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

Conserved cysteine residues are necessary for nickel-induced allosteric regulation of the metalloregulatory protein YqjI (NfeR) in E. coli. J Inorg Biochem. 2018 Apr 26;184:123-133 Authors: Blahut M, Dzul S, Wang S, Kandegedara A, Grossoehme NE, Stemmler T, Outten FW Abstract Transition metal homeostasis is necessary to sustain life. First row transition metals act as cofactors within the cell, performing vital functions ranging from DNA repair to respiration. However, intracellular metal concentrations exceeding physiological requirements may be toxic. In E. coli, the YqjH flavoprotein is thought to play a role in iron homeostasis. YqjH is transcriptionally regulated by the ferric uptake regulator and a newly discovered regulator encoded by yqjI. The apo-form of YqjI is a transcriptional repressor of both the yqjH and yqjI genes. YqjI repressor function is disrupted upon binding of nickel. The YqjI N-terminus is homologous to nickel-binding proteins, implicating this region as a nickel-binding domain. Based on function, yqjI and yqjH should be renamed Ni-responsive Fe-uptake regulator (nfeR) and Ni-responsive Fe-uptake flavoprotein (nfeF), respectively. X-ray Absorption Spectroscopy was employed to characterize the nickel binding site(s) within YqjI. Putative nickel binding ligands were targeted by site-directed mutagenesis and resulting variants were analyzed in vivo for repressor function. Isothermal titration calorimetry and comp...
Source: Journal of Inorganic Biochemistry - Category: Biochemistry Authors: Tags: J Inorg Biochem Source Type: research