Lingaraju Mahesh, Schuller Jan M, Falk Sebastian, Gerlach Piotr, Bonneau Fabien, Basquin Jérôme, Benda Christian, Conti Elena
Max-Planck-Institute of Biochemistry, Department of Structural Cell Biology, D-82152 Martinsried/Munich, Germany.
Max Perutz Labs, Department of Structural and Computational Biology, University of Vienna, 1030, Vienna, Austria.
Cold Spring Harb Symp Quant Biol. 2019;84:155-163. doi: 10.1101/sqb.2019.84.040295. Epub 2020 Jun 3.
The RNA exosome was originally discovered in yeast as an RNA-processing complex required for the maturation of 5.8S ribosomal RNA (rRNA), one of the constituents of the large ribosomal subunit. The exosome is now known in eukaryotes as the major 3'-5' RNA degradation machine involved in numerous processing, turnover, and surveillance pathways, both in the nucleus and the cytoplasm. Yet its role in maturing the 5.8S rRNA in the pre-60S ribosomal particle remains probably the most intricate and emblematic among its functions, as it involves all the RNA unwinding, degradation, and trimming activities embedded in this macromolecular complex. Here, we propose a comprehensive mechanistic model, based on current biochemical and structural data, explaining the dual functions of the nuclear exosome-the constructive versus the destructive mode.
RNA外切体最初是在酵母中作为5.8S核糖体RNA（rRNA）成熟所必需的一种RNA加工复合体被发现的，5.8S rRNA是大核糖体亚基的组成成分之一。现在已知外切体在真核生物中是参与细胞核和细胞质中众多加工、周转及监测途径的主要3'-5' RNA降解机器。然而，它在60S前核糖体颗粒中使5.8S rRNA成熟的作用可能仍是其所有功能中最复杂且最具代表性的，因为这涉及到该大分子复合体中所有的RNA解旋、降解和修剪活动。在此，我们基于当前的生化和结构数据提出了一个全面的机制模型，用以解释核外切体的双重功能——建设性模式与破坏性模式。
