title: Sequence-specific 1H and 15N resonance assignments and secondary structure of GDP-bound human c-Ha-Ras protein in solution.
abstract: All the backbone 1H and 15N magnetic resonances (except for Pro residues) of the GDP-bound form of a truncated human c-Ha-ras proto-oncogene product (171 amino acid residues, the Ras protein) were assigned by 15N-edited two-dimensional NMR experiments on selectively 15N-labeled Ras proteins in combination with three-dimensional NMR experiments on the uniformly 15N-labeled protein. The sequence-specific assignments were made on the basis of the nuclear Overhauser effect (NOE) connectivities of amide protons with preceding amide and/or C alpha protons. In addition to sequential NOEs, vicinal spin coupling constants for amide protons and C alpha protons and deuterium exchange rates of amide protons were used to characterize the secondary structure of the GDP-bound Ras protein; six beta stands and five helices were identified and the topology of these elements was determined. The secondary structure of the Ras protein in solution was mainly consistent with that in crystal as determined by X-ray analyses. The deuterium exchange rates of amide protons were examined to elucidate the dynamic properties of the secondary structure elements of the Ras protein in solution. In solution, the beta-sheet structure in the Ras protein is rigid, while the second helix (A66-R73) is much more flexible, and the first and fifth helices (S17-124 and V152-L171) are more rigid than other helices. Secondary structure elements at or near the ends of the effector-region loop were found to be much more flexible in solution than in the crystalline state.
authors: Department of Biophysics and Biochemistry, Faculty of Science, University of Tokyo, Japan.
authors: Y
authors: Y
authors: Muto
authors: K
authors: K
authors: Yamasaki
authors: Y
authors: Y
authors: Ito
authors: S
authors: S
authors: Yajima
authors: H
authors: H
authors: Masaki
authors: T
authors: T
authors: Uozumi
authors: M
authors: M
authors: Wälchli
authors: S
authors: S
authors: Nishimura
authors: T
authors: T
authors: Miyazawa
authors: S
authors: S
authors: Yokoyama
mesh_terms: D000595:Amino Acid Sequence; D005813:Genes, Synthetic; D006153:Guanosine Diphosphate / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D006859:Hydrogen; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009587:Nitrogen Isotopes; D011485:Protein Binding; D017433:Protein Structure, Secondary; D000090063:Proto-Oncogene Mas; D016283:Proto-Oncogene Proteins p21(ras) / Q000737:chemistry* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D012996:Solutions; D014867:Water
chemical_list: C000715470:MAS1 protein, human; D009587:Nitrogen Isotopes; D000090063:Proto-Oncogene Mas; D011993:Recombinant Fusion Proteins; D012996:Solutions; D014867:Water; D006153:Guanosine Diphosphate; D006859:Hydrogen; C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)