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

Abstract

Summary 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)12–18, 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)12–18 and poly(rCm).oligo (dG)12–18 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.