title: High genetic variability of the agr locus in Staphylococcus species.
abstract: The agr quorum-sensing and signal transduction system was initially described in Staphylococcus aureus, where four distinct allelic variants have been sequenced. Western blotting suggests the presence of homologous loci in many other staphylococci, and this has been confirmed for S. epidermidis and S. lugdunensis. In this study we isolated agr-like loci from a range of staphylococci by using PCR amplification from primers common to the six published agr sequences and bracketing the most variable region, associated with quorum-sensing specificity. Positive amplifications were obtained from 14 of 34 staphylococcal species or subspecies tested. Sequences of the amplicons identified 24 distinct variants which exhibited extensive sequence divergence with only 10% of the nucleotides absolutely conserved on multiple alignment. This variability involved all three open reading frames involved in quorum sensing and signal transduction. However, these variants retained several protein signatures, including the conserved cysteine residue of the autoinducing peptide, with the exception of S. intermedius of pigeon origin, which contained a serine in place of cysteine at this position. We discuss hypotheses on the mode of action and the molecular evolution of the agr locus based on comparisons between the newly determined sequences.
authors.affiliation: Centre Nationale des Toxémies à Staphylococques, EA1655, Faculté de Médecine Laennec, Lyon, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Dufour
authors.forename: Sophie
authors.initials: S
authors.lastname: Jarraud
authors.forename: Francois
authors.initials: F
authors.lastname: Vandenesch
authors.forename: Timothy
authors.initials: T
authors.lastname: Greenland
authors.forename: Richard P
authors.initials: RP
authors.lastname: Novick
authors.forename: Michele
authors.initials: M
authors.lastname: Bes
authors.forename: Jerome
authors.initials: J
authors.lastname: Etienne
authors.forename: Gerard
authors.initials: G
authors.lastname: Lina
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D017124:Conserved Sequence; D019143:Evolution, Molecular; D005798:Genes, Bacterial; D014644:Genetic Variation; D000071677:Histidine Kinase; D010456:Peptides, Cyclic; D011494:Protein Kinases / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013210:Staphylococcus / Q000145:classification / Q000235:genetics*
chemical_list: C414533:AgrB protein, Staphylococcus aureus; C414532:AgrD protein, Staphylococcus; D001426:Bacterial Proteins; D010456:Peptides, Cyclic; D011494:Protein Kinases; D000071677:Histidine Kinase