Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA.
Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520, USA; Department of Chemistry, Yale University, New Haven, CT 06520, USA; Howard Hughes Medical Institute, Chevy Chase, MD 20815, USA.
Curr Opin Struct Biol. 2017 Dec;47:30-39. doi: 10.1016/j.sbi.2017.05.002. Epub 2017 May 18.
The splicing of group II introns in vivo requires the assistance of a multifunctional intron encoded protein (IEP, or maturase). Each IEP is also a reverse-transcriptase enzyme that enables group II introns to behave as mobile genetic elements. During splicing or retro-transposition, each group II intron forms a tight, specific complex with its own encoded IEP, resulting in a highly reactive holoenzyme. This review focuses on the structural basis for IEP function, as revealed by recent crystal structures of an IEP reverse transcriptase domain and cryo-EM structures of an IEP-intron complex. These structures explain how the same IEP scaffold is utilized for intron recognition, splicing and reverse transcription, while providing a physical basis for understanding the evolutionary transformation of the IEP into the eukaryotic splicing factor Prp8.
内含子的剪接需要多功能内含子编码蛋白（IEP，或成熟酶）的辅助。每个 IEP 也是一种逆转录酶，使 II 组内含子能够表现为移动遗传元件。在剪接或 retro-transposition 过程中，每个 II 组内含子与其自身编码的 IEP 形成紧密、特异的复合物，形成高度反应性的全酶。本综述重点介绍了最近的 IEP 逆转录酶结构域晶体结构和 IEP-内含子复合物的 cryo-EM 结构揭示的 IEP 功能的结构基础。这些结构解释了相同的 IEP 支架如何用于内含子识别、剪接和逆转录，同时为理解 IEP 向真核剪接因子 Prp8 的进化转变提供了物理基础。
