title: Protein quality control systems associated with no-go and nonstop mRNA surveillance in yeast.
abstract: Quality control systems eliminate aberrant proteins derived from aberrant mRNAs. Two E3 ubiquitin ligases, Ltn1 and Not4, are involved in proteasomal protein degradation coupled to translation arrest. Here, we evaluated nonstop and translation arrest products degraded in a poly(A) tail-independent manner. Ltn1 was found to degrade aberrant nonstop polypeptides derived from nonstop mRNA lacking a termination codon, but not peptidyl-tRNA, even in the absence of the ribosome dissociation complex Dom34:Hbs1. The receptor for activated C kinase (RACK1/ASC1) was identified as a factor required for nascent peptide-dependent translation arrest as well as Ltn1-dependent protein degradation. Both Not4 and Ltn1 were involved in the degradation of various arrest products in a poly(A) tail-independent manner. Furthermore, carboxyl terminus-truncated degradation intermediates of arrest products were stabilized in a cdc48-3 mutant defective in unfolding or the disassembly related to proteasomal degradation. Thus, we propose that stalled ribosomes may be dissociated into subunits and that peptidyl-tRNA on the 60S subunit is ubiquitinated by Ltn1 and Cdc48 is required for the degradation following release from tRNA.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, 980-8578, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Matsuda
authors.forename: Ken
authors.initials: K
authors.lastname: Ikeuchi
authors.forename: Sene
authors.initials: S
authors.lastname: Nomura
authors.forename: Toshifumi
authors.initials: T
authors.lastname: Inada
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D018388:Codon, Terminator; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D010445:Peptide Elongation Factors / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D014176:Protein Biosynthesis / Q000235:genetics; D059748:Proteolysis; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D012346:RNA, Transfer, Amino Acyl / Q000378:metabolism; D012097:Repressor Proteins; 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; D000074405:Valosin Containing Protein
chemical_list: C111825:ASC1 protein, S cerevisiae; D048868:Adaptor Proteins, Signal Transducing; D018797:Cell Cycle Proteins; D018388:Codon, Terminator; C077247:HBS1 protein, S cerevisiae; D018840:HSP70 Heat-Shock Proteins; D010445:Peptide Elongation Factors; D012333:RNA, Messenger; D012346:RNA, Transfer, Amino Acyl; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; C019037:tRNA, peptidyl-; C552998:Ltn1 protein, S cerevisiae; C086923:MOT2 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases; C112808:Dom34 protein, S cerevisiae; D004722:Endoribonucleases; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases; D019204:GTP-Binding Proteins; C000614177:CDC48 protein, S cerevisiae; D000074405:Valosin Containing Protein