Abstract
Purified rice dwarf virus (RDV) particles catalyze incorporation of H3-UMP from H3-UTP into an acid-insoluble polynucleotide product. Optimal synthesis of the polynucleotide occurs at 35C and within a pH range of 8.5-9.0. The H3-UMP incorporation is strictly dependent on all other three ribonucleoside triphosphates and Mg++ ion, and is partially dependent on energy regenerating system. The reaction is stimulated slightly by chymotrypsin, not inhibited by actinomycin D or DNase, and strongly inhibited by RNase or pyrophosphate. The reaction proceeds for at least two hours without any detectable lag and is directly proportional to the amount of RDV particles. The polymerase activity cosediments with intact RDV particles in sucrose density gradient and little activity is associated with the empty shells of RDV. The reaction product is RNase-sensitive and is specifically hybridized with heat-denatured, unlabeled RDV-RNA but not with heat-denatured RNA from cytoplasmic polyhedrosis virus of silkworm.
