title: Exosome-mediated recognition and degradation of mRNAs lacking a termination codon.
abstract: One role of messenger RNA (mRNA) degradation is to maintain the fidelity of gene expression by degrading aberrant transcripts. Recent results show that mRNAs without translation termination codons are unstable in eukaryotic cells. We used yeast mutants to demonstrate that these "nonstop" mRNAs are degraded by the exosome in a 3'-to-5' direction. The degradation of nonstop transcripts requires the exosome-associated protein Ski7p. Ski7p is closely related to the translation elongation factor EF1A and the translation termination factor eRF3. This suggests that the recognition of nonstop mRNAs involves the binding of Ski7p to an empty aminoacyl-(RNA-binding) site (A site) on the ribosome, thereby bringing the exosome to a mRNA with a ribosome stalled near the 3' end. This system efficiently degrades mRNAs that are prematurely polyadenylated within the coding region and prevents their expression.
authors.affiliation: Howard Hughes Medical Institute, 4000 Jones Bridge Road, Chevy Chase, MD 20815, USA. : ambro@u.arizona.edu
authors.forename: Ambro
authors.initials: A
authors.lastname: van Hoof
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Frischmeyer
authors.forename: Harry C
authors.initials: HC
authors.lastname: Dietz
authors.forename: Roy
authors.initials: R
authors.lastname: Parker
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000483:Alleles; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D018388:Codon, Terminator / Q000235:genetics*; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal / Q000235:genetics; D006207:Half-Life; D008969:Molecular Sequence Data; D026723:Polyadenylation; D011485:Protein Binding; D014176:Protein Biosynthesis; D026721:RNA 3' End Processing; D012323:RNA Processing, Post-Transcriptional; D020871:RNA Stability; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017384:Sequence Deletion / Q000235:genetics*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D018388:Codon, Terminator; D005656:Fungal Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; C118668:SKI7 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D019204:GTP-Binding Proteins