A protein extension to shorten RNA: elongated elongation factor-Tu recognizes the D-arm of T-armless tRNAs in nematode mitochondria.
A protein extension to shorten RNA: elongated elongation factor-Tu recognizes the D-arm of T-armless tRNAs in nematode mitochondria.
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DOI：
10.1042/bj20060781
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发表时间：
2006-10
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影响因子：
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通讯作者：
M. Sakurai;Yoh‐ichi Watanabe;Kimitsuna Watanabe;T. Ohtsuki
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文献类型：
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作者：
M. Sakurai;Yoh‐ichi Watanabe;Kimitsuna Watanabe;T. Ohtsuki
线虫线粒体具有极短的trna。在22个trna中，有20个缺少整个t臂。t臂对于典型trna和EF（伸长因子）-Tu（热不稳定因子）的结合是必需的。线虫线粒体翻译系统使用两种不同的EF-Tu因子EF-Tu1和EF-Tu2。我们之前的研究表明，秀丽隐杆线虫EF-Tu1特异性结合t臂无tRNA。秀丽隐杆线虫EF-Tu1具有典型EF-Tu缺失的57个氨基酸的c端延伸，典型EF-Tu的t臂结合残基不保守。本研究探讨了EF-Tu1对无t臂tRNA的识别机制。交联三元配合物的修饰干扰实验和引物延伸分析表明，EF-Tu1不仅与tRNA受体干相互作用，还与d臂相互作用。这是EF-Tu识别tRNA d臂的第一个例子。EF-Tu1的结合活性仅因c端缺失14个残基而受损，表明EF-Tu1的c端是其与无t臂tRNA结合所必需的。这些结果表明秀丽隐杆线虫EF-Tu1通过涉及其c端区域的机制识别d臂而不是t臂。本研究揭示了线虫线粒体中RNA和RNA结合蛋白的共同进化。
Nematode mitochondria possess extremely truncated tRNAs. Of 22 tRNAs, 20 lack the entire T-arm. The T-arm is necessary for the binding of canonical tRNAs and EF (elongation factor)-Tu (thermo-unstable). The nematode mitochondrial translation system employs two different EF-Tu factors named EF-Tu1 and EF-Tu2. Our previous study showed that nematode Caenorhabditis elegans EF-Tu1 binds specifically to T-armless tRNA. C. elegans EF-Tu1 has a 57-amino acid C-terminal extension that is absent from canonical EF-Tu, and the T-arm-binding residues of canonical EF-Tu are not conserved. In this study, the recognition mechanism of T-armless tRNA by EF-Tu1 was investigated. Both modification interference assays and primer extension analysis of cross-linked ternary complexes revealed that EF-Tu1 interacts not only with the tRNA acceptor stem but also with the D-arm. This is the first example of an EF-Tu recognizing the D-arm of a tRNA. The binding activity of EF-Tu1 was impaired by deletion of only 14 residues from the C-terminus, indicating that the C-terminus of EF-Tu1 is required for its binding to T-armless tRNA. These results suggest that C. elegans EF-Tu1 recognizes the D-arm instead of the T-arm by a mechanism involving its C-terminal region. This study sheds light on the co-evolution of RNA and RNA-binding proteins in nematode mitochondria.