Fig. S5.

Steric requirement for facial triad modification in HygX. (A) Stereoview of hygromycin B binding in HygX active site. Protein–ligand interactions are shown as black dashed lines and metal interactions with gray dashed lines. (B–D) Overlay of HygX with AviO1 (B), EvdO1 (C), and EvdO2 (D) show steric clashes with the acidic residue of the facial triad. In AviO1, EvdO1, and EvdO2, the protein backbone bends toward the active site to provide the acidic residue for coordination. Each illustration has had the major sheet of HygX excluded for clarity and is rotated 90° from A. HygX secondary structure is colored gray, AviO1 is pale orange, EvdO1 is light cyan, and EvdO2 is colored pink.