Figure 6.

Residues in the second-shell region of the active site are reconfigured in wDUT. A, the second-shell region around the conserved Arg¹²⁸ in hDUT. B, the second-shell region around Arg²⁴ in wDUT, in an aligned view of A. C–E, the conformations of Arg²⁴ in the free wDUT (C), wDUT^D88N/R158E-dUTP-Mg²⁺ (D), and wDUT-dU-PP_i-Mg²⁺ (E), shown in aligned views. The σA-weighted 2F_o − F_c electron density maps (contoured at 1σ level) are shown as gray mesh. For all panels, hydrogen bonds are shown as red dotted lines. Residues are in subunit-based colors. Ligands are shown as sticks.