FIG 3.

Expression of IutA and IutE is controlled by DtxR and Zur. (A) Protein levels of IutA and IutE were assessed following growth in mPGT with iron supplementation (final concentrations are indicated) by Western blotting. (B) Protein levels of IutA and IutE were assessed in the wild-type C. diphtheriae and isogenic ΔdtxR and Δzur mutants. Iron (μM) and Zn were supplemented where indicated; Zn was added to a final concentration of 5 μM. (C) ELISA on whole C. diphtheriae 1737 cells (wild type [wt] or Δiut mutant [Δ]) adsorbed to plastic microtiter plates following growth in mPGT with metal supplementation as indicated (μM). Antiserum against IutE or IutA was used for detection. Statistical significance was determined by two-way analysis of variance (ANOVA) and multiple-comparison test. *, P < 0.05 when comparing the indicated sample against the respective Δiut sample (n = 3).