Conserved cysteine residues are necessary for nickel-induced allosteric regulation of the metalloregulatory protein YqjI (NfeR) in E. coli

The unstructured N-terminus of the metalloregulatory protein YqjI is rich in metal-binding residues but specifically requires two conserved cysteine residues to coordinate nickel-binding with negative allosteric regulation of the DNA-binding domain, thereby inhibiting the YqjI transcriptional repressor function. Based on its function, yqjI should be renamed Ni-responsive Fe-uptake regulator, nfeR.209