Mia40 is a trans-site receptor that drives protein import into the mitochondrial intermembrane space by hydrophobic substrate binding
Mia40 is a trans-site receptor that drives protein import into the mitochondrial intermembrane space by hydrophobic substrate binding
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DOI：
10.7554/elife.16177
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发表时间：
2016-06-25
期刊：
影响因子：
7.7
通讯作者：
Herrmann, Johannes M.
中科院分区：
文献类型：
--
作者：
Peleh, Valentina;Cordat, Emmanuelle;Herrmann, Johannes M.
线粒体 IMS 的许多蛋白质都含有保守的半胱氨酸，这些半胱氨酸在导入过程中会被氧化成二硫键。保守的 IMS 蛋白 Mia40 对于这些蛋白的氧化和输入至关重要。 Mia40 由两个功能元件组成：N 端半胱氨酸-脯氨酸-半胱氨酸基序赋予底物氧化，以及 C 端疏水口袋用于底物结合。在这项研究中，我们生成了酵母突变体，以从遗传和生物化学角度剖析 Mia40 的活性。因此，我们表明 Mia40 的底物结合结构域对于促进蛋白质输入既必要又充分，表明 Mia40 的捕获驱动蛋白质易位。氧化酶缺陷的 Mia40 突变体是无法存活的，但可以通过添加化学氧化剂二酰胺来部分挽救。我们的结果表明，Mia40 主要充当线粒体的易位受体，通过疏水相互作用结合传入的蛋白质，从而通过“固定陷阱”而不是“折叠陷阱”机制介导蛋白质跨外膜易位。
Many proteins of the mitochondrial IMS contain conserved cysteines that are oxidized to disulfide bonds during their import. The conserved IMS protein Mia40 is essential for the oxidation and import of these proteins. Mia40 consists of two functional elements: an N-terminal cysteine-proline-cysteine motif conferring substrate oxidation, and a C-terminal hydrophobic pocket for substrate binding. In this study, we generated yeast mutants to dissect both Mia40 activities genetically and biochemically. Thereby we show that the substrate-binding domain of Mia40 is both necessary and sufficient to promote protein import, indicating that trapping by Mia40 drives protein translocation. An oxidase-deficient Mia40 mutant is inviable, but can be partially rescued by the addition of the chemical oxidant diamide. Our results indicate that Mia40 predominantly serves as a trans-site receptor of mitochondria that binds incoming proteins via hydrophobic interactions thereby mediating protein translocation across the outer membrane by a 'holding trap' rather than a 'folding trap' mechanism.