THE VACCINIA VIRUS K3L-GENE PRODUCT POTENTIATES TRANSLATION BY INHIBITING DOUBLE-STRANDED-RNA-ACTIVATED PROTEIN-KINASE AND PHOSPHORYLATION OF THE ALPHA SUBUNIT OF EUKARYOTIC INITIATION FACTOR-II
THE VACCINIA VIRUS K3L-GENE PRODUCT POTENTIATES TRANSLATION BY INHIBITING DOUBLE-STRANDED-RNA-ACTIVATED PROTEIN-KINASE AND PHOSPHORYLATION OF THE ALPHA SUBUNIT OF EUKARYOTIC INITIATION FACTOR-II
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DOI：
10.1128/jvi.66.4.1943-1950.1992
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发表时间：
1992-04-01
影响因子：
5.4
通讯作者：
KAUFMAN, RJ
中科院分区：
文献类型：
--
作者：
DAVIES, MV;ELROYSTEIN, O;KAUFMAN, RJ
痘苗病毒的干扰素抗性是通过双链 RNA 激活 (DAI) 蛋白激酶对真核起始因子 2 (eIF-2-α) α 亚基磷酸化的特异性抑制来介导的。痘苗病毒编码 eIF-2-α 的同源物 K3L，其缺失使病毒对干扰素治疗敏感。我们研究了这种蛋白质产品在瞬时 DNA 转染系统中引发干扰素抗性的机制，该系统旨在评估 eIF-2-α 磷酸化的调节剂。在该系统中，由于 DAI 蛋白激酶介导的 eIF-2 磷酸化，报告基因 mRNA 的翻译效率低下。 K3L 基因的共转染增强了该系统中报告基因 mRNA 的翻译。 K3L 蛋白抑制 eIF-2-α 磷酸化和 DAI 激酶激活，显然其本身并未被磷酸化。由旨在模拟磷酸化丝氨酸的突变体 Ser-51 --> Asp eIF-2-α 的表达引起的蛋白质合成抑制不会因 K3L 的存在而缓解，这表明 K3L 无法绕过 eIF-2-α 磷酸化所施加的阻断。结果表明，K3L 充当 eIF-2-α 的诱饵，抑制 DAI 激酶自身磷酸化和激活。另一种痘苗病毒基因产物 K1L 是痘苗病毒在人体细胞上生长所必需的，但在此测定中不会增强翻译。
Interferon resistance of vaccinia virus is mediated by specific inhibition of phosphorylation of the alpha subunit of eukaryotic initiation factor 2 (eIF-2-alpha) by the double-stranded-RNA-activated (DAI) protein kinase. Vaccinia virus encodes a homolog of eIF-2-alpha, K3L, the deletion of which renders the virus sensitive to interferon treatment. We have studied the mechanism by which this protein product elicits interferon resistance in a transient DNA transfection system designed to evaluate regulators of eIF-2-alpha phosphorylation. In this system, translation of a reporter gene mRNA is inefficient because of eIF-2 phosphorylation mediated by the DAI protein kinase. Cotransfection of the K3L gene enhances translation of the reporter mRNA in this system. The K3L protein inhibits eIF-2-alpha phosphorylation and DAI kinase activation, apparently without being phosphorylated itself. Inhibition of protein synthesis, elicited by expression of a mutant Ser-51 --> Asp eIF-2-alpha designed to mimic a phosphorylated serine, is not relieved by the presence of K3L, suggesting that K3L cannot bypass a block imposed by eIF-2-alpha phosphorylation. The results suggest that K3L acts as a decoy of eIF-2-alpha to inhibit DAI kinase autophosphorylation and activation. Another vaccinia virus gene product, K1L, which is required for growth of vaccinia virus on human cells, does not enhance translation in this assay.