title: Assignments, secondary structure, global fold, and dynamics of chemotaxis Y protein using three- and four-dimensional heteronuclear (13C,15N) NMR spectroscopy.
abstract: NMR spectroscopy has been used to study recombinant Escherichia coli CheY, a 128-residue protein involved in regulating bacterial chemotaxis. Heteronuclear three- and four-dimensional (3D and 4D) experiments have provided sequence-specific resonance assignments and quantitation of short-, medium-, and long-range distance restraints from nuclear Overhauser enhancement (NOE) intensities. These distance restraints were further supplemented with measurements of three-bond scalar coupling constants to define the local dihedral angles, and with the identification of amide protons undergoing slow solvent exchange from which hydrogen-bonding patterns were identified. The current model structure shows the same global fold of CheY as existing X-ray structures (Volz & Matsumura, 1991; Stock et al. 1993) with a (beta/alpha)5 motif of five parallel beta-strands at the central core surrounded by three alpha-helices on one face and with two on the opposite side. Heteronuclear 15N-1H relaxation experiments are interpreted to show portions of the protein structure in the Mg2+ binding loop are ill-defined because of slow motion (chemical exchange) on the NMR time scale. Moreover, the presence of Mg2+ disrupts the salt bridge between the highly conserved Lys-109 and Asp-57, the site of phosphorylation.
authors.affiliation: DuPont Merck Pharmaceutical Company, Wilmington, Delaware 19880-0328.
authors.forename: F J
authors.initials: FJ
authors.lastname: Moy
authors.forename: D F
authors.initials: DF
authors.lastname: Lowry
authors.forename: P
authors.initials: P
authors.lastname: Matsumura
authors.forename: F W
authors.initials: FW
authors.lastname: Dahlquist
authors.forename: J E
authors.initials: JE
authors.lastname: Krywko
authors.forename: P J
authors.initials: PJ
authors.lastname: Domaille
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry; D004926:Escherichia coli / Q000737:chemistry; D029968:Escherichia coli Proteins; D006859:Hydrogen / Q000737:chemistry; D006860:Hydrogen Bonding; D008274:Magnesium / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008565:Membrane Proteins / Q000737:chemistry*; D000072236:Methyl-Accepting Chemotaxis Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D011994:Recombinant Proteins; C000607606:cheY protein, E coli; D006859:Hydrogen; D008274:Magnesium