Coupling of two motors: T7 helicase-primase and DNA polymerase

Abstract

T7 bacteriophage encodes all the proteins it needs to replicate its duplex DNA genome. The T7 replisome consists of the homo-hexameric T7 gp4 helicase-primase protein, T7 DNA polymerase (T7 gp5 complexed with E. coli Thioredoxin) and the T7 gene 2.5 protein (the single stranded DNA binding protein). The simplicity of the T7 replisome makes it a model enzyme complex to understand the mechanisms of DNA replication and the roles of the motor proteins in DNA replication. T7 helicase is a ring-shaped motor protein that binds ssDNA within its central channel and uses the energy of dTTP hydrolysis to move processively along ssDNA as well as to unwind the strands of duplex DNA.