Elucidation of basic principle in genetic information translation system by using the specialty of animal mitochondria

本项目的目的是利用动物线粒体的特性，阐明遗传信息翻译系统的基本原理。这可以通过将研究充分的大肠杆菌翻译系统与动物线粒体的特殊翻译系统相结合来实现。（1）tRNA的最小必要结构：通过NMR检查了线虫线粒体（mt）tRNA^ _的高级结构<Ser><UCU>，它是现存生物中最小的tRNA（54个核苷酸，没有D臂和由3个碱基对和4个碱基组成的环组成的小T臂）。结果表明，几乎所有的碱基对预测从它的三叶草结构存在于解决方案和连接器区域所组成的截断的D环和额外的环具有相当灵活的结构。这种移动性对于tRNA^<Ser>_<UCU>保持3 '端和反密码子的相对排列与通常的tRNA相同是必不可少的。（2）最小前提结构 ...更多信息 核糖体e：在动物线粒体核糖体中，rRNA的含量约为大肠杆菌核糖体的一半，而蛋白质的含量则是大肠杆菌核糖体的两倍。mt rRNA的功能区在两个核糖体亚基的中心部分是严格保守的，mt核糖体中缺少的rRNA的外围区域被蛋白质包埋，从而保持mt和大肠杆菌之间几乎相同的核糖体的整体形状。结果表明，mt核糖体周边区域的一些茎/环结构是不对称的。（3）作为翻译系统能量来源的GTP水解反应的触发因子是什么：根据EF-G的GTP酶活性被L7/L12激活的事实，推测GTP水解反应的触发因子是50 S核糖体亚基中的L7/L12蛋白。我们通过阐明大肠杆菌EF-G可以在只有L7/L12蛋白被大肠杆菌核糖体的对应物取代的mt核糖体上起作用来证实这一提议，尽管大肠杆菌EF-G不能在天然mt核糖体上起作用。少

The aim of this project is to elucidate the basic principle in genetic information translation system by using the specialty of animal mitochondria. This can be done by combining the well-studied E.coli translation system with the special translation system of animal mitochondria. (1)The minimal prerequisite structure of tRNA : The higher-order structure of nematode mitochondrial (mt) tRNA^<Ser>_<UCU>, which is the smallest tRNA in the extant organisms (54 nucleotides, having no D arm and small T arm consisting of 3 base pairs and a loop with 4 bases), was examined by using NMR. It turned out that almost all the base-pairs predicted from its clover-leaf structure existed in solution and the connector region consisting of the truncated D loop and extra loop had a rather flexible structure. This mobility is indispensable for the tRNA^<Ser>_<UCU> to maintain the relative arrangement of the 3'-terminus and the anticodon equal to that of the usual tRNAs. (2)The minimal prerequisite structur … More e of ribosome : In the animal mt ribosome, the content of rRNA is about a half, but that of proteins is doubled, as compared with the counterparts of E.coli ribosome. The functional regions of mt rRNA are strictly conserved in the central parts of two ribosomal subunits and the peripheral regions of rRNA lacking in the mt ribosome are embedded by proteins so as to maintain the whole shapes of ribosomes almost equal between mt and E.coli. It turned out that some of the stem/loop structures in the peripheral regions of mt ribosome are dispensable. (3)What is the trigger in the hydrolysis reaction of GTP which is an energy source in the translation system : It was suggested that the trigger in the hydrolysis reaction of GTP is L7/L12 protein in 50S ribosomal subunit, on the basis of the fact that GTPase activity of EF-G is activated by L7/L12. We have confirmed this proposal by elucidating that E.coli EF-G can function on the mt ribosome in which only the L7/L12 protein is replaced by the counterpart of E.coli ribosome, although E.coli EF-G cannot work on the native mt ribosome. Less