Interaction of poliovirus-encoded 2C/2BC polypeptides with the 3 ' terminus negative-strand cloverleaf requires an intact stem-loop b

The poliovirus-encoded, membrane-associated polypeptide 2C and its precurso r, 2BC, is believed to be required for initiation and elongation of viral R NA synthesis. Previous studies have shown that the 2C polypeptide specifica lly interacts with the 3'-terminal sequence of poliovirus negative-strand R NA. This interaction is facilitated by the presence of the conserved sequen ce UGUUUU in the "stem a" within the 3'-terminal cloverleaf structure, We s how that the 2C precursor. 2BC, also interacts with the 3'-terminal cloverl eaf of the negative-strand RNA. We also demonstrate here that interaction o f 2C/2BC with the negative strand 3'-terminal sequence not only depends on an intact "stem a" containing the UGUUUU sequence but is equally influenced by the presence of an intact "stem b" within the negative-strand cloverlea f, The results presented here suggest that the spatial configuration of ste m a UGUUUU sequence with respect to an intact stem-b is crucial for 2C/2BC interaction with the 3'-terminal negative-strand cloverleaf structure. (C) 2001 Academic Press.