title: GraXSR proteins interact with the VraFG ABC transporter to form a five-component system required for cationic antimicrobial peptide sensing and resistance in Staphylococcus aureus.
abstract: The GraSR two-component system (TCS) controls cationic antimicrobial peptide (CAMP) resistance in Staphylococcus aureus through the synthesis of enzymes that increase bacterial cell surface positive charges, by d-alanylation of teichoic acids and lysylination of phosphatidylglycerol, leading to electrostatic repulsion of CAMPs. The GraS histidine kinase belongs to the "intramembrane-sensing kinases" subfamily, with a structure featuring a short amino-terminal sensing domain, and two transmembrane helices separated only by a short loop, thought to be buried in the cytoplasmic membrane. The GraSR TCS is in fact a multicomponent system, requiring at least one accessory protein, GraX, in order to function, which, as we show here, acts by signaling through the GraS kinase. The graXRS genes are located immediately upstream from genes encoding an ABC transporter, vraFG, whose expression is controlled by GraSR. We demonstrated that the VraFG transporter does not act as a detoxification module, as it cannot confer resistance when produced on its own, but instead plays an essential role by sensing the presence of CAMPs and signaling through GraS to activate GraR-dependent transcription. A bacterial two-hybrid approach, designed to identify interactions between the GraXSR and VraFG proteins, was carried out in order to understand how they act in detecting and signaling the presence of CAMPs. We identified many interactions between these protein pairs, notably between the GraS kinase and both GraX and the VraG permease, indicating the existence of an original five-component system involved in CAMP sensing and signal transduction to promote S. aureus resistance.
authors: Institut Pasteur, Biology of Gram-Positive Pathogens, Department of Microbiology, Paris, France.
authors: Mélanie
authors: M
authors: Falord
authors: Gouzel
authors: G
authors: Karimova
authors: Aurélia
authors: A
authors: Hiron
authors: Tarek
authors: T
authors: Msadek
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D000071677:Histidine Kinase; D006801:Humans; D026901:Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D016297:Mutagenesis, Site-Directed; D010957:Plasmids; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D011494:Protein Kinases; D000071677:Histidine Kinase