Acid labile ComX pheromone from Bacillus mojavensis RO-H-1

Bacillus mojavensis strain RO-H-1 produces a post-translationally modified hexapeptide, the COMXRO-H-1 pheromone, that stimulates natural genetic competence controlled by quorum sensing. LC/ESI-MS analysis of partially purification of the ComX(RO-H-1) pheromone suggested a precise modification in its tryptophan residue. The corresponding COMXRO-H-1 pheromone prepared by solid-phase synthesis was identical to the natural pheromone, and showed significant biological activity. These results indicated that the posttranslational modification of the COMXRO-H-1 pheromone was geranylation on the tryptophan residue, resulting in the formation of a tricyclic structure. The COMXRO-H-1 pheromone was immediately dehydrated by acid because of its extreme acid lability.