CHARACTERIZATION OF RNA PRODUCTS ASSOCIATED WITH OR ABORTED BY A VIRAL RNA-DEPENDENT RNA-POLYMERASE

Ternary RNA-dependent RNA polymerase complexes were arrested at variou s stages of synthesis in vitro by limiting one or more NTPs. The RNAs synthesized prior to/during the arrest of the complex were characteriz ed and the ability of the arrested complexes to continue elongation of these nascent RNAs in the presence of all four NTPs was analyzed. Nas cent RNAs of 10 nt and longer remained associated with the RdRp comple x and could be extended into full-length RNAs while shorter nascent RN As were released by the complex. These results establish that previous ly observed RdRp-synthesized oligoribonucleotides of 8 nt or less are abortive initiation products and confirms that RdRp undergoes a transi tion from initiation to elongation after the synthesis of 8 nt. (C) 19 97 Academic Press.