FIGURE 3.

Sheared configuration of incoming dCTP and O⁶-MeG in a hpol η insertion stage complex. A, the active site viewed into the DNA major groove. B, rotated by ∼180° around the vertical axis and viewed into the minor groove. Selected active site residues are colored by atom with carbon atoms shown in purple (O⁶-MeG), cyan (dCTP), or green (Arg-61 and Gln-38 from the finger domain as well as Asp/Glu coordinated to Ca²⁺ (brown spheres)). The remaining nucleotides are shown in yellow, except for dC9 (blue), which was added to the primer during crystallization. H-bonds involving the adducted residue are depicted as dashed lines.