(A and B) Overlay of the nascent base pair in the insertion structures with an undamaged reference structure (2PFO, black). Binding of 8-oxo-dG (green) in both the anti- (A) or syn-(B) conformation involves a repositioning of the 5′-phosphate (red arrow). Furthermore, the Arg514 side chain (purple) that normally stacks with the templating base and interacts with the 5′-phosphate (blue-dotted line), also repositions (black arrow). In both structures, Arg514 interacts with the C6-carbonyl of the templating 8-oxo-dG(anti) (A) or the C6-amino group of the incoming dATP (B). The incoming nucleotide is shown in magenta. 