Distinct types of translation termination generate substrates for ribosome-associated quality control.
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.
Department of Cell Biology, Rowan University, School of Osteopathic Medicine, Stratford, NJ 08084, USA shcherna@rowan.edu.
Natalia
0000-0002-2127-8939
N
Shcherbik
Department of Biochemistry, Emory University, School of Medicine, Atlanta, GA 30322, USA.
Tatiana A
TA
Chernova
School of Biology, Georgia Institute of Technology, Atlanta, GA 30322, USA Laboratory of Amyloid Biology & Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg 199034, Russia.
Yury O
YO
Chernoff
Department of Cell Biology, Rowan University, School of Osteopathic Medicine, Stratford, NJ 08084, USA.
Dimitri G
0000-0002-1425-9879
DG
Pestov
D008954:Models, Biological; D008970:Molecular Weight; D010443:Peptide Chain Termination, Translational / Q000235:genetics*; D010455:Peptides / Q000378:metabolism; D054683:Ribosome Subunits, Large, Eukaryotic / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D054875:Ubiquitination
D010455:Peptides; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; D044767:Ubiquitin-Protein Ligases