The characterization of the conformational landscape of the RNA backbone is rather complex due to the ability of RNA to assume a large variety of conformations. These backbone conformations can be depicted by pseudotorsional angles linking RNA backbone atoms, from which Ramachandran-like plots can be built. We explore here different definitions of these pseudotorsional angles, finding that the most accurate ones are the traditional η (eta) and θ (theta) angles, which represent the relative position of RNA backbone atoms P and C4′. We explore the distribution of η − θ in known experimental structures, comparing the pseudotorsional space generated with structures determined exclusively by one experimental technique. We found that the complete picture only appears when combining data from different sources. The maps provide a quite comprehensive representation of the RNA accessible space, which can be used in RNA-structural predictions. Finally, our results highlight that protein interactions lead to significant changes in the population of the η − θ space, pointing toward the role of induced-fit mechanisms in protein–RNA recognition.

中文翻译：

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RNA 的赝扭转空间

由于 RNA 能够呈现多种构象，因此 RNA 主链构象景观的表征相当复杂。这些主链构象可以通过连接 RNA 主链原子的赝扭转角来描述，从中可以构建类似 Ramachandran 的图。我们在这里探讨了这些赝扭转角的不同定义，发现最准确的是传统的η (eta) 和θ (theta) 角，它们代表了 RNA 主链原子 P 和 C4' 的相对位置。我们探索已知实验结构中η − θ的分布，将生成的赝扭转空间与仅由一种实验技术确定的结构进行比较。我们发现，只有结合不同来源的数据时，才会出现完整的情况。这些图谱提供了 RNA 可及空间的相当全面的表示，可用于 RNA 结构预测。最后，我们的结果强调蛋白质相互作用导致η − θ空间群体的显着变化，指出诱导拟合机制在蛋白质-RNA 识别中的作用。