title: G1/S cyclin-dependent kinase regulates small GTPase Rho1p through phosphorylation of RhoGEF Tus1p in Saccharomyces cerevisiae.
abstract: Rho1p is an essential small GTPase that plays a key role in the morphogenesis of Saccharomyces cerevisiae. We show here that the activation of Rho1p is regulated by a cyclin-dependent kinase (CDK). Rho1p is activated at the G1/S transition at the incipient-bud sites by the Cln2p (G1 cyclin) and Cdc28p (CDK) complex, in a process mediated by Tus1p, a guanine nucleotide exchange factor for Rho1p. Tus1p interacts physically with Cln2p/Cdc28p and is phosphorylated in a Cln2p/Cdc28p-dependent manner. CDK phosphorylation consensus sites in Tus1p are required for both Cln2p-dependent activation of Rho1p and polarized organization of the actin cytoskeleton. We propose that Cln2p/Cdc28p-dependent phosphorylation of Tus1p is required for appropriate temporal and spatial activation of Rho1p at the G1/S transition.
authors.affiliation: Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Chiba 277-8562, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Kono
authors.forename: Satoru
authors.initials: S
authors.lastname: Nogami
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Abe
authors.forename: Masafumi
authors.initials: M
authors.lastname: Nishizawa
authors.forename: Shinichi
authors.initials: S
authors.lastname: Morishita
authors.forename: David
authors.initials: D
authors.lastname: Pellman
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Ohya
mesh_terms: D000199:Actins / Q000378:metabolism; D001665:Binding Sites; D017489:CDC28 Protein Kinase, S cerevisiae / Q000235:genetics / Q000378:metabolism; D002455:Cell Division; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism*; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D004789:Enzyme Activation; D016193:G1 Phase; D005800:Genes, Fungal; D020662:Guanine Nucleotide Exchange Factors / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D009154:Mutation; D010766:Phosphorylation; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016196:S Phase; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; C082721:CLN2 protein, S cerevisiae; D016213:Cyclins; D020662:Guanine Nucleotide Exchange Factors; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; C448998:TUS1 protein, S cerevisiae; D017489:CDC28 Protein Kinase, S cerevisiae; D018844:Cyclin-Dependent Kinases; C051302:RHO1 protein, S cerevisiae; D020741:rho GTP-Binding Proteins