科學家解析出過渡狀態下90S小核糖體亞基前體的冷凍電鏡結構
作者：
小柯機器人發布時間：2020/9/22 14:17:36
中國科學院生物物理研究所葉克窮課題組解析出過渡狀態下90S小核糖體亞基前體的冷凍電鏡結構。相關論文於2020年9月18日發表於國際學術期刊《科學》。
據研究人員介紹，90S前核糖體是小核糖體亞基的大型早期組裝中間體，會經歷結構變化來產生40S前核糖體。
研究人員通過確定釀酒酵母中間體從90S到40S前體途徑的冷凍電鏡結構，來獲得了對這種轉變的了解。完整的過渡被RNA解旋酶Dhr1的缺失所阻斷。一系列結構快照顯示，切除的5'外部轉錄間隔子（5'ETS）在90S內被降解，從而導致組裝因子的逐步拆卸和核糖體成熟。
核外泌體是一種RNA降解機器，它通過解旋酶Mtr4停靠在90S上，並被活化從而消化5'ETS的3'末端。在3.2至8.6埃解析度之間解析的結構揭示了關鍵的中間體以及5'ETS降解在90S進展中的關鍵作用。
附：英文原文
Title: Cryo-EM structure of 90S small ribosomal subunit precursors in transition states
Author: Yifei Du, Weidong An, Xing Zhu, Qi Sun, Jia Qi, Keqiong Ye
Issue&Volume: 2020/09/18
Abstract: The 90S preribosome is a large, early assembly intermediate of small ribosomal subunits that undergoes structural changes to give a pre-40S ribosome. Here, we gained insight into this transition by determining cryo–electron microscopy structures of Saccharomyces cerevisiae intermediates in the path from the 90S to the pre-40S. The full transition is blocked by deletion of RNA helicase Dhr1. A series of structural snapshots revealed that the excised 5′ external transcribed spacer (5′ ETS) is degraded within 90S, driving stepwise disassembly of assembly factors and ribosome maturation. The nuclear exosome, an RNA degradation machine, docks on the 90S through helicase Mtr4 and is primed to digest the 3′ end of the 5′ ETS. The structures resolved between 3.2- and 8.6-angstrom resolution reveal key intermediates and the critical role of 5′ ETS degradation in 90S progression.
DOI: 10.1126/science.aba9690
Source: https://science.sciencemag.org/content/369/6510/1477
Science：《科學》，創刊於1880年。隸屬於美國科學促進會，最新IF：41.037