Mechanical Identities of RNA and DNA Double Helices Unveiled at the Single-Molecule Level
Mechanical Identities of RNA and DNA Double Helices Unveiled at the Single-Molecule Level
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DOI：
10.1021/ja3054755
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发表时间：
2013-01-09
影响因子：
15
通讯作者：
Ricardo Arias-Gonzalez, J.
中科院分区：
文献类型：
--
作者：
Herrero-Galan, Elias;Eugenia Fuentes-Perez, Maria;Ricardo Arias-Gonzalez, J.
双链（ds）RNA是多种病毒的遗传物质，并且由于其调节作用而最近被认为是细胞中的相关分子。尽管近年来在单分子拉伸实验中已经彻底表征了dsDNA的弹性响应，但仍然缺乏对dsRNA的等效研究。在这里，我们已经设计了长dsRNA分子，用于其与相同序列的dsDNA分子的单独表征对比信息。已知dsRNA是A型分子，而dsDNA在生理条件下表现出B型。这些结构类型是在单分子水平上用原子力显微镜（AFM）区分的，是理解它们不同弹性响应的基础。力延伸曲线的dsRNA与光学和磁性镊子表现出两个主要的制度的弹性，熵制度，其结束是由A-形式的轮廓长度和内在的制度，结束在一个低的合作过度拉伸过渡，其中分子延伸到1.7倍的A-形式的轮廓长度。双链RNA在力的存在下不会在A和B构象之间转换。最后，与dsDNA相比，双链RNA具有较低的拉伸模量和过度拉伸转变力，而静电和固有对持续长度的贡献更大。
Double-stranded (ds) RNA is the genetic material of a variety of viruses and has been recently recognized as a relevant molecule in cells for its regulatory role. Despite that the elastic response of dsDNA has been thoroughly characterized in recent years in single-molecule stretching experiments, an equivalent study with dsRNA is still lacking. Here, we have engineered long dsRNA molecules for their individual characterization contrasting information with dsDNA molecules of the same sequence. It is known that dsRNA is an A-form molecule unlike dsDNA, which exhibits B-form in physiological conditions. These structural types are distinguished at the single-molecule level with atomic force microscopy (AFM) and are the basis to understand their different elastic response. Force extension curves of dsRNA with optical and magnetic tweezers manifest two main regimes of elasticity, an entropic regime whose end is marked by the A-form contour-length and an intrinsic regime that ends in a low cooperative overstretching transition in which the molecule extends to 1.7 times its A-form contour-length. DsRNA does not switch between the A and B conformations in the presence of force. Finally, dsRNA presents both a lower stretch modulus and overstretching transition force than dsDNA, whereas the electrostatic and intrinsic contributions to the persistence length are larger.