Specific in vitro phosphorylation of plant eIF2α by eukaryotic eIF2α kinases
Specific in vitro phosphorylation of plant eIF2α by eukaryotic eIF2α kinases
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DOI：
10.1023/a:1006379623534
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发表时间：
1999-10-01
影响因子：
5.1
通讯作者：
Roth, D
中科院分区：
文献类型：
--
作者：
Chang, LY;Yang, WY;Roth, D
已知真核起始因子 2 (eIF2 α) α 亚基的磷酸化是除植物外的所有真核生物中重要的翻译控制机制。哺乳动物和酵母 eIF2 α 活性的调节直接受 Ser-51 上的特异性磷酸化的控制。我们现在证明，重组小麦野生型 (51S) 而不是突变型 51-Ala (51A) 蛋白被人 PKR 和酵母 GCN2 磷酸化，它们被定义为 eIF2 α 激酶。此外，只有小麦野生型 eIF2 α 是植物编码的双链 RNA 依赖性激酶 (pPKR) 活性的底物。植物 PKR 和 GCN2 磷酸化重组酵母 eIF2 α 51S，但不磷酸化 51A 突变体，这表明 pPKR 具有与已建立的 eIF2 α 激酶相似的识别位点能力。包含 51S 但不包含 KGYID 基序的野生型小麦 eIF2 α 的截短版本不会被 hPKR 或 pPKR 磷酸化，这表明该推定的 eIF2 α 激酶对接结构域对于磷酸化至关重要。综上所述，这些结果证明了真核 eIF2 α 物种和 eIF2 α 激酶之间的同源性，并支持植物 eIF2 α 磷酸化途径的存在。
Phosphorylation of the alpha subunit of eukaryotic initiation factor 2 (eIF2 alpha) is known to be an important translational control mechanism in all eukaryotes with the major exception of plants. Regulation of mammalian and yeast eIF2 alpha activity is directly governed by specific phosphorylation on Ser-51. We now demonstrate that recombinant wheat wild-type (51S) but not mutant 51-Ala (51A) protein is phosphorylated by human PKR and yeast GCN2, which are defined eIF2 alpha kinases. Further, only wheat wild-type eIF2 alpha is a substrate for plant-encoded, double-stranded RNA-dependent kinase (pPKR) activity. Plant PKR and GCN2 phosphorylate recombinant yeast eIF2 alpha 51S but not the 51A mutant demonstrating that pPKR has recognition site capability similar to established eIF2 alpha kinases. A truncated version of wild-type wheat eIF2 alpha containing 51S but not the KGYID motif is not phosphorylated by either hPKR or pPKR suggesting that this putative eIF2 alpha kinase docking domain is essential for phosphorylation. Taken together, these results demonstrate the homology among eukaryotic eIF2 alpha species and eIF2 alpha kinases and support the presence of a plant eIF2 alpha phosphorylation pathway.