氟离子核糖开关调控行为的动力学研究

Kinetic Study for Regulation Behaviors of the Fluoride Riboswitch

核糖开关位于RNA(ribonucleic acid)的非编码区,参与调控很多重要的生物过程。本文利用已发展的RNA转录折叠预测方法,研究了位于Thermotoga petrophila中的氟离子核糖开关。计算结果表明,该核糖开关在转录过程中先折叠成一个包含假结并可以特异性结合配体的适体域结构。当氟离子浓度较低时,随着RNA序列的延长,转录终止子开始成核、延长,最终完全形成,引起转录提前终止;当氟离子浓度较高时,配体和适体域结构结合形成一个稳定的复合体结构,阻止了转录终止子的形成,从而使得下游基因可以正常表达。该核糖开关受转录速度和配体浓度的联合控制,体现出动力学调控特性。

Riboswitches, resided within non-coding region of certain RNA, are involved in many important biological processes.By using the recently developed RNA co-transcription folding prediction methods, we studied the regulation of the fluoride riboswitch from Thermotoga petrophila. The results suggest that the riboswitch folds into the terminator(T) with a pseudoknot, which can specially bind fluoride ions during transcription. At a low fluoride concentration, with the elongation of the nascent RNA chain, the terminator is nucleated and formed, which leads to the transcription termination. At a high fluoride concentration, the aptamer structure binds the ligand to form a stable complex structure, which prevents the full formation of the terminator and promotes expression of downstream genes. The transcription speed and ligand concentration are coupled to control regulation activities of the riboswitch, which are consistent with a kinetic control model.