Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476, Potsdam-Golm, Germany.
Institut de Biologie Moléculaire des Plantes du CNRS, 12 Rue du Général Zimmer, 67084, Strasbourg, France.
Plant J. 2019 Feb;97(3):447-459. doi: 10.1111/tpj.14133. Epub 2018 Nov 27.
All present-day mitochondria originate from a single endosymbiotic event that gave rise to the last eukaryotic common ancestor more than a billion years ago. However, to date, many aspects of mitochondrial evolution have remained unresolved. Comparative genomics and proteomics have revealed a complex evolutionary origin for many mitochondrial components. To understand the evolution of the respiratory chain, we have examined both the components and the mechanisms of the assembly pathway of complex I. Complex I represents the first enzyme in the respiratory chain, and complex I deficiencies have dramatic consequences in both animals and plants. The complex is located in the mitochondrial inner membrane and possesses two arms: one embedded in the inner membrane and one protruding in the matrix. Here, we describe the assembly pathway of complex I in the model plant Arabidopsis thaliana. Using a proteomics approach called complexome profiling, we have resolved the different steps in the assembly process in plants. We propose a model for the stepwise assembly of complex I, including every subunit. We then compare this pathway with the corresponding pathway in humans and find that complex I assembly in plants follows a different, and likely ancestral, pathway compared with the one in humans. We show that the main evolutionary changes in complex I structure and assembly in humans occurred at the level of the membrane arm, whereas the matrix arm remained rather conserved.
所有现代的线粒体都起源于一个单一的内共生事件，该事件导致了超过 10 亿年前最后一个真核生物共同祖先的出现。然而，迄今为止，线粒体进化的许多方面仍未得到解决。比较基因组学和蛋白质组学揭示了许多线粒体成分复杂的进化起源。为了了解呼吸链的进化，我们既检查了复合物 I 的组件，也检查了其组装途径的机制。复合物 I 代表呼吸链中的第一个酶，复合物 I 的缺陷在动物和植物中都有巨大的影响。该复合物位于线粒体的内膜中，具有两个臂：一个嵌入在内膜中，一个突出在基质中。在这里，我们描述了模型植物拟南芥中复合物 I 的组装途径。使用一种称为复合物组学分析的蛋白质组学方法，我们已经解析了植物中组装过程的不同步骤。我们提出了一个包括每个亚基的复合物 I 逐步组装的模型。然后，我们将该途径与人类的相应途径进行比较，发现植物中复合物 I 的组装遵循与人类不同的、可能是祖先的途径。我们表明，人类中复合物 I 结构和组装的主要进化变化发生在膜臂水平，而基质臂则相对保守。
