FIGURE 1.
Schematic diagram illustrating the three interconnected metalloregulatory circuits that control iron and manganese homeostasis in B. subtilis. The intracellular levels of manganese and iron are regulated by MntR and Fur, respectively. PerR senses the Fe/Mn ratio and represses peroxide stress genes, fur, and perR itself. However, only the PerR:Zn,Mn form represses fur expression. Representative structures are shown for the activated metalloregulators including PerR:Zn,Mn (66) (representative also of the PerR:Zn,Fe form), for MntR:Mn2 (55), and for a homology model of the Fur:Zn,Fe2 repressor (4).