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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Mechanistic stoichiometry of proton translocation by cytochrome cbb3
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Mechanistic stoichiometry of proton translocation by cytochrome cbb3

机译：细胞色素cbb3质子移位的机械化学计量

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摘要

Cytochrome cbb_3 belongs to the superfamily of respiratory heme-copper oxidases that couple the reduction of molecular oxygen to proton translocation across the bacterial or mitochondrial membrane. The cbb3-type enzymes are found only in bacteria, and are both structurally and functionally the most distant from their mitochondrial counterparts. The mechanistic H+/e~- stoichiometry of proton translocation in these cbb_3-type cytochrome c oxidases has remained controversial. A stoichiometric efficiency of only one-half that of the mitochondrial aa_3-type enzyme was recently proposed to be related to adaptation of the organism to micro-aerobic environments. Here, proton translocation by the Rhodo-bacter sphaeroides enzyme was studied using purified cytochrome cbb_3 reconstituted into liposomes. An H+/e- stoichiometry of proton translocation close to unity was observed using the oxygen pulse method, but solely in conditions in which the vast majority of the enzyme was fully reduced in the anaerobic state before the O_2 pulse. These data were compared with results using whole cells or spheroplasts, and the discrepancies in the literature data were discussed. Our results suggest that a proton-pumping efficiency of 1 H+/e~- may be achieved using the single-proton uptake pathway identified in the structure of cytochrome cbb_3. The mechanism of proton pumping thus differs from that of the aa_3-type oxidases of mitochondria and bacteria.
机译：细胞色素cbb_3属于呼吸血红素-铜氧化酶的超家族，其将分子氧的还原与质子在细菌或线粒体膜上的移位结合在一起。 cbb3型酶仅在细菌中发现，在结构和功能上都与线粒体对应物最远。在这些cbb_3型细胞色素c氧化酶中质子易位的机械H + / e-化学计量仍存在争议。最近提出的化学计量效率仅为线粒体aa_3型酶的化学计量效率的一半，与该生物适应微需氧环境有关。在这里，使用重组到脂质体中的纯化的细胞色素cbb_3研究了球形红球菌酶对质子的转运。使用氧脉冲法观察到质子易位的H + /化学计量接近于统一，但仅在O_2脉冲之前厌氧状态下绝大多数酶完全还原的条件下。将这些数据与使用全细胞或原生质球的结果进行比较，并讨论文献数据中的差异。我们的结果表明，使用在细胞色素cbb_3结构中鉴定的单质子吸收途径可以实现1 H + / e〜-的质子泵浦效率。因此，质子泵送的机理不同于线粒体和细菌的aa_3型氧化酶。

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  • 作者

    Virve Rauhamaki; Dmitry A. Bloch; Marten Wikstrom;

  • 作者单位

    Helsinki Bioenergetics Group, Program for Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, 00014, Helsinki, Finland;

    Helsinki Bioenergetics Group, Program for Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, 00014, Helsinki, Finland;

    Helsinki Bioenergetics Group, Program for Structural Biology and Biophysics, Institute of Biotechnology, University of Helsinki, 00014, Helsinki, Finland;

  • 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

    cell respiration; proton pumping;

    机译：细胞呼吸质子泵;

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