Abstract
DNA helicase has a vital role for DNA metabolism. Some genetic diseases are caused by a missing function of such DNA helicases. It has been demonstrated that such DNA helicase has essential function to protect cells from UV or ionizing radiation, since cells defective in such DNA helicases exhibited severe sensitivity to UV or ionizing radiation.
PIF1, which is encoding a SFI superfamily of DNA helicase, was identified by yeast genetics as a gene required for prevention of replication fork stalling. This gene has been well conserved from yeast to mammals, suggesting crucial function for chromosome maintenance.
In this work, we identified a human PIF1 homologue in database, and cloned it from HeLa cDNA library. The PIF1 cDNA encoded a 69 kDa protein consisting of 641 amino acid residues. The PIF1 gene consisted of 13 exons located on chromosome 15q22. For further analysis of the gene product, we purified the recombinant proteins from over produced E. coli cells. Then we demonstrated that the gene has an ATPase activity in a single stranded DNA dependent manner, just like standard DNA helicases.
