A unique tRNA recognition mechanism of Caenorhabditis elegans mitochondrial EF-Tu2
A unique tRNA recognition mechanism of Caenorhabditis elegans mitochondrial EF-Tu2
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DOI：
10.1093/nar/gki784
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发表时间：
2005-08
影响因子：
14.9
通讯作者：
Takuma Suematsu;A. Sato;M. Sakurai;Kimitsuna Watanabe;T. Ohtsuki
中科院分区：
文献类型：
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作者：
Takuma Suematsu;A. Sato;M. Sakurai;Kimitsuna Watanabe;T. Ohtsuki
线虫线粒体表达两种极端截断的trna，它们被两种不同的伸长因子Tu （EF-Tu）物种EF-Tu1和EF-Tu2特异性识别。这与参与标准蛋白质生物合成系统的典型EF-Tu分子不同，标准蛋白质生物合成系统基本上识别所有伸长体trna。EF-Tu2特异性识别Ser-tRNASer缺乏D臂但具有短T臂。我们之前的研究使我们推测D臂的缺失可能对EF-Tu2的tRNA识别至关重要。然而，在这里，我们发现EF-Tu2可以结合携带D臂的ser - trna，其中D -t臂的相互作用被突变削弱。乙基亚硝基源修饰干扰实验表明，EF-Tu2是独特的，因为它与典型EF-Tu结合的相反侧的T茎上的磷酸基团相互作用。使用几个EF-Tu2突变体进行的水解保护实验强烈表明，EF-Tu2的7个c端氨基酸残基对其氨基酰基- trna结合活性至关重要。我们的研究结果表明，线虫线粒体（mt） EF-Tu2/GTP/氨基酰基-tRNA三元配合物的形成可能是由EF-Tu2的c端延伸与tRNA之间独特的相互作用支持的。
Nematode mitochondria expresses two types of extremely truncated tRNAs that are specifically recognized by two distinct elongation factor Tu (EF-Tu) species named EF-Tu1 and EF-Tu2. This is unlike the canonical EF-Tu molecule that participates in the standard protein biosynthesis systems, which basically recognizes all elongator tRNAs. EF-Tu2 specifically recognizes Ser-tRNASer that lacks a D arm but has a short T arm. Our previous study led us to speculate the lack of the D arm may be essential for the tRNA recognition of EF-Tu2. However, here, we showed that the EF-Tu2 can bind to D arm-bearing Ser-tRNAs, in which the D–T arm interaction was weakened by the mutations. The ethylnitrosourea-modification interference assay showed that EF-Tu2 is unique, in that it interacts with the phosphate groups on the T stem on the side that is opposite to where canonical EF-Tu binds. The hydrolysis protection assay using several EF-Tu2 mutants then strongly suggests that seven C-terminal amino acid residues of EF-Tu2 are essential for its aminoacyl-tRNA-binding activity. Our results indicate that the formation of the nematode mitochondrial (mt) EF-Tu2/GTP/aminoacyl-tRNA ternary complex is probably supported by a unique interaction between the C-terminal extension of EF-Tu2 and the tRNA.