Sequences of homologous beta-lactamases from clinical isolates of Serratia marcescens with different substrate specificities

Antimicrob Agents Chemother. 1998 Jan;42(1):176-9. doi: 10.1128/AAC.42.1.176.

Abstract

Genes for two group 1 beta-lactamases, SRT-1 and SST-1, were sequenced. These beta-lactamases were produced by clinical isolates of Serratia marcescens, isolates GN16694 and GN19450, respectively. The resulting enzymes were 96% identical. SRT-1 hydrolyzed oxyimino cephalosporins, but SST-1 hardly hydrolyzed them. At residue 213 in the third motif, which is conserved among group 1 beta-lactamases, SRT-1 and SST-1 had Lys and Glu, respectively. By site-directed mutagenesis, the substitution of Glu by Lys at residue 213 in SST-1 resulted in an enzyme that hydrolyzed oxyimino cephalosporins.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Cephalosporins / metabolism
  • Humans
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Serratia marcescens / enzymology*
  • Serratia marcescens / genetics
  • Substrate Specificity
  • beta-Lactamases / genetics*
  • beta-Lactamases / metabolism*

Substances

  • Cephalosporins
  • beta-Lactamases

Associated data

  • GENBANK/AB008454
  • GENBANK/AB008455