Role of cell surface glycoconjugates in E. faecalis virulence and pathogenesis

With an increasing number of bacterial antibiotic resistances, studying bacterial pathogenicity determinants has become a focus of microbiological research. E. faecalis is one of the leading causes of nosocomial infections, posing a serious threat to hospitalized patients, due to an always growing isolation of strains resistant to even last resort antibiotics, e. g. vancomycin. In this study we examined enterococcal surface components, focusing on their role in a row of important features of pathogenicity, like biofilm formation, the tremendous importance of which in the clinical setting had been underestimated for decades. Using E. faecalis deletion mutants we were able to show that modifications of enterococcal cell surface glycoconjugates like teichoic acids, leading to alterations of biophysical properties, play an important role in bacterial adaptation to and interaction with the environment. Teichoic acids are central components of the gram positive surface. Both biofilm formation and bacteria-host interactions proved to be strongly dependent on teichoic acid structure: we showed a significant impairment of these enterococcal features in both a mutant deficient in teichoic acid alanylation and a mutant with defects in glycolipid synthesis, which is necessary for correct anchoring of the lipoteichoic acid to the cell membrane. This study will help understanding the dynamics of E. faecalis pathogenicity and contribute to the search for targets of novel antibacterial therapeutics and vaccines.