title: Cdc48-associated complex bound to 60S particles is required for the clearance of aberrant translation products.
abstract: Ribosome stalling on eukaryotic mRNAs triggers cotranslational RNA and protein degradation through conserved mechanisms. For example, mRNAs lacking a stop codon are degraded by the exosome in association with its cofactor, the SKI complex, whereas the corresponding aberrant nascent polypeptides are ubiquitinated by the E3 ligases Ltn1 and Not4 and become proteasome substrates. How translation arrest is linked with polypeptide degradation is still unclear. Genetic screens with SKI and LTN1 mutants allowed us to identify translation-associated element 2 (Tae2) and ribosome quality control 1 (Rqc1), two factors that we found associated, together with Ltn1 and the AAA-ATPase Cdc48, to 60S ribosomal subunits. Translation-associated element 2 (Tae2), Rqc1, and Cdc48 were all required for degradation of polypeptides synthesized from Non-Stop mRNAs (Non-Stop protein decay; NSPD). Both Ltn1 and Rqc1 were essential for the recruitment of Cdc48 to 60S particles. Polysome gradient analyses of mutant strains revealed unique intermediates of this pathway, showing that the polyubiquitination of Non-Stop peptides is a progressive process. We propose that ubiquitination of the nascent peptide starts on the 80S and continues on the 60S, on which Cdc48 is recruited to escort the substrate for proteasomal degradation.
authors.affiliation: Institut Pasteur, Génétique des Interactions Macromoléculaires, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 3525, F-75724 Paris, France.
authors.forename: Quentin
authors.initials: Q
authors.lastname: Defenouillère
authors.forename: Yanhua
authors.initials: Y
authors.lastname: Yao
authors.forename: John
authors.initials: J
authors.lastname: Mouaikel
authors.forename: Abdelkader
authors.initials: A
authors.lastname: Namane
authors.forename: Aurélie
authors.initials: A
authors.lastname: Galopier
authors.forename: Laurence
authors.initials: L
authors.lastname: Decourty
authors.forename: Antonia
authors.initials: A
authors.lastname: Doyen
authors.forename: Christophe
authors.initials: C
authors.lastname: Malabat
authors.forename: Cosmin
authors.initials: C
authors.lastname: Saveanu
authors.forename: Alain
authors.initials: A
authors.lastname: Jacquier
authors.forename: Micheline
authors.initials: M
authors.lastname: Fromont-Racine
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis / Q000502:physiology*; D059748:Proteolysis; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D054683:Ribosome Subunits, Large, Eukaryotic / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism; D054875:Ubiquitination / Q000502:physiology*; D000074405:Valosin Containing Protein
chemical_list: D018797:Cell Cycle Proteins; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; C577644:Rqc1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C577643:Tae2 protein, S cerevisiae; C086923:MOT2 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases; C000614177:CDC48 protein, S cerevisiae; D000074405:Valosin Containing Protein