Yoshida Yamato
Department of Science, College of Science, Ibaraki University, Ibaraki, 310-8512, Japan.
J Plant Res. 2018 Sep;131(5):727-734. doi: 10.1007/s10265-018-1050-9. Epub 2018 Jun 12.
Chloroplasts (plastids) and mitochondria evolved from endosymbiotic bacteria. These organelles perform vital functions in photosynthetic eukaryotes, such as harvesting and converting energy for use in biological processes. Consistent with their evolutionary origins, plastids and mitochondria proliferate by the binary fission of pre-existing organelles. Here, I review the structures and functions of the supramolecular machineries driving plastid and mitochondrial division, which were discovered and first studied in the primitive red alga Cyanidioschyzon merolae. In the past decade, intact division machineries have been isolated from plastids and mitochondria and examined to investigate their underlying structure and molecular mechanisms. A series of studies has elucidated how these division machineries assemble and transform during the fission of these organelles, and which of the component proteins generate the motive force for their contraction. Plastid- and mitochondrial-division machineries have important similarities in their structures and mechanisms despite sharing no component proteins, implying that these division machineries evolved in parallel. The establishment of these division machineries might have enabled the host eukaryotic ancestor to permanently retain these endosymbiotic organelles by regulating their binary fission and the equal distribution of resources to daughter cells. These findings provide key insights into the establishment of endosymbiotic organelles and have opened new avenues of research into their evolution and mechanisms of proliferation.
叶绿体（质体）和线粒体起源于内共生细菌。这些细胞器在光合真核生物中发挥着至关重要的功能，比如收集和转换能量以供生物过程使用。与它们的进化起源一致，质体和线粒体通过已有细胞器的二分裂进行增殖。在此，我综述了驱动质体和线粒体分裂的超分子机器的结构与功能，这些机器是在原始红藻梅氏嗜热栖热菌中首次被发现并研究的。在过去十年里，完整的分裂机器已从质体和线粒体中分离出来，并对其进行研究以探究其潜在结构和分子机制。一系列研究阐明了这些分裂机器在这些细胞器分裂过程中是如何组装和转变的，以及哪些组成蛋白产生了它们收缩的动力。质体和线粒体分裂机器在结构和机制上有重要的相似之处，尽管它们没有共同的组成蛋白，这意味着这些分裂机器是平行进化的。这些分裂机器的建立可能使宿主真核生物祖先能够通过调节它们的二分裂以及向子细胞平等分配资源来永久保留这些内共生细胞器。这些发现为内共生细胞器的建立提供了关键见解，并开辟了关于其进化和增殖机制的新研究途径。
