March 01, 2021. http://hdl.handle.net/10724/28104.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Septer, Alecia Noelle. “The effects of environmental cues on luminescence regulation in Vibrio fischeri.” 2014. Web. 01 Mar 2021.

Vancouver:

Septer AN. The effects of environmental cues on luminescence regulation in Vibrio fischeri. [Internet] [Thesis]. University of Georgia; 2014. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/10724/28104.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Septer AN. The effects of environmental cues on luminescence regulation in Vibrio fischeri. [Thesis]. University of Georgia; 2014. Available from: http://hdl.handle.net/10724/28104

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Texas A&M University

28. Widmer, Kenneth Walter. Influence of autoinducer 2 (AI-2) and AI-2 inhibitors generated from processed poultry on virulence and growth of Salmonella enterica serovar Typhimurium.

Degree: PhD, Food Science and Technology, 2009, Texas A&M University

URL: http://hdl.handle.net/1969.1/ETD-TAMU-1313

► Bacteria produce and respond to external stimuli using molecules termed autoinducers. Poultry meat contains inhibitors which interfere with AI-2 signaling. The primary objective of this… (more)

▼ Bacteria produce and respond to external stimuli using molecules termed autoinducers. Poultry meat contains inhibitors which interfere with AI-2 signaling. The primary objective of this work was to understand the effects of AI-2 on the virulence and growth of Salmonella Typhimurium, and if the introduction of AI-2 inhibiting compounds would influence these effects. Using DNA microarray analysis, expression of 1136 virulence-related genes in a Salmonella Typhimurium wild type and a luxS mutant strain, PJ002 (unable to produce AI-2), was monitored after exposure to treatments containing in vitro synthesized AI-2 (AI-2) and poultry meat (PM) inhibitors. Responding gene expression was unique in the presence of AI-2, with 23 genes differentially expressed at least 1.5-fold (p < 0.05). The combined AI-2 + PM treatment resulted in 22 genes being differentially expressed. Identification of inhibitory compounds was attempted using GC analysis on a hexane solvent extract obtained from a PM wash. From this analysis, chemical standards of linoleic, oleic, palmitic, and stearic acid were tested for inhibition using V. harveyi BB170. Combined fatty acids (FA) demonstrated inhibition against AI-2 at 60 % while 10-fold and 100-fold concentrations had inhibition of 84 % and 70 %, respectively. Growth of PJoo2, was studied using M-9 minimal medium with FA of varying concentrations, supplemented with either AI-2, or 1X phosphate buffered saline (PBS). Comparative analysis was done calculating the growth constants based on OD 600 values for each treatment. No significant difference in the combined FA + AI-2 treatments was observed against the AI-2 treatment. A significant increase in the growth rate constants of the AI-2 treatments was observed, however, compared to the PBS control (P = 0.01). Bacterial invasiveness, using a murine macrophage cell line, RAW 264.7, was also studied. AI-2 decreased cell invasiveness (P = 0.02), while the addition of combined FA improved invasiveness to normal levels. The results of these studies indicate that AI-2 does have an effect on the growth and virulence of Salmonella, but this is not uniformly modulated by the introduction of fatty acids, that inhibit AI-2 activity, suggesting that inhibition may be based on species specific transport systems. Advisors/Committee Members: Pillai, Suresh D. (advisor), Berghman, Luc R. (committee member), Hume, Michael E. (committee member), Venkateswaran, Kasthuri (committee member), Zhu, James J. (committee member).

Subjects/Keywords: Salmonella; Quorum Sensing

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Widmer, K. W. (2009). Influence of autoinducer 2 (AI-2) and AI-2 inhibitors generated from processed poultry on virulence and growth of Salmonella enterica serovar Typhimurium. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/ETD-TAMU-1313

Chicago Manual of Style (16^th Edition):

Widmer, Kenneth Walter. “Influence of autoinducer 2 (AI-2) and AI-2 inhibitors generated from processed poultry on virulence and growth of Salmonella enterica serovar Typhimurium.” 2009. Doctoral Dissertation, Texas A&M University. Accessed March 01, 2021. http://hdl.handle.net/1969.1/ETD-TAMU-1313.

MLA Handbook (7^th Edition):

Widmer, Kenneth Walter. “Influence of autoinducer 2 (AI-2) and AI-2 inhibitors generated from processed poultry on virulence and growth of Salmonella enterica serovar Typhimurium.” 2009. Web. 01 Mar 2021.

