(A) Ribbon representation of the AlkA-(Fm7dG:C DNA) complex. (B) View of an AlkA monomer interacting with the DNA. The side chain of Leu125 is in blue, the helix–hairpin–helix motif, in red, and the DNA, in gold except the Fm7dG:C base pair, which is in green/natural atom. (C) Side view of the DNA duplex, with the Fm7dG:C base pair highlighted as in B. (D) Superposition of Fm7dG:C with the G:C base pair. The Fm7dG:C is in green/natural atom with fluorine in sky blue; the G:C is in yellow/natural atom.