Crystal structure of the nickel-responsive transcription factor NikR

• Published in: Nature structural & molecular biology Vol. 10; no. 10; pp. 794 - 799
• Main Authors: Drennan, Catherine L, Schreiter, Eric R, Sintchak, Michael D, Guo, Yayi, Chivers, Peter T, Sauer, Robert T
• Format: Journal Article
• Language: English
• Published: United States Nature Publishing Group 01.10.2003
• Subjects: Amino Acid Sequence; Crystallography, X-Ray; Escherichia coli; Escherichia coli - chemistry; Escherichia coli - enzymology; Escherichia coli - metabolism; Escherichia coli Proteins; Molecular Sequence Data; Nickel - metabolism; NikR protein; Protein Structure, Tertiary; Repressor Proteins - chemistry; Repressor Proteins - metabolism
• ISSN: 1072-8368; 1545-9993; 2331-365X; 1545-9985
• DOI: 10.1038/nsb985

NikR is a metal-responsive transcription factor that controls nickel uptake in Escherichia coli by regulating expression of a nickel-specific ATP-binding cassette (ABC) transporter. We have determined the first two structures of NikR: the full-length apo repressor at a resolution of 2.3 A and the nickel-bound C-terminal regulatory domain at a resolution of 1.4 A. NikR is the only known metal-responsive member of the ribbon-helix-helix family of transcription factors, and its structure has a quaternary arrangement consisting of two dimeric DNA-binding domains separated by a tetrameric regulatory domain that binds nickel. The position of the C-terminal regulatory domain enforces a large spacing between the contacts that each NikR DNA-binding domain can make with the nik operator. The regulatory domain of NikR contains four nickel-binding sites at the tetramer interface, each exhibiting a novel square-planar coordination by three histidines and one cysteine side chain.