Ohtsuki Takashi, Watanabe Yoh-ichi
Department of Bioscience and Biotechnology, Okayama University, Okayama, Japan.
IUBMB Life. 2007 Feb;59(2):68-75. doi: 10.1080/15216540701218722.
Most tRNAs share a common secondary structure containing a T arm, a D arm, an anticodon arm and an acceptor stem. However, there are some exceptions. Most nematode mitochondrial tRNAs and some animal mitochondrial tRNAs lack the T arm, which is necessary for binding to canonical elongation factor Tu (EF-Tu). The mitochondria of the nematode Caenorhabditis elegans have a unique EF-Tu, named EF-Tu1, whose structure has supplied clues as to how truncated tRNAs can work in translation. EF-Tu1 has a C-terminal extension of about 60 aa that is absent in canonical EF-Tu. Recent data from our laboratory strongly suggests that EF-Tu1 recognizes the D-arm instead of the T arm by a mechanism involving this C-terminal region. Further biochemical analysis of mitochondrial tRNAs and EF-Tu from the distantly related nematode Trichinella spp. and sequence information on nuclear and mitochondrial DNA in arthropods suggest that T-armless tRNAs may have arisen as a result of duplication of the EF-Tu gene. These studies provide valuable insights into the co-evolution of RNA and RNA-binding proteins.
大多数转运RNA（tRNA）具有共同的二级结构，包含一个T臂、一个D臂、一个反密码子臂和一个受体茎。然而，也有一些例外情况。大多数线虫线粒体tRNA和一些动物线粒体tRNA缺乏T臂，而T臂对于与经典延伸因子Tu（EF-Tu）结合是必需的。线虫秀丽隐杆线虫的线粒体有一种独特的EF-Tu，名为EF-Tu1，其结构为截短的tRNA如何在翻译中发挥作用提供了线索。EF-Tu1有一个约60个氨基酸的C端延伸，这在经典EF-Tu中是不存在的。我们实验室最近的数据强烈表明，EF-Tu1通过涉及该C端区域的机制识别D臂而非T臂。对远缘线虫旋毛虫属线粒体tRNA和EF-Tu的进一步生化分析以及节肢动物核DNA和线粒体DNA的序列信息表明，无T臂的tRNA可能是EF-Tu基因复制的结果。这些研究为RNA与RNA结合蛋白的共同进化提供了有价值的见解。
