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#glucose repression

2 public questions tagged with this topic.

Microbial Physiology

In catabolite repression, bacteria:

Catabolite repression represents global regulatory strategy ensuring efficient use of carbon sources by prioritizing best substrate. In presence of rapidly metabolizable glucose, intracellular cyclic AMP cAMP falls dramatically due to inhibition of adenylate cyclase CyaA by dephosphorylated EIIA-Glc component of phosphotransferase system and increased phosphodiesterase activity. Low cAMP prevents formation of active CRP-cAMP complex that binds conserved motif TGTGA upstream of catabolic operons such as lacZYA for lactose, araBAD for arabinose and malEFG for maltose required for alternative sug

Ref: Prescott's Microbiology, 11th ed., Chapter 6: Catabolite Repression and Efficient Carbon Source Prioritization.

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Eukaryotes gene regulation

Which protein represses GAL1 gene in yeast in presence of glucose?

Saccharomyces cerevisiae GAL regulon glucose repression is mediated predominately by C2H2 zinc finger transcription factor Mig1, functional homolog of mammalian EGR proteins. Under high glucose, hexokinase Hxk2 signals inactivation of Snf1 kinase, permitting Mig1 nuclear localization and binding to GC-rich consensus CCCCG motifs in GAL1, GAL4, GAL3 promoters. Mig1 does not mask Gal4 activation domain like Gal80, but actively recruits corepressors to block transcription of structural genes and regulatory activators. Deletion of MIG1 partially relieves glucose repression, allowing galactose-inde

Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 7: Yeast GAL Regulation – Mig1 Glucose Repression

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