title: Characterization of RAP, a quorum sensing activator of Staphylococcus aureus.
abstract: Staphylococcus aureus are Gram-positive bacteria and cause diverse serious diseases in humans and animals through the production of toxins. The production of toxins is regulated by quorum sensing mechanisms, where proteins such as RNAIII activating protein (RAP) are secreted by the bacteria and induce virulence. Antibodies to RAP have been shown to protect mice from infection, but the molecular structure of RAP was not known and hindered vaccine development. To characterize RAP, recombinant protein was made and tested for its ability to induce genes important for pathogenesis (agr). In addition, monoclonal antibodies were produced to identify its cellular localization. Results shown here indicate that RAP is a 277-aa protein that is an ortholog of the ribosomal protein L2. Like the native molecule, recombinant RAP activates the production of RNAIII (encoded by agr). Using RAP specific monoclonal antibodies we demonstrate that RAP is continuously secreted and while RAP is expressed also in other bacteria (like Staphylococcus epidermidis, Staphylococcus xylosus and Escherichia coli), it is secreted to the culture medium only by S. aureus. Our results show that the ribosomal protein L2 has an extraribosomal function and that when secreted RAP acts as an autoinducer of virulence to regulate S. aureus pathogenesis.
authors.affiliation: Department of Human Microbiology, Sackler School of Medicine, Tel Aviv University, Israel.
authors.forename: Moshe
authors.initials: M
authors.lastname: Korem
authors.forename: Abhineet S
authors.initials: AS
authors.lastname: Sheoran
authors.forename: Yael
authors.initials: Y
authors.lastname: Gov
authors.forename: Saul
authors.initials: S
authors.lastname: Tzipori
authors.forename: Ilya
authors.initials: I
authors.lastname: Borovok
authors.forename: Naomi
authors.initials: N
authors.lastname: Balaban
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins; D002352:Carrier Proteins / Q000235:genetics* / Q000276:immunology / Q000378:metabolism; D005260:Female; D015964:Gene Expression Regulation, Bacterial; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000378:metabolism; D016372:RNA, Antisense / Q000378:metabolism; D012329:RNA, Bacterial / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D013203:Staphylococcal Infections / Q000382:microbiology*; D013211:Staphylococcus aureus / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D014774:Virulence
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins; D002352:Carrier Proteins; D010750:Phosphoproteins; C428447:RAP protein, Staphylococcus aureus; D016372:RNA, Antisense; D012329:RNA, Bacterial; C096035:RNAIII, Staphylococcus aureus; D011994:Recombinant Proteins; C428446:TRAP protein, Staphylococcus