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.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Fungal Proteins / genetics
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Fungal Proteins / metabolism
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Gene Expression Regulation, Fungal
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Glucosyltransferases / genetics
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Glucosyltransferases / metabolism*
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Glutathione Transferase / genetics
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Glutathione Transferase / metabolism
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Glycogen / metabolism*
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Glycogen Synthase Kinase 3
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Hexokinase / genetics
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Hexokinase / metabolism
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Mutation
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Nuclear Proteins / genetics
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Nuclear Proteins / metabolism
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Protein-Tyrosine Kinases / genetics
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Protein-Tyrosine Kinases / metabolism
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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Saccharomyces cerevisiae Proteins*
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Spores, Fungal / physiology
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Transcription Factors*
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Trehalose / analogs & derivatives
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Trehalose / biosynthesis
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Yeasts / metabolism
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Yeasts / physiology*
Substances
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Fungal Proteins
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IME1 protein, S cerevisiae
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Nuclear Proteins
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Recombinant Fusion Proteins
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Saccharomyces cerevisiae Proteins
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Transcription Factors
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alpha,alpha-trehalose 6,6'-diphosphate
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Glycogen
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Trehalose
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Glucosyltransferases
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trehalose-6-phosphate synthase
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Glutathione Transferase
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Hexokinase
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Protein-Tyrosine Kinases
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Glycogen Synthase Kinase 3
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MCK1 protein, S cerevisiae