Department of Physics and POSTECH Center for Theoretical Physics, Pohang University of Science and Technology, Pohang 790-784, Republic of Korea.
Proc Natl Acad Sci U S A. 2012 Sep 4;109(36):14410-5. doi: 10.1073/pnas.1202952109. Epub 2012 Aug 20.
In addition to thermal noise, which is essential to promote conformational transitions in biopolymers, the cellular environment is replete with a spectrum of athermal fluctuations that are produced from a plethora of active processes. To understand the effect of athermal noise on biological processes, we studied how a small oscillatory force affects the thermally induced folding and unfolding transition of an RNA hairpin, whose response to constant tension had been investigated extensively in both theory and experiments. Strikingly, our molecular simulations performed under overdamped condition show that even at a high (low) tension that renders the hairpin (un)folding improbable, a weak external oscillatory force at a certain frequency can synchronously enhance the transition dynamics of RNA hairpin and increase the mean transition rate. Furthermore, the RNA dynamics can still discriminate a signal with resonance frequency even when the signal is mixed among other signals with nonresonant frequencies. In fact, our computational demonstration of thermally induced resonance in RNA hairpin dynamics is a direct realization of the phenomena called stochastic resonance and resonant activation. Our study, amenable to experimental tests using optical tweezers, is of great significance to the folding of biopolymers in vivo that are subject to the broad spectrum of cellular noises.
除了对促进生物聚合物构象转变至关重要的热噪声外，细胞环境中还充斥着大量非热波动，这些波动是由多种活跃过程产生的。为了了解非热噪声对生物过程的影响，我们研究了一个小的振荡力如何影响 RNA 发夹的热诱导折叠和展开转变，其对恒定张力的响应在理论和实验中都得到了广泛的研究。引人注目的是，我们在过阻尼条件下进行的分子模拟表明，即使在一个高（低）张力下，发夹（不）折叠的可能性很小，一个弱的外部振荡力在一定的频率下可以同时增强 RNA 发夹的转变动力学，并增加平均转变率。此外，RNA 动力学仍然可以区分具有共振频率的信号，即使信号与具有非共振频率的其他信号混合。事实上，我们在 RNA 发夹动力学中诱导热共振的计算演示是被称为随机共振和共振激活现象的直接实现。我们的研究适用于使用光学镊子进行实验测试，对于生物聚合物在体内的折叠具有重要意义，因为它们受到广泛的细胞噪声的影响。
