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You searched for +publisher:"Worcester Polytechnic Institute" +contributor:("Robert E. Dempski, Committee Member"). Showing records 1 – 2 of 2 total matches.

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1. Patel, Sarju. Functional Diversity of Homologous P1B-ATPases in Metal Homeostasis and Host-Microbe Interaction.

Degree: PhD, 2016, Worcester Polytechnic Institute

Copper and iron are trace elements that form an indispensable part of many proteins and are crucial for the well-being of all cells. At the same time, the intracellular levels of these metals require careful regulation, as excess or deficiency may be lethal. P1B-ATPases are key players in metal homeostasis. They belong to the superfamily of P-type ATPases, transmembrane proteins present in virtually all life forms, are responsible for solute translocation across biological membranes. The goal of this thesis is to improve our understanding of the structural and functional roles of P1B-ATPases in metal homeostasis by focusing on the host-microbe interaction. The thesis first describes the importance of Cu+ distribution in the outcome of host-microbe interaction. Copper is an important element in host-microbe interactions, acting both as a catalyst in enzymes and as a potential toxin. Cu+-ATPases drive cytoplasmic Cu+ efflux and protect bacteria against metal overload. Many pathogenic and symbiotic bacteria contain multiple Cu+-ATPase genes within particular genetic environments, suggesting alternative roles for each resulting protein. This hypothesis was tested by characterizing five homologous Cu+-ATPases present in the symbiotic organism <I>Sinorhizobium meliloti</I>. Mutation of each gene led to different phenotypes and abnormal nodule development in the alfalfa host. Distinct responses were detected in free-living <I>S. meliloti</I> mutant strains exposed to metal and redox stresses. Differential gene expression was detected under Cu+, oxygen or nitrosative stress. These observations suggest that CopA1a maintains the cytoplasmic Cu+ quota and its expression is controlled by Cu+ levels. CopA1b is also regulated by Cu+ concentrations and is required during symbiosis for bacteroid maturation. CopA2-like proteins, FixI1 and FixI2, are necessary for the assembly of two different cytochrome <I>c</I> oxidases at different stages of bacterial life. CopA3 is a phylogenetically distinct Cu+-ATPase that does not contribute to Cu+ tolerance. It is regulated by redox stress and required during symbiosis. We postulated a model where non-redundant homologous Cu+-ATPases, operating under distinct regulation, transport Cu+ to different target proteins. In its second part, the thesis describes the novel Fe2+-ATPases and their influence in the host-microbe interaction. Little is known about iron efflux transporters in bacterial systems. Recently, the participation of <I>Bacillus subtilis</I> PfeT, a P1B4-ATPase, in cytoplasmic Fe2+ efflux has been proposed. We report here the distinct roles of mycobacterial P1B4-ATPases in the homeostasis of Co2+ and Fe2+. Mutation of <I>Mycobacterium smegmatis ctpJ</I> affects the homeostasis of both ions. Alternatively, a <I>M. tuberculosis ctpJ</I>… Advisors/Committee Members: Arne Gericke, Committee Member, José M. Argüello, Advisor, Robert E. Dempski, Committee Member, Reeta Prusty Rao, Committee Member.

Subjects/Keywords: Metal transport; Metal homeostasis; P1B-ATPase

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APA (6th Edition):

Patel, S. (2016). Functional Diversity of Homologous P1B-ATPases in Metal Homeostasis and Host-Microbe Interaction. (Doctoral Dissertation). Worcester Polytechnic Institute. Retrieved from etd-040416-140014 ; https://digitalcommons.wpi.edu/etd-dissertations/473

Chicago Manual of Style (16th Edition):

Patel, Sarju. “Functional Diversity of Homologous P1B-ATPases in Metal Homeostasis and Host-Microbe Interaction.” 2016. Doctoral Dissertation, Worcester Polytechnic Institute. Accessed October 23, 2020. etd-040416-140014 ; https://digitalcommons.wpi.edu/etd-dissertations/473.

MLA Handbook (7th Edition):

Patel, Sarju. “Functional Diversity of Homologous P1B-ATPases in Metal Homeostasis and Host-Microbe Interaction.” 2016. Web. 23 Oct 2020.

