Dynamic DNA helicase-DNA polymerase interactions assure processive replication fork movement

Mol Cell. 2007 Aug 17;27(4):539-49. doi: 10.1016/j.molcel.2007.06.020.


A single copy of bacteriophage T7 DNA polymerase and DNA helicase advance the replication fork with a processivity greater than 17,000 nucleotides. Nonetheless, the polymerase transiently dissociates from the DNA without leaving the replisome. Ensemble and single-molecule techniques demonstrate that this dynamic processivity is made possible by two modes of DNA polymerase-helicase interaction. During DNA synthesis the polymerase and the helicase interact at a high-affinity site. In this polymerizing mode, the polymerase dissociates from the DNA approximately every 5000 bases. The polymerase, however, remains bound to the helicase via an electrostatic binding mode that involves the acidic C-terminal tail of the helicase and a basic region in the polymerase to which the processivity factor also binds. The polymerase transfers via the electrostatic interaction around the hexameric helicase in search of the primer-template.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacteriophage T7 / enzymology*
  • Catalysis
  • Crystallography, X-Ray
  • DNA Helicases / metabolism*
  • DNA Primers / metabolism
  • DNA Replication*
  • DNA, Viral / biosynthesis
  • DNA-Directed DNA Polymerase / chemistry
  • DNA-Directed DNA Polymerase / metabolism*
  • Models, Biological
  • Protein Binding
  • Protein Structure, Tertiary
  • Protein Subunits / metabolism
  • Sequence Deletion
  • Solvents
  • Templates, Genetic
  • Viral Proteins / chemistry


  • DNA Primers
  • DNA, Viral
  • Protein Subunits
  • Solvents
  • Viral Proteins
  • bacteriophage T7 induced DNA polymerase
  • DNA-Directed DNA Polymerase
  • DNA Helicases