3' poly(A) is dispensable for translation.
In wild-type cells, the 3' poly(A) structure is necessary for translation of mRNA and for mRNA stability. The superkiller 2 (ski2), ski3, ski6, ski7, and ski8 mutations enhance the expression of the poly(A)(-) mRNAs of yeast RNA viruses. Ski2p is a DEVH-box RNA helicase and Slh1p resembles Ski2p. Both repress L-A double-stranded RNA (dsRNA) virus copy number, further suggesting that their functions may overlap. We find that slh1Delta ski2Delta double mutants are healthy (in the absence of viruses) and show normal rates of turnover of several cellular mRNAs. The slh1Delta ski2Delta strains translate electroporated nonpoly(A) mRNA with the same kinetics as polyA(+) mRNA. Thus, the translation apparatus is inherently capable of efficiently using nonpoly(A) mRNA even in the presence of normal amounts of competing poly(A)(+) mRNA, but is normally prevented from doing so by the combined action of the nonessential proteins Ski2p and Slh1p.
Laboratory of Biochemistry and Genetics, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, 8 Center Drive, MSC 0830, Bethesda, MD 20892-0830, USA.
A M
AM
Searfoss
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RB
Wickner
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D005095:Exoribonucleases / Q000235:genetics / Q000378:metabolism; D063326:Exosome Multienzyme Ribonuclease Complex; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D010735:Phosphoglycerate Kinase / Q000235:genetics; D011061:Poly A / Q000378:metabolism*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators / Q000235:genetics; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D005656:Fungal Proteins; D012333:RNA, Messenger; C081929:SKI2 protein, S cerevisiae; C111978:SKI6 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C414202:TRAF3IP2 protein, human; D015534:Trans-Activators; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins; D011061:Poly A; D010735:Phosphoglycerate Kinase; D005095:Exoribonucleases; D063326:Exosome Multienzyme Ribonuclease Complex