FIGURE 4.

Iron metabolism in suf negative mutants supplied with ⁵⁹Fe-chrysobactin. A, native PAGE analysis of protein extracts was performed as described in Fig. 1. ⁵⁹Fe-chrysobactin was supplied at the concentration of 0.25 μm for the indicated times. B, immunoblotting of bacterioferritin in protein extracts from ⁵⁹Fe-chrysobactin-treated cultures of relevant strains. C, native PAGE analysis of protein extracts from sufC cells was performed as described for Fig. 2B. D, aconitase activity produced in parental and relevant mutant cells. Enzyme activity was assayed in cells from iron-deprived cultures treated with 0.5 μm ⁵⁹Fe-chrysobactin for 4 h. For the parental strain, enzyme activity was assayed with no iron supplementation (P-Fe). One unit of aconitase activity corresponds to the conversion of 1 μmol of citrate to isocitrate/min; specific activity is given in units/mg of protein/min. The data are the means of measurements obtained in three separate experiments with error bars representing S.D. The relevant genotypes are indicated.