Common mechanistic features among metallo-beta-lactamases: a computational study of Aeromonas hydrophila CphA enzyme

J Biol Chem. 2009 Oct 9;284(41):28164-28171. doi: 10.1074/jbc.M109.049502. Epub 2009 Aug 11.

Abstract

Metallo-beta-lactamases (MbetaLs) constitute an increasingly serious clinical threat by giving rise to beta-lactam antibiotic resistance. They accommodate in their catalytic pocket one or two zinc ions, which are responsible for the hydrolysis of beta-lactams. Recent x-ray studies on a member of the mono-zinc B2 MbetaLs, CphA from Aeromonas hydrophila, have paved the way to mechanistic studies of this important subclass, which is selective for carbapenems. Here we have used hybrid quantum mechanical/molecular mechanical methods to investigate the enzymatic hydrolysis by CphA of the antibiotic biapenem. Our calculations describe the entire reaction and point to a new mechanistic description, which is in agreement with the available experimental evidence. Within our proposal, the zinc ion properly orients the antibiotic while directly activating a second catalytic water molecule for the completion of the hydrolytic cycle. This mechanism provides an explanation for a variety of mutagenesis experiments and points to common functional facets across B2 and B1 MbetaLs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aeromonas hydrophila / enzymology*
  • Aeromonas hydrophila / genetics
  • Anti-Infective Agents / chemistry
  • Anti-Infective Agents / metabolism
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Binding Sites
  • Computer Simulation*
  • Drug Resistance, Microbial / physiology
  • Models, Molecular
  • Molecular Structure
  • Protein Conformation
  • Quantum Theory
  • Substrate Specificity
  • Thienamycins / chemistry
  • Thienamycins / metabolism
  • beta-Lactamases / chemistry*
  • beta-Lactamases / genetics
  • beta-Lactamases / metabolism*

Substances

  • Anti-Infective Agents
  • Bacterial Proteins
  • Thienamycins
  • beta-Lactamases
  • cphA protein, Aeromonas hydrophila
  • biapenem