Differential susceptibilities of DNA polymerases-αand -βto polyanions

Abstract
The effects of various polyanions including synthetic polynucleotides on DNA polymerasesand-α and -β from blastulae of the sea urchin Hemicentrotuspulcherrimus and HeLa cells were studied. Only DNA polymerase-α was inhibited by polyanions, such as polyvinyl sulfate, dextran sulfate, heparin, poly(G), poly(I), poly(U) and poly(ADP-Rib). Of the various polynucleotides tested, poly(G) and poly(I) were the strongest inhibitors. Kinetic studies showed that the Ki value for poly(G) was 0.3µg/ml and that poly(G) had 20-fold higher affinity than activated DNA for the template-primer site of DNA polynierase-α. Poly(U) and poly(ADP-Rib) were also inhibitory, but they were one hundredth as inhibitory as poly(G) or poly(I). Poly(A), poly(C), poly(A).poly(U) and poly(I).poly(C) were not inhibitory to DNA polymerase-α. In contrast, DNA polymerase-β was not affected at all by these polyanions under the same conditions.