(C) 8-oxo-dG (green) establishes a Hoogsteen base pair with dATP (magenta). Asn513 and Arg517 (purple) interact with the minor groove of the nascent base pair. The base pair geometry (C1′ distance and λ angles) is indicated at the bottom of the figure. A simulated annealing Fo-Fc omit density map for the pair is also shown (contoured at 3σ). 