小亚基核糖体组装体的完整结构。
The complete structure of the small-subunit processome.
机构信息
Laboratory of Protein and Nucleic Acid Chemistry, The Rockefeller University, New York, New York, USA.
Tri-Institutional Training Program in Chemical Biology, The Rockefeller University, New York, New York, USA.
出版信息
Nat Struct Mol Biol. 2017 Nov;24(11):944-953. doi: 10.1038/nsmb.3472. Epub 2017 Sep 25.
The small-subunit processome represents the earliest stable precursor of the eukaryotic small ribosomal subunit. Here we present the cryo-EM structure of the Saccharomyces cerevisiae small-subunit processome at an overall resolution of 3.8 Å, which provides an essentially complete near-atomic model of this assembly. In this nucleolar superstructure, 51 ribosome-assembly factors and two RNAs encapsulate the 18S rRNA precursor and 15 ribosomal proteins in a state that precedes pre-rRNA cleavage at site A1. Extended flexible proteins are employed to connect distant sites in this particle. Molecular mimicry and steric hindrance, as well as protein- and RNA-mediated RNA remodeling, are used in a concerted fashion to prevent the premature formation of the central pseudoknot and its surrounding elements within the small ribosomal subunit.
小亚基加工体代表了真核生物小核糖体亚基最早的稳定前体。在这里，我们呈现了酿酒酵母小亚基加工体的 cryo-EM 结构，整体分辨率为 3.8Å，为这个组装体提供了一个基本完整的近原子模型。在这个核仁超结构中，51 个核糖体组装因子和两个 RNA 将 18S rRNA 前体和 15 个核糖体蛋白包裹在 A1 位点前 rRNA 切割之前的状态。扩展的柔性蛋白用于连接这个粒子中遥远的部位。分子模拟和空间位阻，以及蛋白质和 RNA 介导的 RNA 重塑，以协同的方式被用来防止中央假结及其在小核糖体亚基内的周围元件过早形成。
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