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Structural investigations of the inhibition of Escherichia coli AmpC β-lactamase by diazabicyclooctanes

DOI: 10.1128/AAC.02073-20 DOI Help

Authors: Pauline A. Lang (University of Oxford) , Thomas M. Leissing (University of Oxford) , Malcolm G. P. Page (Jacobs University Bremen GmbH) , Christopher J. Schofield (University of Oxford) , Jurgen Brem (University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Antimicrobial Agents And Chemotherapy

State: Published (Approved)
Published: November 2020
Diamond Proposal Number(s): 19069 , 19458

Open Access Open Access

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 (SBL). The diazabicyclooctane (DBO) avibactam is a potent AmpC inhibitor; the clinical success of avibactam combined with ceftazidime has stimulated efforts to optimise 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 (AmpCEC) 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 AmpCEC inhibition. The results reveal that, under our assay conditions, zidebactam manifests increased potency (Kiapp 0.69 μM) against AmpCEC compared to the other DBOs (Kiapp 5.0-7.4 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 AmpCEC-zidebactam carbamoyl-complex compared to those for the other DBOs. The results suggest carbamoyl-complex lifetime should be a consideration in development of DBO-based SBL inhibitors for the clinically important class C SBLs.

Journal Keywords: antimicrobial resistance; serine β-lactamase inhibitors; diazabicyclooctane; avibactam; 12 relebactam; nacubactam; zidebactam; Avycaz; cephalosporin resistance

Subject Areas: Biology and Bio-materials, Chemistry, Medicine


Instruments: I03-Macromolecular Crystallography

Documents:
Antimicrobial Agents and Chemotherapy-2020-Lang-AAC.02073-20.full.pdf