Stringent control of peptidoglycan biosynthesis in Escherichia coli K-12

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Abstract
[3H]Diaminopimelic acid (Dap) was incorporated exclusively into peptidoglycan by E. coli strains auxotrophic for both lysine and Dap. The rate of [3H]Dap incorporation by stringent (rel+) strains was significantly decreased when cells were deprived of required amino acids. The addition of chloramphenicol to amino acid-starved rel+ cultures stimulated peptidoglycan and RNA synthesis. A relaxed (relA) derivative incorporated [3H]Dap at comparable rates in the presence or absence of required amino acids. Physiologically significant concentrations of guanosine 5''-diphosphate 3''-diphosphate (ppGpp) inhibited the in vitro synthesis of carrier lipid-linked intermediate and peptidoglycan catalyzed by a particulate enzyme system. The degree of inhibition was dependent on the concentration of ppGpp in the reaction mixture. Peptidoglycan synthesis is apparently stringently controlled in E. coli.