Two zinc-finger-containing repressors are responsible for glucose repression of SUC2 expression.
Expression of the SUC2 gene in Saccharomyces cerevisiae, which encodes invertase, is repressed about 200-fold by high levels of glucose. Mig1p is a Cys2His2 zinc-finger-containing protein required for glucose repression of SUC2 and several other genes. However, SUC2 expression is still about 13-fold repressed by glucose in a mig1 mutant. We have identified a second repressor, Mig2p, containing zinc fingers very similar to those of Mig1p that is responsible for this remaining glucose repression of SUC2 expression. Overexpression of MIG2 represses SUC2 under nonrepressing conditions, and a LexA-Mig2p fusion represses transcription of a lexO-containing promoter in a glucose-dependent manner, supporting the idea that Mig2p is a glucose-activated repressor. We have shown that Mig2p binds to the Miglp-binding sites in the SUC2 promoter. Even though Mig1p and Mig2p bind to similar sites and share almost identical zinc fingers, they differ in their relative affinities for various Mig1p-binding sites. This could explain our observation that MIG2 appears to have little role in glucose repression of other promoters with MIG1-binding sites.
Lutfiyya
L L
LL
Department of Genetics, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
Johnston
M
M
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D004268:DNA-Binding Proteins / Q000502:physiology*; D004790:Enzyme Induction / Q000187:drug effects; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects*; D005947:Glucose / Q000494:pharmacology*; D006026:Glycoside Hydrolases / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000378:metabolism; D016335:Zinc Fingers / Q000502:physiology*; D043324:beta-Fructofuranosidase; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D005947:Glucose; D006026:Glycoside Hydrolases; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases; D043324:beta-Fructofuranosidase; D000099160:LexA Repressor Protein; C085976:MIG1 protein, S cerevisiae