Specific activation of the Bacillus quorum-sensing systems by isoprenylated pheromone variants.
Natural genetic competence in Bacillus subtilis is controlled by quorum-sensing (QS). The ComP- ComA two-component system detects the signalling molecule ComX, and this signal is transduced by a conserved phosphotransfer mechanism. ComX is synthesized as an inactive precursor and is then cleaved and modified by ComQ before export to the extracellular environment. The comQXP' loci of a set of natural Bacillus isolates have been sequenced and shown to possess a striking polymorphism that determines specific patterns of both activation and inhibition of the quorum-sensing response. We have developed a simple purification method for the modified peptide signalling pheromones allowing the characterization of four distinct ComX molecules representing different pherotypes. Genetic and biochemical evidence demonstrate that all the ComX variants are isoprenylated by the post-translational modification of a conserved tryptophan residue and that the modifications on the ComX peptide backbones vary in mass among the various pherotypes. These results give new insights into peptidemediated quorum-sensing signalling in Gram-positive bacteria and emphasize the role of isoprenylation in bacterial signal transduction.
Ansaldi
Mireille
M
Public Health Research Institute, 225 Warren Street, Newark, NJ 07103, USA.
Marolt
Darja
D
Stebe
Tina
T
Mandic-Mulec
Ines
I
Dubnau
David
D
D001412:Bacillus subtilis / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D008565:Membrane Proteins; D010453:Peptide Synthases / Q000235:genetics; D010675:Pheromones / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D011110:Polymorphism, Genetic; D017368:Protein Prenylation; D011499:Protein Processing, Post-Translational; D015398:Signal Transduction / Q000502:physiology*; D013045:Species Specificity; D014166:Transferases
D001426:Bacterial Proteins; C087040:ComX protein, Bacillus subtilis; D008565:Membrane Proteins; D010675:Pheromones; C070739:comQ protein, Bacillus subtilis; D014166:Transferases; C064995:comP protein, Bacillus subtilis; D010453:Peptide Synthases