title: Transmembrane topology and histidine protein kinase activity of AgrC, the agr signal receptor in Staphylococcus aureus.
abstract: The agr P2 operon in Staphylococcus aureus codes for the elements of a density-sensing cassette made up of a typical two-component signalling system and its corresponding inducer. It is postulated that the autoinducer, a post-translationally modified octapeptide generated from the AgrD peptide, interacts with a receptor protein, coded by agrC, to transmit a signal via AgrA regulating expression of staphylococcal virulence genes through expression of agr RNA III. We show by analysis of PhoA fusions that AgrC is a transmembrane protein, and confirm using Western blotting that a 46 kDa protein corresponding to AgrC is present in the bacterial membrane. This protein is autophosphorylated on a histidine residue only in response to supernatants from an agr+ strain, and can also respond to the purified native octapeptide. A recombinant fusion protein where most of the N-terminal region of AgrC is replaced by the Escherichia coli maltose-binding protein is also autophosphorylated in response to stimulation by agr+ supernatants or purified octapeptide. We conclude that AgrC is the sensor molecule of a typical two-component signal system in S. aureus, and that the ligand-binding site of AgrC is probably located in the third extracellular loop of the protein.
authors.affiliation: UPRES EA1655, Faculté de Médecine Laennec, Lyon, France. geralina@univ-lyon1.fr
authors.forename: G
authors.initials: G
authors.lastname: Lina
authors.forename: S
authors.initials: S
authors.lastname: Jarraud
authors.forename: G
authors.initials: G
authors.lastname: Ji
authors.forename: T
authors.initials: T
authors.lastname: Greenland
authors.forename: A
authors.initials: A
authors.lastname: Pedraza
authors.forename: J
authors.initials: J
authors.lastname: Etienne
authors.forename: R P
authors.initials: RP
authors.lastname: Novick
authors.forename: F
authors.initials: F
authors.lastname: Vandenesch
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D015153:Blotting, Western; D002458:Cell Fractionation; D015964:Gene Expression Regulation, Bacterial; D006639:Histidine / Q000378:metabolism*; D000071677:Histidine Kinase; D010766:Phosphorylation; D011485:Protein Binding; D011494:Protein Kinases / Q000737:chemistry* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D011995:Recombination, Genetic; D015398:Signal Transduction; D013211:Staphylococcus aureus / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014774:Virulence / Q000235:genetics
chemical_list: C095698:Agr protein, Staphylococcus aureus; D001426:Bacterial Proteins; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D006639:Histidine; D011494:Protein Kinases; D000071677:Histidine Kinase