Supplementary Figure 2: Pol θ active site and insert 2.
From: Human DNA polymerase θ grasps the primer terminus to mediate DNA repair
(a) The NCS averaged 2mFo-DFc electron density map (light blue mesh), calculated with regard to each of the four molecules of the ASU in the THF–ddATP structure, is contoured at 1.0 σ about insert 2 and the triphosphate tail of the incoming ddATP, and displayed in a wall-eyed stereo view. Interactions from conserved basic residues R2379 and K2383 are shown (black dashes). The putative salt bridge between R2254 of insert 2 (yellow) and the 3’-terminal phosphate of the primer strand stabilizes the primer terminus. (b) Thin amino acid side chains and the NCS averaged mFo-Dfc residual electron density map (red and green meshes), contoured at a level of ±3.5 σ, are added to the view appearing in panel a. The residual peak evident near the primer terminal 3’-OH suggests that an unmodeled metal ion might reside with partial occupancy in metal binding site A.
