Role of protein synthesis in the survival of carbon-starved Escherichia coli K-12

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Abstract
In a typical E. coli K-12 culture starved for glucose, 50% of the cells lose viability in .apprx. 6 days. Inhibition of protein synthesis by chloramphenicol resulted in a more rapid loss of viability in glucose-starved E. coli K-12 cultures. The more chloramphenicol added (i.e., the more protein synthesis was inhibited) and the earlier during starvation it was added, the greater was its effect on culture viability. Chloramphenicol had the same effect on a relA strains as on an isogenic relA+ strain of E. coli. Addition of the amino acid analogs S-2-aminoethylcysteine, 7-azatryptophan and p-fluorophenylalanine to C-starved cultures to induce synthesis of abnormal proteins had an effect on viability similar to that observed when 50 .mu.g of chloramphenicol/ml was added at 0 time for starvation. Both chloramphenicol and the amino acid analogs had delayed effects on viability compared with their effects on synthesis of normal proteins. The need for protein synthesis did not arise from cryptic growth, since no cryptic growth of the starving cells was observed under the conditions used. These and previous results obtained from work with peptidase-deficient mutants of E. coli K-12 and Salmonella typhimurium LT2, indicate that a number of survival-related proteins are synthesized by E. coli K-12 cells as a response to C starvation. These proteins are largely synthesized during the early hours of starvation, but their continued activity is required for long-term survival.