Roles of trehalose phosphate synthase in yeast glycogen metabolism and sporulation.
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.
Mesh Terms:
Fungal Proteins, Gene Expression Regulation, Fungal, Glucosyltransferases, Glutathione Transferase, Glycogen, Glycogen Synthase Kinase 3, Hexokinase, Mutation, Nuclear Proteins, Protein-Tyrosine Kinases, Recombinant Fusion Proteins, Saccharomyces cerevisiae Proteins, Spores, Fungal, Transcription Factors, Trehalose, Yeasts
Fungal Proteins, Gene Expression Regulation, Fungal, Glucosyltransferases, Glutathione Transferase, Glycogen, Glycogen Synthase Kinase 3, Hexokinase, Mutation, Nuclear Proteins, Protein-Tyrosine Kinases, Recombinant Fusion Proteins, Saccharomyces cerevisiae Proteins, Spores, Fungal, Transcription Factors, Trehalose, Yeasts
Mol. Microbiol.
Date: Jun. 01, 2001
PubMed ID: 11442833
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