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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Mechanism of oxygen detoxification by the surprisingly oxygen-tolerant hyperthermophilic archaeon, Pyrococcus furiosus
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Mechanism of oxygen detoxification by the surprisingly oxygen-tolerant hyperthermophilic archaeon, Pyrococcus furiosus

机译：令人惊讶的耐氧高温嗜热古菌Pyrococcus furiosus解毒的机理

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摘要

The anaerobic archaeon Pyrococcus furiosus grows by fermenting carbohydrates producing H_2, CO_2, and acetate. We show here that it is surprisingly tolerant to oxygen, growing well in the presence of 8% (vol/vol) O_2. Although cell growth and acetate production were not significantly affected by O_2, H_2 production was reduced by 50% (using 8% O_2). The amount of H_2 produced decreased in a linear manner with increasing concentrations of O_2 over the range 2-12% (vol/vol), and for each mole of O_2 consumed, the amount of H_2 produced decreased by approximately 2 mol. The recycling of H_2 by the two cytoplasmic hydrogenases appeared not to play a role in O_2 resistance because a mutant strain lacking both enzymes was not more sensitive to O_2 than the parent strain. Decreased H_2 production was also not due to inactivation of the H_2-producing, ferredoxin-dependent membrane-bound hydrogenase because its activity was unaffected by O_2 exposure. Electrons from carbohydrate oxidation must therefore be diverted to relieve O_2 stress at the level of reduced ferredoxin before H_2 production. Deletion strains lacking superoxide reductase (SOR) and putative flavo-diiron protein A showed increased sensitivity to O_2, indicating that these enzymes play primary roles in resisting O_2. However, a mutant strain lacking the proposed electron donor to SOR, rubre-doxin, was unaffected in response to O_2. Hence, electrons from sugar oxidation normally used to produce H_2 are diverted to O_2 detoxification by SOR and putative flavodiiron protein A, but the electron flow pathway from ferredoxin does not necessarily involve rubredoxin.
机译：厌氧古细菌激烈热球菌通过发酵产生H_2，CO_2和乙酸盐的碳水化合物而生长。我们在这里表明，它令人惊讶地耐受氧气，在8％（vol / vol）O_2存在下生长良好。尽管O_2对细胞的生长和乙酸盐的产生没有显着影响，但H_2的产生却减少了50％（使用8％的O_2）。在2-12％（体积/体积）范围内，随着O_2浓度的增加，产生的H_2量呈线性下降，并且每消耗一摩尔O_2，产生的H_2量减少约2 mol。两种胞质氢化酶对H_2的循环利用似乎不对O_2产生抗性，因为缺少这两种酶的突变菌株对O_2的敏感性不比亲本菌株高。减少H_2的产生也不是由于产生H_2的铁氧还蛋白依赖性膜结合氢酶的失活，因为其活性不受O_2暴露的影响。因此，在H_2产生之前，必须将碳水化合物氧化产生的电子转移以减轻O_2氧化还原铁水平的水平。缺少超氧化物还原酶（SOR）和推定的黄酮-二铁蛋白A的删除菌株显示出对O_2的敏感性增加，表明这些酶在抵抗O_2中起主要作用。但是，缺少对SOR提议的电子供体rubre-doxin的突变株，对O_2的反应不受影响。因此，通常用于产生H_2的糖氧化电子被SOR和推定的黄酮二铁蛋白A转移至O_2解毒，但是来自铁氧还蛋白的电子流动路径不一定涉及红氧还蛋白。

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    Michael P. Thorgersen; Karen Stirrett; Robert A. Scott; Michael W. W. Adams;

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    Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602;

    Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602;

    Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602;

    Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602;

  • 收录信息 美国《科学引文索引》(SCI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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