Mutation analysis of cis-elements in the 3 '- and 5 '-untranslated regionsof satellite tobacco necrosis virus strain C RNA

The putative, 3'-terminal stem-loop structure in satellite tobacco necrosis virus strain C (STNV-C) RNA constitutes an essential cia-acting structure for the promotion of negative-strand RNA synthesis and a single-stranded ta il is also important. The putative, 5'-terminal stem-loop structure in STNV -C RNA is not essential for productive, plus-strand RNA accumulation but is required for optimal accumulation. Residues 2 and 3 are the minimal cis-ac ting sequences required for RNA synthesis. The RNA of chimeric mutants, whi ch exchanged 3'- and 5'-untranslated regions between STNV-C and helper toba cco necrosis virus strain D RNAs, accumulated in protoplasts, implying simi lar replication mechanisms for both RNAs. (C) 1999 Academic Press.