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
Mol. Microbiol.
Date: Jun. 01, 2001
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