Acid Labile ComX Pheromone from Bacillus mojavensis RO-H-1

Abstract

Bacillus mojavensis strain RO-H-1 produces a posttranslationally modified hexapeptide, the ComX_RO-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 ComX_RO-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 ComX_RO-H-1 pheromone was geranylation on the tryptophan residue, resulting in the formation of a tricyclic structure. The ComX_RO-H-1 pheromone was immediately dehydrated by acid because of its extreme acid lability.