Ferric uptake regulator(Fur) and related metalloregulatory proteins; typically iron-dependent, DNA-binding repressors and activators
Ferric uptake regulator (Fur) and related metalloregulatory proteins are iron-dependent, DNA-binding repressors and activators mainly involved in iron metabolism. A general model for Fur repression under iron-rich conditions is that activated Fur (a dimer having one Fe2+ coordinated per monomer) binds to specific DNA sequences (Fur boxes) in the promoter region of iron-responsive genes, hindering access of RNA polymerase, and repressing transcription. Positive regulation by Fur can be direct or indirect, as in the Fur repression of an anti-sense regulatory small RNA. Some members sense metal ions other than Fe2+. For example, the zinc uptake regulator (Zur) responds to Zn2+, the manganese uptake regulator (Mur) responds to Mn2+, and the nickel uptake regulator (Nur) responds to Ni2+. Other members sense signals other than metal ions. For example, PerR, a metal-dependent sensor of hydrogen peroxide. PerR regulates DNA-binding activity through metal-based protein oxidation, and co-ordinates Mn2+ or Fe2+ at its regulatory site. Fur family proteins contain an N-terminal winged-helix DNA-binding domain followed by a dimerization domain; this CD spans both those domains.