InterPro domain: IPR006551

These proteins catalyse the dephosphorylation of DNA 3'-phosphates. It is believed that this activity is important for the repair of single-strand breaks in DNA caused by radiation or oxidative damage. This region is often [ 1 , 2 ], but not always linked to a DNA 5'-kinase domain [ 3 , 4 ]. As is common in this superfamily, DNA 3-phosphatase is magnesium dependent. A difference between this enzyme and other HAD-superfamily phosphatases is in the third conserved catalytic motif which usually contains two conserved aspartate residues believed to be involved in binding the magnesium ion. Here, the second aspartate is usually replaced by an arginine residue which may indicate an interaction with the phosphate backbone of the substrate. Alternatively, there is an additional conserved aspartate downstream of the usual site which may indicate a slightly different fold in this region.

1. Molecular cloning of the human gene, PNKP, encoding a polynucleotide kinase 3'-phosphatase and evidence for its role in repair of DNA strand breaks caused by oxidative damage. J. Biol. Chem. 274, 24176-86
2. Molecular characterization of a human DNA kinase. J. Biol. Chem. 274, 24187-94
3. Uncoupling of 3'-phosphatase and 5'-kinase functions in budding yeast. Characterization of Saccharomyces cerevisiae DNA 3'-phosphatase (TPP1). J. Biol. Chem. 276, 15073-81
4. A plant 3'-phosphoesterase involved in the repair of DNA strand breaks generated by oxidative damage. J. Biol. Chem. 276, 18038-45