ジャーナル: Elife / 年: 2018 タイトル: Translational initiation factor eIF5 replaces eIF1 on the 40S ribosomal subunit to promote start-codon recognition. 著者: Jose Luis Llácer / Tanweer Hussain / Adesh K Saini / Jagpreet Singh Nanda / Sukhvir Kaur / Yuliya Gordiyenko / Rakesh Kumar / Alan G Hinnebusch / Jon R Lorsch / V Ramakrishnan / 要旨: In eukaryotic translation initiation, AUG recognition of the mRNA requires accommodation of Met-tRNA in a 'P' state, which is antagonized by the factor eIF1. eIF5 is a GTPase activating protein (GAP) ...In eukaryotic translation initiation, AUG recognition of the mRNA requires accommodation of Met-tRNA in a 'P' state, which is antagonized by the factor eIF1. eIF5 is a GTPase activating protein (GAP) of eIF2 that additionally promotes stringent AUG selection, but the molecular basis of its dual function was unknown. We present a cryo-electron microscopy (cryo-EM) reconstruction of a yeast 48S pre-initiation complex (PIC), at an overall resolution of 3.0 Å, featuring the N-terminal domain (NTD) of eIF5 bound to the 40S subunit at the location vacated by eIF1. eIF5 interacts with and allows a more accommodated orientation of Met-tRNA. Substitutions of eIF5 residues involved in the eIF5-NTD/tRNA interaction influenced initiation at near-cognate UUG codons and the closed/open PIC conformation in vitro, consistent with direct stabilization of the codon:anticodon duplex by the wild-type eIF5-NTD. The present structure reveals the basis for a key role of eIF5 in start-codon selection.
凍結剤: ETHANE / チャンバー内湿度: 100 % / チャンバー内温度: 277 K / 装置: FEI VITROBOT MARK I
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電子顕微鏡法
顕微鏡
FEI POLARA 300
温度
最低: 90.0 K / 最高: 100.0 K
撮影
フィルム・検出器のモデル: FEI FALCON III (4k x 4k) 検出モード: INTEGRATING / 撮影したグリッド数: 3 / 実像数: 3600 / 平均露光時間: 1.1 sec. / 平均電子線量: 40.0 e/Å2 詳細: Images were collected in movie-mode at 32 frames per second