Long-distance RNA–RNA interactions between terminal elements and the same subset of internal elements on the potato virus X genome mediate minus-and plus-strand RNA synthesis

摘要: Potexvirus genomes contain conserved terminal elements that are complementary to multiple internal octanucleotide elements. Both local sequences and structures at the 5′ terminus and long-distance interactions between this region and internal elements are important for accumulation of potato virus X (PVX) plus-strand RNA in vivo. In this study, the role of the conserved hexanucleotide motif within SL3 of the 3′ NTR and internal conserved octanucleotide elements in minus-strand RNA synthesis was analyzed using both a template-dependent, PVX RNA-dependent RNA polymerase (RdRp) extract and a protoplast replication system. Template analyses in vitro indicated that 3′ terminal templates of 850 nucleotides (nt), but not 200 nt, supported efficient, minus-strand RNA synthesis. Mutational analyses of the longer templates indicated that optimal transcription requires the hexanucleotide motif in SL3 within …