Université Pierre et Marie Curie, The Marine Plants and Biomolecules Laboratory, UMR 7139, Station Biologique de Roscoff, Roscoff, France.
PLoS One. 2011;6(5):e19540. doi: 10.1371/journal.pone.0019540. Epub 2011 May 18.
The acquisition of mitochondria was a key event in eukaryote evolution. The aim of this study was to identify homologues of the components of the mitochondrial protein import machinery in the brown alga Ectocarpus and to use this information to investigate the evolutionary history of this fundamental cellular process. Detailed searches were carried out both for components of the protein import system and for related peptidases. Comparative and phylogenetic analyses were used to investigate the evolution of mitochondrial proteins during eukaryote diversification. Key observations include phylogenetic evidence for very ancient origins for many protein import components (Tim21, Tim50, for example) and indications of differences between the outer membrane receptors that recognize the mitochondrial targeting signals, suggesting replacement, rearrangement and/or emergence of new components across the major eukaryotic lineages. Overall, the mitochondrial protein import components analysed in this study confirmed a high level of conservation during evolution, indicating that most are derived from very ancient, ancestral proteins. Several of the protein import components identified in Ectocarpus, such as Tim21, Tim50 and metaxin, have also been found in other stramenopiles and this study suggests an early origin during the evolution of the eukaryotes.
线粒体的获得是真核生物进化中的一个关键事件。本研究的目的是鉴定褐藻(Ectocarpus)中线粒体蛋白输入机制的成分的同源物，并利用这些信息来研究这一基本细胞过程的进化历史。我们对线粒体蛋白输入系统的成分以及相关肽酶进行了详细的搜索。通过比较和系统发育分析来研究真核生物多样化过程中线粒体蛋白的进化。主要观察结果包括许多蛋白输入成分（例如 Tim21、Tim50）具有非常古老的起源的系统发育证据，以及识别线粒体靶向信号的外膜受体之间存在差异的迹象，这表明在主要真核生物谱系中发生了替代、重排和/或新成分的出现。总的来说，本研究中分析的线粒体蛋白输入成分在进化过程中表现出高度的保守性，表明它们大多数都来自非常古老的、原始的蛋白质。在褐藻中鉴定出的一些蛋白输入成分，如 Tim21、Tim50 和 metaxin，也在其他不等鞭毛类生物中发现，本研究表明它们在真核生物进化的早期就出现了。
