Visualizing large RNA molecules in solution
Visualizing large RNA molecules in solution
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DOI：
10.1261/rna.027557.111
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发表时间：
2012-02-01
期刊：
影响因子：
4.5
通讯作者：
Gelbart, William M.
中科院分区：
文献类型：
--
作者：
Gopal, Ajaykumar;Zhou, Z. Hong;Gelbart, William M.
长度超过几百个核苷酸的单链RNA（ssRNA）在溶液中没有独特的结构。因此，它们的平衡性质反映了结构系综的平均值。我们使用冷冻电子显微镜图像投影的个人长的ssRNA分子和表征其在溶液中的合奏的各向异性。一个扁平的扁长体积被发现最能代表这些合奏的形状。测量的尺寸和各向异性是在良好的协议与互补的测定，使用小角度X射线散射和粗粒分子动力学模拟。一个长的病毒ssRNA与较短的非编码转录本进行比较，以证明扁长的几何形状和平坦度是独立于序列长度和起源的通用属性。在生理和低离子强度条件下，各向异性持续存在，揭示了二级结构不对称性与3D形状和大小之间的直接相关性。我们讨论的物理起源的通用各向异性及其生物学意义。
Single-stranded RNAs (ssRNAs) longer than a few hundred nucleotides do not have a unique structure in solution. Their equilibrium properties therefore reflect the average of an ensemble of structures. We use cryo-electron microscopy to image projections of individual long ssRNA molecules and characterize the anisotropy of their ensembles in solution. A flattened prolate volume is found to best represent the shapes of these ensembles. The measured sizes and anisotropies are in good agreement with complementary determinations using small-angle X-ray scattering and coarse-grained molecular dynamics simulations. A long viral ssRNA is compared with shorter noncoding transcripts to demonstrate that prolate geometry and flatness are generic properties independent of sequence length and origin. The anisotropy persists under physiological as well as low-ionic-strength conditions, revealing a direct correlation between secondary structure asymmetry and 3D shape and size. We discuss the physical origin of the generic anisotropy and its biological implications.