5ZA2

Fox-4 beta-lactamase complexed with avibactam

Summary for 5ZA2

• Entry DOI: 10.2210/pdb5za2/pdb
• Descriptor: Beta-lactamase, (2S,5R)-1-formyl-5-[(sulfooxy)amino]piperidine-2-carboxamide, GLYCEROL, ... (6 entities in total)
• Functional Keywords: beta-lactamase drug resistance, hydrolase
• Biological source: Escherichia coli; More
• Total number of polymer chains: 2
• Total formula weight: 77306.15

Authors

Nukaga, M.,Hoshino, T.,Papp-Wallace, K.M.,Bonomo, R.A. (deposition date: 2018-02-06, release date: 2018-03-07, Last modification date: 2024-10-30)

Primary citation

Nukaga, M.,Papp-Wallace, K.M.,Hoshino, T.,Lefurgy, S.T.,Bethel, C.R.,Barnes, M.D.,Zeiser, E.T.,Johnson, J.K.,Bonomo, R.A.
Probing the Mechanism of Inactivation of the FOX-4 Cephamycinase by Avibactam
Antimicrob. Agents Chemother., 62:-, 2018

PubMed Abstract: Ceftazidime-avibactam is a "second-generation" β-lactam-β-lactamase inhibitor combination that is effective against expressing class A extended-spectrum β-lactamases, class A carbapenemases, and/or class C cephalosporinases. Knowledge of the interactions of avibactam, a diazabicyclooctane with different β-lactamases, is required to anticipate future resistance threats. FOX family β-lactamases possess unique hydrolytic properties with a broadened substrate profile to include cephamycins, partly as a result of an isoleucine at position 346, instead of the conserved asparagine found in most AmpCs. Interestingly, a single amino acid substitution at N346 in the AmpC is implicated in resistance to the aztreonam-avibactam combination. In order to understand how diverse active-site topologies affect avibactam inhibition, we tested a panel of clinical isolates producing using ceftazidime-avibactam, determined the biochemical parameters for inhibition using the FOX-4 variant, and probed the atomic structure of avibactam with FOX-4. Avibactam restored susceptibility to ceftazidime for most isolates producing ; two isolates, one expressing and the other producing , displayed an MIC of 16 μg/ml for the combination. FOX-4 possessed a / value of 1,800 ± 100 M · s and an off rate () of 0.0013 ± 0.0003 s Mass spectrometry showed that the FOX-4-avibactam complex did not undergo chemical modification for 24 h. Analysis of the crystal structure of FOX-4 with avibactam at a 1.5-Å resolution revealed a unique characteristic of this AmpC β-lactamase. Unlike in the -derived cephalosporinase 1 (PDC-1)-avibactam crystal structure, interactions (e.g., hydrogen bonding) between avibactam and position I346 in FOX-4 are not evident. Furthermore, another residue is not observed to be close enough to compensate for the loss of these critical hydrogen-bonding interactions. This observation supports findings from the inhibition analysis of FOX-4; FOX-4 possessed the highest (dissociation constant) value (1,600 nM) for avibactam compared to other AmpCs (7 to 660 nM). Medicinal chemists must consider the properties of extended-spectrum AmpCs, such as the FOX β-lactamases, for the design of future diazabicyclooctanes.

PubMed: 29439972
DOI: 10.1128/AAC.02371-17

Experimental method

X-RAY DIFFRACTION (1.503 Å)