Poliovirus-specific primer-dependent RNA polymerase able to copy poly(A).

Abstract
A template-dependent RNA polymerase was isolated from poliovirus-infected cells by assaying for the ability of the enzyme to copy poly(A) complexed to an oligo(U) primer. The polymerase was solubilized with detergent, and RNA was removed by precipitation with 2 M LiCl. The solubilized polymerase required poly(A) and oligo(U) for activity and was stimulated by Mg2+ but was inhibited by Mn2+. Poly(A) .cntdot. oligo(U)-dependent poly(U) polymerase was not found in extracts of [human cervical carcinoma] HeLa cells until about 2 h after poliovirus infection, and then there was a linear increase in activity until about 5 h. Analysis of the polymerase by glycerol gradient centrifugation showed that the majority of the activity sedimented at about 4 S, indicating that it was no longer complexed with high-MW RNA or cellular membranes. This poly(A) .cntdot. oligo(U)-dependent polymerase activity could represent an important component of the poliovirus RNA-dependent RNA polymerase.