Abstract
Conversion in vitro of single-stranded circular DNA of phage G4 (related to phage phiX174) to the double-stranded replicative form (RF-II) depends on a novel and relatively simple group of three proteins: a priming protein of approximately 65,000 daltons, the DNA unwinding protein, and the DNA polymerase III holoenzyme. Stimulation by ATP and GTP suggests an RNA synthetic step in the priming of DNA synthesis. The synthetic strand in the RF-II contains a small gap at a unique position relative to the template strand; the 5' end of the gap is about 250 nucleotide residues (5% of the genome length) away from the single site of cleavage by a restriction endonuclease (Eco RI).
Highlights
Conversion in uitro of single-stranded circular DNA of phage G4 to the double-stranded replicative form (RF-II) depends on a novel and relatively simple group of three proteins: a priming protein of approximately 65,000 daltons, the DNA unwinding protein, and the DNA polymerase III holoenzyme
As with 4X174, the enzymes required for initiation of DNA synthesis on the G4 template are resistant to rifampicin
Rapid Conversion of G4 DNA to RF-II by Soluble
Summary
Conversion in uitro of single-stranded circular DNA of phage G4 (related to phage 4X174) to the double-stranded replicative form (RF-II) depends on a novel and relatively simple group of three proteins: a priming protein of approximately 65,000 daltons, the DNA unwinding protein, and the DNA polymerase III holoenzyme. One, exemplified by filamentous phage M13, is inhibited by rifampicin because RNA polymerase action is required for priming of DNA replication [2]. As with 4X174, the enzymes required for initiation of DNA synthesis on the G4 template are resistant to rifampicin. We (a) compare the G4 replication system with the others, [6] describe a partially purified protein which primes G4 DNA synthesis, and provide some evidence for its RNA polymerase action, and (c) show that initiation is at a unique location on the viral template. A subsequent report’ will present further information using purified enzymes for G4 replication and details of the novel RNA synthetic action by the priming protein, tentatively identified as the dnaG protein
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
