Two different repressors collaborate to restrict expression of the yeast glucose transporter genes HXT2 and HXT4 to low levels of glucose.
Transcription of the yeast HXT2 and HXT4 genes, which encode glucose transporters, is induced only by low levels of glucose. This low-glucose-induced expression is mediated by two independent repression mechanisms: in the absence of glucose, transcription of both genes is prevented by Rgt1p, a C6 zinc cluster protein; at high levels of glucose, expression of HXT2 and HXT4 is repressed by Mig1p. Only at low glucose concentrations are both repressors inactive, leading to a 10- to 20-fold induction of gene expression. Mig1p and Rgt1p act directly on HXT2 and HXT4 by binding to their promoters. This transcriptional regulation is physiologically very important to the yeast cell because it causes these glucose transporters to be expressed only in low-glucose media, in which they are required for growth.
Ozcan
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S
Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Johnston
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M
D001483:Base Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism; D005656:Fungal Proteins / Q000096:biosynthesis; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects*; D005800:Genes, Fungal / Q000187:drug effects; D005838:Genotype; D005947:Glucose / Q000494:pharmacology*; D051246:Glucose Transport Proteins, Facilitative; D008565:Membrane Proteins / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000096:biosynthesis*; D016296:Mutagenesis; D009838:Oligodeoxyribonucleotides; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000302:isolation & purification / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017384:Sequence Deletion; D016335:Zinc Fingers; D001616:beta-Galactosidase / Q000096:biosynthesis
D017931:DNA Primers; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D051246:Glucose Transport Proteins, Facilitative; C084498:HXT2 protein, S cerevisiae; C090593:HXT4 protein, S cerevisiae; C085976:MIG1 protein, S cerevisiae; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D009838:Oligodeoxyribonucleotides; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D001616:beta-Galactosidase; D005947:Glucose