MAMMALIAN EUKARYOTIC INITIATION FACTOR-2-ALPHA KINASES FUNCTIONALLY SUBSTITUTE FOR GCN2 PROTEIN-KINASE IN THE GCN4 TRANSLATIONAL CONTROL MECHANISM OF YEAST
MAMMALIAN EUKARYOTIC INITIATION FACTOR-2-ALPHA KINASES FUNCTIONALLY SUBSTITUTE FOR GCN2 PROTEIN-KINASE IN THE GCN4 TRANSLATIONAL CONTROL MECHANISM OF YEAST
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DOI：
10.1073/pnas.90.10.4616
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发表时间：
1993-05-15
影响因子：
11.1
通讯作者：
HINNEBUSCH, AG
中科院分区：
文献类型：
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作者：
DEVER, TE;CHEN, JJ;HINNEBUSCH, AG
酿酒酵母中真核起始因子2 α亚基（eIF-2 α）通过GCN 2蛋白激酶磷酸化刺激GCN 4 mRNA的翻译。蛋白激酶血红素调节翻译抑制剂（HRI）和双链RNA依赖性eIF-2 α蛋白激酶（dsRNA-PK）通过磷酸化eIF-2 α的Ser-51抑制哺乳动物细胞中翻译的起始。我们发现HRI和dsRNA-PK在体外和体内磷酸化酵母eIF-2 α，并在功能上取代GCN 2蛋白，以刺激GCN 4在酵母中的翻译。此外，在酵母中高水平表达任一哺乳动物激酶降低生长速率，这一发现类似于哺乳动物细胞中这些激酶对总蛋白质合成的抑制。eIF-2 α的磷酸化通过螯合eIF-2B（eIF-2上GTP交换为GDP所需的因子）来抑制哺乳动物细胞中的起始。GCN 3基因（编码酵母eIF-2B复合物的亚基）的突变消除了HRI和dsRNA-PK对酵母中全局和GCN 4特异性翻译的影响。这些结果提供了进一步的体内证据，即eIF-2 α的磷酸化通过损害eIF-2B功能来抑制翻译，并将GCN 3鉴定为eIF-2B的调节亚基。这些结果也表明，GCN 4的翻译控制将是一个很好的模型系统，研究哺乳动物的eIF-2 α激酶是如何通过环境信号和病毒调节因子的调节。
Phosphorylation of the alpha subunit of eukaryotic initiation factor 2 (eIF-2alpha) in Saccharomyces cerevisiae by the GCN2 protein kinase stimulates the translation of GCN4 mRNA. The protein kinases heme-regulated inhibitor of translation (HRI) and double-stranded RNA-dependent eIF-2alpha protein kinase (dsRNA-PK) inhibit initiation of translation in mammalian cells by phosphorylating Ser-51 of eIF-2alpha. We show that HRI and dsRNA-PK phosphorylate yeast eIF-2alpha in vitro and in vivo and functionally substitute for GCN2 protein to stimulate GCN4 translation in yeast. In addition, high-level expression of either mammalian kinase in yeast decreases the growth rate, a finding analogous to the inhibition of total protein synthesis by these kinases in mammalian cells. Phosphorylation of eIF-2alpha inhibits initiation in mammalian cells by sequestering eIF-2B, the factor required for exchange of GTP for GDP on eIF-2. Mutations in the GCN3 gene, encoding a subunit of the yeast eIF-2B complex, eliminate the effects of HRI and dsRNA-PK on global and GCN4-specific translation in yeast. These results provide further in vivo evidence that phosphorylation of eIF-2alpha inhibits translation by impairing eIF-2B function and identify GCN3 as a regulatory subunit of eIF-2B. These results also suggest that GCN4 translational control will be a good model system to study how mammalian eIF-2alpha kinases are modulated by environmental signals and viral regulatory factors.