Figure 6.

Putative YiuA site 1 amino-acid residues. The basic triad binding motif and auxiliary residues are shown, emphasizing their location at the arch of the c-clamp. A representative vibriobactin docking result demonstrates how site 1 residues might interact with a metal-chelate cargo. In this simulation, arginine and histidine residues shield substrate O atoms as the tyrosine residue is positioned to coordinate an Fe atom.