Cloning and expression of APE, the cDNA encoding the major human apurinic endonuclease: definition of a family of DNA repair enzymes.
Abasic (AP) sites are common, potentially mutagenic DNA damages that are attacked by AP endonucleases. The biological roles of these enzymes in metazoans have not been tested. We have cloned the human cDNA (APE) that encodes the main nuclear AP endonuclease. The predicted Ape protein, which contains likely nuclear transport signals, is a member of a family of DNA repair enzymes that includes two bacterial AP endonucleases (ExoA protein of Streptococcus pneumoniae and exonuclease III of Escherichia coli) and Rrp1 protein of Drosophila melanogaster. Purified Ape protein lacks the 3'-exonuclease activity against undamaged DNA that is found in the bacterial and Drosophila enzymes, but the lack of obvious amino acid changes to account for this difference suggests that the various enzyme functions evolved by fine tuning a conserved active site. Expression of the active human enzyme in AP endonuclease-deficient E. coli conferred significant resistance to killing by the DNA-alkylating agent methyl methanesulfonate. The APE cDNA provides a molecular tool for analyzing the role of this central enzyme in maintaining genetic stability in humans.
Demple
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Department of Molecular and Cellular Toxicology, Harvard University, School of Public Health, Boston, MA 02115.
Herman
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Chen
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D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics* / Q000302:isolation & purification; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043223:Deoxyribonuclease IV (Phage T4-Induced); D004706:Endodeoxyribonucleases / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D005260:Female; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D009838:Oligodeoxyribonucleotides; D012516:Osteosarcoma; D010920:Placenta / Q000201:enzymology; D011247:Pregnancy; D012689:Sequence Homology, Nucleic Acid
D029968:Escherichia coli Proteins; D009838:Oligodeoxyribonucleotides; D004247:DNA; D004706:Endodeoxyribonucleases; D043223:Deoxyribonuclease IV (Phage T4-Induced); C468972:endonuclease IV, E coli; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase