Mechanism of DNA replication by highly purified DNA polymerase of chicken embryo.

Highly purified DNA polymerase of chicken embryo was used to investigate the mechanism of DNA replication. The templates used included synthetic homopolymer pairs, as well as DNA of bacteriophage f1 and DNA-RNA hybrids prepared by partial or complete transcription of f1 DNA. The evidence suggests that the DNA synthesized is complementary either to the DNA or the RNA strand of the hybrid, depending on the relative lengths of the two strands, with the longer serving as the template and the shorter as the primer. While f1 DNA itself lacks template properties, the f1 DNA-RNA hybrids are efficient templates; and composition studies show the DNA synthesized to be complementary to the DNA strand of the hybrid. These observations suggest a mechanism of DNA replication in which the initial synthesis of a stable primer by RNA polymerase plays a pivotal role.