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Collided ribosomes form a unique structural interface to induce Hel2‐driven quality control pathways
Author(s) -
Ikeuchi Ken,
Tesina Petr,
Matsuo Yoshitaka,
Sugiyama Takato,
Cheng Jingdong,
Saeki Yasushi,
Tanaka Keiji,
Becker Thomas,
Beckmann Roland,
Inada Toshifumi
Publication year - 2019
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.15252/embj.2018100276
Subject(s) - biology , ribosome , microbiology and biotechnology , computational biology , genetics , gene , rna
Ribosome stalling triggers quality control pathways targeting the mRNA ( NGD : no‐go decay) and the nascent polypeptide ( RQC : ribosome‐associated quality control). RQC requires Hel2‐dependent uS 10 ubiquitination and the RQT complex in yeast. Here, we report that Hel2‐dependent uS 10 ubiquitination and Slh1/Rqt2 are crucial for RQC and NGD induction within a di‐ribosome (disome) unit, which consists of the leading stalled ribosome and the following colliding ribosome. Hel2 preferentially ubiquitinated a disome over a monosome on a quality control inducing reporter mRNA in an in vitro translation reaction. Cryo‐ EM analysis of the disome unit revealed a distinct structural arrangement suitable for recognition and modification by Hel2. The absence of the RQT complex or uS 10 ubiquitination resulted in the elimination of NGD within the disome unit. Instead, we observed Hel2‐mediated cleavages upstream of the disome, governed by initial Not4‐mediated monoubiquitination of eS 7 and followed by Hel2‐mediated K63‐linked polyubiquitination. We propose that Hel2‐mediated ribosome ubiquitination is required both for canonical NGD ( NGD RQC + ) and RQC coupled to the disome and that RQC ‐uncoupled NGD outside the disome ( NGD RQC − ) can occur in a Not4‐dependent manner.