title: Identification of critical active-site residues in the multifunctional human DNA repair enzyme HAP1.
abstract: All organisms express dedicated repair enzymes for counteracting the cytotoxic and mutagenic potential of apurinic/apyrimidinic (AP) lesions, which would otherwise pose a serious threat to genome integrity. We present the predicted three-dimensional structure of the major human AP site-specific DNA repair endonuclease, HAP1, and show that an aspartate/histidine pair, in conjunction with a metal ion-coordinating glutamate residue, are critical for catalyzing the multiple repair activities of HAP1. We suggest that this catalytic mechanism is conserved in certain reverse transcriptases, but is distinct from the two metal ion-mediated mechanism defined for other hydrolytic nucleases.
authors.affiliation: Imperial Cancer Research Fund, University of Oxford, John Radcliffe Hospital, UK.
authors.forename: G
authors.initials: G
authors.lastname: Barzilay
authors.forename: C D
authors.initials: CD
authors.lastname: Mol
authors.forename: C N
authors.initials: CN
authors.lastname: Robson
authors.forename: L J
authors.initials: LJ
authors.lastname: Walker
authors.forename: R P
authors.initials: RP
authors.lastname: Cunningham
authors.forename: J A
authors.initials: JA
authors.lastname: Tainer
authors.forename: I D
authors.initials: ID
authors.lastname: Hickson
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D019757:Carbon-Oxygen Lyases; D002384:Catalysis; D018360:Crystallography, X-Ray; D017931:DNA Primers / Q000737:chemistry; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D004926:Escherichia coli / Q000201:enzymology; D005090:Exodeoxyribonucleases / Q000737:chemistry / Q000648:ultrastructure; D006801:Humans; D008667:Metalloproteins / Q000737:chemistry / Q000648:ultrastructure; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000737:chemistry* / Q000648:ultrastructure; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D017931:DNA Primers; D008667:Metalloproteins; D009687:Nuclear Proteins; D005090:Exodeoxyribonucleases; C020133:exodeoxyribonuclease III; D019757:Carbon-Oxygen Lyases; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase