G&L Kyosei Institute, Koharu Bld. 202, Hokkeji 153-4, Nara, 630-8001, Japan.
The International Institute for Advanced Studies of Japan, Kizugawadai 9-3, Kizugawa, Kyoto, 619-0225, Japan.
Orig Life Evol Biosph. 2019 Jun;49(1-2):61-75. doi: 10.1007/s11084-019-09573-w. Epub 2019 May 10.
The riddle of the origin of life is unsolved as yet. One of the best ways to solve the riddle would be to find a vestige of the first life from databases of DNA and/or protein of modern organisms. It would be, especially, important to know the origin of tRNA, because it mediates between genetic information and the amino acid sequence of a protein. Here I attempt to find a vestige of the origin and evolution of tRNA from base sequences of Pseudomonas aeruginosa tRNA gene. It was first perceived that 5' anticodon (AntiC) stem sequences of P. aeruginosa tRNA for translation of G-start codon (GNN) are intimately and mutually related. Then, mutual relations among all of the forty-two 5' AntiC stem sequences of P. aeruginosa tRNA were examined. These relationships imply that P. aeruginosa tRNA originated from four anticodon stem-loops (AntiC-SL) translating GNC codons to the corresponding four amino acids, Gly, Ala, Asp and Val (where N is G, C, A, or T). In contrast to the case of AntiC-stem sequence, a mutual relation map could not be drawn with D-, T- and acceptor-stem sequences of P. aeruginosa tRNA. Thus I conclude that the four AntiC-SLs were the first primeval tRNAs.
生命起源之谜尚未解开。解决这个谜的最好方法之一是从现代生物的 DNA 和/或蛋白质数据库中找到生命起源的痕迹。了解 tRNA 的起源尤为重要，因为它在遗传信息和蛋白质的氨基酸序列之间起媒介作用。在这里，我试图从铜绿假单胞菌 tRNA 基因的碱基序列中找到 tRNA 的起源和进化的痕迹。首先发现，铜绿假单胞菌 tRNA 用于翻译 G 起始密码子（GNN）的 5'反密码子（AntiC）茎序列密切相关。然后，检查了铜绿假单胞菌 tRNA 的所有 42 个 5' AntiC 茎序列之间的相互关系。这些关系表明，铜绿假单胞菌 tRNA 起源于四个反密码子茎环（AntiC-SL），将 GNC 密码子翻译成相应的四个氨基酸：甘氨酸、丙氨酸、天冬氨酸和缬氨酸（其中 N 是 G、C、A 或 T）。与 AntiC-茎序列的情况不同，铜绿假单胞菌 tRNA 的 D-、T-和受体茎序列之间无法绘制相互关系图。因此，我得出结论，这四个 AntiC-SL 是最初的原始 tRNA。
