title: A dominant activating mutation in the effector region of RAS abolishes IRA2 sensitivity.
abstract: Previously described mutations in RAS genes that cause a dominant activated phenotype affect the intrinsic biochemical properties of RAS proteins, either decreasing the intrinsic GTPase or reducing the affinity for guanine nucleotides. In this report, we describe a novel activating mutation in the RAS2 gene of Saccharomyces cerevisiae that does not alter intrinsic biochemical properties of the mutant RAS2 protein. Rather, this mutation, RAS2-P41S (proline 41 to serine), which lies in the effector region of RAS, is shown to abolish the ability of the IRA2 protein to stimulate the GTPase activity of the mutant RAS protein. This mutation also modestly reduced the ability of the mutant protein to stimulate the target adenylate cyclase in an in vitro assay, although in vivo the phenotypes it induced suggest that it retains potency in stimulation of adenylate cyclase. Our results demonstrate that although the effector region of RAS appears to be important for interaction with both target effector and negative regulators of RAS, it is possible to eliminate negative regulator responsiveness and retain potency in effector stimulation.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Chicago, Illinois 60637.
authors.forename: K
authors.initials: K
authors.lastname: Tanaka
authors.forename: D R
authors.initials: DR
authors.lastname: Wood
authors.forename: B K
authors.initials: BK
authors.lastname: Lin
authors.forename: M
authors.initials: M
authors.lastname: Khalil
authors.forename: F
authors.initials: F
authors.lastname: Tamanoi
authors.forename: J F
authors.initials: JF
authors.lastname: Cannon
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D004789:Enzyme Activation; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism; D020690:GTPase-Activating Proteins; D005799:Genes, Dominant / Q000235:genetics; D011905:Genes, ras / Q000235:genetics*; D006160:Guanosine Triphosphate / Q000378:metabolism; D007700:Kinetics; D009154:Mutation / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras) / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D005656:Fungal Proteins; D020690:GTPase-Activating Proteins; C064960:IRA2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases; D016283:Proto-Oncogene Proteins p21(ras); D000262:Adenylyl Cyclases