Structure of human apurinic/apyrimidinic endonuclease 1 with the essential Mg2+ cofactor
Journal Article
·
· Acta Crystallographica. Section D: Biological Crystallography
- Univ. of Maryland Baltimore County (UMBC), Baltimore, MD (United States). School of Medicine. Dept. of Biochemistry and Molecular Biology; DOE/OSTI
- Univ. of Maryland Baltimore County (UMBC), Baltimore, MD (United States). School of Medicine. Pharmaceutical Sciences
- Univ. of Maryland Baltimore County (UMBC), Baltimore, MD (United States). School of Medicine. Dept. of Biochemistry and Molecular Biology
Apurinic/apyrimidinic endonuclease 1 (APE1) mediates the repair of abasic sites and other DNA lesions and is essential for base-excision repair and strand-break repair pathways. APE1 hydrolyzes the phosphodiester bond at abasic sites, producing 5'-deoxyribose phosphate and the 3'-OH primer needed for repair synthesis. It also has additional repair activities, including the removal of 3'-blocking groups. APE1 is a powerful enzyme that absolutely requires Mg2+, but the stoichiometry and catalytic function of the divalent cation remain unresolved for APE1 and for other enzymes in the DNase I superfamily. Previously reported structures of DNA-free APE1 contained either Sm3+ or Pb2+ in the active site. However, these are poor surrogates for Mg2+ because Sm3+is not a cofactor and Pb2+ inhibits APE1, and their coordination geometry is expected to differ from that of Mg2+. A crystal structure of human APE1 was solved at 1.92 Å resolution with a single Mg2+ ion in the active site. The structure reveals ideal octahedral coordination of Mg2+ via two carboxylate groups and four water molecules. One residue that coordinates Mg2+ directly and two that bind inner-sphere water molecules are strictly conserved in the DNase I superfamily. This structure, together with a recent structure of the enzyme–product complex, inform on the stoichiometry and the role of Mg2+ in APE1-catalyzed reactions.
- Research Organization:
- Univ. of Maryland, College Park, MD (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER). Biological Systems Science Division
- OSTI ID:
- 1625685
- Journal Information:
- Acta Crystallographica. Section D: Biological Crystallography, Journal Name: Acta Crystallographica. Section D: Biological Crystallography Journal Issue: 12 Vol. 69; ISSN ABCRE6; ISSN 0907-4449
- Publisher:
- International Union of CrystallographyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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