The ferric uptake regulation (Fur) repressor is a zinc metalloprotein

An examination of zinc-binding sites in ferric uptake regulation (Fur) protein reveals that its purified form contains tightly bound zinc. Results also suggest that Zn(II) is bound to the protein in vivo and that one of the zinc-bound forms of Fur is a resting state of the protein in cell. The existence of Zn(II) binding sites in Fur has implications on Zur, a Fur homologue in Escherichia coli that is responsible for regulating zinc-responsive genes.