Rational Design of Potent Activators and Inhibitors of the Enterococcus faecalis Fsr Quorum Sensing Circuit.

The increasing rate of resistance development to conventional antibiotics by bacteria necessitates the identification of alternative treatment possibilities that can reduce the ability of bacteria to adapt. Enterococcus faecalis remains the leading cause of clinical enterococci infections and has exhibited quorum sensing (QS)-dependent pathogenicity. Here, we report the development of macrocyclic peptide-based activators and inhibitors of the E. faecalis Fsr QS circuitry. To this end, we developed, optimized, and compared three synthetic routes for lactone-containing macrocyclic peptide scaffolds. We then utilized previous and current structure-activity relationship (SAR) insights of the native QS signaling peptide to rationally design the most potent activators and inhibitors of the Fsr QS circuitry identified to date. The application of these peptides could provide a means to attenuate the pathogenicity of E. faecalis without introducing significant selective pressure on the bacteria to develop resistance.