ジャーナル: Nat Struct Mol Biol / 年: 2014 タイトル: Visualization of distinct substrate-recruitment pathways in the yeast exosome by EM. 著者: Jun-Jie Liu / Matthew A Bratkowski / Xueqi Liu / Chu-Ya Niu / Ailong Ke / Hong-Wei Wang / 要旨: The eukaryotic exosome is a multisubunit complex typically composed of a catalytically inactive core and the Rrp44 protein, which contains 3'-to-5' exo- and endo-RNase activities. RNA substrates have ...The eukaryotic exosome is a multisubunit complex typically composed of a catalytically inactive core and the Rrp44 protein, which contains 3'-to-5' exo- and endo-RNase activities. RNA substrates have been shown to be recruited through the core to reach Rrp44's exo-RNase (EXO) site. Using single-particle EM and biochemical analysis, we provide visual evidence that two distinct substrate-recruitment pathways exist. In the through-core route, channeling of the single-stranded substrates from the core to Rrp44 induces a characteristic conformational change in Rrp44. In the alternative direct-access route, this conformational change does not take place, and the RNA substrate is visualized to avoid the core and enter Rrp44's EXO site directly. Our results provide mechanistic explanations for several RNA processing scenarios by the eukaryotic exosome and indicate substrate-specific modes of degradation by this complex.
タイプ: NEGATIVE 詳細: All samples were diluted to a final concentration of ~80 nM of the exosome in the non-digestive buffer and negatively stained in 2% (w/v) uranyl acetate solution following the standard deep ...詳細: All samples were diluted to a final concentration of ~80 nM of the exosome in the non-digestive buffer and negatively stained in 2% (w/v) uranyl acetate solution following the standard deep stain procedure on holey-carbon coated EM copper grids covered with a thin layer of continuous carbon
グリッド
詳細: 300 mesh continus carbon
凍結
凍結剤: NONE / 装置: OTHER
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電子顕微鏡法
顕微鏡
FEI TECNAI 12
日付
2011年10月10日
撮影
カテゴリ: CCD フィルム・検出器のモデル: GATAN ULTRASCAN 4000 (4k x 4k)