Development of a Peptide Antagonist against fsr Quorum Sensing of Enterococcus faecalis

Enterococcus faecalis fsr quorum sensing (QS) involves an 11-residue cyclic peptide named gelatinase biosynthesis-activating pheromone (GBAP) that autoinduces two pathogenicity-related extracellular proteases in a cell density-dependent fashion. To identify anti-pathogenic agents that target fsr QS signaling, peptide antagonists of GBAP were created by our unique drug design approach based on reverse alanine scanning. First of all, a receptor-binding scaffold (RBS), [Ala4,5,6,8,9,11]Z-GBAP, was created, in which all amino acids within the ring region of GBAP, except for two essential aromatic residues, were substituted to alanine. Next, the substituted alanine residues were changed back to the original amino acid one by one, permitting selection of those peptide combinations exhibiting increased antagonist activity. After three cycles of this reverse alanine scan, [Ala5,9,11]Z-GBAP was obtained as a maximally reverted peptide (MRP) holding the strongest antagonist activity. Then, the fifth residue in MRP,...