PMCID: PMC1635332
Article available at http://dx.doi.org/10.1093/nar/gkl769
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 Km value for dATP of the Nf DNA polymerase by >20-fold. Whereas Nf DNA polymerase, as the 29 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 29
This investigation was aided by
research grant BFU 2005-00733 from the Spanish Ministry
of Education and Science and by an institutional grant from
Fundación Ramón Areces to the Centro de Biología
Molecular ‘Severo Ochoa’. E.L. was a pre-doctoral fellow
of the Ministerio de Educación y Ciencia. Funding to pay the
Open Access publication charges for this article was provided
by research grant BFU 2005-00733 from the Spanish Ministry
of Education and Science.
Peer reviewed