Fig. 4.

In vitro Cr-DFO/FO competition assay using YxeB-L142-6×His (A and B) and YxeB-S142-6×His (C and D). After DFO had been bound to the YxeB proteins, Cr-DFO and FO were added to the samples and the bound or unbound amounts of Cr-DFO and FO to YxeB were then measured by ICP, as described in Materials and Methods. (A and C) Amounts of bound (■) and unbound (□) chromium derived from Cr-DFO. (B and D) Amounts of bound (●) and unbound (○) iron derived from FO. The amounts of chromium and iron bound to Ni-agarose beads without YxeB are shown in closed triangles (▲, control experiment). Data represent the average of three independent experiments. Bars are SEs.