Glucose starvation response in Enterococcus faecalis JH2-2: survival and protein analysis

We investigated the survival of Enterococcus faecalis following starvation provoked by energy source glucose exhaustion. Inhibition of protein synthesis by chloramphenicol before 3 h of starvation resulted in a dramatic decrease in viable bacteria. Antibiotic treatment of cells after 3 or 6 h of starvation had a progressively lesser influence on bacterial survival. During the first 24 h of deprivation, a total of 42 proteins were identified as glucose-starvation-inducible; 4 temporal classes of proteins (A, B, C and D) were defined in relation to their enhanced synthesis after glucose exhaustion. Our results show that proteins from the two early classes (A and B) seem to be the most important for long-term survival in E. faecalis. One protein of each of these classes was analysed at the molecular level. The N-terminal sequence of one of them, belonging to class A, showed strong homology with the N-terminal sequence of carbamate kinase from Streptococcus faecium. This enzyme could be implicated in the development of alternative metabolic pathways of energy production and could be compared to the Cst proteins of Escherichia coli.