Cell wall polymers of Bacillus sphaericus: activities of enzymes involved in peptidoglycan precursor synthesis during sporulation

Abstract

In synchronously sporulating cells of Bacillus sphaericus 9602, the specific activities of those enzymes specifically required for the synthesis of the UDP-N-acetyl-muramyl-pentapeptide precursor of vegetative cell wall peptidoglycan decay by 50% after the end of exponential cell division, probably as a consequence of dilution by newly synthesized protein. The meso-diaminopimelate ligase is the only new activity whose synthesis is required for synthesis of the nucleotide-pentapeptide precursor of spore cortex peptidoglycan. The addition of d-Ala-d-Ala to the nucleotide tripeptide is catalyzed by an enzyme present in both vegetative and sporulating cells, which apparently does not discriminate between lysine- and diaminopimelate-containing acceptors. The activities of the l-Ala and d-Ala-d-Ala ligases and of the d-Ala-d-Ala synthetase increases in parallel with the appearance of the diaminopimelate ligase, indicating coordinate derepression and suggesting operon-like organization of the appropriate structural genes.