DISSOCIATION OF ALPHA-BETA DNA-POLYMERASE OF AVIAN-MYELOBLASTOSIS VIRUS BY DIMETHYL-SULFOXIDE

The .alpha..beta. DNA polymerase of avian myeloblastosis virus was treated with dimethyl sulfoxide [DMSO] to dissociate the enzyme subunits. The DMSO-treated enzymes were passed over phosphocellulose to pirify and characterize the dissociated subunits and to remove the DMSO. RNA-directed DNA polymerase, RNase H, nucleic acid-binding activity, and the subunit structure (on sodium dodecyl sulfate-polyacrylamide gels) of the various enzyme species obtained were monitored. With 30% DMSO the majority of DNA polymerase and RNase H activities and the .alpha. subunit were displaced from the .alpha..beta. DNA polymerase position on phosphocellulose (0.23 M potassium phosphate) to the .alpha. DNA polymerase position (0.1 M). The association of DNA polymerase and RNase H activities with the .alpha. subunit suggests that .alpha. is the enzymatically active subunit in .alpha..beta.. In addition to .alpha. DNA polymerase, a minor polymerase species eluted from phosphocellulose at 0.4 M potassium phosphate. The dissociated .beta. subunit eluted from phosphocellulose at a wide range of salt concentrations (0.28-0.5 M potassium phosphate). The dissociated .beta. subunit bound 3H-labeled murine leukemia virus RNA and [3H]poly(dT).cntdot. poly(dA) approximately 20-fold more avidly than .alpha. DNA polymerase alone. There was no correlation between DNA polymerase and RNase H activity profiles and the elution profile of the .beta. subunit from phosphocellulose. The .beta. subunit is either enzymatically inactive or possesses limited DNA polymerase and RNase H activity when compared with the .alpha. subunit.