Effects of Poly(1-vinyluracil) and Poly(9-vinyladenine) on viral RNA-directed DNA polymerase

The effects of poly(1-vinyluracil) [poly(vU)] and poly(9-vinyladenine) [poly(vA)] on the RNA-dependent DNA polymerase activity of murine leukemia virus (Moloney strain) were studied. Vinyl polymers themselves cannot act as templates for the polymerase. However, if a vinyl polymer is added to a polymerase reaction mixture in which a complementary polynucleotide serves as the template, the reaction is inhibited: thus with polyribocytidylic acid as template and oligodeoxyguanylic acid as primer, neither poly(vU) nor poly(vA) had a significant effect; when polyribouridylic acid was used as template and oligodeoxyadenylic acid as primer, poly(vA) inhibited polymerase activity while poly(vU) had little effect; when polyriboadenylic acid was a template and oligodeoxy thymidylic acid was a primer, poly(vU) was an inhibitor. Complex effects were noted with the latter system and poly(vA); either stimulation or inhibition of the reaction was observed, depending on the concentration of poly(vA). The stimulation brings about a decrease in the amount of lower-molecular-weight materials in the product and is caused by the interaction of poly(vA) with the template-primer. Thus vinyl polymers differ from polynucleotides in their mechanism of inhibition of viral polymerase, since the latter inhibit the enzyme by binding to it.