The stress proteome of Enterococcus faecalis

Enterococcus faecalis is a resident bacterium of the intestinal tract of hu mans and animals. This bacterium can be responsible for serious diseases an d is one of the largest causes of hospital-based infections. This hardy org anism resists many kinds of stresses and is used as a major indicator of th e hygienic quality of food, milk, and drinking water. On the other side, en terococci seem to have beneficial role in the development of cheese aroma a nd are added in certain starter cultures. Since ten years, our laboratory h as used the two-dimensional electrophoresis (2-DE) technique to study the r esponse of E, faecalis to physical or chemical stresses as well as to gluco se and total starvation. Twenty-seven protein spots on 2-D gels have been i dentified by N-terminal sequencing or Western blotting which make up the fi rst proteome database of this species. The proteins were classified in four different groups according to their function and their regulation. The fir st group comprises well-characterized proteins with known protective functi ons towards stresses. The second group contains enzymes of catabolic pathwa ys. Their implication in stress resistance seems not obvious. A third group are proteins induced in glucose-starved cells belonging to the CcpA regulo n. Induction of these enzymes under starvation may serve to increase the sc avenging capacity of the cells for nutrients or may be important to mobiliz e endogenous energetic reserves. Lastly, nine N-terminal amino acid sequenc es or open reading frames (ORF) showed no homologies with sequences in data bases. A comprehensive description of stress proteins of E faecalis and ana lysis of their patterns of expression under different environmental conditi ons would greatly increase our understanding of the molecular mechanisms un derlying the extraordinary capacity of this bacterium to survive under host ile conditions.