title: Multicopy suppression screen in the msb3 msb4 Saccharomyces cerevisiae double mutant, affected in Ypt/RabGAP activity.
abstract: The Msb3p and Msb4p proteins of Saccharomyces cerevisiae are members of the Ypt/Rab-specific GTPase-activating protein (GAP) family. They are essential to vesicular trafficking and involved in the regulation of exocytosis and in the organization of the actin cytoskeleton, but their exact biological roles have yet to be determined. The msb3 msb4 yeast double mutation causes growth inhibition in the presence of DMSO and/or caffeine, affects the organization of the actin cytoskeleton, produces a random budding pattern in diploid cells, and affects segregation of the nucleus. To find cell components that interact genetically with the products of the MSB3 and MSB4 genes, we screened a genomic library for multicopy suppressor genes restoring normal growth of the double mutant in the presence of DMSO and caffeine. Six genes were identified, and the extent to which each gene corrects specific growth defects of the msb3 msb4 mutant is described. The encoded suppressors were classified on the basis of functional features into four groups: vesicular transport proteins (Sec7p, Vps35p, and Uso1p), a protein involved in cell division (Sap155p), a molecular chaperon (Ssz1p), and a protein associated with the 25S proteasome (Cic1p).
authors.affiliation: Animal and Microbial Biology Unit, Gembloux Agricultural University, Avenue Maréchal Juin 6, B-5030, Gembloux, Belgium. dechamps.c@fsagx.ac.be
authors.forename: Christophe
authors.initials: C
authors.lastname: Dechamps
authors.forename: Daniel
authors.initials: D
authors.lastname: Portetelle
authors.forename: Micheline
authors.initials: M
authors.lastname: Vandenbol
mesh_terms: D000199:Actins / Q000737:chemistry*; D002110:Caffeine / Q000494:pharmacology; D003599:Cytoskeleton / Q000235:genetics*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D020690:GTPase-Activating Proteins / Q000235:genetics* / Q000378:metabolism; D016153:Genes, Suppressor; D015698:Genomic Library; D006128:Growth / Q000187:drug effects; D047908:Intracellular Signaling Peptides and Proteins; D009154:Mutation; D010641:Phenotype; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D000199:Actins; D020690:GTPase-Activating Proteins; D047908:Intracellular Signaling Peptides and Proteins; C076360:MSB2 protein, S cerevisiae; C540987:MSB3 protein, S cerevisiae; C540988:MSB4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D002110:Caffeine; D004121:Dimethyl Sulfoxide