A viral member of the ERV1/ALR protein family participates in a cytoplasmic pathway of disulfide bond formation.
A viral member of the ERV1/ALR protein family participates in a cytoplasmic pathway of disulfide bond formation.
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DOI：
10.1073/pnas.210397997
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发表时间：
2000-10
影响因子：
11.1
通讯作者：
T. Senkevich;C. L. White;E. Koonin;B. Moss
中科院分区：
文献类型：
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作者：
T. Senkevich;C. L. White;E. Koonin;B. Moss
ERV1/ALR家族的蛋白由所有真核生物和细胞质DNA病毒编码，这些病毒的大量序列信息是可用的。然而，这些蛋白质的作用还不是很清楚。ERV1/ALR蛋白的多重比对表明了一个不变的C-X-X-C基序，但二级结构预测没有显示出与硫氧还蛋白折叠的相似性。我们选择了一个病毒模型来研究这些蛋白质作为硫醇氧化还原酶的作用。当细胞感染突变的痘苗病毒时，编码ERV1/ALR家族蛋白的E10R基因被抑制，其他三种病毒蛋白-L1R和F9L蛋白以及G4L谷氧还蛋白-的二硫键完全减少。当E10R蛋白的氧化还原半胱氨酸Cys-43或Cys-46突变为丝氨酸时，也出现了同样的结果。这两个半胱氨酸在正常病毒感染期间是二硫键结合的，但如果其他病毒晚期蛋白的合成受到抑制或E10R蛋白在未感染的细胞中自行表达，则不会形成二硫键，这表明需要上游病毒硫醇氧化还原酶。值得注意的是，E10R和L1R病毒膜蛋白的半胱氨酸区和谷氧还蛋白位于细胞质中，在细胞质中发生牛痘病毒粒子的组装，而不是在内质网的氧化环境中。这些数据表明，E10R蛋白在病毒的二硫键形成途径中起着核心作用。此外，ERV1/ALR家族可能代表了一类普遍存在的细胞内与谷氧还蛋白或硫氧还蛋白相互作用的硫醇氧化还原酶。
Proteins of the ERV1/ALR family are encoded by all eukaryotes and cytoplasmic DNA viruses for which substantial sequence information is available. Nevertheless, the roles of these proteins are imprecisely known. Multiple alignments of ERV1/ALR proteins indicated an invariant C-X-X-C motif, but no similarity to the thioredoxin fold was revealed by secondary structure predictions. We chose a virus model to investigate the role of these proteins as thiol oxidoreductases. When cells were infected with a mutant vaccinia virus in which the E10R gene encoding an ERV1/ALR family protein was repressed, the disulfide bonds of three other viral proteins-namely, the L1R and F9L proteins and the G4L glutaredoxin-were completely reduced. The same outcome occurred when Cys-43 or Cys-46, the putative redox cysteines of the E10R protein, was mutated to serine. These two cysteines were disulfide bonded during a normal virus infection but not if the synthesis of other viral late proteins was inhibited or the E10R protein was expressed by itself in uninfected cells, suggesting a requirement for an upstream viral thiol oxidoreductase. Remarkably, the cysteine-containing domains of the E10R and L1R viral membrane proteins and the glutaredoxin are in the cytoplasm, in which assembly of vaccinia virions occurs, rather than in the oxidizing environment of the endoplasmic reticulum. These data indicated a viral pathway of disulfide bond formation in which the E10R protein has a central role. By extension, the ERV1/ALR family may represent a ubiquitous class of cellular thiol oxidoreductases that interact with glutaredoxins or thioredoxins.