Molecular Bases of Cyclic and Specific Disulfide Interchange between Human ERO1α Protein and Protein-disulfide Isomerase (PDI)
Molecular Bases of Cyclic and Specific Disulfide Interchange between Human ERO1α Protein and Protein-disulfide Isomerase (PDI)
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DOI：
10.1074/jbc.m111.231357
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发表时间：
2011-05-06
影响因子：
4.8
通讯作者：
Inaba, Kenji
中科院分区：
文献类型：
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作者：
Masui, Shoji;Vavassori, Stefano;Inaba, Kenji
在人类细胞的内质网（ER）中，ERO 1 α和蛋白质二硫键异构酶（PDI）构成催化分泌蛋白氧化折叠的主要电子流途径之一。ERO 1 α特异性和有限的PDI氧化对于避免ER过度氧化至关重要。为了研究ERO 1 α如何在20多种ER-居民PDI家族成员蛋白中选择性地氧化PDI，我们进行了对接模拟和系统的生化分析。我们的研究结果揭示，ERO 1 α的突出β-发夹通过其芳香族残基之间的堆叠与存在于氧化还原失活的PDI b '-结构域中的疏水口袋特异性相互作用，导致C-末端PDI a'-结构域的优选氧化。ERO 1 α优先与还原的PDI相关，解释了逐步二硫键穿梭机制，首先从ERO 1 α到PDI，然后从氧化的PDI到与其疏水口袋结合的未折叠多肽。还分析了ERO 1 α与另一种PDI家族成员蛋白ERp 44的相互作用。值得注意的是，ERO 1 α依赖性PDI氧化被一个过度活跃的ERp 44突变体抑制，该突变体缺乏隐藏底物结合疏水区的C-末端尾部。ERp 44抑制ERO 1 α活性的潜在能力可能表明其在ER氧化还原和蛋白质稳态中的生理作用。
In the endoplasmic reticulum (ER) of human cells, ERO1 alpha and protein-disulfide isomerase (PDI) constitute one of the major electron flow pathways that catalyze oxidative folding of secretory proteins. Specific and limited PDI oxidation by ERO1 alpha is essential to avoid ER hyperoxidation. To investigate how ERO1 alpha oxidizes PDI selectively among more than 20 ER-resident PDI family member proteins, we performed docking simulations and systematic biochemical analyses. Our findings reveal that a protruding beta-hairpin of ERO1 alpha specifically interacts with the hydrophobic pocket present in the redox-inactive PDI b'-domain through the stacks between their aromatic residues, leading to preferred oxidation of the C-terminal PDI a'-domain. ERO1 alpha associated preferentially with reduced PDI, explaining the stepwise disulfide shuttle mechanism, first from ERO1 alpha to PDI and then from oxidized PDI to an unfolded polypeptide bound to its hydrophobic pocket. The interaction of ERO1 alpha with ERp44, another PDI family member protein, was also analyzed. Notably, ERO1 alpha-dependent PDI oxidation was inhibited by a hyperactive ERp44 mutant that lacks the C-terminal tail concealing the substrate-binding hydrophobic regions. The potential ability of ERp44 to inhibit ERO1 alpha activity may suggest its physiological role in ER redox and protein homeostasis.