title: Involvement of NADH Oxidase in Competition and Endocarditis Virulence in Streptococcus sanguinis.
abstract: Here, we report for the first time that the Streptococcus sanguinis nox gene encoding NADH oxidase is involved in both competition with Streptococcus mutans and virulence for infective endocarditis. An S. sanguinis nox mutant was found to fail to inhibit the growth of Streptococcus mutans under microaerobic conditions. In the presence of oxygen, the recombinant Nox protein of S. sanguinis could reduce oxygen to water and oxidize NADH to NAD(+) The oxidation of NADH to NAD(+) was diminished in the nox mutant. The nox mutant exhibited decreased levels of extracellular H2O2; however, the intracellular level of H2O2 in the mutant was increased. Furthermore, the virulence of the nox mutant was attenuated in a rabbit endocarditis model. The nox mutant also was shown to be more sensitive to blood killing, oxidative and acid stresses, and reduced growth in serum. Thus, NADH oxidase contributes to multiple phenotypes related to competitiveness in the oral cavity and systemic virulence.
authors.affiliation: Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA.
authors.forename: Xiuchun
authors.initials: X
authors.lastname: Ge
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Science, Nanjing, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yu
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Science, Nanjing, China.
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Chen
authors.affiliation: Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA.
authors.forename: Weihua
authors.initials: W
authors.lastname: Chen
authors.affiliation: Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA.
authors.forename: Fadi
authors.initials: F
authors.lastname: Elrami
authors.affiliation: State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Science, Nanjing, China.
authors.forename: Fanxiang
authors.initials: F
authors.lastname: Kong
authors.affiliation: Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA.|Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia, USA.
authors.forename: Todd
authors.initials: T
authors.lastname: Kitten
authors.affiliation: Philips Institute for Oral Health Research, Virginia Commonwealth University, Richmond, Virginia, USA pxu@vcu.edu.|Department of Microbiology and Immunology, Virginia Commonwealth University, Richmond, Virginia, USA.
authors.forename: Ping
authors.initials: P
authors.lastname: Xu
mesh_terms: D000332:Aerobiosis; D000818:Animals; D000898:Antibiosis; D004195:Disease Models, Animal; D004697:Endocarditis, Bacterial / Q000382:microbiology / Q000473:pathology*; D055786:Gene Knockout Techniques; D006801:Humans; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D009243:NAD / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D010084:Oxidation-Reduction; D011817:Rabbits; D013290:Streptococcal Infections / Q000382:microbiology / Q000473:pathology*; D013295:Streptococcus mutans / Q000254:growth & development; D013298:Streptococcus sanguis / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity*; D014774:Virulence; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D009097:Multienzyme Complexes; D037521:Virulence Factors; D009243:NAD; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases