Juxtaposition of two distant, serine-arginine-rich protein-binding elements is required for optimal polyadenylation in Rous sarcoma virus. J Virol 2011 Nov;85(21):11351-60
Date
08/19/2011Pubmed ID
21849435Pubmed Central ID
PMC3194969DOI
10.1128/JVI.00721-11Scopus ID
2-s2.0-80055120941 (requires institutional sign-in at Scopus site) 5 CitationsAbstract
The Rous sarcoma virus (RSV) polyadenylation site (PAS) is very poorly used in vitro due to suboptimal upstream and downstream elements, and yet ∼85% of viral transcripts are polyadenylated in vivo. The mechanisms that orchestrate polyadenylation at the weak PAS are not completely understood. It was previously shown that serine-arginine (SR)-rich proteins stimulate RSV PAS use in vitro and in vivo. It has been proposed that viral RNA polyadenylation is stimulated through a nonproductive splice complex that forms between a pseudo 5' splice site (5'ss) within the negative regulator of splicing (NRS) and a downstream 3'ss, which repositions NRS-bound SR proteins closer to the viral PAS. This repositioning is thought to be important for long-distance poly(A) stimulation by the NRS. We report here that a 308-nucleotide deletion downstream of the env 3'ss decreased polyadenylation efficiency, suggesting the presence of an additional element required for optimal RSV polyadenylation. Mapping studies localized the poly(A) stimulating element to a region coincident with the Env splicing enhancer, which binds SR proteins, and inactivation of the enhancer and SR protein binding decreased polyadenylation efficiency. The positive effect of the Env enhancer on polyadenylation could be uncoupled from its role in splicing. As with the NRS, the Env enhancer also stimulated use of the viral PAS in vitro. These results suggest that a critical threshold of SR proteins, achieved by juxtaposition of SR protein binding sites within the NRS and Env enhancer, is required for long-range polyadenylation stimulation.
Author List
Hudson SW, McNally MTAuthor
Mark T. McNally PhD Associate Professor in the Microbiology and Immunology department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Nuclear ProteinsPolyadenylation
Protein Binding
RNA, Messenger
RNA, Viral
RNA-Binding Proteins
Rous sarcoma virus
Sequence Deletion
Serine-Arginine Splicing Factors