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首页> 外文期刊>Journal of bacteriology >An Iron-Binding Protein, Dpr, from Streptococcus mutans Prevents Iron-Dependent Hydroxyl Radical Formation In Vitro
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An Iron-Binding Protein, Dpr, from Streptococcus mutans Prevents Iron-Dependent Hydroxyl Radical Formation In Vitro

机译：来自变形链球菌的铁结合蛋白Dpr可以防止铁依赖性羟基自由基的体外形成

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The dpr gene is an antioxidant gene which was isolated from the Streptococcus mutans chromosome by its ability to complement an alkyl hydroperoxide reductase-deficient mutant of Escherichia coli, and it was proven to play an indispensable role in oxygen tolerance in S. mutans. Here, we purified the 20-kDa dpr gene product, Dpr, from a crude extract of S. mutans as an iron-binding protein and found that Dpr formed a spherical oligomer about 9 nm in diameter. Molecular weight determinations of Dpr in solution by analytical ultracentrifugation and light-scattering analyses gave values of 223,000 to 292,000, consistent with a subunit composition of 11.5 to 15 subunits per molecule. The purified Dpr contained iron and zinc atoms and had an ability to incorporate up to 480 iron and 11.2 zinc atoms per molecule. Unlike E. coli Dps and two other members of the Dps family, Dpr was unable to bind DNA. One hundred nanomolar Dpr prevented by more than 90% the formation of hydroxyl radical generated by 10 μM iron(II) salt in vitro. The data shown in this study indicate that Dpr may act as a ferritin-like iron-binding protein in S. mutans and may allow this catalase- and heme-peroxidase-deficient bacterium to grow under air by limiting the iron-catalyzed Fenton reaction.
机译： dpr 基因是一种抗氧化基因，它是从变形链球菌染色体中分离出来的，具有补充大肠杆菌烷基氢过氧化物还原酶缺陷型突变体的能力。 >，并被证明对 S的耐氧性起着不可或缺的作用。变形。在这里，我们从 S的粗提物中纯化了20 kDa dpr 基因产物Dpr。突变体作为铁结合蛋白，发现Dpr形成了直径约9 nm的球形低聚物。通过分析超速离心和光散射分析测定溶液中Dpr的分子量，结果为223,000至292,000，与每个分子11.5至15个亚基的亚基组成一致。纯化的Dpr包含铁和锌原子，每个分子最多可结合480个铁和11.2个锌原子。与 E不同。大肠杆菌Dps和Dps家族的其他两个成员，Dpr无法结合DNA。一百纳摩尔Dpr可以阻止90％以上的10μM铁（II）盐在体外产生的羟基自由基的形成。这项研究中显示的数据表明Dpr可能在 S中充当铁蛋白样铁结合蛋白。并可能限制这种过氧化氢酶和血红素过氧化物酶的细菌通过限制铁催化的Fenton反应在空气中生长。

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