Function of oxygen resistance proteins in the anaerobic, sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough
Function of oxygen resistance proteins in the anaerobic, sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough
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DOI：
10.1128/jb.185.1.71-79.2003
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发表时间：
2003-01-01
影响因子：
3.2
通讯作者：
Voordouw, G
中科院分区：
文献类型：
--
作者：
Fournier, M;Zhang, Y;Voordouw, G
构建了两株缺失胞质超氧化物歧化酶sod基因和胞质过氧化氢还原酶rbr基因的普通硫弧菌突变株。他们对氧化应激的抵抗力与野生型和缺乏细胞质超氧化物还原酶基因的SOR突变体进行了比较。SOR突变体比sod突变体对暴露在空气中或内部或外部产生的超氧化物更敏感，而sod突变体又比野生型突变株更敏感。Rbr突变体没有发现明显的氧化胁迫表型，这表明普通石杉基因组中的另外两个rbr基因也可能与H_2O_2抗性有关。叠氮和H_2O_2抑制超氧化物歧化酶的活性，而氰化物则不抑制，表明它是一种含铁的超氧化物歧化酶。用双向凝胶电泳法(2DE)定位Fe-Sod和Sor的位置。2DE结果表明，连续通气细胞中SOR的显著降低可能是导致小球藻细胞死亡的一个关键因素。因此，在全好氧条件下，当超氧化物主要在细胞质中产生时，Sor在普通假丝酵母的氧气防御中起着关键作用。在微好氧条件下，当周质中含有氧敏感的、产生超氧化物的靶标时，铁-超氧化物歧化酶可能更重要。
Two mutant strains of Desulfiovibrio vulgaris Hildenborough lacking either the sod gene for periplasmic superoxide dismutase or the rbr gene for rubrerythrin, a cytoplasmic hydrogen peroxide (H2O2) reductase, were constructed. Their resistance to oxidative stress was compared to that of the wild-type and of a sor mutant lacking the gene for the cytoplasmic superoxide reductase. The sor mutant was more sensitive to exposure to air or to internally or externally generated superoxide than was the sod mutant, which was in turn more sensitive than the wild-type strain. No obvious oxidative stress phenotype was found for the rbr mutant, indicating that H2O2 resistance may also be conferred by two other rbr genes in the D. vulgaris genome. Inhibition of Sod activity by azide and H2O2, but not by cyanide, indicated it to be an iron-containing Sod. The positions of Fe-Sod and Sor were mapped by two-dimensional gel electrophoresis (2DE). A strong decrease of Sor in continuously aerated cells, indicated by 2DE, may be a critical factor in causing cell death of D. vulgaris. Thus, Sor plays a key role in oxygen defense of D. vulgaris under fully aerobic conditions, when superoxide is generated mostly in the cytoplasm. Fe-Sod may be more important under microaerophilic conditions, when the periplasm contains oxygen-sensitive, superoxide-producing targets.