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Molecular Mechanism and Evolution of Nuclear Pre-mRNA and Group II Intron Splicing: Insights from Cryo-Electron Microscopy Structures
Chemical Reviews ( IF 51.4 ) Pub Date : 2018-01-29 00:00:00 , DOI: 10.1021/acs.chemrev.7b00499
Wojciech P Galej 1 , Navtej Toor 2 , Andrew J Newman 3 , Kiyoshi Nagai 3
Affiliation  

Nuclear pre-mRNA splicing and group II intron self-splicing both proceed by two-step transesterification reactions via a lariat intron intermediate. Recently determined cryo-electron microscopy (cryo-EM) structures of catalytically active spliceosomes revealed the RNA-based catalytic core and showed how pre-mRNA substrates and reaction products are positioned in the active site. These findings highlight a strong structural similarity to the group II intron active site, strengthening the notion that group II introns and spliceosomes evolved from a common ancestor. Prp8, the largest and most conserved protein in the spliceosome, cradles the active site RNA. Prp8 and group II intron maturase have a similar domain architecture, suggesting that they also share a common evolutionary origin. The interactions between maturase and key group II intron RNA elements, such as the exon-binding loop and domains V and VI, are recapitulated in the interactions between Prp8 and key elements in the spliceosome’s catalytic RNA core. Structural comparisons suggest that the extensive RNA scaffold of the group II intron was gradually replaced by proteins as the spliceosome evolved. A plausible model of spliceosome evolution is discussed.

中文翻译:

核前体 mRNA 和 II 组内含子剪接的分子机制和进化:来自低温电子显微镜结构的见解

核前 mRNA 剪接和 II 组内含子自剪接均通过套索内含子中间体的两步酯交换反应进行。最近确定的催化活性剪接体的低温电子显微镜 (cryo-EM) 结构揭示了基于 RNA 的催化核心,并显示了前 mRNA 底物和反应产物如何定位在活性位点中。这些发现突出了与 II 组内含子活性位点的强烈结构相似性,强化了 II 组内含子和剪接体从共同祖先进化而来的概念。Prp8 是剪接体中最大和最保守的蛋白质,是活性位点 RNA 的摇篮。Prp8 和 II 组内含子成熟酶具有相似的域结构,表明它们也具有共同的进化起源。成熟酶和关键组 II 内含子 RNA 元件之间的相互作用,例如外显子结合环和结构域 V 和 VI,在 Prp8 和剪接体催化 RNA 核心中的关键元件之间的相互作用中得到了概括。结构比较表明,随着剪接体的进化,II 组内含子的广泛 RNA 支架逐渐被蛋白质取代。讨论了剪接体进化的合理模型。
更新日期:2018-01-29
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