The response of Escherichia coli NikR to nickel: a second nickel-binding site.

摘要: The Escherichia coli transcription factor NikR mediates two levels of regulatory control Ni(II) uptake in response to changes the available nickel. Despite evidence that metal binding distinct sites on NikR, referred as high- and low-affinity sites, is required for Ni(II)-selective DNA by protein, role latter set ions activation remains controversial, position putative Ni(II)-binding site(s) has not been determined. In this study we confirm a high-affinity site maintained upon binding. ligands were examined using selective chemical modification mass spectrometry performed presence excess DNA. We localized region at interface between metal- DNA-binding domains identified His48 His110 residues participate response. Mutation asparagines reduces significantly both NikR's tendency precipitate affinity DNA-bound complex Ni(II). A complete scheme involving all metal-binding contribute function E. nickel homeostasis described.