Phage T7 has the simplest known DNA replisome, consisting of a helicase and primase that reside in a single polypeptide chain that forms a hexamer in the presence of DNA and ATP or dTTP.
The Phage T7 DNA replication system features an uncomplicated assembly consisting of a single polypeptide chain containing both helicase and primase functions, which aggregate into a hexameric structure when interacting with DNA and nucleotides.