title: Conformational and dynamic differences between N-ras P21 bound to GTPgammaS and to GMPPNP as studied by NMR.
abstract: Heteronuclear-edited proton-detected NMR methods are used to study the nucleotide-dependent conformational changes between the GMPPNP form of human N-ras P21 as compared to GDP and GTPgammaS forms. Full-length N-ras P21 was also compared with protein truncated beyond residue 167, to search for interaction points between the more invariant part of the protein and the variable C-terminal section. In both cases, the reporter was the 15N-H 2D spectrum of aspartate amide groups labeled with 15N. Small truncation-induced changes were seen in the spectrum at the resonances of Asp-54, -108, and -109 which are not far from the C-terminal and, surprisingly, at Asp-57 which is more remote. The spectrum obtained for the GMPPNP-ligated form is similar to that of the GTPgammaS form, except that peaks of several residues are weak at low temperature, and strongly temperature-dependent in their intensity, and a new resonance appears at 15 degrees C and above. The observations are discussed in terms of a two-state model for the GMPPNP-ligated protein, previously proposed by Geyer et al. [(1996) Biochemistry 35, 10308-10320].
authors.affiliation: Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02254, USA.
authors.forename: J S
authors.initials: JS
authors.lastname: Hu
authors.forename: A G
authors.initials: AG
authors.lastname: Redfield
mesh_terms: D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000737:chemistry / Q000378:metabolism*; D006165:Guanylyl Imidodiphosphate / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D016283:Proto-Oncogene Proteins p21(ras) / Q000737:chemistry / Q000378:metabolism*
chemical_list: D006165:Guanylyl Imidodiphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C501009:HRAS protein, human; D016283:Proto-Oncogene Proteins p21(ras)