Figure 3
From: Structural basis for polymerase η–promoted resistance to the anticancer nucleoside analog cytarabine
The Polη AraC post-insertion binary complex. (A) Overall structure of the complex; the palm, fingers, thumb and PAD domains are shown in cartoon representation in cyan, yellow, light orange, and green, respectively. The DNA template–primer duplex is shown in gray sticks with the 3′-terminal primer AraC residue in orange. (B) A close-up view of the AraC in the active site of Polη. Asp13, Asp115, and Glu116 are the catalytic residues. (C) A simulated annealing Fo − Fc omit map (contoured at 3.0σ-level at 1.83 Å resolution and colored in blue) showing the clear electron density for the entire AraC residue. The sugar moiety of the AraC is stacked against the steric gate residue Phe18 and its 2′-OH group points away from it. (D) Superposition of the AraC and the unmodified (PDB ID: 4J9P)36 post-insertion binary complexes. The unmodified complex is in white and has an unmodified A residue at the 3′-end of the primer strand; the structures are superimposed by the palm and fingers domains of the polymerase. Both, the AraC and the unmodified A sugar moieties have C3′-endo conformations.
