Characterization of the endoplasmic reticulum-resident peroxidases GPx7 and GPx8 shows the higher oxidative activity of GPx7 and its linkage to oxidative protein folding
Characterization of the endoplasmic reticulum-resident peroxidases GPx7 and GPx8 shows the higher oxidative activity of GPx7 and its linkage to oxidative protein folding
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DOI：
10.1074/jbc.ra120.013607
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发表时间：
2020-09-04
影响因子：
4.8
通讯作者：
Inaba, Kenji
中科院分区：
文献类型：
--
作者：
Kanemura, Shingo;Sofia, Elza Firdiani;Inaba, Kenji
氧化性蛋白质折叠主要发生在哺乳动物内质网中，由包括20多个蛋白质二硫键异构酶（PDI）家族成员和5个以上PDI氧化酶的多样化网络实现。虽然到目前为止，涉及Ero 1 α和PDI的典型二硫键形成途径已经得到了很好的研究，但新鉴定的PDI氧化酶谷胱甘肽过氧化物酶-7（GPx 7）和-8（GPx 8）的生理作用仅知之甚少。我们在此证明，人GPx 7与H（2）O（2）具有更高的反应性，因此比人GPx 8具有更高的PDI氧化活性。GPx 7的高反应性是由于在氧化还原活性位点存在催化四联体，其稳定了与H2 O2反应后产生的亚磺酰化物质。尽管先前假设GPx 7催化涉及可被H2 O2磺酰化的高反应性过氧化物半胱氨酸，但我们揭示了解析半胱氨酸反而调节GPx 7的PDI氧化活性。我们还确定，GPx 7形成复合物优先与PDI和P5在H2 O2处理的细胞。总之，这些结果表明，人GPx 7作为H2 O2依赖性PDI氧化酶在细胞中发挥作用，而PDI氧化可能不是人GPx 8的中心生理作用。
Oxidative protein folding occurs primarily in the mammalian endoplasmic reticulum, enabled by a diverse network comprising more than 20 members of the protein disulfide isomerase (PDI) family and more than five PDI oxidases. Although the canonical disulfide bond formation pathway involving Ero1 alpha and PDI has been well-studied so far, the physiological roles of the newly identified PDI oxidases, glutathione peroxidase-7 (GPx7) and -8 (GPx8), are only poorly understood. We here demonstrated that human GPx7 has much higher reactivity with H(2)O(2)and hence greater PDI oxidation activity than human GPx8. The high reactivity of GPx7 is due to the presence of a catalytic tetrad at the redox-active site, which stabilizes the sulfenylated species generated upon the reaction with H2O2. Although it was previously postulated that GPx7 catalysis involved a highly reactive peroxidatic cysteine that can be sulfenylated by H2O2, we revealed that a resolving cysteine instead regulates the PDI oxidation activity of GPx7. We also determined that GPx7 formed complexes preferentially with PDI and P5 in H2O2-treated cells. Altogether, these results suggest that human GPx7 functions as an H2O2-dependent PDI oxidase in cells, whereas PDI oxidation may not be the central physiological role of human GPx8.