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-Structure paper
タイトル | Mimicry of Canonical Translation Elongation Underlies Alanine Tail Synthesis in RQC. |
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ジャーナル・号・ページ | Mol Cell, Vol. 81, Issue 1, Page 104-114.e6, Year 2021 |
掲載日 | 2021年1月7日 |
![]() | Sebastian Filbeck / Federico Cerullo / Helge Paternoga / George Tsaprailis / Claudio A P Joazeiro / Stefan Pfeffer / ![]() ![]() |
PubMed 要旨 | Aborted translation produces large ribosomal subunits obstructed with tRNA-linked nascent chains, which are substrates of ribosome-associated quality control (RQC). Bacterial RqcH, a widely conserved ...Aborted translation produces large ribosomal subunits obstructed with tRNA-linked nascent chains, which are substrates of ribosome-associated quality control (RQC). Bacterial RqcH, a widely conserved RQC factor, senses the obstruction and recruits tRNA to modify nascent-chain C termini with a polyalanine degron. However, how RqcH and its eukaryotic homologs (Rqc2 and NEMF), despite their relatively simple architecture, synthesize such C-terminal tails in the absence of a small ribosomal subunit and mRNA has remained unknown. Here, we present cryoelectron microscopy (cryo-EM) structures of Bacillus subtilis RQC complexes representing different Ala tail synthesis steps. The structures explain how tRNA is selected via anticodon reading during recruitment to the A-site and uncover striking hinge-like movements in RqcH leading tRNA into a hybrid A/P-state associated with peptidyl-transfer. Finally, we provide structural, biochemical, and molecular genetic evidence identifying the Hsp15 homolog (encoded by rqcP) as a novel RQC component that completes the cycle by stabilizing the P-site tRNA conformation. Ala tailing thus follows mechanistic principles surprisingly similar to canonical translation elongation. |
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手法 | EM (単粒子) |
解像度 | 2.99 - 3.1 Å |
構造データ | EMDB-11862, PDB-7aqc: EMDB-11864, PDB-7aqd: |
由来 |
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![]() | RIBOSOME / rqch / rqc / rqc2 / hsp15 / fibronectin-binding protein / NEMF / ribosome-associated quality control / ribosome-associated / 50s / Alanine-tailing |