Characterization and amino acid sequence analysis of a new oxyimino cephalosporin-hydrolyzing class A beta-lactamase from Serratia fonticola CUV

Biochim Biophys Acta. 1997 Aug 15;1341(1):58-70. doi: 10.1016/s0167-4838(97)00020-4.


Serratia fonticola CUV produces two isoenzymes (forms I and II) with beta-lactamase activity which were purified by a five-step procedure. The isoenzymes had identical kinetic parameters and isoelectric point (pI = 8.12). They were characterized by a specific activity towards benzylpenicillin of 1650 U/mg. The beta-lactamase hydrolyzed benzylpenicillin, amoxycillin, ureidopenicillins, first- and second-generation cephalosporins. Carboxypenicillins and isoxazolylpenicillins were hydrolyzed to a lesser extent. Towards cefotaxime and ceftriaxone (third-generation cephalosporins), the S. fonticola enzyme exhibited catalytic efficiencies much higher than those of MEN-1 and extended-spectrum TEM derivative beta-lactamases. The beta-lactamase from S. fonticola was markedly inhibited by beta-lactamase inhibitors such as clavulanic acid, sulbactam and tazobactam. The purified isoenzymes were digested by trypsin, endoproteinase Asp-N and chymotrypsin. Amino acid sequence determinations of the resulting peptides allowed the alignment of 267 amino acid residues (Swiss-Prot, accession number P 80545) for form I beta-lactamase. Form II is five residues shorter than form I at its N-terminus. From amino acid sequence comparisons, S. fonticola CUV beta-lactamase was found to share more than 69.3% identity with the chromosomally encoded beta-lactamases of Klebsiella oxytoca, Proteus vulgaris, Citrobacter diversus and the plasmid-mediated enzymes MEN-1 and Toho-1. Therefore, the oxyimino cephalosporin-hydrolyzing beta-lactamase of S. fonticola belongs to Ambler's class A. Contribution of the serine at ABL 237 in the broad-spectrum activity of these beta-lactamases is discussed.

Publication types

  • Comparative Study

MeSH terms

  • Amino Acid Sequence
  • Cephalosporins / metabolism*
  • Chymotrypsin
  • Drug Resistance, Microbial
  • Endopeptidases
  • Isoenzymes / isolation & purification
  • Isoenzymes / metabolism
  • Kinetics
  • Metalloendopeptidases
  • Molecular Sequence Data
  • Sequence Alignment
  • Serratia / enzymology*
  • Serratia / genetics
  • Serratia / isolation & purification
  • Trypsin
  • beta-Lactamases / isolation & purification
  • beta-Lactamases / metabolism*


  • Cephalosporins
  • Isoenzymes
  • Endopeptidases
  • Chymotrypsin
  • Trypsin
  • Metalloendopeptidases
  • endoproteinase Asp-N
  • beta-Lactamases

Associated data

  • PDB/2BLM