Characterization of the new AmpC β-lactamase FOX-8 reveals a single mutation, Phe313Leu, located in the R2 loop that affects ceftazidime hydrolysis

Antimicrob Agents Chemother. 2013 Oct;57(10):5158-61. doi: 10.1128/AAC.00818-13. Epub 2013 Jul 22.

Abstract

A novel class C β-lactamase (FOX-8) was isolated from a clinical strain of Escherichia coli. The FOX-8 enzyme possessed a unique substitution (Phe313Leu) compared to FOX-3. Isogenic E. coli strains carrying FOX-8 showed an 8-fold reduction in resistance to ceftazidime relative to FOX-3. In a kinetic analysis, FOX-8 displayed a 33-fold reduction in kcat/Km for ceftazidime compared to FOX-3. In the FOX family of β-lactamases, the Phe313 residue located in the R2 loop affects ceftazidime hydrolysis and alters the phenotype of E. coli strains carrying this variant.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Ceftazidime / metabolism*
  • Escherichia coli / enzymology*
  • Escherichia coli / genetics
  • Escherichia coli / metabolism
  • Hydrolysis
  • Mutation
  • beta-Lactamases / genetics
  • beta-Lactamases / metabolism*

Substances

  • Bacterial Proteins
  • Ceftazidime
  • AmpC beta-lactamases
  • beta-Lactamases