Streptococcus mutans H2O2-forming NADH oxidase is an alkyl hydroperoxide reductase protein.
Streptococcus mutans H2O2-forming NADH oxidase is an alkyl hydroperoxide reductase protein.
复制标题
变形链球菌 H2O2 形成 NADH 氧化酶是一种烷基氢过氧化物还原酶蛋白。
DOI：
10.1016/s0891-5849(99)00218-x
复制
发表时间：
2000
影响因子：
7.4
通讯作者：
Kamio,Y
中科院分区：
文献类型：
--
作者：
Poole,LB;Higuchi,M;Shimada,M;Calzi,ML;Kamio,Y
Nox-1 from Streptococcus mutans, the bacteria which cause dental caries, was previously identified as an H2O2-forming reduced nicotinamide adenine dinucleotide (NADH) oxidase. Nox-1 is homologous with the flavoprotein component, AhpF, of Salmonella typhimurium alkyl hydroperoxide reductase. A partial open reading frame upstream of nox1, homologous with the other (peroxidase) component, ahpC, from the S. typhimurium system, was also identified. We report here the complete sequence of S. mutans ahpC. Analyses of purified AhpC together with Nox-1 have verified that these proteins act as a cysteine-based peroxidase system in S. mutans, catalyzing the NADH-dependent reduction of organic hydroperoxides or H2O2to their respective alcohols and/or H2O. These proteins also catalyze the four-electron reduction of O2to H2O, clarifying the role of Nox-1 as a protective protein against oxygen toxicity. Major differences between Nox-1 and AhpF include: (i) the absolute specificity of Nox-1 for NADH; (ii) lower amounts of flavin semiquinone and a more prominent FADH2to NAD+charge transfer absorbance band stabilized by Nox-1; and (iii) even higher redox potentials of disulfide centers relative to flavin for Nox-1. Although Nox-1 and AhpC from S. mutans were shown to play a protective role against oxidative stress in vitro and in vivo in Escherichia coli, the lack of a significant effect on deletion of these genes from S. mutans suggests the presence of additional antioxidant proteins in these bacteria.
