FIG 1 .

Crystal structures of WT and I38T PA_N in complex with RO-7. (A) Overall view of the RO-7 complex with the WT (Ile38) PA_N showing the binding locale in the large RNA substrate-binding cleft. (B) Close-up view of panel A with the key residues labeled. (C) Close-up view of the RO-7 complex with mutant Thr38 PA_N. (D) Close-up view of holo-Thr38 PA_N. The orientations of PA_N are identical in all four panels, and the WT and mutant proteins are shown as green and salmon ribbons, respectively, to distinguish these variants. Residues are shown as green carbon sticks, Mn²⁺ ions are violet balls, water molecules are red balls, and RO-7 is shown in the ball-and-stick representation with magenta carbon atoms. Metal coordination bonds, hydrogen bonds, and salt bridges are shown as purple, red, and gray dashed lines, respectively.