Structural and functional homology between mammalian DNase IV and the 5'-nuclease domain of Escherichia coli DNA polymerase I.
A nuclear 42-kDa 5'-->3'-exonuclease, DNase IV, was found previously in animal tissues. The enzyme has been purified from HeLa cells and shown to possess two catalytic properties characteristic of the 5'-nuclease function of Escherichia coli DNA polymerase I,-DNase IV removes single-stranded 5' regions from splayed-arm DNA structures by endonucleolytic incision at the bifurcation point and possesses RNase H activity. Determination of the molecular masses of tryptic and V8 peptides of DNase IV by mass spectrometry identified the enzyme as the human homolog of the Schizosaccharomyces pombe Rad2 protein. The protein sequence retains conserved residues and shows significant homology to the sequences of the 5'-nuclease domain of E. coli DNA polymerase I and related microbial enzymes.
Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Hertfordshire, United Kingdom.
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D000595:Amino Acid Sequence; D004256:DNA Polymerase I / Q000737:chemistry* / Q000378:metabolism; D004268:DNA-Binding Proteins; D004706:Endodeoxyribonucleases; D004926:Escherichia coli / Q000201:enzymology*; D005090:Exodeoxyribonucleases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D045585:Flap Endonucleases; D005656:Fungal Proteins / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; C073998:RAD2 protein, S cerevisiae; D004256:DNA Polymerase I; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; D045585:Flap Endonucleases