Fig. S4.

Metal substitution in HygX. (A) Stereoview of the iron binding site in HygX. Coordinating residues and ligands are shown in ball-and-stick representation. The iron ion is shown as a brown sphere; 2|F_O| − |F_C| density for the facial triad and iron are shown as blue mesh, contoured at 1.5σ, and the iron anomalous density is shown as yellow mesh and contoured at 5σ. (B) Active site of apo-HygX showing that removal of the metal ion is not associated with significant change in active site structure.