Sequential initiation of lagging and leading strand synthesis by two different polymerase complexes at the SV40 DNA replication origin

Enzymatic synthesis of DNA from the simian virus 40 origin of DNA replication has been reconstituted in vitro with eight purified components. DNA polymerase α-primase complex first initiates DNA synthesis at the replication origin and continues as the lagging strand polymerase. Subsequently, the DNA polymerase δ complex initiates replication on the leading strand template. Some prokaryotic DNA polymerase complexes can replace the eukaryotic polymerase δ complex. A model for polymerase switching during initiation of DNA replication is presented.