Structural Insights into the Roles of Metazoan-Specific Splicing Factors in the Human Step 1 Spliceosome
Structural Insights into the Roles of Metazoan-Specific Splicing Factors in the Human Step 1 Spliceosome
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DOI：
10.1016/j.molcel.2020.09.012
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发表时间：
2020-10-01
期刊：
影响因子：
16
通讯作者：
Luehrmann, Reinhard
中科院分区：
文献类型：
--
作者：
Bertram, Karl;El Ayoubi, Leyla;Luehrmann, Reinhard
人类剪接体含有许多酵母中不存在的蛋白质，其功能在很大程度上仍然未知。在这里，我们报告了一个3D的cryo-EM结构的人spliceosomal C复合物在3.4埃的核心分辨率和4.5-5.7埃在其周边，并协助蛋白质交联，我们确定其分子结构。我们的结构提供了额外的见解剪接体的结构之间的剪接的催化步骤，以及蛋白质如何帮助剪接体的催化活性RNP（核糖核蛋白）构象的形成。它揭示了人类C复合物中后生动物特异性蛋白PPWD 1，WDR 70，FRG 1和CIR 1的空间组织，表明它们在B-act向C过渡期间稳定功能重要的蛋白质结构域和重新排列/重新定位的RNA结构。与人类B-行为，C*，P复合物的结构比较揭示了一个复杂的级联的RNP重排在剪接催化，中间RNP构象没有发现在酵母中，并进一步阐明了后生动物特异性spliceosomal蛋白的顺序招聘的结构基础。
Human spliceosomes contain numerous proteins absent in yeast, whose functions remain largely unknown. Here we report a 3D cryo-EM structure of the human spliceosomal C complex at 3.4 angstrom core resolution and 4.5-5.7 angstrom at its periphery, and aided by protein crosslinking we determine its molecular architecture. Our structure provides additional insights into the spliceosome's architecture between the catalytic steps of splicing, and how proteins aid formation of the spliceosome's catalytically active RNP (ribonucleoprotein) conformation. It reveals the spatial organization of the metazoan-specific proteins PPWD1, WDR70, FRG1, and CIR1 in human C complexes, indicating they stabilize functionally important protein domains and RNA structures rearranged/repositioned during the B-act to C transition. Structural comparisons with human B-act, C*, and P complexes reveal an intricate cascade of RNP rearrangements during splicing catalysis, with intermediate RNP conformations not found in yeast, and additionally elucidate the structural basis for the sequential recruitment of metazoan-specific spliceosomal proteins.