ジャーナル: Proc Natl Acad Sci U S A / 年: 2008 タイトル: Structure of ratcheted ribosomes with tRNAs in hybrid states. 著者: Patricia Julián / Andrey L Konevega / Sjors H W Scheres / Melisa Lázaro / David Gil / Wolfgang Wintermeyer / Marina V Rodnina / Mikel Valle / 要旨: During protein synthesis, tRNAs and mRNA move through the ribosome between aminoacyl (A), peptidyl (P), and exit (E) sites of the ribosome in a process called translocation. Translocation is ...During protein synthesis, tRNAs and mRNA move through the ribosome between aminoacyl (A), peptidyl (P), and exit (E) sites of the ribosome in a process called translocation. Translocation is accompanied by the displacement of the tRNAs on the large ribosomal subunit toward the hybrid A/P and P/E states and by a rotational movement (ratchet) of the ribosomal subunits relative to one another. So far, the structure of the ratcheted state has been observed only when translation factors were bound to the ribosome. Using cryo-electron microscopy and classification, we show here that ribosomes can spontaneously adopt a ratcheted conformation with tRNAs in their hybrid states. The peptidyl-tRNA molecule in the A/P state, which is visualized here, is not distorted compared with the A/A state except for slight adjustments of its acceptor end, suggesting that the displacement of the A-site tRNA on the 50S subunit is passive and is induced by the 30S subunit rotation. Simultaneous subunit ratchet and formation of the tRNA hybrid states precede and may promote the subsequent rapid and coordinated tRNA translocation on the 30S subunit catalyzed by elongation factor G.
超分子 #1: 70S E.coli ribosome in the pretranslocation state
超分子
名称: 70S E.coli ribosome in the pretranslocation state / タイプ: complex / ID: 1 / Name.synonym: pretranslocation ribosome / 組換発現: No / Ribosome-details: ribosome-prokaryote: ALL
由来(天然)
生物種: Escherichia coli (大腸菌)
-
実験情報
-
構造解析
手法
ネガティブ染色法, クライオ電子顕微鏡法
解析
単粒子再構成法
試料の集合状態
particle
-
試料調製
緩衝液
pH: 7.5 詳細: 50 mM Tris-HCl, pH 7.5 30mM KCl 70 mM NH4Cl 20 mM MgCl2 2 mM spermine
染色
タイプ: NEGATIVE / 詳細: cryoEM
グリッド
詳細: Quantifoil 300 mesh copper
凍結
凍結剤: ETHANE / チャンバー内湿度: 100 % / チャンバー内温度: 90 K / 装置: OTHER / 詳細: Vitrification instrument: Vitrobot / 手法: single blot for 1.5 seconds