title: Roles of trehalose phosphate synthase in yeast glycogen metabolism and sporulation.
abstract: Trehalose is a major storage carbohydrate in budding yeast, Saccharomyces cerevisiae. Alterations in trehalose synthesis affect carbon source-dependent growth, accumulation of glycogen and sporulation. Trehalose is synthesized by trehalose phosphate synthase (TPS), which is a complex of at least four proteins. In this work, we show that the Tps1p subunit protein catalyses trehalose phosphate synthesis in the absence of other TPS components. The tps1-H223Y allele (glc6-1) that causes a semidominant decrease in glycogen accumulation exhibits greater enzyme activity than wild-type TPS1 because, unlike the wild-type enzyme, TPS activity in tps1-H223Y cells is not inhibited by phosphate. Poor sporulation in tps1 null diploids is caused by reduced expression of meiotic inducers encoded by IME1, IME2 and MCK1. Furthermore, high-copy MCK1 or heterozygous hxk2 mutations can suppress the tps1 sporulation trait. These results suggest that the trehalose-6-phosphate inhibition of hexokinase activity is required for full induction of MCK1 in sporulating yeast cells.
authors.affiliation: Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, Missouri, MO 65212, USA.
authors.forename: M N
authors.initials: MN
authors.lastname: De Silva-Udawatta
authors.forename: J F
authors.initials: JF
authors.lastname: Cannon
mesh_terms: D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism*; D005982:Glutathione Transferase / Q000235:genetics / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism*; D038362:Glycogen Synthase Kinase 3; D006593:Hexokinase / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D013172:Spores, Fungal / Q000502:physiology; D014157:Transcription Factors; D014199:Trehalose / Q000031:analogs & derivatives / Q000096:biosynthesis; D015003:Yeasts / Q000378:metabolism / Q000502:physiology*
chemical_list: D005656:Fungal Proteins; C080326:IME1 protein, S cerevisiae; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C089002:alpha,alpha-trehalose 6,6'-diphosphate; D006003:Glycogen; D014199:Trehalose; D005964:Glucosyltransferases; C023180:trehalose-6-phosphate synthase; D005982:Glutathione Transferase; D006593:Hexokinase; D011505:Protein-Tyrosine Kinases; D038362:Glycogen Synthase Kinase 3; C068124:MCK1 protein, S cerevisiae