Mimicry of canonical translation elongation underlies alanine tail synthesis in RQC
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 tRNAAla(UGC) to modify nascent-chain C termini with...
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| Hauptverfasser: | , , , , , |
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| Dokumenttyp: | Article (Journal) |
| Sprache: | Englisch |
| Veröffentlicht: |
7 January 2021
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| In: |
Molecular cell
Year: 2021, Jahrgang: 81, Heft: 1, Pages: 104-114, e1-e6 |
| ISSN: | 1097-4164 |
| DOI: | 10.1016/j.molcel.2020.11.001 |
| Online-Zugang: | Verlag, lizenzpflichtig, Volltext: https://doi.org/10.1016/j.molcel.2020.11.001 Verlag, lizenzpflichtig, Volltext: https://www.sciencedirect.com/science/article/pii/S1097276520307796 
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| Verfasserangaben: | Sebastian Filbeck, Federico Cerullo, Helge Paternoga, George Tsaprailis, Claudio A.P. Joazeiro, and Stefan Pfeffer |
| Zusammenfassung: | 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 tRNAAla(UGC) 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 tRNAAla is selected via anticodon reading during recruitment to the A-site and uncover striking hinge-like movements in RqcH leading tRNAAla 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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| Beschreibung: | Online veröffentlicht am 30. November 2020, Artikelversion vom 7. Januar 2021 Gesehen am 21.05.2021 |
| Beschreibung: | Online Resource |
| ISSN: | 1097-4164 |
| DOI: | 10.1016/j.molcel.2020.11.001 |