title: Saccharomyces cerevisiae cdc42p GTPase is involved in preventing the recurrence of bud emergence during the cell cycle.
abstract: The Saccharomyces cerevisiae Cdc42p GTPase interacts with multiple regulators and downstream effectors through an approximately 25-amino-acid effector domain. Four effector domain mutations, Y32K, F37A, D38E, and Y40C, were introduced into Cdc42p and characterized for their effects on these interactions. Each mutant protein showed differential interactions with a number of downstream effectors and regulators and various levels of functionality. Specifically, Cdc42(D38E)p showed reduced interactions with the Cla4p p21-activated protein kinase and the Bem3p GTPase-activating protein and cdc42(D38E) was the only mutant allele able to complement the Deltacdc42 null mutant. However, the mutant protein was only partially functional, as indicated by a temperature-dependent multibudded phenotype seen in conjunction with defects in both septin ring localization and activation of the Swe1p-dependent morphogenetic checkpoint. Further analysis of this mutant suggested that the multiple buds emerged consecutively with a premature termination of bud enlargement preceding the appearance of the next bud. Cortical actin, the septin ring, Cla4p-green fluorescent protein (GFP), and GFP-Cdc24p all predominantly localized to one bud at a time per multibudded cell. These data suggest that Cdc42(D38E)p triggers a morphogenetic defect post-bud emergence, leading to cessation of bud growth and reorganization of the budding machinery to another random budding site, indicating that Cdc42p is involved in prevention of the initiation of supernumerary buds during the cell cycle.
authors.affiliation: Department of Microbiology and Molecular Genetics and Markey Center for Molecular Genetics, University of Vermont Burlington, Vermont 05405, USA.
authors.forename: T J
authors.initials: TJ
authors.lastname: Richman
authors.forename: D I
authors.initials: DI
authors.lastname: Johnson
mesh_terms: D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D002453:Cell Cycle / Q000502:physiology*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism; D020690:GTPase-Activating Proteins; D049452:Green Fluorescent Proteins; D020662:Guanine Nucleotide Exchange Factors; D047908:Intracellular Signaling Peptides and Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D020930:MAP Kinase Kinase Kinases; D008969:Molecular Sequence Data; D009154:Mutation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D013696:Temperature; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*
chemical_list: D000199:Actins; C084220:BEM3 protein, S cerevisiae; C073594:CDC24 protein, S cerevisiae; D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; D047908:Intracellular Signaling Peptides and Proteins; D008164:Luminescent Proteins; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; C099685:SWE1 protein, S cerevisiae; D011505:Protein-Tyrosine Kinases; C095212:CLA4 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; D020930:MAP Kinase Kinase Kinases; C078754:STE20 protein, S cerevisiae; D020846:cdc42 GTP-Binding Protein, Saccharomyces cerevisiae