抄録
The ComX pheromone is an extracellular signaling molecule that stimulates natural genetic competence controlled by quorum sensing in Bacillus subtilis. It has been suggested that ComX pheromone is posttranslationally modified oligopeptide with an isoprenoid at its tryptophan residue, but the precise structure was not known. Recently we determined the structure of the ComXRO-E-2 pheromone, from strain RO-E-2, showing that addition of a geranyl group to a tryptophan residue results in the formation of a tricyclic structure.
Here we report the structural determination of the ComXRO-E-2 pheromone with a focus on synthetic studies as follows : syntheses of six putative ComXRO-E-2 pheromones containing 1-, 2-, 4-, 5-, 6-, or 7-geranyl substituted tryptophan residues based on the HRMS analysis of the natural pheromone, and syntheses of ComXRO-E-2 pheromone and three diastereomers containing all possible geranyl modified tryptophan residues to confirm the precise stereochemistry based on the NMR analyses of the natural pheromone.
