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Title:Chemical approaches to understanding small-molecule accumulation in bacteria and poly(ADP-ribosyl)ation
Author(s):Drown, Bryon Shane
Director of Research:Hergenrother, Paul J.
Doctoral Committee Chair(s):Hergenrother, Paul J.
Doctoral Committee Member(s):Burke, Martin D.; Silverman, Scott K.; Zimmerman, Steven C.
Department / Program:Chemistry
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):drug development
Abstract:The introduction of antibiotics revolutionized modern medicine. Surgical procedures became safer to perform, neonatal fatalities plummeted, and the risk of death from simple injuries was virtually eliminated. Since their initial discovery and introduction to the clinic in the 1940s, a steady supply of new agents helped establish this “antibiotic era.” In large part due to their remarkable success, antibiotics are today expected to be safe, cheap, and effective at a level unparalleled by any other class of drugs. The expansive use and misuse of antibiotics has caused a rise in antibiotic microbial resistance (AMR) at a time that new antibiotic discovery has slowed to a crawl. The time of picking low-hanging fruit has ended. New approaches to antibiotic discovery are sorely needed to avoid entering the “post-antibiotic era.” One critical component of any new strategy is a better understanding of how to get drugs into bacterial cells. A combined effort featuring complex molecule synthesis, microbiology, and cheminformatics has led to the development of guidelines that enable compound entry. These guidelines can jump-start stalled antibiotic projects and help usher new classes of drugs into the clinic. Several initial examples of converting gram-positive-only antibiotics into broad-spectrum agents shown here demonstrate the potential impact of this kind of approach. Poly(ADP-ribose) (PAR) signaling is an important component of DNA damage repair, cell division regulation, and initiation of controlled cell death. Despite extensive knowledge and a powerful toolkit available for studying the synthesis of PAR (including several approved drugs), significantly less is known about the degraders of PAR. This lack of knowledge is attributed to a lack of tool compounds and assays that can inhibit or measure the activity of the major PAR degraders (PARG and ARH3). Towards filling this need, novel fluorogenic substrates of PARG and ARH3 were designed and synthesized. Using these tools, the first continuous enzyme activity assays for PARG and ARH3 were developed for use with purified enzymes and in cell lysate. Critically, a substrate selective for ARH3 was utilized to identify an endogenous inhibitor of ARH3, ADP-ribosylated arginine. This compound is produced in cells treated with cholera toxin and is a potent and selective inhibitor of ARH3. With a new activity assay for measuring PARG and ARH3 activity and the first selective inhibitor of ARH3, we now have the tools necessary to make new discoveries about PAR regulation.
Issue Date:2018-12-10
Rights Information:Copyright 2019 Bryon Drown
Date Available in IDEALS:2019-08-23
Date Deposited:2019-05

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