FIGURE 4.

Effects of depletion of intracellular iron on cell growth of wild-type E. coli cells and on recombinant IscS expressed in wild-type E. coli cells. A, inhibition of cell growth of wild-type E. coli by 2,2′-dipyridyl. The same amount of overnight E. coli cultures was inoculated in fresh LB medium supplemented with the indicated concentrations of 2,2′-dipyridyl (0–1.0 mm). Cell growth was measured at 0 (white columns) and 3 h (black columns) under aerobic growth conditions. The dotted line represents the cell growth of the E. coli iscA/sufA mutant in LB medium without 2,2′-dipyridyl for 3 h under aerobic growth conditions. B, recombinant IscS was expressed in wild-type E. coli cells grown in LB medium supplemented with the indicated concentrations of 2,2′-dipyridyl (0–1.0 mm). Purified IscS proteins (30 μm) were subjected to UV-visible absorption measurements. The results are representatives from three independent experiments.