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elF5 has GDI activity necessary for translational control by elF2 phosphorylation

机译:elF5具有通过elF2磷酸化进行翻译控制所需的GDI活性

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摘要

In protein synthesis initiation, the eukaryotic translation initiation factor (elF) 2 (a G protein) functions in its GTP-bound state to deliver initiator methionyl-tRNA (tRNAjMet) to the small ribosomal subunit and is necessary for protein synthesis in all cells12. Phosphorylation of eIF2 [eIF2(aP)] is critical for translational control in diverse settings including nutrient deprivation, viral infection and memory formation3"5. eIF5 functions in start site selection as a GTPase accelerating protein (GAP) for the eIF2?GTP?tRNAiMet ternary complex within the ribosome-bound pre-initiation complex6^8. Here we define new regulatory functions of eIF5 in the recycling of eIF2 from its inactive eIF2?GDP state between successive rounds of translation initiation. First we show that eIF5 stabilizes the binding of GDP to eIF2 and is therefore a bi-functional protein that acts as a GDP dissociation inhibitor (GDI). We find that this activity is independent of the GAP function and identify conserved residues within eIF5 that are necessary for this role. Second we show that eIF5 is a critical component of the eIF2(aP) regulatory complex that inhibits the activity of the guanine-nucleotide exchange factor (GEF) eIF2B. Together our studies define a new step in the translation initiation pathway, one that is critical for normal translational controls.
机译:在蛋白质合成起始过程中,真核翻译起始因子(elF)2(一种G蛋白)以其GTP结合状态起作用,将启动子甲硫氨酰-tRNA(tRNAjMet)传递至小的核糖体亚基,并且是所有细胞中蛋白质合成所必需的12。 eIF2 [eIF2(aP)]的磷酸化对于多种环境下的翻译控制至关重要,包括营养剥夺,病毒感染和记忆形成3“5。eIF5在起始位点选择中作为eIF2?GTP?tRNAiMet的GTPase加速蛋白(GAP)起作用。核糖体结合的起始复合物6 ^ 8中的三元复合物,在此我们定义了eIF5在eIF2从其无活性的eIF2?GDP状态开始的连续轮回翻译之间的循环中的新调控功能。 GDP到eIF2,因此是一种双功能蛋白,起着GDP离解抑制剂(GDI)的作用,我们发现该活性与GAP功能无关,并确定了eIF5中该作用所必需的保守残基。 eIF5是eIF2(aP)调节复合物的关键成分,可抑制鸟嘌呤-核苷酸交换因子(GEF)eIF2B的活性,我们的研究共同确定了这一新的步骤翻译起始途径,对正常翻译控制至关重要。

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  • 来源
    《Nature》 |2010年第7296期|p.378-381|共4页
  • 作者单位

    Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK;

    Faculty of Life Sciences, University of Manchester, Michael Smith Building, Oxford Road, Manchester M13 9PT, UK;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
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