Identity elements of Thermus thermophilus tRNAThr

FEBS Letters

Asahara, Haruichi¹  Hasegawa, Tsunemi¹  Nameki, Nobukazu² 

[1] Institute of Space and Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229, Japan;Department of Biology, Faculty of Science, Hirosaki University, Hirosaki 036, Japan

关键词: tRNA;    Aminoacyl-tRNA synthetase;    T7 transcript;    tRNA identity;   

DOI  :  10.1016/0014-5793(96)01094-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

In this study, we identified nucleotides that specify aminoacylation of tRNA^Thr by Thermus thermophilus threonyl-tRNA synthetase (ThrRS) using in vitro transcripts. Mutation studies showed that the first base pair in the acceptor stem as well as the second and third positions of the anticodon are major identity elements of T. thermophilus tRNA^Thr, which are essentially the same as those of Escherichia coli tRNA^Thr. The discriminator base, U₇₃, also contributed to the specific aminoacylation, but not the second base pair in the acceptor stem. These findings are in contrast to E. coli tRNA^Thr, where the second base pair is required for threonylation, with the discriminator base, A₇₃, playing no roles. In addition, among several mutations at the third base pair in the acceptor stem, only the G₃-U₇₀ mutant was a poor substrate for ThrRS, suggesting that the G₃-U₇₀ wobble pair, which is the identity determinant of tRNA^Ala, acts as a negative element for ThrRS. Similar results were obtained in E. coli and yeast. Thus, this manner of rejection of tRNA^Ala is also likely to have been retained in the threonine system throughout evolution.

【 授权许可】

Unknown