Potassium is critical for the Ni(II)-responsive DNA-binding activity of Escherichia coli NikR.

Journal article

The Escherichia coli NikR transcription factor is a Ni(II)-dependent repressor that regulates the production of a nickel ion transporter. The X-ray crystal structure of the Ni(II)-NikR-DNA bound complex revealed a K(+)-binding site positioned at the interface of the metal- and DNA-binding domains, but the significance of the potassium was unclear. Mutation of one of the K(+) ligands impairs the affinity and specificity of DNA binding in the presence of either stoichiometric or excess Ni(II). Removal of K(+) abrogates Ni(II)-responsive DNA binding completely while the addition of K(+) restores this activity. Furthermore, the observed K(+) dependence can be relieved by replacing the K(+) ligand Asp34 with an arginine. These mutagenesis and cation exchange experiments reveal that K(+) is a critical structural component for the activation of Ni(II)-responsive DNA binding by NikR.

Authors: Wang, S; Li, Y; Robinson, C; Zamble, D

• Publication status: Published
• Journal: Journal of the American Chemical Society
• Volume: 132
• Issue: 5
• Pages: 1506-1507
• Publication date: 2010-02-01
• DOI: 10.1021/ja909136h
• EISSN: 1520-5126
• ISSN: 0002-7863
• Language: English
• Keywords: DNA; Binding Sites; Protein Binding; Models, Molecular; Nickel; Potassium; Repressor Proteins; Escherichia coli; Escherichia coli Proteins; Crystallography, X-Ray; Mutation