Vancouver:

Patel S. Functional Diversity of Homologous P1B-ATPases in Metal Homeostasis and Host-Microbe Interaction. [Internet] [Doctoral dissertation]. Worcester Polytechnic Institute; 2016. [cited 2020 Oct 23]. Available from: etd-040416-140014 ; https://digitalcommons.wpi.edu/etd-dissertations/473.

Council of Science Editors:

Patel S. Functional Diversity of Homologous P1B-ATPases in Metal Homeostasis and Host-Microbe Interaction. [Doctoral Dissertation]. Worcester Polytechnic Institute; 2016. Available from: etd-040416-140014 ; https://digitalcommons.wpi.edu/etd-dissertations/473

2. Collins, Jessica M. FixI and FixI2: Homologous proteins with unique functions in Sinorhizobium meliloti.

Degree: MS, 2014, Worcester Polytechnic Institute

Cu+-ATPases are transmembrane enzymes that couple the efflux of cytoplasmic Cu+ to the hydrolysis of ATP. It is well established that Cu+-ATPases control cytoplasmic Cu+ levels. However, bacterial genomes, particularly those of symbiotic/pathogenic organisms, contain multiple copies of genes encoding Cu+-ATPases, challenging the idea of a singular role for these enzymes. Our lab has demonstrated that one of the two Cu+-ATPases in Pseudomonas aeruginosa, a FixI-type ATPase, has an alternative role, most likely Cu+ loading of cytochrome c oxidase (Cox). To further study alternative roles of Cu+-ATPases, we study the symbiont Sinorhizobium meliloti. Rhizobia are soil-dwelling bacteria that interact with legumes, forming plant root nodules that actively fix N2. The S. meliloti genome contains five Cu+-ATPases, two of which are FixI-type. Both of these enzymes, termed FixI1 and FixI2, are downstream of Cox operons. We hypothesized that the presence of multiple FixI-type ATPases was not an example of redundancy, but rather is an evolutionary adaptation that allows rhizobia to survive under the wide variety of adverse conditions faced during early infection and establishment of symbiosis. Towards this goal, this work focused on examining the effects of mutation of each ATPase on both free-living bacteria and on the ability of rhizobia to establish an effective symbiosis with its host legume. Each of these mutants presents a different phenotype at varying points of the nodulation process, and only the fixI2 mutation produces a respiratory-deficient phenotype during aerobic growth. These results are consistent with our hypothesis that the two proteins have non-redundant physiological functions. Understanding the factors that contribute to an effective symbiosis is beneficial, since N2 fixation in legumes is important to both agriculture and industry. Advisors/Committee Members: Arne Gericke, Department Head, Robert E. Dempski, Committee Member, José M. Argüello, Advisor, Pamela J. Weathers, Committee Member.

Subjects/Keywords: copper; Cu-ATPases; cytochrome c oxidase; rhizobium

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

APA (6th Edition):

Collins, J. M. (2014). FixI and FixI2: Homologous proteins with unique functions in Sinorhizobium meliloti. (Thesis). Worcester Polytechnic Institute. Retrieved from etd-031914-102227 ; https://digitalcommons.wpi.edu/etd-theses/177

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

Chicago Manual of Style (16th Edition):

Collins, Jessica M. “FixI and FixI2: Homologous proteins with unique functions in Sinorhizobium meliloti.” 2014. Thesis, Worcester Polytechnic Institute. Accessed October 23, 2020. etd-031914-102227 ; https://digitalcommons.wpi.edu/etd-theses/177.

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

MLA Handbook (7th Edition):

Collins, Jessica M. “FixI and FixI2: Homologous proteins with unique functions in Sinorhizobium meliloti.” 2014. Web. 23 Oct 2020.

Vancouver:

Collins JM. FixI and FixI2: Homologous proteins with unique functions in Sinorhizobium meliloti. [Internet] [Thesis]. Worcester Polytechnic Institute; 2014. [cited 2020 Oct 23]. Available from: etd-031914-102227 ; https://digitalcommons.wpi.edu/etd-theses/177.

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

Council of Science Editors:

Collins JM. FixI and FixI2: Homologous proteins with unique functions in Sinorhizobium meliloti. [Thesis]. Worcester Polytechnic Institute; 2014. Available from: etd-031914-102227 ; https://digitalcommons.wpi.edu/etd-theses/177

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

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