FIG 6.

catDE is induced upon iron depletion and plays an important role in iron homeostasis. (A, B) Expression of catD was monitored in WT cells (A, sfp⁰; B, sfp⁺) grown in LB medium before (0 min) and after treatment of 100 µM dipyridyl. A significant difference between treated and untreated groups is indicated as **, P < 0.01. (C, D) Dipyridyl sensitivity of WT, single (catD and catE), and double (catDE) mutant strains in both sfp⁰ (C) and sfp⁺ (D) backgrounds was evaluated using a disk diffusion assay. The data are expressed as the diameter (mean ± SEM; n = 3) of the inhibition zone (mm). Significant differences between WT and mutant strains are indicated: *, P < 0.05; **, P < 0.01.