Biochemical evidence for glucose-independent induction of HXT expression in Saccharomyces cerevisiae.

The yeast glucose sensors Rgt2 and Snf3 generate a signal in response to glucose that leads to degradation of Mth1 and Std1, thereby relieving repression of Rgt1-repressed genes such as the glucose transporter genes (HXT). Mth1 and Std1 are degraded via the Yck1/2 kinase-SCF(Grr1)-26S proteasome pathway triggered by the glucose ...
sensors. Here, we show that RGT2-1 promotes ubiquitination and subsequent degradation of Mth1 and Std1 regardless of the presence of glucose. Site-specific mutagenesis reveals that the conserved lysine residues of Mth1 and Std1 might serve as attachment sites for ubiquitin, and that the potential casein kinase (Yck1/2) sites of serine phosphorylation might control their ubiquitination. Finally, we show that active Snf1 protein kinase in high glucose prevents degradation of Mth1 and Std1.
Mesh Terms:
Adaptor Proteins, Signal Transducing, Binding Sites, Casein Kinase I, Enzyme Activation, F-Box Proteins, Gene Expression Regulation, Fungal, Glucose, Intracellular Signaling Peptides and Proteins, Lysine, Membrane Proteins, Monosaccharide Transport Proteins, Phosphorylation, Protein Isoforms, Protein Processing, Post-Translational, Protein-Serine-Threonine Kinases, SKP Cullin F-Box Protein Ligases, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Ubiquitin, Ubiquitin-Protein Ligases
FEBS Lett.
Date: Jul. 10, 2007
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