FIG 3.

Three-dimensional structures of the apo and holo forms of FosA^KP and FosA3. (A) Overlay of the apo forms of FosA^PA (red), FosA3 (blue), and FosA^KP (green). (B) Active-site residues in the apo forms of FosA with residues labeled using FosA^KP numbering. (C) Excitation scan of Zn-K edge in apo FosA^KP crystal. (D) E98, which sits on the K⁺-binding loop, exhibits two conformations in apo FosA^KP. (E) Superimposition of holo forms of FosA^PA (cyan) and FosA^KP (green) with a second nonphysiological fosfomycin (gray) bound in the FosA^PA structure. (F) The holo active site is highly conserved with the exception of Y65, which adopts a different rotamer in FosA^PA, likely due to a contact with a second fosfomycin molecule (not shown).