title: TOR2 is required for organization of the actin cytoskeleton in yeast.
abstract: The Saccharomyces cerevisiae gene TOR2 encodes a putative phosphatidylinositol kinase that has two essential functions. One function is redundant with TOR1, a TOR2 homolog, and is required for signaling translation initiation and early G1 progression. The second essential function is unique to TOR2. Here we report that loss of the TOR2-unique function disrupts polarized distribution of the actin cytoskeleton. A screen for dosage suppressors of a dominant negative TOR2 allele identified TCP20/CCT6, encoding a subunit of the cytosolic chaperonin TCP-1 that is involved in the biogenesis of actin structures. Overexpression of TCP20 restores growth and polarized distribution of the actin cytoskeleton in a tor2 mutant. TCP20 overexpression does not restore growth in a tor1 tor2 double mutant. We suggest that the unique function of the phosphatidylinositol kinase homolog TOR2 is required for signaling organization of the actin cytoskeleton during the cell cycle. TOR2, via its two functions, may thus integrate temporal and spatial control of cell growth.
authors.affiliation: Department of Biochemistry, University of Basel, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Schmidt
authors.forename: J
authors.initials: J
authors.lastname: Kunz
authors.forename: M N
authors.initials: MN
authors.lastname: Hall
mesh_terms: D000199:Actins / Q000378:metabolism*; D018797:Cell Cycle Proteins; D003599:Cytoskeleton / Q000502:physiology* / Q000648:ultrastructure; D017931:DNA Primers; D005656:Fungal Proteins / Q000378:metabolism; D015870:Gene Expression; D005799:Genes, Dominant; D005800:Genes, Fungal; D005838:Genotype; D016297:Mutagenesis, Site-Directed; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000096:biosynthesis / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D013489:Suppression, Genetic
chemical_list: D000199:Actins; D018797:Cell Cycle Proteins; D017931:DNA Primers; D005656:Fungal Proteins; D019869:Phosphatidylinositol 3-Kinases; D017853:Phosphotransferases (Alcohol Group Acceptor); D029701:Saccharomyces cerevisiae Proteins; C083324:TOR1 protein, S cerevisiae; C081135:TOR2 protein, S cerevisiae