Non-mitochondrial complex I proteins in a hydrogenosomal oxidoreductase complex
Non-mitochondrial complex I proteins in a hydrogenosomal oxidoreductase complex
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DOI：
10.1038/nature02990
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发表时间：
2004-10-28
期刊：
影响因子：
64.8
通讯作者：
Johnson, PJ
中科院分区：
文献类型：
--
作者：
Dyall, SD;Yan, WH;Johnson, PJ
阴道毛滴虫是一种单细胞微需氧真核生物，缺乏线粒体，但含有参与丙酮酸代谢的替代细胞器，氢酶体。这两种细胞器之间的途径有很大的不同：在氢小体中，丙酮酸氧化是由丙酮酸：铁氧还蛋白氧化还原酶（PFOR）催化的，电子被提供给产生氢的[ Fe]氢化酶。与线粒体中的氧化磷酸化相反，ATP仅通过氢化体中底物水平的磷酸化产生（1）。PFOR和氢化酶存在于真细菌和无线粒体真核生物中，但不存在于典型的线粒体中（2-4）。线粒体基因组的分析表明，线粒体具有来自α-变形菌型祖先的单一内共生起源（5）。毛滴虫氢化酶体中缺少基因组（6）排除了这种比较，使这种细胞器的内共生历史不清楚（7）。尽管一些蛋白质的系统发育重建表明毛滴虫氢化酶体与线粒体具有共同的起源（8-11），但其他蛋白质则没有（2- 4，7）。在这里，我们描述了一种新的呼吸复合物I的NADH脱氢酶模块，它与中央氢体发酵途径相结合，形成一个氢体氧化还原酶复合物，该复合物似乎独立于醌类发挥作用。系统发育分析氢体复合物I样蛋白Ndh 51和Ndh 24显示，既没有一个共同的起源与线粒体同源物。这些研究反对毛滴虫氢化酶体从原线粒体内共生体的垂直起源。
Trichomonas vaginalis is a unicellular microaerophilic eukaryote that lacks mitochondria yet contains an alternative organelle, the hydrogenosome, involved in pyruvate metabolism. Pathways between the two organelles differ substantially: in hydrogenosomes, pyruvate oxidation is catalysed by pyruvate: ferredoxin oxidoreductase (PFOR), with electrons donated to an [ Fe]hydrogenase which produces hydrogen. ATP is generated exclusively by substrate-level phosphorylation in hydrogenosomes, as opposed to oxidative phosphorylation in mitochondria(1). PFOR and hydrogenase are found in eubacteria and amitochondriate eukaryotes, but not in typical mitochondria(2-4). Analyses of mitochondrial genomes indicate that mitochondria have a single endosymbiotic origin from an alpha-proteobacterial-type progenitor(5). The absence of a genome in trichomonad hydrogenosomes(6) precludes such comparisons, leaving the endosymbiotic history of this organelle unclear(7). Although phylogenetic reconstructions of a few proteins indicate that trichomonad hydrogenosomes share a common origin with mitochondria(8-11), others do not(2-4,7). Here we describe a novel NADH dehydrogenase module of respiratory complex I that is coupled to the central hydrogenosomal fermentative pathway to form a hydrogenosomal oxidoreductase complex that seems to function independently of quinones. Phylogenetic analyses of hydrogenosomal complex I-like proteins Ndh51 and Ndh24 reveal that neither has a common origin with mitochondrial homologues. These studies argue against a vertical origin of trichomonad hydrogenosomes from the proto-mitochondrial endosymbiont.