Evidence that a threshold of serine/arginine-rich (SR) proteins recruits CFIm to promote rous sarcoma virus mRNA 3' end formation.
The weak polyadenylation site (PAS) of Rous sarcoma virus (RSV) is activated by the juxtaposition of SR protein binding sites within the spatially separate negative regulator of splicing (NRS) element and the env RNA splicing enhancer (Env enhancer), which are far upstream of the PAS. Juxtaposition occurs by formation of the NRS - 3' ss splicing regulatory complex and is thought to provide a threshold of SR proteins that facilitate long-range stimulation of the PAS. We provide evidence for the threshold model by showing that greater than three synthetic SR protein binding sites are needed to substitute for the Env enhancer, that either the NRS or Env enhancer alone promotes polyadenylation when the distance to the PAS is decreased, and that SR protein binding sites promote binding of the polyadenylation factor cleavage factor I (CFIm) to the weak PAS. These observations may be relevant for cellular PASs.
Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
Stephen W
SW
Hudson
Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA.
Lisa M
LM
McNally
Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226, USA. Electronic address: mtm@mcw.edu.
Mark T
MT
McNally
D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D023061:Gene Order; D016366:Open Reading Frames; D011061:Poly A; D026723:Polyadenylation; D011485:Protein Binding; D012333:RNA, Messenger; D012367:RNA, Viral; D016601:RNA-Binding Proteins / Q000378:metabolism*; D052736:Rous sarcoma virus / Q000235:genetics* / Q000378:metabolism*; D039221:mRNA Cleavage and Polyadenylation Factors / Q000378:metabolism*
D012333:RNA, Messenger; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D039221:mRNA Cleavage and Polyadenylation Factors; D011061:Poly A
3′ end processing; CFIm; Polyadenylation; RNA splicing; Rous sarcoma virus; SR proteins