FIG. 2.

Transport of ⁵⁵Fe³⁺ into E. coli IS1031 aroB fecA by plasmid-encoded FecA and FecA TonB box derivatives. (A) Transport mediated by citrate of plasmid pT7-7-encoded wild-type FecA (FecA WT), FecA with a deletion in the DALTV TonB box (del TonB box), FecA with the TonB box of FepA or FhuA, or no FecA. (B) Transport of plasmid pBAD18-encoded wild-type FecA (WT) or FecA with cysteine substitutions in the TonB box (as indicated). Production of FecA and FecA derivatives was induced by the addition of 0.2% arabinose.