Distinct types of translation termination generate substrates for ribosome-associated quality control

• Type of Material: Article
• Authors: Natalia Shcherbik, Rowan University; Tatiana Chernova, Emory University; Yury O. Chernoff, Georgia Institute of Technology; Dimitri G. Pestov, Rowan University
• Language: English
• Date: 2016-08-19
• Publisher: Oxford University Press (OUP)
• Publication Version: Final Published Version
• Copyright Statement: © 2016 The Author(s) 2016. Published by Oxford University Press on behalf of Nucleic Acids Research. For commercial re-use, please contact [e-mail].
• License: Creative Commons Attribution-NonCommercial 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1093/nar/gkw566
• Title of Journal or Parent Work: Nucleic Acids Research
• ISSN: 0305-1048
• Volume: 44
• Issue: 14
• Start Page: 6840
• End Page: 6852
• Grant/Funding Information: UMDNJ Foundation (to N.S.); National Institutes of Health [GM093294 to T.A.C. and GM074091 to D.G.P.]; National Science Foundation [MCB-1516872 to Y.O.C.].; Funding for open access charge: Rowan University intramural support funds (to N.S.).
• Keywords: E3 UBIQUITIN LIGASE; COTRANSLATIONAL UBIQUITINATION; Biochemistry & Molecular Biology; Science & Technology; CONTROL COMPLEX; YEAST SACCHAROMYCES-CEREVISIAE; NO-GO DECAY; HYGROMYCIN-B; STRUCTURAL BASIS; MESSENGER-RNA; PEPTIDYL-TRANSFER-RNA; CHAIN RELEASE FACTORS; Life Sciences & Biomedicine
• Research Categories: Chemistry, Biochemistry; Biology, Cell

Abstract

Cotranslational degradation of polypeptide nascent chains plays a critical role in quality control of protein synthesis and the rescue of stalled ribosomes. In eukaryotes, ribosome stalling triggers release of 60S subunits with attached nascent polypeptides, which undergo ubiquitination by the E3 ligase Ltn1 and proteasomal degradation facilitated by the ATPase Cdc48. However, the identity of factors acting upstream in this process is less clear. Here, we examined how the canonical release factors Sup45-Sup35 (eRF1-eRF3) and their paralogs Dom34-Hbs1 affect the total population of ubiquitinated nascent chains associated with yeast ribosomes. We found that the availability of the functional release factor complex Sup45-Sup35 strongly influences the amount of ubiquitinated polypeptides associated with 60S ribosomal subunits, while Dom34-Hbs1 generate 60S-associated peptidyl-tRNAs that constitute a relatively minor fraction of Ltn1 substrates. These results uncover two separate pathways that target nascent polypeptides for Ltn1-Cdc48-mediated degradation and suggest that in addition to canonical termination on stop codons, eukaryotic release factors contribute to cotranslational protein quality control.