Functional characterization of highly processive protein-primed DNA polymerases from phages Nf and GA-1, endowed with a potent strand displacement capacity

Nucleic Acids Res. 2006;34(20):6051-63. doi: 10.1093/nar/gkl769. Epub 2006 Oct 28.


This paper shows that the protein-primed DNA polymerases encoded by bacteriophages Nf and GA-1, unlike other DNA polymerases, do not require unwinding or processivity factors for efficient synthesis of full-length terminal protein (TP)-DNA. Analysis of their polymerization activity shows that both DNA polymerases base their replication efficiency on a high processivity and on the capacity to couple polymerization to strand displacement. Both enzymes are endowed with a proofreading activity that acts coordinately with the polymerization one to edit polymerization errors. Additionally, Nf double-stranded DNA binding protein (DBP) greatly stimulated the in vitro formation of the TP-dAMP initiation complex by decreasing the K(m) value for dATP of the Nf DNA polymerase by >20-fold. Whereas Nf DNA polymerase, as the phi29 enzyme, is able to use its homologous TP as well as DNA as primer, GA-1 DNA polymerase appears to have evolved to use its corresponding TP as the only primer of DNA synthesis. Such exceptional behaviour is discussed in the light of the recently solved structure of the DNA polymerase/TP complex of the related bacteriophage phi29.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Bacillus Phages / enzymology*
  • DNA / biosynthesis
  • DNA / metabolism
  • DNA Replication*
  • DNA-Directed DNA Polymerase / chemistry
  • DNA-Directed DNA Polymerase / metabolism*
  • Exonucleases / metabolism
  • Molecular Sequence Data
  • Viral Proteins / metabolism


  • Viral Proteins
  • terminal protein, Bacillus phage Nf
  • DNA
  • DNA-Directed DNA Polymerase
  • Exonucleases