title: NMR structure of the DNA-binding domain of the cell cycle protein Mbp1 from Saccharomyces cerevisiae.
abstract: The three-dimensional solution structure of the DNA-binding domain of Mlu-1 box binding protein (Mbp1) has been determined by multidimensional NMR spectroscopy. Mbp1 is a cell cycle transcription factor from Saccharomyces cerevisiae and consists of an N-terminal DNA-binding domain, a series of ankyrin repeats, and a heterodimerization domain at the C-terminus. A set of conformers comprising 19 refined structures was calculated via a molecular dynamics simulated annealing protocol using distance, dihedral angle, and residual dipolar coupling restraints derived from either double or triple resonance NMR experiments. The solution structure consists of a six-stranded beta-sheet segment folded against two pairs of alpha-helices in the topology of the winged helix-turn-helix family of proteins and is in agreement with the X-ray structures. In addition, the solution structure shows that the C-terminal tail region of this domain folds back and makes specific interactions with the N-terminal beta-strand of the protein. This C-terminal region is essential for full DNA-binding activity but appears in the X-ray structure to be disordered. The fold-back structure extends the region of positive electrostatic potential, and this may enhance the nonspecific contribution to binding by favorable electrostatic interactions with the DNA backbone.
authors.affiliation: Division of Molecular Structure, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, United Kingdom.
authors.forename: Margie
authors.initials: M
authors.lastname: Nair
authors.forename: Pauline B
authors.initials: PB
authors.lastname: McIntosh
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Frenkiel
authors.forename: Geoff
authors.initials: G
authors.lastname: Kelly
authors.forename: Ian A
authors.initials: IA
authors.lastname: Taylor
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Smerdon
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Lane
mesh_terms: D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000737:chemistry*; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000737:chemistry*; D019077:Helix-Turn-Helix Motifs; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D010446:Peptide Fragments / Q000737:chemistry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D012996:Solutions; D055672:Static Electricity; D013816:Thermodynamics; D014157:Transcription Factors / Q000737:chemistry*
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C083209:MBP1 protein, S cerevisiae; D010446:Peptide Fragments; D029701:Saccharomyces cerevisiae Proteins; D012996:Solutions; D014157:Transcription Factors