FIG. 4.

Roles of PerR and Fur in metalloregulation of PerR regulon genes. Resuspension experiments were performed as described in the legend to Fig. 3 with all seven promoter fusions (indicated at the bottom of panel C) in either the wild-type (A) background or the fur (B) or perR (C) mutant strain background. All samples were measured 3 h. after resuspension and normalized to the level in medium lacking manganese and iron supplementation (white bars; absolute values are shown above the bars). The cells were resuspended in minimal medium either containing (from left to right) no added Mn(II) or Fe(III) (white bars) or containing 10 μM Fe(III) (hatched), 5 μM Mn(II) (stippled), or both (black). The data in panel A are the same as those shown for the 3-h time point in Fig. 3.