Friday, May 16, 2025
5/16/2025
NMR Fragment-based Design of New b-lactamase Inhibitors - NMR Fragment-based Design of New β-lactamase Inhibitors. SUMMARY A rapid and widespread increase in antimicrobial resistance over the past few decades has seriously threatened our capability to treat bacterial infections that may persist following treatment with last-resort antibiotics such as carbapenems and polymyxins. Given bacterial β-lactamase enzymes can degrade β-lactam antibiotics, β- lactamase inhibitors have been widely sought to improve the efficacy of this antibiotics class. Since the majority of recently approved antimicrobial agents for Gram-negative pathogens are β-lactam + β-lactamase inhibitor combinations, the validity of this approach is widely accepted. However, microbial β-lactamases are constantly evolving into new forms that can evade the activity of β-lactamase inhibitors. Nuclear magnetic resonance (NMR) spectroscopy can generate high-resolution structural and dynamics information on proteins like β-lactamases and map atomic details of interacting chemical entities like β-lactamase inhibitors. These structural details create new opportunities such as fragment-based drug discovery (FBDD). These techniques are at the forefront of many research programs and have proven successful in antimicrobial drug development. The fragment-based approach is distinct from high-throughput screening of drug libraries and has yet to be applied to β-lactamase inhibitor development. Here our objective is to expand the use of FBDD and discover new chemistry by designing inhibitors against β-lactamases TEM-1, SHV-1, PDC-3, and OXA-40. The specific goals for this project are to develop new inhibitors based on the diazabicyclooctane scaffold and to generate detailed NMR maps of this set of β-lactamases. Backed by our preliminary data that has identified 69 TEM-1 interacting fragments, our multi- faceted approach relies on structural biology, medicinal chemistry, and microbiology approaches to advance the fragment-based methodology for the identification of new β-lactamase inhibitors. These inhibitors will be designed around a drug scaffold that targets the active site of broad-spectrum β-lactamases, therefore our approach should result in the identification of potent inhibitors active against a broad spectrum of resistant bacteria. Moreover, we will perform NMR relaxation studies to explore allosteric mechanisms in β-lactamases. Public Health Impact: The World Health Organization has given the highest priority to anti-microbial research on the Gram-negative bacteria genera Acinetobacter and Pseudomonas, as well as specific species of Enterobacterales in which extensively-drug resistant strains are increasingly emerging. These resistant strains can cause systemic infection and may not respond to known antibiotics that are rendered ineffective due to specialized enzymes produced by the bacteria that degrade and thereby confer resistance to important classes of antibiotics such as β-lactams. The goal of this project is to develop a structure-based methodology to devise inhibitors against a model β-lactamase and then extend the methodology to other enzymes synthesized by extensively-drug resistant bacterial strains. The efficacy of our inhibitors will be tested in conjunction with known β-lactam antibiotics using clinical bacterial isolates and appropriate infection models.
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