title: Staphylococcus aureus SrrAB Affects Susceptibility to Hydrogen Peroxide and Co-Existence with Streptococcus sanguinis.
abstract: Staphylococcus aureus is a pathogen and a commensal bacterial species that is found in humans. Bacterial two-component systems (TCSs) sense and respond to environmental stresses, which include antimicrobial agents produced by other bacteria. In this study, we analyzed the relation between the TCS SrrAB and susceptibility to the hydrogen peroxide (H2O2) that is produced by Streptococcus sanguinis, which is a commensal oral streptococcus. An srrA-inactivated S. aureus mutant demonstrated low susceptibility to the H2O2 produced by S. sanguinis. We investigated the expression of anti-oxidant factors in the mutant. The expression of katA in the mutant was significantly higher than in the wild-type (WT) in the presence or absence of 0.4 mM H2O2. The expression of dps in the mutant was significantly increased compared with the WT in the presence of H2O2 but not in the absence of H2O2. A katA or a dps-inactivated mutant had high susceptibility to H2O2 compared with WT. In addition, we found that the nitric oxide detoxification protein (flavohemoglobin: Hmp), which is regulated by SrrAB, was related to H2O2 susceptibility. The hmp-inactivated mutant had slightly lower susceptibility to the H2O2 produced by S. sanguinis than did WT. When a srrA-inactivated mutant or the WT were co-cultured with S. sanguinis, the population percentage of the mutant was significantly higher than the WT. In conclusion, SrrAB regulates katA, dps and hmp expression and affects H2O2 susceptibility. Our findings suggest that SrrAB is related in vivo to the co-existence of S. aureus with S. sanguinis.
authors.affiliation: Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Oogai
authors.affiliation: Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Miki
authors.initials: M
authors.lastname: Kawada-Matsuo
authors.affiliation: Department of Oral Microbiology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Komatsuzawa
mesh_terms: D000975:Antioxidants; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D020868:Gene Silencing; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D009154:Mutation; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D013211:Staphylococcus aureus / Q000187:drug effects / Q000502:physiology*; D013298:Streptococcus sanguis / Q000502:physiology*; D013559:Symbiosis
chemical_list: D000975:Antioxidants; D001426:Bacterial Proteins; D012097:Repressor Proteins; C422459:SrrA protein, Staphyolococcus aureus; C422460:SrrB protein, Staphyolococcus aureus; D006861:Hydrogen Peroxide