Crystal structure of the nickel-responsive transcription factor NikR.
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.
Schreiter
Eric R
ER
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139 USA.
Sintchak
Michael D
MD
Guo
Yayi
Y
Chivers
Peter T
PT
Sauer
Robert T
RT
Drennan
Catherine L
CL
D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism; D029968:Escherichia coli Proteins; D008969:Molecular Sequence Data; D009532:Nickel / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism
D029968:Escherichia coli Proteins; C402409:NikR protein, E coli; D012097:Repressor Proteins; D009532:Nickel