Watanabe Y, Kawai G, Yokogawa T, Hayashi N, Kumazawa Y, Ueda T, Nishikawa K, Hirao I, Miura K, Watanabe K
Department of Chemistry and Biotechnology, Faculty of Engineering, University of Tokyo, Japan.
Nucleic Acids Res. 1994 Dec 11;22(24):5378-84. doi: 10.1093/nar/22.24.5378.
On the basis of enzymatic probing and phylogenetic comparison, we have previously proposed that mammalian mitochondrial tRNA(sSer) (anticodon UGA) possess a slightly altered cloverleaf structure in which only one nucleotide exists between the acceptor stem and D stem (usually two nucleotides) and the anticodon stem consists of six base pairs (usually five base pairs) [Yokogawa et al. (1991) Nucleic Acids Res. 19, 6101-6105]. To ascertain whether such tRNA(sSer) can be folded into a normal L-shaped tertiary structure, the higher-order structure of bovine mitochondrial tRNA(SerUGA) was examined by chemical probing using dimethylsulfate and diethylpyrocarbonate, and on the basis of the results a tertiary structure model was obtained by computer modeling. It was found that a one-base-pair elongation in the anticodon stem was compensated for by multiple-base deletions in the D and extra loop regions of the tRNA(SerUGA), which resulted in preservation of an L-shaped tertiary structure similar to that of conventional tRNAs. By summarizing the findings, the general structural requirements of mitochondrial tRNAs necessary for their functioning in the mitochondrial translation system are considered.
基于酶切探测和系统发育比较，我们先前提出哺乳动物线粒体tRNA（sSer）（反密码子UGA）具有略微改变的三叶草结构，其中在接受茎和D茎之间仅存在一个核苷酸（通常为两个核苷酸），并且反密码子茎由六个碱基对组成（通常为五个碱基对）[横川等人（1991年）《核酸研究》19，6101 - 6105]。为了确定这种tRNA（sSer）是否可以折叠成正常的L形三级结构，通过使用硫酸二甲酯和焦碳酸二乙酯的化学探测来研究牛线粒体tRNA（SerUGA）的高级结构，并基于这些结果通过计算机建模获得了三级结构模型。结果发现，反密码子茎中的一个碱基对延伸通过tRNA（SerUGA）的D环和额外环区域中的多个碱基缺失得到补偿，这导致保留了与传统tRNA类似的L形三级结构。通过总结这些发现，考虑了线粒体tRNA在线粒体翻译系统中发挥功能所必需的一般结构要求。
