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Transcriptional slippage in the positive-sense RNA virus family Potyviridae.

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Olspert, Allan 
Chung, Betty Y-W 
Atkins, John F 
Carr, John P 
Firth, Andrew E 


The family Potyviridae encompasses ~30% of plant viruses and is responsible for significant economic losses worldwide. Recently, a small overlapping coding sequence, termed pipo, was found to be conserved in the genomes of all potyvirids. PIPO is expressed as part of a frameshift protein, P3N-PIPO, which is essential for virus cell-to-cell movement. However, the frameshift expression mechanism has hitherto remained unknown. Here, we demonstrate that transcriptional slippage, specific to the viral RNA polymerase, results in a population of transcripts with an additional "A" inserted within a highly conserved GAAAAAA sequence, thus enabling expression of P3N-PIPO. The slippage efficiency is ~2% in Turnip mosaic virus and slippage is inhibited by mutations in the GAAAAAA sequence. While utilization of transcriptional slippage is well known in negative-sense RNA viruses such as Ebola, mumps and measles, to our knowledge this is the first report of its widespread utilization for gene expression in positive-sense RNA viruses.



P3N‐PIPO, Potyvirus, RNA virus, gene expression, transcriptional slippage, DNA-Directed RNA Polymerases, Frameshifting, Ribosomal, Gene Expression Regulation, Viral, Genome, Viral, High-Throughput Nucleotide Sequencing, Open Reading Frames, Plant Leaves, Potyvirus, RNA, Viral, Tobacco, Transcription, Genetic, Viral Proteins

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EMBO Press
Biotechnology and Biological Sciences Research Council (BB/J007072/1)
Biotechnology and Biological Sciences Research Council (BB/J015652/1)
Isaac Newton Trust (1207(1))
Wellcome Trust (106207/Z/14/Z)
Wellcome Trust (088789/Z/09/Z)
Biotechnology and Biological Sciences Research Council (BB/J011762/1)
Wellcome Trust (096082/Z/11/Z)
Work in the AEF laboratory was funded by grants from the WellcomeTrust [088789], [106207] and Biotechnology and Biological ResearchCouncil (BBSRC) [BB/J007072/1], [BB/J015652/1]. Work in the JPC laboratorywas funded by BBSRC grants [BB/J015652/1], [BB/J011762/1]. BYWC wassupported by a Sir Henry Wellcome Postdoctoral Fellowship [096082]and an EMBL long-term postdoctoral fellowship.