Characterization of the mechanical unfolding of RNA pseudoknots.
Characterization of the mechanical unfolding of RNA pseudoknots.
复制标题
RNA伪诺的机械展开的表征。
DOI：
10.1016/j.jmb.2007.05.058
复制
发表时间：
2008-01-11
影响因子：
5.6
通讯作者：
Tinoco I Jr
中科院分区：
文献类型：
--
作者：
Green L;Kim CH;Bustamante C;Tinoco I Jr
伪结是一种重要的RNA结构元件，它为研究三级相互作用对RNA稳定性和折叠动力学的贡献提供了一个很好的模型系统。RNA伪结也引起了人们的兴趣，因为它们在控制病毒RNA的核糖体移码方面发挥了关键作用。它们的机械性能与它们在翻译过程中被核糖体打开直接相关。我们用光钳研究了单个RNA分子机械去折叠和复性的动力学和热力学。在这里，我们描述了传染性支气管炎病毒(IBV)的移码假结、三个组成发夹和IBV假结的三个突变体的展开。这四个假结都会导致−-1程序性核糖体移码。我们测量了四个移帧假结的机械展开和再折叠的自由能和速率。我们的结果表明，IBV假结需要比其对应的发夹更大的力才能展开。此外，与发夹的展开速率相比，其展开速率随力的增加而变化不大。镁离子的存在显著增加了IBV假结解开的动力学势垒，但对发夹的解开影响不大。与发夹相比，伪结的机械稳定性更大，而且它们对力的动力学不敏感，支持−1移码取决于解开难度的假说。
The pseudoknot is an important RNA structural element that provides an excellent model system for studying the contributions of tertiary interactions to RNA stability and to folding kinetics. RNA pseudoknots are also of interest because of their key role in the control of ribosomal frameshifting by viral RNAs. Their mechanical properties are directly relevant to their unfolding by ribosomes during translation. We have used optical tweezers to study the kinetics and thermodynamics of mechanical unfolding and refolding of single RNA molecules. Here we describe the unfolding of the frameshifting pseudoknot from infectious bronchitis virus (IBV), three constituent hairpins, and three mutants of the IBV pseudoknot. All four pseudoknots cause −1 programmed ribosomal frameshifting. We have measured the free energies and rates of mechanical unfolding and refolding of the four frameshifting pseudoknots. Our results show that the IBV pseudoknot requires a higher force than its corresponding hairpins to unfold. Furthermore, its rate of unfolding changes little with increasing force, in contrast with the rate of hairpin unfolding. The presence of Mg2+ significantly increases the kinetic barriers to unfolding the IBV pseudoknot, but has only a minor effect on the hairpin unfolding. The greater mechanical stability of pseudoknots compared to hairpins, and their kinetic insensitivity to force supports the hypothesis that −1 frameshifting depends on the difficulty of unfolding the mRNA.
登录
查看更多内容
影响因子：
5.6
作者：
Brierley I;Rolley NJ;Jenner AJ;Inglis SC
通讯作者：
Inglis SC
影响因子：
5.8
作者：
Bekaert, M;Bidou, L;Termier, M
通讯作者：
Termier, M
影响因子：
5.3
作者：
Kontos, H;Napthine, S;Brierley, I
通讯作者：
Brierley, I
影响因子：
5.4
作者：
DINMAN, JD;WICKNER, RB
通讯作者：
WICKNER, RB
影响因子：
64.5
作者：
Brierley I;Digard P;Inglis SC
通讯作者：
Inglis SC