title: Structure of the winged-helix protein hRFX1 reveals a new mode of DNA binding.
abstract: Regulatory factor X (RFX) proteins are transcriptional activators that recognize X-boxes (DNA of the sequence 5'-GTNRCC(0-3N)RGYAAC-3', where N is any nucleotide, R is a purine and Y is a pyrimidine) using a highly conserved 76-residue DNA-binding domain (DBD). DNA-binding defects in the protein RFX5 cause bare lymphocyte syndrome or major histocompatibility antigen class II deficiency. RFX1, -2 and -3 regulate expression of other medically important gene products (for example, interleukin-5 receptor alpha chain, IL-5R alpha). Fusions of the ligand-binding domain of the oestrogen receptor with the DBD of RFX4 occur in some human breast tumours. Here we present a 1.5 A-resolution structure of two copies of the DBD of human RFX1 (hRFX1) binding cooperatively to a symmetrical X-box. hRFX1 is an unusual member of the winged-helix subfamily of helix-turn-helix proteins because it uses a beta-hairpin (or wing) to recognize DNA instead of the recognition helix typical of helix-turn-helix proteins. A new model for interactions between linker histones and DNA is proposed.
authors.affiliation: Laboratories of Molecular Biophysics, Pels Family Center for Biochemistry and Structural Biology, The Rockefeller University, New York, New York 10021, USA.
authors.forename: K S
authors.initials: KS
authors.lastname: Gajiwala
authors.forename: H
authors.initials: H
authors.lastname: Chen
authors.forename: F
authors.initials: F
authors.lastname: Cornille
authors.forename: B P
authors.initials: BP
authors.lastname: Roques
authors.forename: W
authors.initials: W
authors.lastname: Reith
authors.forename: B
authors.initials: B
authors.lastname: Mach
authors.forename: S K
authors.initials: SK
authors.lastname: Burley
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D004563:Electrochemistry; D019077:Helix-Turn-Helix Motifs; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D000071701:Regulatory Factor X Transcription Factors; D000071716:Regulatory Factor X1; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; C000605537:RFX1 protein, human; D000071701:Regulatory Factor X Transcription Factors; D000071716:Regulatory Factor X1; D014157:Transcription Factors; D004247:DNA