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首页> 外文期刊>Molecular and Cellular Biology >The A1 x U72 base pair conserved in eukaryotic initiator tRNAs is important specifically for binding to the eukaryotic translation initiation factor eIF2.
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The A1 x U72 base pair conserved in eukaryotic initiator tRNAs is important specifically for binding to the eukaryotic translation initiation factor eIF2.

机译：真核启动子tRNA中保守的A1 x U72碱基对对于与真核翻译起始因子eIF2的结合特别重要。

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摘要

The formation of a specific ternary complex between eukaryotic initiation factor 2 (eIF2), the initiator methionyl-tRNA (Met-tRNA), and GTP is a critical step in translation initiation in the cytoplasmic protein-synthesizing system of eukaryotes. We show that the A1 x U72 base pair conserved at the end of the acceptor stem in eukaryotic and archaebacterial initiator methionine tRNAs plays an important role in this interaction. We changed the A1 x U72 base pair of the human initiator tRNA to G1 x C72 and expressed the wild-type and mutant tRNA genes in the yeast Saccharomyces cerevisiae by using constructs previously developed in our laboratory for expression of the human initiator tRNA gene in yeasts. We show that both the wild-type and mutant human initiator tRNAs are aminoacylated well in vivo. We have isolated the wild-type and mutant human initiator tRNAs in substantially pure form, free of the yeast initiator tRNA, and have analyzed their properties in vitro. The G1 x C72 mutation affects specifically the binding affinity of eIF2 for the initiator tRNA. It has no effect on the subsequent formation of 40S or 80S ribosome initiator Met-tRNA-AUG initiation complexes in vitro or on the puromycin reactivity of the Met-tRNA in the 80S initiation complex.
机译：真核生物起始因子2（eIF2），启动子甲硫氨酰-tRNA（Met-tRNA）和GTP之间的特定三元复合物的形成是真核细胞质蛋白合成系统中翻译起始的关键步骤。我们显示在真核和古细菌引发剂蛋氨酸tRNAs受体茎末端保守的A1 x U72碱基对在这种相互作用中起重要作用。我们将人类启动子tRNA的A1 x U72碱基对更改为G1 x C72，并通过使用以前在我们实验室中开发的用于在酵母中表达人类启动子tRNA基因的构建体，在酿酒酵母中表达了野生型和突变tRNA基因。 。我们表明，野生型和突变型人类启动子tRNA都在体内被氨酰化。我们已经分离出基本上纯净的野生型和突变型人类启动子tRNA，不含酵母启动子tRNA，并在体外分析了它们的特性。 G1 x C72突变特别影响eIF2对引发剂tRNA的结合亲和力。它对随后体外形成40S或80S核糖体引发剂Met-tRNA-AUG起始复合物或80S起始复合物中Met-tRNA的嘌呤霉素反应性没有影响。

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