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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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Main Authors: Filbeck, Sebastian (Author) , Cerullo, Federico (Author) , Paternoga, Helge (Author) , Tsaprailis, George (Author) , Joazeiro, Claudio A. P. (Author) , Pfeffer, Stefan (Author)
Format: Article (Journal)
Language:English
Published: 7 January 2021
In: Molecular cell
Year: 2021, Volume: 81, Issue: 1, Pages: 104-114, e1-e6
ISSN:1097-4164
DOI:10.1016/j.molcel.2020.11.001
Online Access: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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Author Notes:Sebastian Filbeck, Federico Cerullo, Helge Paternoga, George Tsaprailis, Claudio A.P. Joazeiro, and Stefan Pfeffer
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Summary: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.
Item Description:Online veröffentlicht am 30. November 2020, Artikelversion vom 7. Januar 2021
Gesehen am 21.05.2021
Physical Description:Online Resource
ISSN:1097-4164
DOI:10.1016/j.molcel.2020.11.001

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