DNA-bound AP Endonuclease (APE1) structures and mutants reveal abasic DNA binding to coordinate DNA repair

Substrate AP-DNA (orange) is oriented by the bound divalent metal ion (green) and APE1 active site residues for attack of an hydroxyl nucleophile activated by Asp 210 acting as a Lewis base (lower right). Collapse of the pentacovalent transition state leads to cleavage of the scissile P-O3' bond, with the transition state reaction products and O3' leaving group stabilised by the metal ion, and the inversion of the stereochemical configuration of the phosphate.

DNA Damage Excision Enzyme Structures

animation of the X-ray structure of the entire APE1-DNA complex