Single-membrane-bounded peroxisome division revealed by isolation of dynamin-based machinery
Single-membrane-bounded peroxisome division revealed by isolation of dynamin-based machinery
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DOI：
10.1073/pnas.1303483110
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发表时间：
2013-06-04
影响因子：
11.1
通讯作者：
Kuroiwa, Tsuneyoshi
中科院分区：
文献类型：
--
作者：
Imotoa, Yuuta;Kuroiwaa, Haruko;Kuroiwa, Tsuneyoshi
过氧化物酶体（微生物）是普遍存在的单膜细胞器，在细胞代谢中发挥重要作用。它们几乎存在于所有真核细胞中，并且基本上通过分裂繁殖。然而，参与过氧化物酶体分裂的机械化学机制仍然难以捉摸。在这里，我们首先确定了过氧化物酶体分裂（POD）机制。我们从 Cyanidioschyzon merolae（一种含有单一过氧化物酶体的单细胞红藻）中分离出 POD 机制。 C. merolae 中的过氧化物酶体分裂可以通过光/暗循环和微管破坏剂安磺灵高度同步。通过基于 C. merolae 完整基因组序列的蛋白质组学分析，我们鉴定了动力相关蛋白 3 (DRP3) 直系同源物 CmDnm1 (Dnm1)，它主要与过氧化氢酶一起在分裂过氧化物酶体部分中积累。免疫荧光显微镜证明Dnm1在过氧化物酶体的分裂位点形成环。通过相差显微镜模糊地观察到分离的动力环的轮廓，并且对 Dnm1 进行了清晰的染色。电子显微镜显示 POD 机制是在赤道的细胞质侧形成的。免疫电镜显示 POD 机制由外层动力环和内层丝状环组成。 Dnm1 的下调会损害过氧化物酶体分裂。令人惊讶的是，相同的 Dnm1 在线粒体分裂后连续控制过氧化物酶体分裂。由于多过氧化物酶体生物体中 Dnm1 直系同源物的遗传缺陷抑制了线粒体和过氧化物酶体增殖，因此认为通过基于动力的机器收缩来进行过氧化物酶体分裂在真核生物中是普遍存在的。这些发现有助于理解真核细胞的基本系统。
Peroxisomes (microbodies) are ubiquitous single-membrane-bounded organelles and fulfill essential roles in the cellular metabolism. They are found in virtually all eukaryotic cells and basically multiply by division. However, the mechanochemical machinery involved in peroxisome division remains elusive. Here, we first identified the peroxisome- dividing (POD) machinery. We isolated the POD machinery from Cyanidioschyzon merolae, a unicellular red alga containing a single peroxisome. Peroxisomal division in C. merolae can be highly synchronized by light/dark cycles and the microtubule-disrupting agent oryzalin. By proteomic analysis based on the complete genome sequence of C. merolae, we identified a dynamin-related protein 3 (DRP3) ortholog, CmDnm1 (Dnm1), that predominantly accumulated with catalase in the dividing-peroxisome fraction. Immunofluorescence microscopy demonstrated that Dnm1 formed a ring at the division site of the peroxisome. The outlines of the isolated dynamin rings were dimly observed by phase-contrast microscopy and clearly stained for Dnm1. Electron microscopy revealed that the POD machinery was formed at the cytoplasmic side of the equator. Immunoelectron microscopy showed that the POD machinery consisted of an outer dynamin-based ring and an inner filamentous ring. Down-regulation of Dnm1 impaired peroxisomal division. Surprisingly, the same Dnm1 serially controlled peroxisomal division after mitochondrial division. Because genetic deficiencies of Dnm1 orthologs in multiperoxisomal organisms inhibited both mitochondrial and peroxisomal proliferation, it is thought that peroxisomal division by contraction of a dynamin-based machinery is universal among eukaryotes. These findings are useful for understanding the fundamental systems in eukaryotic cells.