Characterization of an RNA-directed DNA polymerase from a cell line derived from a radiation-induced lymphoma in mice

Abstract

An RNA-directed DNA polymerase was purified from a cell line derived from a radiation-induced lymphoma in NIH Swiss mice which produced non-infectious type C virus particles. The enzyme was isolated from a high speed particulate fraction which bands at a density of 1.16–1.19 g/ml in a sucrose gradient, and purified by successive chromatography on DEAE-cellulose, phosphocellulose and hydroxyapatite. The purified DNA polymerase has a molecular weight of 68 000, a pH optimum of 7.5, a KCl optimum of 50 mM, and a Mn 2+ optimum of 0.25 mM. It prefers (dT) 15 · (A) n to (dT) 15 · (dA) n as the primer template and transcribes the poly(C) strand of (dG) 15 · (C) n and (dG) 15 · (OMeC) n . It transcribes heteropolymeric regions of avian myeloblastosis virus 70 S RNA, and is inhibited by antiserum to Rauscher murine leukemia virus DNA polymerase. Comparison of the properties of DNA polymerase purified from radiation-induced lymphoma cells with the DNA polymerase purified from non-defective murine type C RNA tumor viruses shows that the mouse lymphoma enzyme is both biochemically and immunologically related to murine leukemia virus DNA polymerases.