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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Menaquinone as pool quinone in a purple bacterium
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Menaquinone as pool quinone in a purple bacterium

机译：甲萘醌作为紫色细菌中的池醌

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摘要

Purple bacteria have thus far been considered to operate light-driven cyclic electron transfer chains containing ubiquinone (UQ) as liposoluble electron and proton carrier. We show that in the purple γ-proteobacterium Halorhodospira halophila, menaquinone-8 (MK-8) is the dominant quinone component and that it operates in the Q_B-site of the photosynthetic reaction center (RC). The redox potentials of the photooxidized pigment in the RC and of the Rieske center of the bc_1 complex are significantly lower (E_m = +270 mV and +110 mV, respectively) than those determined in other purple bacteria but resemble those determined for species containing MK as pool quinone. These results demonstrate that the photosynthetic cycle in H. halophila is based on MK and not on UQ. This finding together with the unusual organization of genes coding for the bc_1 complex in H. halophila suggests a specific scenario for the evolutionary transition of bioenergetic chains from the low-potential menaquinones to higher-potential UQ in the proteobacterial phylum, most probably induced by rising levels of dioxygen 2.5 billion years ago. This transition appears to necessarily proceed through bioenergetic ambivalence of the respective organisms, that is, to work both on MK- and on UQ-pools. The establishment of the corresponding low- and high-potential chains was accompanied by duplication and redox optimization of the bc_1 complex or at least of its crucial subunit oxidizing quinols from the pool, the Rieske protein. Evolutionary driving forces rationalizing the empirically observed redox tuning of the chain to the quinone pool are discussed.
机译：迄今为止，紫色细菌被认为可以操作包含泛醌（UQ）作为脂溶性电子和质子载体的光驱动循环电子转移链。我们表明，在紫色的γ-变形杆菌嗜盐螺旋藻中，甲萘醌8（MK-8）是主要的醌成分，并且它在光合作用反应中心（RC）的Q_B位运行。 RC中的光氧化色素和bc_1络合物的Rieske中心的氧化还原电势比其他紫色细菌中测得的显着低（分别为E_m = +270 mV和+110 mV），但与对含有MK的物种确定的相似作为游泳池醌。这些结果表明嗜盐嗜盐菌的光合循环是基于MK而不是基于UQ。这一发现与嗜盐杆菌中编码bc_1复合物的基因的异常组织一起，提出了一种特殊的情况，即生物能链从低电位甲萘醌向高电位UQ的进化过程，发生在蛋白杆菌门中，这很可能是由上升引起的。 25亿年前的双氧水平。这种转变似乎必须通过各个生物体的生物能矛盾来进行，也就是说，既要在MK池中也要在UQ池中工作。相应的低和高电势链的建立伴随着bc_1复合物或其至少重要的亚基氧化喹诺酮（Rieske蛋白）的复制和氧化还原优化。讨论了进化驱动力，以合理化经验观察到的链到醌池的氧化还原调节。

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    Barbara Schoepp-Cothenet; Clement Lieutaud; Frauke Baymann; Andre Vermeglio; Thorsten Friedrich; David M. Kramer; Wolfgang Nitschke;

  • 作者单位

    Laboratoire de Bioenergetique et Ingenierie des Proteines, Unite Propre de Recherche 9036, Institut Federatif de Recherche 88, Centre National de la Recherche Scientifique, F-13402 Marseille Cedex 20, France;

    Laboratoire de Bioenergetique et Ingenierie des Proteines, Unite Propre de Recherche 9036, Institut Federatif de Recherche 88, Centre National de la Recherche Scientifique, F-13402 Marseille Cedex 20, France;

    Laboratoire de Bioenergetique et Ingenierie des Proteines, Unite Propre de Recherche 9036, Institut Federatif de Recherche 88, Centre National de la Recherche Scientifique, F-13402 Marseille Cedex 20, France;

    Laboratoire de Bioenergetique Cellulaire, Unite Mixte de Recherche 163, Centre National de la Recherche Scientifique-Commissariat a I'Energie Atomique, Universite de la Mediterranee-Commissariat a I'Energie Atomique 1000, Commissariat a I'Energie Atomique Cadarache, Direction des Sciences du Vivant, Departement d'Ecophysiologie Vegetale et Microbiologie, F-13108 Saint Paul Lez Durance Cedex, France;

    Institut fur Organische Chemie und Biochemie, Albert-Ludwigs-Universitat Freiburg, Albertstr. 21, D-79104 Freiburg, Germany;

    Institute of Biological Chemistry, Washington State University, Pullman, WA 99164-6340;

    Laboratoire de Bioenergetique et Ingenierie des Proteines, Unite Propre de Recherche 9036, Institut Federatif de Recherche 88, Centre National de la Recherche Scientifique, F-13402 Marseille Cedex 20, France;

  • 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);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    electron transport; evolution; photosynthesis;

    机译：电子传输演化;光合作用;

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