Polynucleotide recognition by DNA of α-polymerase

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Abstract
In a survey of template-primer preference of a mouse myeloma DNA α-po-lymerase, the fastest rate of DNA synthesis was with poly(dT) as template and (rA) 24 as primer. Such a preference for poly(dT)·-oligo(rA) was not observed with other DNA polymerases of mouse origin. DNA synthesis in this system resulted in formation of oligo(dA) chains, not template-length poly(dA); thus, the average enzyme molecule bound to a poly(dT)·(rA) 24 complex and initiated a new oligo(dA) chain many times during the incubation. Binding experiments revealed that the α-polymerase had high affinity for poly(dT). Although the α-polymerase did not bind to poly(dl) and failed to replicate it in reactions with a base pair complementary primer, poly(dl) was replicated after a (dT) block had been grafted to Its 3'-end and the oligo(rA) primer had been added. In similar experiments, the (dT) block was found to be much more effective than other 3'-terminal blocks in promoting replication of denatured calf thymus DNA. The results indicate that specific base sequences may regulate Initiation of DNA synthesis by this α-polymerase.