ジャーナル: Science / 年: 2015 タイトル: Protein synthesis. Rqc2p and 60S ribosomal subunits mediate mRNA-independent elongation of nascent chains. 著者: Peter S Shen / Joseph Park / Yidan Qin / Xueming Li / Krishna Parsawar / Matthew H Larson / James Cox / Yifan Cheng / Alan M Lambowitz / Jonathan S Weissman / Onn Brandman / Adam Frost / 要旨: In Eukarya, stalled translation induces 40S dissociation and recruitment of the ribosome quality control complex (RQC) to the 60S subunit, which mediates nascent chain degradation. Here we report ...In Eukarya, stalled translation induces 40S dissociation and recruitment of the ribosome quality control complex (RQC) to the 60S subunit, which mediates nascent chain degradation. Here we report cryo-electron microscopy structures revealing that the RQC components Rqc2p (YPL009C/Tae2) and Ltn1p (YMR247C/Rkr1) bind to the 60S subunit at sites exposed after 40S dissociation, placing the Ltn1p RING (Really Interesting New Gene) domain near the exit channel and Rqc2p over the P-site transfer RNA (tRNA). We further demonstrate that Rqc2p recruits alanine- and threonine-charged tRNA to the A site and directs the elongation of nascent chains independently of mRNA or 40S subunits. Our work uncovers an unexpected mechanism of protein synthesis, in which a protein--not an mRNA--determines tRNA recruitment and the tagging of nascent chains with carboxy-terminal Ala and Thr extensions ("CAT tails").
Particles were selected using the semi-automated swarm tool in e2boxer.py of the EMAN2 package. All 2D and 3D processing was performed in RELION.
CTF補正
詳細: each particle
最終 再構成
想定した対称性 - 点群: C1 (非対称) / 解像度のタイプ: BY AUTHOR / 解像度: 3.5 Å / 解像度の算出法: OTHER / ソフトウェア - 名称: RELION, CTFFIND3 詳細: micrographs were motion-corrected via the UCSFImage4 package; final resolution was calculated by applying a soft mask around the ribosome 使用した粒子像数: 79423