title: Mutation of the Streptococcus gordonii Thiol-Disulfide Oxidoreductase SdbA Leads to Enhanced Biofilm Formation Mediated by the CiaRH Two-Component Signaling System.
abstract: Streptococcus gordonii is a commensal inhabitant of human oral biofilms. Previously, we identified an enzyme called SdbA that played an important role in biofilm formation by S. gordonii. SdbA is thiol-disulfide oxidoreductase that catalyzes disulfide bonds in secreted proteins. Surprisingly, inactivation of SdbA results in enhanced biofilm formation. In this study we investigated the basis for biofilm formation by the ΔsdbA mutant. The results revealed that biofilm formation was mediated by the interaction between the CiaRH and ComDE two-component signalling systems. Although it did not affect biofilm formation by the S. gordonii parent strain, CiaRH was upregulated in the ΔsdbA mutant and it was essential for the enhanced biofilm phenotype. The biofilm phenotype was reversed by inactivation of CiaRH or by the addition of competence stimulating peptide, the production of which is blocked by CiaRH activity. Competition assays showed that the enhanced biofilm phenotype also corresponded to increased oral colonization in mice. Thus, the interaction between SdbA, CiaRH and ComDE affects biofilm formation both in vitro and in vivo.
authors.affiliation: Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, B3H 1X5, Canada.|Canadian Center for Vaccinology, Dalhousie University and the IWK Health Centre, Halifax, NS, B3K 6R8, Canada.
authors.forename: Lauren
authors.initials: L
authors.lastname: Davey
authors.affiliation: Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, B3H 1X5, Canada.|Canadian Center for Vaccinology, Dalhousie University and the IWK Health Centre, Halifax, NS, B3K 6R8, Canada.|Department of Pediatrics, Faculty of Medicine, Dalhousie University and the IWK Health Centre, Halifax, NS, B3K 6R8, Canada.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Halperin
authors.affiliation: Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, B3H 1X5, Canada.|Canadian Center for Vaccinology, Dalhousie University and the IWK Health Centre, Halifax, NS, B3K 6R8, Canada.|Department of Pediatrics, Faculty of Medicine, Dalhousie University and the IWK Health Centre, Halifax, NS, B3K 6R8, Canada.|Department of Applied Oral Sciences, Faculty of Dentistry, Dalhousie University, Halifax, NS, B3H 4R2, Canada.
authors.forename: Song F
authors.initials: SF
authors.lastname: Lee
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D018441:Biofilms / Q000254:growth & development; D015964:Gene Expression Regulation, Bacterial; D000071677:Histidine Kinase / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D009154:Mutation; D009876:Operon / Q000235:genetics; D010641:Phenotype; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D013290:Streptococcal Infections / Q000235:genetics / Q000382:microbiology*; D054773:Streptococcus gordonii / Q000235:genetics* / Q000472:pathogenicity
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; C105449:SdbA protein, bacteria; D011494:Protein Kinases; D000071677:Histidine Kinase; C088910:CiaR protein, Streptococcus pneumoniae