A defect in cell wall recycling triggers autolysis during the stationary growth phase of Escherichia coli

The first gene of a family of prokaryotic proteases with a specificity for L,D-configured peptide bonds has been identified in Escherichia coli, The g ene named IdcA encodes a cytoplasmic L,D-carboxypeptidase, which releases t he terminal D-alanine from L-alanyl-D-glutamyl-meso-diaminpimelyl-D-alanine containing turnover products of the cell wall polymer murein, This reactio n turned our to be essential for survival, since disruption of the gene res ults in bacteriolysis during the stationary growth phase. Owing to a defect in muropeptide recycling the unusual murein precursor uridine 51-pyrophosp horyl N-acetylmuramyl-tetrapeptide accumulates in the mutant, The dramatic decrease observed in overall cross-linkage of the murein is explained by th e increased incorporation of tetrapeptide precursors. They can only functio n as accepters and not as donors in the crucial cross-linking reaction. It is concluded that murein recycling is a promising target for novel antibact erial agents.