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

Area of Science:

• Microbiology
• Molecular Biology
• Biochemistry

Background:

• Bacillus mojavensis strain RO-H-1 utilizes quorum sensing for natural genetic competence.
• The ComX pheromone plays a crucial role in regulating this process.
• Previous studies suggested posttranslational modification of the ComX pheromone.

Purpose of the Study:

• To elucidate the precise posttranslational modification of the ComX(RO-H-1) pheromone.
• To confirm the structure and biological activity of the modified pheromone.
• To understand the implications of this modification for quorum sensing.

Main Methods:

• Liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) analysis of partially purified ComX(RO-H-1).
• Solid-phase synthesis of the ComX(RO-H-1) pheromone.
• Biological activity assays to assess the function of the synthesized pheromone.

Main Results:

• LC/ESI-MS analysis indicated a specific modification on the tryptophan residue of ComX(RO-H-1).
• Synthesized ComX(RO-H-1) was identical to the natural pheromone and exhibited significant biological activity.
• The modification was identified as geranylation on the tryptophan residue, forming a tricyclic structure.

Conclusions:

• The ComX(RO-H-1) pheromone undergoes geranylation on its tryptophan residue, creating a unique tricyclic structure.
• This modified pheromone is essential for stimulating natural genetic competence in Bacillus mojavensis.
• The extreme acid lability of the pheromone was noted, requiring careful handling.