Vancouver:

Widmer KW. Influence of autoinducer 2 (AI-2) and AI-2 inhibitors generated from processed poultry on virulence and growth of Salmonella enterica serovar Typhimurium. [Internet] [Doctoral dissertation]. Texas A&M University; 2009. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-1313.

Council of Science Editors:

Widmer KW. Influence of autoinducer 2 (AI-2) and AI-2 inhibitors generated from processed poultry on virulence and growth of Salmonella enterica serovar Typhimurium. [Doctoral Dissertation]. Texas A&M University; 2009. Available from: http://hdl.handle.net/1969.1/ETD-TAMU-1313

Texas A&M University

29. Zhang, Xinyang. Effect of Quorum Sensing by Staphylococcus epidermidis on the Attraction Response by Female Adult Yellow Fever Mosquito, Aedes aegypti (Linnaeus)(Diptera: Culicidae) to a Blood-feeding Source.

Degree: MS, Entomology, 2014, Texas A&M University

URL: http://hdl.handle.net/1969.1/158653

► Aedes aegypti, the principle vector of yellow fever, is responsible for more than 30,000 deaths annually. Compounds like carbon dioxide, amino acids, fatty acids and… (more)

Subjects/Keywords: quorum sensing; staphylococcus epidermidis; aedes aegypti

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Zhang, X. (2014). Effect of Quorum Sensing by Staphylococcus epidermidis on the Attraction Response by Female Adult Yellow Fever Mosquito, Aedes aegypti (Linnaeus)(Diptera: Culicidae) to a Blood-feeding Source. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/158653

Chicago Manual of Style (16^th Edition):

Zhang, Xinyang. “Effect of Quorum Sensing by Staphylococcus epidermidis on the Attraction Response by Female Adult Yellow Fever Mosquito, Aedes aegypti (Linnaeus)(Diptera: Culicidae) to a Blood-feeding Source.” 2014. Masters Thesis, Texas A&M University. Accessed March 01, 2021. http://hdl.handle.net/1969.1/158653.

MLA Handbook (7^th Edition):

Zhang, Xinyang. “Effect of Quorum Sensing by Staphylococcus epidermidis on the Attraction Response by Female Adult Yellow Fever Mosquito, Aedes aegypti (Linnaeus)(Diptera: Culicidae) to a Blood-feeding Source.” 2014. Web. 01 Mar 2021.

Vancouver:

Zhang X. Effect of Quorum Sensing by Staphylococcus epidermidis on the Attraction Response by Female Adult Yellow Fever Mosquito, Aedes aegypti (Linnaeus)(Diptera: Culicidae) to a Blood-feeding Source. [Internet] [Masters thesis]. Texas A&M University; 2014. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/1969.1/158653.

Council of Science Editors:

Zhang X. Effect of Quorum Sensing by Staphylococcus epidermidis on the Attraction Response by Female Adult Yellow Fever Mosquito, Aedes aegypti (Linnaeus)(Diptera: Culicidae) to a Blood-feeding Source. [Masters Thesis]. Texas A&M University; 2014. Available from: http://hdl.handle.net/1969.1/158653

University of Waterloo

30. Dupont, Andrea. Role of NOS-like proteins found in bacteria.

Degree: 2007, University of Waterloo

URL: http://hdl.handle.net/10012/2678

► Nitric oxide (•NO) is a molecule with diverse biological effects involved in both signaling and defense mechanisms in mammalian systems. The production of •NO is… (more)

Subjects/Keywords: NOS; quorum-sensing

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APA (6^th Edition):

Dupont, A. (2007). Role of NOS-like proteins found in bacteria. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/2678

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Dupont, Andrea. “Role of NOS-like proteins found in bacteria.” 2007. Thesis, University of Waterloo. Accessed March 01, 2021. http://hdl.handle.net/10012/2678.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Dupont, Andrea. “Role of NOS-like proteins found in bacteria.” 2007. Web. 01 Mar 2021.

Vancouver:

Dupont A. Role of NOS-like proteins found in bacteria. [Internet] [Thesis]. University of Waterloo; 2007. [cited 2021 Mar 01]. Available from: http://hdl.handle.net/10012/2678.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Dupont A. Role of NOS-like proteins found in bacteria. [Thesis]. University of Waterloo; 2007. Available from: http://hdl.handle.net/10012/2678

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Open Access Theses and Dissertations