NikR is a ribbon-helix-helix DNA-binding protein.
Escherichia coli NikR, a repressor with homologs in other bacteria and archaea, was identified as a potential new member of the ribbon-helix-helix (beta-alpha-alpha) family of transcription factors in profile based sequence searches and in structure prediction experiments. Biophysical and biochemical characterization of the N-terminal domain of NikR show that it has many features expected of a beta-alpha-alpha protein including alpha-helical content, dimeric solution form, concentration dependent thermal stability, and ability to bind DNA in sequence-specific manner. Mutation of a residue predicted to be important for DNA-binding reduces operator affinity but does not affect the secondary structure or stability of the protein.
Chivers
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Department of Biology, Massachusetts Institute of Technology, Cambridge 02139, USA.
Sauer
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D000595:Amino Acid Sequence; D001483:Base Sequence; D002151:Calorimetry; D002942:Circular Dichroism; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009876:Operon; D011401:Promoter Regions, Genetic; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry; D012097:Repressor Proteins / Q000737:chemistry* / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D029968:Escherichia coli Proteins; C402409:NikR protein, E coli; D011994:Recombinant Proteins; D012097:Repressor Proteins