FIGURE 7.

FetMP is an iron uptake system. Uptake of ⁵⁵Fe by cells of strain ECA458 (ΔentC ΔfecABCDE ΔfeoABC ΔmntH ΔzupT) and its fet derivatives were compared using the filtration method. Strain ECA458 containing the vector pASK-IBA3 only (○), fetMP (●), fetM (■), or fetP (▴) was incubated with 200 μg of anhydrotetracycline per liter for 1 h to induce expression of the cloned genes. For the uptake experiments, ⁵⁵Fe(II)Cl₃ at a final 1 μCi, 1 mm ascorbate, 5 μm FeSO₄ were added to the cells, and samples were removed at the indicated time points. Averages of three independent experiments with S.D. values (error bars) are shown. d.w., dry weight.