The Characteristics of the RNA-dependent DNA Polymerase of Baboon Endogenous Virus

The characteristics of the virion-associated RNA-dependent DNA polymerase (RDPase) of a baboon endogenous virus, M7, were studied extensively; the optimal conditions for the exogenous RDPase reaction were obtained with 0.4 mM-Mn²⁺, 110 mM-NaCl, 24µg/ml poly(rA).oligo(dT)₁₂₁₈, at pH 7.6 in the presence of 0.01% Brij-58. Under these conditions, the incorporation of ³H-TMP proceeded up to 90 min at a speed of 0.1 pmol TMP/µg virus protein/min. Poly(rC).oligo (dG)₁₂₁₈ and poly(rCm).oligo (dG)₁₂₁₈ served as the template-primers in the exogenous reaction with 3 mM-Mg²⁺ and 0.4 mM-Mn²⁺, respectively. Polyuridylic acid, bleomycin, rifampicin, spermidine and inorganic phosphate significantly inhibited the RDPase activity of BaEV. The RDPase of BaEV requires a higher concentration of NaCl, a lower pH and milder conditions of detergent treatment than those of other mammalian retroviruses.