title: S-nitrosylation decreases the adsorption of H-Ras in lipid bilayer and changes intrinsic catalytic activity.
abstract: Structural, chemical, and mutational studies have shown that C-terminal cysteine residues on H-Ras could potentially be oxidized by nitrosylation. For investigating the effect of nitrosylation of Ras molecule on the adsorption of farnesylated H-Ras into lipid layer, experiments with optical waveguide lightmode spectroscopy were used. The analysis of association/dissociation kinetics to planar phospholipids under controlled hydrodynamic conditions has shown that preliminary treatment of protein by S-nitroso-cysteine decreased the adsorption of farnesylated H-Ras. The authors have found that compared with nitrosylated forms, farnesylated H-Ras has more compact configuration, because of the smaller area occupied by protein upon absorption at the membrane. The association rate coefficient for unmodified H-Ras was lower than similar parameter for farnesylated and nitrosylated forms. However, the desorbability, i.e., parameter, which reflects the rate of dissociation of protein from lipids is higher for farnesylated H-Ras. In addition, it was have found that farnesylation of cytoplasmic H-Ras, in contrast to membrane-derived forms, inhibits intrinsic GTPase activity of protein, and preliminary treatment of H-Ras by S-nitroso-cysteine restores the activity to the control level. These data suggest that nitrosylation of H-Ras rearranges the adsorptive potential and intrinsic GTPase activity of H-Ras through modification of C-terminal cysteines of molecule.
authors.affiliation: Department of Biochemistry, I.Beritashvili Institute of Physiology, 14 Gotua st, 0160, Tbilisi, Georgia.
authors.forename: L
authors.initials: L
authors.lastname: Shanshiashvili
authors.forename: N
authors.initials: N
authors.lastname: Narmania
authors.forename: T
authors.initials: T
authors.lastname: Barbakadze
authors.forename: E
authors.initials: E
authors.lastname: Zhuravliova
authors.forename: N
authors.initials: N
authors.lastname: Natsvlishvili
authors.forename: J
authors.initials: J
authors.lastname: Ramsden
authors.forename: D G
authors.initials: DG
authors.lastname: Mikeladze
mesh_terms: D000327:Adsorption; D000818:Animals; D055162:Biocatalysis; D002417:Cattle; D003545:Cysteine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism*; D009154:Mutation; D010084:Oxidation-Reduction; D026403:S-Nitrosothiols / Q000737:chemistry / Q000378:metabolism*; D018631:ras Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D008051:Lipid Bilayers; D026403:S-Nitrosothiols; C021315:S-nitrosocysteine; D018631:ras Proteins; D003545:Cysteine