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Specific activation of the Bacillus quorum‐sensing systems by isoprenylated pheromone variants
Author(s) -
Ansaldi Mireille,
Marolt Darja,
Stebe Tina,
MandicMulec Ines,
Dubnau David
Publication year - 2002
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.2002.02977.x
Subject(s) - quorum sensing , biology , bacillus subtilis , signal transduction , homoserine , genetics , bacteria , microbiology and biotechnology , biofilm
Summary 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.