title: The Ras-RasGAP complex: structural basis for GTPase activation and its loss in oncogenic Ras mutants.
abstract: The three-dimensional structure of the complex between human H-Ras bound to guanosine diphosphate and the guanosine triphosphatase (GTPase)-activating domain of the human GTPase-activating protein p120GAP (GAP-334) in the presence of aluminum fluoride was solved at a resolution of 2.5 angstroms. The structure shows the partly hydrophilic and partly hydrophobic nature of the communication between the two molecules, which explains the sensitivity of the interaction toward both salts and lipids. An arginine side chain (arginine-789) of GAP-334 is supplied into the active site of Ras to neutralize developing charges in the transition state. The switch II region of Ras is stabilized by GAP-334, thus allowing glutamine-61 of Ras, mutation of which activates the oncogenic potential, to participate in catalysis. The structural arrangement in the active site is consistent with a mostly associative mechanism of phosphoryl transfer and provides an explanation for the activation of Ras by glycine-12 and glutamine-61 mutations. Glycine-12 in the transition state mimic is within van der Waals distance of both arginine-789 of GAP-334 and glutamine-61 of Ras, and even its mutation to alanine would disturb the arrangements of residues in the transition state.
authors.affiliation: Max-Planck-Institut für molekulare Physiologie, Abteilung Strukturelle Biologie, Rheinlanddamm 201, 44139 Dortmund, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Scheffzek
authors.forename: M R
authors.initials: MR
authors.lastname: Ahmadian
authors.forename: W
authors.initials: W
authors.lastname: Kabsch
authors.forename: L
authors.initials: L
authors.lastname: Wiesmüller
authors.forename: A
authors.initials: A
authors.lastname: Lautwein
authors.forename: F
authors.initials: F
authors.lastname: Schmitz
authors.forename: A
authors.initials: A
authors.lastname: Wittinghofer
mesh_terms: D017607:Aluminum Compounds / Q000737:chemistry / Q000378:metabolism; D000595:Amino Acid Sequence; D001665:Binding Sites; D002384:Catalysis; D002471:Cell Transformation, Neoplastic; D018360:Crystallography, X-Ray; D004789:Enzyme Activation; D005459:Fluorides / Q000737:chemistry / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D020690:GTPase-Activating Proteins; D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011506:Proteins / Q000737:chemistry* / Q000378:metabolism*; D015398:Signal Transduction; D020703:ras GTPase-Activating Proteins; D018631:ras Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D017607:Aluminum Compounds; D020690:GTPase-Activating Proteins; D011506:Proteins; D020703:ras GTPase-Activating Proteins; D006153:Guanosine Diphosphate; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D018631:ras Proteins; D005459:Fluorides; C032311:aluminum fluoride