Solution structure of the Bacillus subtilis T-box antiterminator RNA:: Seven nucleotide bulge characterized by stacking and flexibility
Solution structure of the Bacillus subtilis T-box antiterminator RNA:: Seven nucleotide bulge characterized by stacking and flexibility
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DOI：
10.1016/s0022-2836(02)01339-6
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发表时间：
2003-02-07
影响因子：
5.6
通讯作者：
Hines, JV
中科院分区：
文献类型：
--
作者：
Gerdeman, MS;Henkin, TM;Hines, JV
T-box转录抗终止调控系统是调控革兰氏阳性菌氨酰基trna合成酶表达、氨基酸生物合成和转运体基因表达的重要机制。反终止依赖于一组复杂的相互作用之间的不带电tRNA和mRNA的调控基因的前导区。在这里，我们报告了基于枯草芽孢杆菌tyrS抗菌剂的模型RNA的溶液结构，确定了所有9个聚合结构的rmsd为3.47埃，代表共识家族的7个结构的rmsd为2.66埃。反消光剂由两个短螺旋组成，中间有一个7nt的凸起。抗终止剂的凸起区域最终与tRNA的受体端相互作用，在3'端（包括高度保守的ACC残基）表现出广泛的堆叠，并且是两个侧翼螺旋之间明显的扭结位点。凸起的5'端显示出构象灵活性的证据。在结构研究的基础上，没有迹象表明凸起的5'端最终与tRNA碱基对的碱基被预先组织以结合。相反，这些数据与一个模型是一致的，在这个模型中，凸起3'端的堆叠诱导结构可能有助于tRNA在结合过程中对一组构象进行预先选择。2003爱思唯尔科学有限公司版权所有。
The T-box transcription antitermination regulatory system is an important mechanism for regulation of expression of aminoacyl-tRNA synthetase, amino acid biosynthesis and transporter gene expression in Gram-positive bacteria. Antitermination is dependent on a complex set of interactions between uncharged tRNA and the leader region of the mRNA of the regulated gene. Here, we report the solution structure of a model RNA, based on the Bacillus subtilis tyrS antiterminator, determined to an rmsd of 3.47 Angstrom for all nine converged structures and 2.66 Angstrom for the seven structures representing the consensus family. The antiterminator is comprised of two short helices with an intervening 7 nt bulge. The bulge region of the antiterminator, which ultimately interacts with the acceptor end of tRNA, exhibits extensive stacking at the 3' end (encompassing the highly conserved ACC residues) and is the site of a pronounced kink between the two flanking helices. The 5' end of the bulge exhibits evidence of conformational flexibility. On the basis of the structural studies, there is no indication that the bases at the 5' end of the bulge that ultimately base-pair with tRNA are pre-organized for binding. Instead, the data are consistent with a model in which the stacking-induced structure at the 3' end of the bulge may facilitate the pre-selection of a set of conformations for the tRNA to sample during binding. (C) 2003 Elsevier Science Ltd. All rights reserved.