Autolysis of a division mutant of Escherichia coli.

Abstract

The pleiotropic character of the envC chain-forming mutant of Escherichia coli was found to include leakage of periplasmic enzymes and an abnormal tendency to autolyse. Washed suspensions of envC cells released murein fragments into the supernatant, and cell extracts from the mutant were richer than those of wild type in exo-beta-N-acetylglucosaminidase (187% of the wild-type value) and in soluble endopeptidase (256%) activities, but n-acetylmuramoylamidase, D,D-carboxypeptidase, L,Dj-carboxypeptidase and transglycosylase were not markedly different. When envC cells were grown in medium containing 0.58 M-sucrose, the chains broke up into rods, the L,D-carboxypeptidase activity increased about sixfold and D,Dj-carboxypeptidase 1B about twofold. It is suggested that L,D-carboxypeptidase is involved in septum splitting. The results suggest that the triggering of autolysis in E. coli envC depends on the alteration of envelope constituents rather than on an enhanced activity of murein hydrolases.