Structural Investigations of the Inhibition of Escherichia coli AmpC β-Lactamase by Diazabicyclooctanes.

Abstract

β-Lactam antibiotics are presently the most important treatments for infections by pathogenic Escherichia coli, but their use is increasingly compromised by β-lactamases, including the chromosomally encoded class C AmpC serine-β-lactamases (SBLs). The diazabicyclooctane (DBO) avibactam is a potent AmpC inhibitor; the clinical success of avibactam combined with ceftazidime has stimulated efforts to optimize the DBO core. We report kinetic and structural studies, including four high-resolution crystal structures, concerning inhibition of the AmpC serine-β-lactamase from E. coli (AmpC EC ) by clinically relevant DBO-based inhibitors: avibactam, relebactam, nacubactam, and zidebactam. Kinetic analyses and mass spectrometry-based assays were used to study their mechanisms of AmpC EC inhibition. The results reveal that, under our assay conditions, zidebactam manifests increased potency (apparent inhibition constant [Kiapp], 0.69 μM) against AmpC EC compared to that of the other DBOs (Kiapp = 5.0 to 7.4 μM) due to an ∼10-fold accelerated carbamoylation rate. However, zidebactam also has an accelerated off-rate, and with sufficient preincubation time, all the DBOs manifest similar potencies. Crystallographic analyses indicate a greater conformational freedom of the AmpC EC -zidebactam carbamoyl complex compared to those for the other DBOs. The results suggest the carbamoyl complex lifetime should be a consideration in development of DBO-based SBL inhibitors for the clinically important class C SBLs.

• Authors: Pauline A Lang, Thomas M Leissing, Malcolm G P Page, Christopher J Schofield, Jürgen Brem
• Journal: Antimicrobial agents and chemotherapy (Antimicrob Agents Chemother) Vol. 65 Issue 2 (01 20 2021) ISSN: 1098-6596 [Electronic] United States
• PMID: 33199391 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2021 Lang et al.

Chemical References

• Anti-Bacterial Agents
• Azabicyclo Compounds
• Bacterial Proteins
• beta-Lactamase Inhibitors
• AmpC beta-lactamases
• beta-Lactamases

Topics

• Anti-Bacterial Agents (pharmacology)
• Azabicyclo Compounds (pharmacology)
• Bacterial Proteins (genetics)
• Escherichia coli (genetics)
• Microbial Sensitivity Tests
• beta-Lactamase Inhibitors (pharmacology)
• beta-Lactamases (genetics)