Mutational evidence for identity of penicillin-binding protein 5 in Escherichia coli with the major D-alanine carboxypeptidase IA activity.

The defect in D-alanine carboxypeptidase IA activity in the dacA11191 mutant of Escherichia coli was correlated with a defect in the release of penicillin G from penicillin-binding protein 5. The results suggest that penicillin-binding protein 5 catalyzes the major D-alanine carboxypeptidase IA activity of the wild type and that the mutation results in a defect in the deacylation step catalyzed by this enzyme.