title: The X-ray structure of the DNA-binding domain from the Saccharomyces cerevisiae cell-cycle transcription factor Mbp1 at 2.1 A resolution.
abstract: The structure of the DNA-binding domain of the Saccharomyces cerevisiae cell-cycle transcription factor Mbp1 has been solved using the multiwavelength anomalous diffraction (MAD) technique on crystals of selenomethionyl protein and refined at 2.1 A resolution. The molecule is globular, consisting of a twisted, six-stranded beta-barrel that is packed against a loose bundle of four alpha-helices. Two of the beta-strands in combination with two of the helices form a structure characteristic of the DNA-binding motif found in the CAP family of helix-turn-helix transcription factors. In Mbp1, this beta2/alpha2 motif is associated with regions of both positive electrostatic potential and sequence conservation within the Mbp1/Swi4 family, suggesting a role in DNA-binding in these proteins. A combination of structural and biochemical data further indicate a similarity to HNF3gamma/fork head, a member of the family of "winged" helix-turn-helix proteins. We propose a model for DNA-binding involving a recognition helix in the major groove, phosphodiester backbone interactions through the beta-hairpin and further base and/or phosphate interactions mediated by a C-terminal, positively charged loop.
authors.affiliation: Division of Protein Structure, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, U.K.
authors.forename: I A
authors.initials: IA
authors.lastname: Taylor
authors.forename: M K
authors.initials: MK
authors.lastname: Treiber
authors.forename: L
authors.initials: L
authors.lastname: Olivi
authors.forename: S J
authors.initials: SJ
authors.lastname: Smerdon
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002453:Cell Cycle; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics; D004926:Escherichia coli; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics; D015870:Gene Expression; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000737:chemistry*; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C083209:MBP1 protein, S cerevisiae; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors