Enzymes Synthesizing and Hydrolyzing Murein in Escherichia coli

Abstract

Envelopes from regions of the cell which in vivo show very little, if any, murein synthesis were isolated using the minicell-producing strain P678-54. Envelopes from minicells, representing in fact cell ends, synthesized murein and carried out transpeptidation in vitro; also all 4 murein hydrolase activities tested, [N-acetylmuramoyl-pentapeptide] carboxypeptidase [EC 3.4.12.6], endopeptidase [EC 3.4.99.-], [N-acetylmuramoyl-L-alanine] amidase EC [3.5.1.28] and [murein] transglycosylase [EC 3.2.1.-], were present. The specific activities of the murein synthesizing and degrading enzymes in envelopes derived from cell poles and from actively growing cells were similar. The topological distribution of murein-synthesizing enzymes and of murein hydrolases over the cell envelope is discussed.