Tazobactam inactivation of SHV-1 and the inhibitor-resistant Ser130 -->Gly SHV-1 beta-lactamase: insights into the mechanism of inhibition.

Article Details

Citation

Pagan-Rodriguez D, Zhou X, Simmons R, Bethel CR, Hujer AM, Helfand MS, Jin Z, Guo B, Anderson VE, Ng LM, Bonomo RA

Tazobactam inactivation of SHV-1 and the inhibitor-resistant Ser130 -->Gly SHV-1 beta-lactamase: insights into the mechanism of inhibition.

J Biol Chem. 2004 May 7;279(19):19494-501. doi: 10.1074/jbc.M311669200. Epub 2004 Feb 2.

PubMed ID
14757767 [ View in PubMed
]
Abstract

The increasing number of bacteria resistant to combinations of beta-lactam and beta-lactamase inhibitors is creating great difficulties in the treatment of serious hospital-acquired infections. Understanding the mechanisms and structural basis for the inactivation of these inhibitor-resistant beta-lactamases provides a rationale for the design of novel compounds. In the present work, SHV-1 and the Ser(130) --> Gly inhibitor-resistant variant of SHV-1 beta-lactamase were inactivated with tazobactam, a potent class A beta-lactamase inhibitor. Apoenzymes and inhibited beta-lactamases were analyzed by liquid chromatography-electrospray ionization mass spectrometry (LC-ESI/MS), digested with trypsin, and the products resolved using LC-ESI/MS and matrix-assisted laser desorption ionization-time of flight mass spectrometry. The mass increases observed for SHV-1 and Ser(130) --> Gly (+ Delta 88 Da and + Delta 70 Da, respectively) suggest that fragmentation of tazobactam readily occurs in the inhibitor-resistant variant to yield an inactive beta-lactamase. These two mass increments are consistent with the formation of an aldehyde (+ Delta 70 Da) and a hydrated aldehyde (+ Delta 88 Da) as stable products of inhibition. Our results reveal that the Ser --> Gly substitution at amino acid position 130 is not essential for enzyme inactivation. By examining the inhibitor-resistant Ser(130) --> Gly beta-lactamase, our data are the first to show that tazobactam undergoes fragmentation while still attached to the active site Ser(70) in this enzyme. After acylation of tazobactam by Ser(130) --> Gly, inactivation proceeds independent of any additional covalent interactions.

DrugBank Data that Cites this Article

Drugs
Drug Targets
DrugTargetKindOrganismPharmacological ActionActions
TazobactamBeta-lactamase SHV-1ProteinEscherichia coli
Yes
Inhibitor
Details