Crystal structure of an AlkB–dsDNA
complex (PDB ID 3BIE). The protein is
colored according to subdomain organization with the N-terminal extension
in yellow (residues 13–44), the nucleotide-recognition lid
in red (residues 45–90), and the catalytic core in blue (residues
91–214). Manganese(II) (orange) replaces iron(II) in the structure
to eliminate catalytic activity. The flipped-base m1A is
shown in blue, α-KG in green, protein residues in white, DNA
backbone in beige, bases in the m1A-containing DNA strand
in cyan, and bases of the complementary strand in purple.