Identification of the murI and murB Genes Coding for Cytoplasmic Peptidoglycan Synthetases in the 90-Min Region of the E. coli Chromosome

The main cytoplasmic precursors of peptidoglycan synthesis are a series of uridine nucleotides which have been previously characterized in Escherichia coli as UDP-N-acetylglucosamine (UDP-GlcNAc), UDP-GlcNAc-enolpyruvate, UDP-N-acetylmuramic acid (UDP-MurNAc) and its four peptide derivatives from UDP-MurNAc-L-Ala to UDP-MurNAc-L-Ala-ǒ-D-Glu-meso-DAP-D-Ala-D-Ala. Their sequential formation is catalyzed by a set of eight highly specific enzymes which were earlier studied in detail (Rogers et al., 1980; Mengin-Lecreulx and van Heijenoort, 1985).