Abstract
We have cloned a yeast gene, SKO1, which in high copy number suppresses lethal overexpression of cAMP-dependent protein kinase. SKO1 encodes a bZIP protein that binds to the CRE motif, TGACGTCA. We found that SKO1 also binds to a CRE-like site in SUC2, a yeast gene encoding invertase which is under positive control by cAMP. A disruption of the SKO1 gene causes a partial derepression of SUC2, indicating that SKO1 is a negative regulator of the SUC2 gene. SKO1 interacts positively with MIG1, a zinc finger protein that mediates glucose repression of SUC2. A kinetic analysis revealed a complex regulation of the SUC2 mRNA in response to glucose. First, MIG1 mediates a rapid and strong repression of SUC2, which is complete within 10 minutes. Second, a MIG1-independent process causes a further slow reduction in the mRNA. Third, in the absence of MIG1, there is also a rapid but transient glucose induction of the SUC2 mRNA. This induction is correlated with a transient loss of SKO1-dependent repression.
MeSH terms
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Amino Acid Sequence
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Base Sequence
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Basic-Leucine Zipper Transcription Factors
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Binding Sites / genetics
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Blotting, Northern
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Cloning, Molecular
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DNA-Binding Proteins / chemistry
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DNA-Binding Proteins / genetics*
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DNA-Binding Proteins / metabolism
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G-Box Binding Factors
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Gene Expression Regulation, Fungal / drug effects
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Gene Expression Regulation, Fungal / physiology
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Genes, Fungal / genetics*
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Glucose / pharmacology
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Glucosyltransferases / genetics
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Leucine Zippers / genetics*
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Molecular Sequence Data
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Oligonucleotide Probes / genetics
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Plant Proteins / chemistry
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Plant Proteins / genetics*
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Plant Proteins / metabolism
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Plasmids / genetics
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Promoter Regions, Genetic / genetics
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Repressor Proteins / chemistry
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Repressor Proteins / genetics*
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Repressor Proteins / metabolism
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Restriction Mapping
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Saccharomyces cerevisiae / chemistry
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Saccharomyces cerevisiae / genetics*
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Saccharomyces cerevisiae / metabolism
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Saccharomyces cerevisiae Proteins*
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Transcription Factors*
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Transcription, Genetic / genetics
Substances
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Basic-Leucine Zipper Transcription Factors
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DNA-Binding Proteins
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G-Box Binding Factors
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Oligonucleotide Probes
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Plant Proteins
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Repressor Proteins
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SKO1 protein, S cerevisiae
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Saccharomyces cerevisiae Proteins
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Transcription Factors
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Glucosyltransferases
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trehalose-6-phosphate synthase
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Glucose