title: AP endonuclease 1 has no biologically significant 3(')-->5(')-exonuclease activity.
abstract: The 3(')-->5(')-exonucleolytic activity of human apurinic/apyrimidinic endonuclease 1 (APE1) on mispaired DNA at the 3(')-termini of recessed, nicked or gapped DNA molecules was analyzed and compared with the primary endonucleolytic activity. We found that under reaction conditions optimal for AP endonuclease activity the 3(')-->5(')-exonuclease activity of APE1 manifests only at enzyme concentration elevated by 6-7 orders of magnitude. This activity does not show a preference to mismatched compared to matched DNA structures as well as to nicked or gapped DNA substrates in comparison to recessed ones. Therefore, the 3(')-->5(')-exonuclease activity associated with APE1 can hardly be considered as key mechanism that improves fidelity of DNA repair.
authors.affiliation: Novosibirsk Institute of Bioorganic Chemistry, Siberian Division of Russian Academy of Sciences, Prospect Lavrentiev 8, 630090, Novosibirsk, Siberia, Russia.
authors.forename: Natalia A
authors.initials: NA
authors.lastname: Lebedeva
authors.forename: Svetlana N
authors.initials: SN
authors.lastname: Khodyreva
authors.forename: Alain
authors.initials: A
authors.lastname: Favre
authors.forename: Olga I
authors.initials: OI
authors.lastname: Lavrik
mesh_terms: D020137:Base Pair Mismatch; D001483:Base Sequence; D019757:Carbon-Oxygen Lyases / Q000378:metabolism*; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase; D043211:Exodeoxyribonuclease V; D005090:Exodeoxyribonucleases / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D011994:Recombinant Proteins / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D011994:Recombinant Proteins; D004247:DNA; D005090:Exodeoxyribonucleases; D043211:Exodeoxyribonuclease V; D019757:Carbon-Oxygen Lyases; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase