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You searched for subject:(Enduracididine). Showing records 1 – 2 of 2 total matches.

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University of Wisconsin – Milwaukee

1. Han, Lanlan. Structure-Function Relationships in Bacterial Regulatory Proteins and an Enzyme Involved in Antibiotic Biosynthesis.

Degree: PhD, Chemistry, 2017, University of Wisconsin – Milwaukee

The first part of my thesis is focused on a new family of two-component response regulator proteins: Aspartate-Less Regulators (ALR). They lack the catalytic aspartate residue required for the phosphorylation mechanism of typical two component response regulators. We are using biophysical tools to characterize two proteins with redox-sensitive ALR domains: repressor of iron transport regulator (RitR) from Streptococcus pneumonia R6 and diguanylate cyclase Q15Z91 from Pseudoalteromonas atalantica. The structure of inactive RitRC128S monomer showed that the ALR domain and the DNA-binding domain are linked by an α-helix that runs the length of the entire protein, with C128 near the C-terminal end. Bioinformatic analysis of all streptococcal RitR homologs showed that Cys128 is strictly conserved, suggesting that RitR may be a novel redox sensor. Hydrogen peroxide was used to oxidize the cysteine thiol group to determine the structure of the oxidized, dimeric form of RitR. Oxidation of C128 to the disulfide caused a conformational change that caused the DBD to release from the ALR domain. Surprisingly, the freed DBD was observed bound to the ALR domain of the other, disulfide-linked molecule of RitR, recapitulating almost exactly the structure of the inactive, monomeric protein. An extended dimeric conformation was found in the RitRL86A/V93A variant. It binds to the target DNA according to gel filtration and differential scanning fluorimetry. The crystal structure of the RitRL86A/V93A ALR domain showed an unprecedented conformational change for a response regulator protein, where helix α4 is disordered and the two protomers swap their α5 helices to form the dimer. Combined with the C128D mutant in vivo studies, it seems that oxidation of C128 is part of the activation mechanism, but there must be an additional factor that leads to dimerization of the ALR domains. The second ALR protein Q15Z91 has R61 replacing the phosphorylatable aspartate residue in the ALR domain. According to the structure of Q15Z91 with GTP and c-di-GMP, purified Q15Z91 is an activated but product-inhibited dimer. C142 is conserved in the same position as C128 in RitR, and substitution demonstrated that C142 residue is also a redox sensor that involved in Q15Z91 activity regulation. The second part is a mechanistic enzymology project aimed at understanding the structure and mechanism of the novel pyridoxal-5’-phosphate (PLP)-dependent L-arginine hydroxylase/deaminase, MppP, from Streptomyces wadayamensis (SwMppP). SwMppP is predicted to be a type I/II aminotransferase based on primary sequence identity. However, NMR and ESI-MS results showed that SwMppP is not an aminotransferase, but rather a hydroxylase. The enzyme catalyzes the oxygen-dependent hydroxylation of L-arginine, forming 4-hydroxy-2-ketoarginine and the abortive side-product 2-ketoargine in a ratio of 1.7:1. This is exciting because SwMppP is the first PLP-dependent enzyme to react with oxygen in any context other than oxidative decarboxylation. The discovery of this new… Advisors/Committee Members: Nicholas R. Silvaggi.

Subjects/Keywords: Antibiotic Biosynthesis; Aspartate-Less Regulators; Enduracididine; Oxidase; Pyridoxal-5’-Phosphate; Redox Sensor; Biochemistry

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

APA (6th Edition):

Han, L. (2017). Structure-Function Relationships in Bacterial Regulatory Proteins and an Enzyme Involved in Antibiotic Biosynthesis. (Doctoral Dissertation). University of Wisconsin – Milwaukee. Retrieved from https://dc.uwm.edu/etd/1636

Chicago Manual of Style (16th Edition):

Han, Lanlan. “Structure-Function Relationships in Bacterial Regulatory Proteins and an Enzyme Involved in Antibiotic Biosynthesis.” 2017. Doctoral Dissertation, University of Wisconsin – Milwaukee. Accessed August 23, 2019. https://dc.uwm.edu/etd/1636.

MLA Handbook (7th Edition):

Han, Lanlan. “Structure-Function Relationships in Bacterial Regulatory Proteins and an Enzyme Involved in Antibiotic Biosynthesis.” 2017. Web. 23 Aug 2019.

Vancouver:

Han L. Structure-Function Relationships in Bacterial Regulatory Proteins and an Enzyme Involved in Antibiotic Biosynthesis. [Internet] [Doctoral dissertation]. University of Wisconsin – Milwaukee; 2017. [cited 2019 Aug 23]. Available from: https://dc.uwm.edu/etd/1636.

