Figure 1.

Cartoon presentation of selected base-specific repair proteins bound to dsDNA. Proteins are colored green, flipped-out bases are magenta, finger residues are blue, and DNA is bright orange. Escherichia coli AlkB (PDB ID 3BIE) is of particular uniqueness in the way of flipping out a 1-meA damaged base into the active pocket lacking a finger residue. Human AAG (PDB ID 1EWN), AGT (PDB ID 1T38), OGG (PDB ID 1EBM), UDG (PDB ID 4SKN), and ABH2 (PDB ID 3BUC) proteins flip εA, O⁶-methylG, 8-oxo-guanine, uracil, and 1-methyladenine out of the DNA helix into specific recognition pockets by intercalating a finger residue into the double helix, respectively.