Abstract
In Saccharomyces cerevisiae maltose utilization requires a functional MAL locus, each composed of three genes: MALR (gene 3) encoding a regulatory protein, MALT (gene 1) encoding maltose permease and MALS (gene 2) encoding maltase. We show that constitutive activation of the RAS/protein kinase A pathway severely reduces growth of MAL1 strains on maltose. This may be a consequence of reduction in MALT mRNA, reduced Vmax and increased catabolite inactivation of the MALT-encoded maltose transporter in the MAL1 strain. Mutations in the GGS1/TPS1 gene, which restricts glucose influx and possibly affects signalling, relieve carbon catabolite repression on both maltase and maltose permease and reduce maltose permease inactivation.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Cyclic AMP-Dependent Protein Kinases / metabolism*
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Genes, Fungal*
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Kinetics
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Maltose / metabolism*
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Membrane Transport Proteins / genetics
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Membrane Transport Proteins / metabolism*
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Monosaccharide Transport Proteins
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RNA, Messenger / biosynthesis
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Recombinant Proteins / metabolism
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Saccharomyces cerevisiae / genetics*
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Saccharomyces cerevisiae / metabolism*
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Trans-Activators / genetics
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Trans-Activators / metabolism*
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Transcription, Genetic
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alpha-Glucosidases / genetics
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alpha-Glucosidases / metabolism*
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ras Proteins / metabolism*
Substances
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Membrane Transport Proteins
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Monosaccharide Transport Proteins
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RNA, Messenger
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Recombinant Proteins
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Trans-Activators
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Maltose
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maltose permease
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Cyclic AMP-Dependent Protein Kinases
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alpha-Glucosidases
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ras Proteins