Cryo-EM structure of a human spliceosome activated for step 2 of splicing
Cryo-EM structure of a human spliceosome activated for step 2 of splicing
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DOI：
10.1038/nature21079
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发表时间：
2017-02-16
期刊：
影响因子：
64.8
通讯作者：
Luehrmann, Reinhard
中科院分区：
文献类型：
--
作者：
Bertram, Karl;Agafonov, Dmitry E.;Luehrmann, Reinhard
在剪接的催化步骤2之前，RNA解旋酶PRP16促进的剪接体重排还知之甚少。在这里，我们报告了一个三维冷冻电子显微镜结构的人剪接体C复合体在PRP16作用后直接停止(C*)。人C*剪接体催化的U2-U6核糖核蛋白(RNP)核心的结构与酵母Prp16C前复合体的结构非常相似。然而，在C*中，分支内含子区域与催化中心相距约20埃，其靠近U6小核RNA ACAGA盒的位置通过与Prp8 RNaseH-like和PRP17 WD40结构域的相互作用而稳定。RNA解旋酶PRP22位于距离催化中心约100埃的地方，这表明它在第二步后从一段距离破坏了剪接的mRNA的稳定性。对酵母C和人类C*复合体结构的比较表明，PRP16可能促进了许多RNP重排，包括U2小核RNP的大规模移动。
Spliceosome rearrangements facilitated by RNA helicase PRP16 before catalytic step two of splicing are poorly understood. Here we report a 3D cryo-electron microscopy structure of the human spliceosomal C complex stalled directly after PRP16 action (C*). The architecture of the catalytic U2-U6 ribonucleoprotein (RNP) core of the human C* spliceosome is very similar to that of the yeast pre-Prp16 C complex. However, in C* the branched intron region is separated from the catalytic centre by approximately 20 angstrom, and its position close to the U6 small nuclear RNA ACAGA box is stabilized by interactions with the PRP8 RNase H-like and PRP17 WD40 domains. RNA helicase PRP22 is located about 100 angstrom from the catalytic centre, suggesting that it destabilizes the spliced mRNA after step two from a distance. Comparison of the structure of the yeast C and human C* complexes reveals numerous RNP rearrangements that are likely to be facilitated by PRP16, including a large-scale movement of the U2 small nuclear RNP.