Isolation and Structure of theEnterococcus faecalisSex Pheromone, cOBl, That Induces Conjugal Transfer of the Hemolysin/Bacteriocin Plasmids, pOBl and pYI1

A bacterial sex pheromone, cOB1, which induces conjugal transfer of the Enterococcus faecalis hemolysin-bacteriocin (Hly/Bac) plasmid, pOB1, was isolated from the culture broth of pOB1-free E. faecalis. Its structure was found to be a hydrophobic octapeptide, H-Val-Ala-Val-Leu-Val-Leu-Gly-Ala-OH. The cOB1 peptide induced the mating response of not only pOB1 but also another incompatibility group Hly/Bac plasmid, pYI1.