INTERACTION BETWEEN THE ACCEPTOR END OF TRANSFER-RNA AND THE T-BOX STIMULATES ANTITERMINATION IN THE BACILLUS-SUBTILIS TYRS GENE - A NEW ROLE FOR THE DISCRIMINATOR BASE
INTERACTION BETWEEN THE ACCEPTOR END OF TRANSFER-RNA AND THE T-BOX STIMULATES ANTITERMINATION IN THE BACILLUS-SUBTILIS TYRS GENE - A NEW ROLE FOR THE DISCRIMINATOR BASE
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DOI：
10.1128/jb.176.15.4518-4526.1994
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发表时间：
1994-08-01
影响因子：
3.2
通讯作者：
HENKIN, TM
中科院分区：
文献类型：
--
作者：
GRUNDY, FJ;ROLLINS, SM;HENKIN, TM
枯草芽孢杆菌 tyrS 基因是一组革兰氏阳性氨酰基-tRNA 合成酶和氨基酸生物合成基因的成员，其受转录抗终止调节。该组中的每个基因都是通过限制适当的氨基酸而特异性诱导的。这种反应是通过同源 tRNA 与 mRNA 前导区的相互作用介导的，以促进抗终止子结构的形成。 tRNA 通过密码子-反密码子配对与前导序列相互作用，该位置指定为反终止子上游的指定序列。在这项研究中，通过前导 mRNA 和 tRNA 序列的共变，确定了 tRNA 和前导序列之间可能接触的另一个位点。 tRNA(Tyr) 受体末端的突变可以抑制反终止子侧面凸起的突变，其模式与碱基配对一致。该碱基配对可能因此直接影响抗终止子的形成和/或功能。 tRNA 的鉴别器位置是许多 tRNA（包括 tRNA(Tyr)）的重要身份决定因素，已被证明可作为第二个特异性决定因素，以确保对适当 tRNA 的反应。此外，在没有酪氨酸限制的情况下，不带电的 tRNA (Tyr) 变体的过量产生会导致抗终止，这支持了不带电的 tRNA 是该系统中效应子的观点。
The Bacillus subtilis tyrS gene is a member of a group of gram-positive aminoacyl-tRNA synthetase and amino acid biosynthesis genes which are regulated by transcription antitermination. Each gene in the group is specifically induced by limitation for the appropriate amino acid. This response is mediated by interaction of the cognate tRNA with the mRNA leader region to promote formation of an antiterminator structure. The tRNA interacts with the leader by codon-anticodon pairing at a position designated the specifier sequence which is upstream of the antiterminator. In this study, an additional site of possible contact between the tRNA and the leader was identified through covariation of leader mRNA and tRNA sequences. Mutations in the acceptor end of tRNA(Tyr) could suppress mutations in the side bulge of the antiterminator, in a pattern consistent with base pairing. This base pairing may thereby directly affect the formation and/or function of the antiterminator. The discriminator position of the tRNA, an important identity determinant for a number of tRNAs, including tRNA(Tyr), was shown to act as a second specificity determinant for assuring response to the appropriate tRNA. Furthermore, overproduction of an unchargeable variant of tRNA(Tyr) resulted in antitermination in the absence of limitation for tyrosine, supporting the proposal that uncharged tRNA is the effector in this system.