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.
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.
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