The replication of bacteriophage P4 DNA in vitro: Partial purification of the P4 α gene product

Abstract

A soluble enzyme system has been prepared from a phage P4-infected Escherichia coli strain that supports the replication of exogenous, supercoiled P4 DNA. This DNA synthesis in vitro depends upon the four deoxyribonucleotides and ATP, but is enhanced about four- to fivefold by the presence of other ribonucleotides. E. coli DNA polymerase III holoenzyme, the E. coli single-strand DNA binding protein, and the partially purified P4 α gene product are required for replication in vitro. Rifamycin does not inhibit P4 replication in vitro. Since the P4 α gene codes for a rifamycin-resistant RNA polymerase (Barrett et al., 1983), and since P4 DNA replication is independent of the host primase (Bowden et al., 1975), we believe the α gene product is functioning as a P4-specific DNA primase.