title: A mutant of Escherichia coli defective in penicillin-binding protein 5 and lacking D-alanine carboxypeptidase IA.
abstract: A mutant of Escherichia coli defective in penicillin-binding protein 5 activity was isolated. The mutation (pfv) was shown to be located at 14.0 min on the E. coli chromosome map. Loss of penicillin-binding protein 5 in the pfv mutant was associated with the loss of D-alanine carboxypeptidase IA activity and increased sensitivity to beta-lactam antibiotics. We conclude that penicillin-binding protein 5 catalyzes the major D-alanine carboxypeptidase IA activity and that the enzyme activity, in vivo, protects E. coli cells from killing by low inhibitory concentrations of beta-lactam antibiotics.
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000502:physiology; D002268:Carboxypeptidases / Q000235:genetics*; D002352:Carrier Proteins / Q000235:genetics* / Q000502:physiology; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D002267:Muramoylpentapeptide Carboxypeptidase / Q000235:genetics* / Q000502:physiology; D009154:Mutation; D010400:Penicillin G / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D002352:Carrier Proteins; D002268:Carboxypeptidases; D002267:Muramoylpentapeptide Carboxypeptidase; D010400:Penicillin G