Subgenomic RNA promoters dictate the mode of recognition by bromoviral RNA-dependent RNA polymerases

Both the brome mosaic virus (BMV) and cowpea chlorotic mottle virus (CCMV) RNA-dependent RNA polymerases (RdRps) were found to recognize the BMV core subgenomic promoter in the same manner, requiring specific functional group s at positions -17, -14, -13, and -11 relative to the subgenomic initiation site (fl). For CCMV subgenomic RNA synthesis, both RdRps required the same nucleotides and four additional nucleotides at positions -20, -16, -15, an d -10. The -20 nucleotide is partially responsible for the differential mod e of recognition of the two promoters. These data provide evidence that the RNA can induce RdRps to alter the mode of promoter recognition. (C) 1998 A cademic Press.