PMID:24490134

Citation	Roy, A, Jouandot, D 2nd, Cho, KH and Kim, JH (2014) Understanding the mechanism of glucose-induced relief of Rgt1-mediated repression in yeast. FEBS Open Bio 4:105-11
Abstract	The yeast Rgt1 repressor inhibits transcription of the glucose transporter (HXT) genes in the absence of glucose. It does so by recruiting the general corepressor complex Ssn6-Tup1 and the HXT corepressor Mth1. In the presence of glucose, Rgt1 is phosphorylated by the cAMP-activated protein kinase A (PKA) and dissociates from the HXT promoters, resulting in expression of HXT genes. In this study, using Rgt1 chimeras that bind DNA constitutively, we investigate how glucose regulates Rgt1 function. Our results show that the DNA-bound Rgt1 constructs repress expression of the HXT1 gene in conjunction with Ssn6-Tup1 and Mth1, and that this repression is lifted when they dissociate from Ssn6-Tup1 in high glucose conditions. Mth1 mediates the interaction between the Rgt1 constructs and Ssn6-Tup1, and glucose-induced downregulation of Mth1 enables PKA to phosphorylate the Rgt1 constructs. This phosphorylation induces dissociation of Ssn6-Tup1 from the DNA-bound Rgt1 constructs, resulting in derepression of HXT gene expression. Therefore, Rgt1 removal from DNA occurs in response to glucose but is not necessary for glucose induction of HXT gene expression, suggesting that glucose regulates Rgt1 function by primarily modulating the Rgt1 interaction with Ssn6-Tup1.
Links	PubMed PMC3907687 Online version:10.1016/j.fob.2013.12.004
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
YEAST:RGT1	enables	GO:0001227: DNA-binding transcription repressor activity, RNA polymerase II-specific	ECO:0000314: direct assay evidence used in manual assertion		F	occurs_at:(SO:0001952)	Seeded From UniProt	complete
YEAST:RGT1		GO:0030528: transcription regulator activity	ECO:0000314:		F		Figure 3: Consistently, LexA-Rgt1 (5SA) was shown to inhibit glucose-induced expression of the reporter gene. These results suggest that the function of the LexA-Rgt1 repressor, bound to the HXT promoters constitutively, is critically regulated by its phosphorylation state.	complete CACAO 10050
YEAST:RGT1		GO:0001227: DNA-binding transcription repressor activity, RNA polymerase II-specific	ECO:0000314: direct assay evidence used in manual assertion		F		Figure 1E: The reporter strains expressing the Rgt1 fusions were shown to grow only in glucose-containing medium (Fig. 1E), suggesting that the Rgt1 constructs repress expression of the HXT1 promoter in the absence of glucose but negatively regulated by glucose.	complete CACAO 10051

References

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