Kinetic properties of four plasmid-mediated AmpC beta-lactamases

Antimicrob Agents Chemother. 2005 Oct;49(10):4240-6. doi: 10.1128/AAC.49.10.4240-4246.2005.


The heterologous production in Escherichia coli, the purification, and the kinetic characterization of four plasmid-encoded class C beta-lactamases (ACT-1, MIR-1, CMY-2, and CMY-1) were performed. Except for their instability, these enzymes are very similar to the known chromosomally encoded AmpC beta-lactamases. Their kinetic parameters did not show major differences from those obtained for the corresponding chromosomal enzymes. However, the K(m) values of CMY-2 for cefuroxime, cefotaxime, and oxacillin were significantly decreased compared to those of the chromosomal AmpC enzymes. Finally, the susceptibility patterns of different E. coli hosts producing a plasmid- or a chromosome-encoded class C enzyme toward beta-lactam antibiotics are mainly due to the overproduction of the beta-lactamase in the periplasmic space of the bacteria rather than to a specific catalytic profile of the plasmid-encoded beta-lactamases.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / biosynthesis
  • Bacterial Proteins / classification
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / isolation & purification
  • Bacterial Proteins / metabolism
  • Escherichia coli / drug effects
  • Escherichia coli / genetics
  • Kinetics
  • Plasmids / genetics*
  • beta-Lactamases / biosynthesis
  • beta-Lactamases / classification
  • beta-Lactamases / genetics*
  • beta-Lactamases / isolation & purification
  • beta-Lactamases / metabolism


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