Council of Science Editors:

Han L. Structure-Function Relationships in Bacterial Regulatory Proteins and an Enzyme Involved in Antibiotic Biosynthesis. [Doctoral Dissertation]. University of Wisconsin – Milwaukee; 2017. Available from: https://dc.uwm.edu/etd/1636


University of Wisconsin – Milwaukee

2. Oehm, Sarah Anne. Studies in Molecular Recognition: Non-proteogenic Amino Acids for Antibiotic Studies and Chemosensors for Recognition and Reporting of Metal-ions.

Degree: PhD, Chemistry, 2018, University of Wisconsin – Milwaukee

The field of molecular recognition focuses on the selective and reversible binding of small guest molecules to larger host molecules. This dissertation describes synthesis of small molecules as binding guests for enzymatic substrates as well as molecules as host chemosensors to detect and identify metal ions. Two approaches to new antibiotic drugs have been explored, and an array of sensors for the quantitation of aqueous metals is being commercialized. As strains of deadly bacteria emerge with evolved resistance to known antibiotics, new drugs are needed with novel mechanisms of action. Natural product antibiotics containing enduracididine, a non-canonical amino acid derived from arginine, have been found effective against resistant organisms. Recently, the biosynthesis of enduracididine has been elucidated by the Silvaggi group. Various derivatives of arginine are of interest as guest molecules for the Mpp family of proteins. We have developed a particularly succinct route to γ-hydroxy-arginine, which has also been used as a precursor to other oxidized arginine derivatives. Our route provides quantities of arginine derivatives which have been synthesized via a four step route utilizing an isoxazoline intermediate. The synthetic methods for formation and subsequent reduction of the isoxazoline have been studied extensively; and this succinct and versatile synthesis yields either γ-hydroxy-arginine or the keto acid derived from it by changing the conditions of the reduction. iii In another approach to developing new antibiotic treatment, we have pursued the inhibition of the β-barrel assembly machine (BAM), through a small molecule scaffold that binds β-sheets. BAMa is the only known β-barrel protein that spontaneously folds, while all others require the help of BAMa. The β-barrel membrane proteins include efflux pumps, proteins for active transport that allow bacterial survival by ejection of antibiotic drugs. Inhibition of BAMa may itself prove bactericidal, or used in combination therapy increase efficacy of drugs rendered previously ineffective due to acquired resistance. We have also developed metal ion chemosensors for simulataneous identification and quantitation of multiple metals. These are useful for monitoring metal ion concentrations in industrial wastewater. Current limitations in measuring metal concentration in wastewater can lead to increased costs and excess solid waste in order to meet compliance standards. Our goal is a simple system to allow continuous, real-time measurement of multiple metals on site to decrease over-treatment and detect spikes in pollutant metals. Utilizing UV/VIS absorption an array of semi-selective sensors each with its own spectral response to metal ions allows identification and concentration of pollutants to be determined. Toward this end, we have prepared chemosensors, demonstrated their sensing ability, and covalently attached them to transparent polymers and transparent supports in several ways that allow repeated use for metal-ion… Advisors/Committee Members: Alan W Schwabacher.

Subjects/Keywords: arginine; azo dyes; chemosensors; enduracididine; isoxazoline; polymers; Analytical Chemistry; Biochemistry; Organic Chemistry

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

APA (6th Edition):

Oehm, S. A. (2018). Studies in Molecular Recognition: Non-proteogenic Amino Acids for Antibiotic Studies and Chemosensors for Recognition and Reporting of Metal-ions. (Doctoral Dissertation). University of Wisconsin – Milwaukee. Retrieved from https://dc.uwm.edu/etd/1889

Chicago Manual of Style (16th Edition):

Oehm, Sarah Anne. “Studies in Molecular Recognition: Non-proteogenic Amino Acids for Antibiotic Studies and Chemosensors for Recognition and Reporting of Metal-ions.” 2018. Doctoral Dissertation, University of Wisconsin – Milwaukee. Accessed August 23, 2019. https://dc.uwm.edu/etd/1889.

MLA Handbook (7th Edition):

Oehm, Sarah Anne. “Studies in Molecular Recognition: Non-proteogenic Amino Acids for Antibiotic Studies and Chemosensors for Recognition and Reporting of Metal-ions.” 2018. Web. 23 Aug 2019.

Vancouver:

Oehm SA. Studies in Molecular Recognition: Non-proteogenic Amino Acids for Antibiotic Studies and Chemosensors for Recognition and Reporting of Metal-ions. [Internet] [Doctoral dissertation]. University of Wisconsin – Milwaukee; 2018. [cited 2019 Aug 23]. Available from: https://dc.uwm.edu/etd/1889.

Council of Science Editors:

Oehm SA. Studies in Molecular Recognition: Non-proteogenic Amino Acids for Antibiotic Studies and Chemosensors for Recognition and Reporting of Metal-ions. [Doctoral Dissertation]. University of Wisconsin – Milwaukee; 2018. Available from: https://dc.uwm.edu/etd/1889

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