From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China and University of Chinese Academy of Sciences, Beijing 100049, China.
From the National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China and.
J Biol Chem. 2014 Nov 7;289(45):31188-99. doi: 10.1074/jbc.M114.602961. Epub 2014 Sep 25.
Protein-disulfide isomerase (PDI) and sulfhydryl oxidase endoplasmic reticulum oxidoreductin-1α (Ero1α) constitute the pivotal pathway for oxidative protein folding in the mammalian endoplasmic reticulum (ER). Ero1α oxidizes PDI to introduce disulfides into substrates, and PDI can feedback-regulate Ero1α activity. Here, we show the regulatory disulfide of Ero1α responds to the redox fluctuation in ER very sensitively, relying on the availability of redox active PDI. The regulation of Ero1α is rapidly facilitated by either a or a' catalytic domain of PDI, independent of the substrate binding domain. On the other hand, activated Ero1α specifically binds to PDI via hydrophobic interactions and preferentially catalyzes the oxidation of domain a'. This asymmetry ensures PDI to function simultaneously as an oxidoreductase and an isomerase. In addition, several PDI family members are also characterized to be potent regulators of Ero1α. The novel modes for PDI as a competent regulator and a specific substrate of Ero1α govern efficient and faithful oxidative protein folding and maintain the ER redox homeostasis.
蛋白质二硫键异构酶（PDI）和巯基氧化酶内质网氧化还原酶 1α（Ero1α）构成了哺乳动物内质网（ER）中氧化蛋白折叠的关键途径。Ero1α 将 PDI 氧化为将二硫键引入底物中，PDI 可以反馈调节 Ero1α 的活性。在这里，我们表明 Ero1α 的调节二硫键对 ER 中的氧化还原波动非常敏感，这依赖于氧化还原活性 PDI 的可用性。PDI 的 a 或 a'催化结构域可独立于底物结合结构域，快速促进 Ero1α 的调节。另一方面，激活的 Ero1α 通过疏水相互作用特异性地与 PDI 结合，并优先催化结构域 a'的氧化。这种不对称性确保 PDI 同时作为氧化还原酶和异构酶发挥作用。此外，还对几种 PDI 家族成员进行了鉴定，它们也是 Ero1α 的有效调节剂。PDI 作为有效调节剂和 Ero1α 的特定底物的新模式控制着有效的、忠实的氧化蛋白折叠，并维持 ER 的氧化还原平衡。
