The production of serine ?-lactamase is one of the primary resistance mechanisms used by Gram-negative bacterial pathogens against ?-lactam antibiotics, which include the widely used penicillins and cephalosporins, as well as last resort antibiotics such as the carbapenems. The development of novel ?-lactamase inhibitors is a pressing need underscored by the continuing mutation of ?-lactamases. We propose the development of high affinity non-covalent ?-lactamase inhibitors by targeting conserved structural motifs, particularly those essential for extended spectrum ?-lactamase activity. Prototypes of these inhibitors have already been identified. Specifically, using the CTX-M Class A ?-lactamases as a model system, we aim to: 1) apply a fragment-based and structure-guided approach to develop novel ?-lactamase inhibitor chemotypes; 2) study resistance and ligand binding by ultrahigh-resolution and room-temperature X-ray crystallography; and 3) investigate the evolution of resistance mutations against non-covalent inhibitors. These experiments will lead to new ?- lactamase inhibitors with clinical potential, while providing a deeper understanding of ?-lactamase mutations relevant to resistance evolution.

Public Health Relevance

CTX-M Class A ? -lactamase, one of the most common extended spectrum ?-lactamases in Gram-negative bacteria, confers bacterial resistance to a broad range of ?-lactam antibiotics and is the cause of great health concern. The studies outlined in this proposal aim to develop a new class of inhibitors against CTX-M and other serine ?-lactamases as well as to understand the catalytic mechanism of these enzymes. The results will contribute to the efforts of novel antibiotic development.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Drug Discovery and Mechanisms of Antimicrobial Resistance Study Section (DDR)
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Xu, Zuoyu
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University of South Florida
Schools of Medicine
United States
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