FIG 2.
Structure-based sequence alignment of PiuA and PirA proteins from P. aeruginosa and A. baumannii. Secondary-structure elements of Ab-PiuA are illustrated above the alignment. Regions predicted to be involved in the binding of the siderophores are boxed in red. Residues spatially equivalent to those involved in substrate binding in FhuA, FptA, and FpvA are highlighted in green. Key residues of the secondary binding site of FepA and conserved in the PirA structure are shown in yellow. Positions of residues of the nonconserved initial binding site are indicated by orange triangles. The plug domain is boxed in cyan. The alignment was drawn using Aline (71).