Recent cryo-EM structures of a group II intron caught in the process of invading DNA have given new insight into the mechanisms of both splicing and retrotransposition. Conformational dynamics involving the branch-site helix domain VI are responsible for substrate exchange between the two steps of splicing. These structural rearrangements have strong parallels with the movement of the branch-site helix in the spliceosome during catalysis. This is strong evidence for the spliceosome evolving from a group II intron ancestor. We observe other topological changes in the overall structure of the catalytic domain V that may occur in the spliceosome as well. Therefore, studying group II introns not only provides us with insight into the evolutionary origins of the spliceosome, but also may inform the design of experiments to further probe structure-function relationships in this eukaryotic splicing apparatus. This article is categorized under: RNA Processing > Splicing Mechanisms RNA Structure and Dynamics > RNA Structure, Dynamics, and Chemistry RNA Structure and Dynamics > Influence of RNA Structure in Biological Systems RNA Evolution and Genomics > RNA and Ribonucleoprotein Evolution.

中文翻译：

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前 mRNA 剪接的逆向元件起源。

最近在入侵 DNA 过程中捕获的 II 组内含子的冷冻电镜结构为剪接和逆转录转座的机制提供了新的见解。涉及分支位点螺旋结构域 VI 的构象动力学负责两个剪接步骤之间的底物交换。这些结构重排与催化过程中剪接体中分支位点螺旋的运动有很强的相似性。这是剪接体从第 II 组内含子祖先进化而来的有力证据。我们观察到剪接体中也可能发生的催化域 V 整体结构的其他拓扑变化。因此，研究组 II 内含子不仅让我们深入了解剪接体的进化起源，但也可以为实验设计提供信息，以进一步探索这种真核剪接装置中的结构 - 功能关系。本文分类如下：RNA 加工 > 剪接机制 RNA 结构和动力学 > RNA 结构、动力学和化学 RNA 结构和动力学 > RNA 结构在生物系统中的影响 RNA 进化和基因组学 > RNA 和核糖核蛋白进化。