Purification and properties of penicillin-binding proteins 5 and 6 from the dacA mutant strain of Escherichia coli (JE 11191).

H Amanuma,J L Strominger

doi:10.1016/s0021-9258(17)43602-7

Abstract

Penicillin-binding proteins 5 and 6 have been purified to homogeneity from the dacA mutant strain of Escherichia coli (JE 11191). Protein 6 from the mutant strain appears to be identical to that from the wild type, but protein 5 is a mutant protein which has no D-alanine carboxypeptidase activity. Moreover, the mutant protein 5 binds, but does not release, [14C]penicillin G. Correspondingly, an acyl-enzyme intermediate derived from a synthetic substrate is accumulated by the mutant protein. A comparison of the acylation site for the synthetic substrate and for penicillin G by limited proteolysis and some other properties of the mutant protein are described.

Highlights

Penicillin-binding proteins 5 and 6 have been puri- plasmic membrane of E. coli contains at least 7 PBPs
Two independently isolated mutants which lack type, but protein 5 is amutant protein which hasno D- CPase IB-C activity were shown to lack PBP 4 simultanealanine carboxypeptidase activity
A comparison of the acylation site for the synthetic substrate and for penicillin G by limited proteolysis and some other properties of the ously, indicating that PBP4 is identical or closely related to CPase IB-C [8,9]B. ased on the observed properties, such as molecular weight and interactions with penicillin G, PBPs 5 and 6 were shown to be identical with the two polypeptides found in the purified CPase IA [10]

Summary

Introduction

Penicillin-binding proteins 5 and 6 have been puri- plasmic membrane of E. coli contains at least 7 PBPs. An acyl-enzyme intermediate derived from a synthetic substrate is accumulated by the mutant protein.

Results

Conclusion