Association of a Novel Mitochondrial Protein M19 with Mitochondrial Nucleoids
Association of a Novel Mitochondrial Protein M19 with Mitochondrial Nucleoids
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DOI：
10.1093/jb/mvp118
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发表时间：
2009-11-01
影响因子：
2.7
通讯作者：
Endo, Hitoshi
中科院分区：
文献类型：
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作者：
Sumitani, Megumi;Kasashima, Katsumi;Endo, Hitoshi
我们通过对HeLa细胞线粒体膜蛋白的蛋白质组学分析，鉴定出一种新的线粒体蛋白，命名为M19。M19在脊椎动物中高度保守，与其他已知蛋白没有同源结构域。Northern和Western印迹显示，小鼠M19在各种组织中都有表达，并且在大脑中尤其丰富。人M19(HM19)存在于线粒体中，酶保护实验表明它在基质中呈亚块化状态。羧基末端标记的hM19出现在线粒体内的斑点信号，并与线粒体DNA(MtDNA)信号共同定位，表明M19包含在mtDNA蛋白复合体(线粒体类核)中。HeLa细胞线粒体核团的分离表明，hM19与已知的核团组分如mtSSB和PHBs具有相似的分布模式，并且确实存在于核团组分中。此外，M19的表达与mtDNA的量密切相关，因为它在mtDNA缺失的(0)HeLa细胞中下调。这些结果表明，M19与类核有关，可能调节mtDNA的组织和代谢。
We have identified a novel mitochondrial protein, termed M19, by proteomic analysis of mitochondrial membrane proteins from HeLa cells. M19 is highly conserved among vertebrates, and possesses no homologous domains with other known proteins. By northern and western blotting, mouse M19 was shown to be expressed in various tissues, and to be especially abundant in the brain. Human M19 (hM19) is present in mitochondria, and protease-protection experiment showed it to be sublocalized in the matrix space. Carboxy-terminally tagged hM19 appeared as spotted signals within mitochondria and co-localized with signals arising from mitochondrial DNA (mtDNA), suggesting the inclusion of M19 in the mtDNAprotein complex (mitochondrial nucleoids). Fractionation of mitochondrial nucleoids from HeLa cells revealed that hM19 has a similar distribution pattern like that of known nucleoid components, such as mtSSB and PHBs, and surely exists in the nucleoid fraction. Furthermore, expression of M19 is closely related to the amount of mtDNA, because it was down-regulated in mtDNA-depleted (0) HeLa cells. These results indicate that M19 associates with the nucleoid and likely regulates the organization and metabolism of mtDNA.