Structural and Functional Roles of the Conserved Cysteine Residues of the Redox-regulated Import Receptor Mia40 in the Intermembrane Space of Mitochondria*
Structural and Functional Roles of the Conserved Cysteine Residues of the Redox-regulated Import Receptor Mia40 in the Intermembrane Space of Mitochondria*
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氧化还原调节输入受体 Mia40 的保守半胱氨酸残基在线粒体膜间空间中的结构和功能作用*
DOI：
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发表时间：
2009
影响因子：
4.8
通讯作者：
K. Hell
中科院分区：
文献类型：
--
作者：
N. Terziyska;Barbara Grumbt;C. Kozany;K. Hell
氧化折叠驱动含有双 CXnC 基序的蛋白质进入线粒体膜间隙。该输入途径采用二硫键中继系统，其关键成分是氧化还原调节的输入受体 Mia40 和硫醇氧化酶 Erv1。 Mia40 在高度保守的结构域中包含 6 个半胱氨酸残基，呈 CPC-CX9C-CX9C 排列。我们证明该结构域足以发挥 Mia40 的功能。通过对 Mia40 半胱氨酸突变体的分析，我们证明半胱氨酸残基具有不同的作用，并且对于 Mia40 功能的重要性并不相同。第二个半胱氨酸残基对于酵母细胞的活力至关重要。它是 Mia40 与 Erv1 在二硫键中间体中相互作用所必需的，并与第一个半胱氨酸残基形成氧化还原敏感的二硫键。在由 Mia40 和 Erv1 组成的重构系统中，底物 Tim10 的氧化需要两个半胱氨酸残基。第三和第六个半胱氨酸残基发生氨基酸交换的突变体在生长和膜间隙蛋白的输入方面具有严重缺陷。这些 Mia40 变体没有紧密折叠。我们得出结论，双 CX9C 基序的半胱氨酸残基具有结构作用并稳定 Mia40。特别是，由第三个和第六个半胱氨酸残基形成的二硫键显然支持对 Mia40 功能至关重要的构象。此外，CPC 片段中的二硫键介导与硫醇氧化酶 Erv1 和线粒体底物蛋白的氧化还原反应。
Oxidative folding drives the import of proteins containing twin CXnC motifs into the intermembrane space of mitochondria. This import pathway employs a disulfide relay system whose key components are the redox-regulated import receptor Mia40 and the thiol oxidase Erv1. Mia40 contains six cysteine residues in a CPC-CX9C-CX9C arrangement in a highly conserved domain. We show that this domain is sufficient for the function of Mia40. By analysis of Mia40 cysteine mutants we demonstrate that the cysteine residues have distinct roles and are not equally important for Mia40 function. The second cysteine residue is essential for viability of yeast cells. It is required for the interaction of Mia40 with Erv1 in a disulfide intermediate and forms a redox-sensitive disulfide bond with the first cysteine residue. Both cysteine residues are required for the oxidation of the substrate, Tim10, in a reconstituted system comprised of Mia40 and Erv1. Mutants with amino acid exchanges in the third and sixth cysteine residues have severe defects in growth and in the import of intermembrane space proteins. These Mia40 variants are not tightly folded. We conclude that the cysteine residues of the twin CX9C motif have a structural role and stabilize Mia40. In particular, the disulfide bond formed by the third and sixth cysteine residues apparently supports a conformation crucial for the function of Mia40. Furthermore, the disulfide bond in the CPC segment mediates the redox reactions with the thiol oxidase Erv1 and substrate proteins in mitochondria.
影响因子：
5.7
作者：
Arnesano, F;Balatri, E;Winge, DR
通讯作者：
Winge, DR
影响因子：
7.7
作者：
Mesecke, Nikola;Bihlmaier, Karl;Herrmann, Johannes M.
通讯作者：
Herrmann, Johannes M.