Regulated nuclear translocation of the Mig1 glucose repressor.

Abstract

Glucose represses the transcription of many genes in bakers yeast (Saccharomyces cerevisiae). Mig1 is a Cys2-His2 zinc finger protein that mediates glucose repression of several genes by binding to their promoters and recruiting the general repression complex Ssn6-Tup1. We have found that the subcellular localization of Mig1 is regulated by glucose. Mig1 is imported into the nucleus within minutes after the addition of glucose and is just as rapidly transported back to the cytoplasm when glucose is removed. This regulated nuclear localization requires components of the glucose repression signal transduction pathway. An internal region of the protein separate from the DNA binding and repression domains is necessary and sufficient for glucose-regulated nuclear import and export. Changes in the phosphorylation status of Mig1 are coincident with the changes in its localization, suggesting a possible regulatory role for phosphorylation. Our results suggest that a glucose-regulated nuclear import and/or export mechanism controls the activity of Mig1.

Negative control of the Mig1p repressor by Snf1p‐dependent phosphorylation in the absence of glucose

“…The samples were treated for 1 h at 37°C with 20 U calf intes-ity [21], nuclear transport of a GFP-Mig1 fusion is not dependent on its presence [22]. In addition to the basic residues, the tine phosphatase (Boehringer) in the presence or absence of 100 mM sodium phosphate.…”

“…Thus, it creates an more constitutive activator, which is only regulated threefold by Snf1p. The ALS domain seems to a GFP-Mig1 fusion protein [22]. The two motifs at Ser278 and Ser311 that match the known target site for Snf1p [17] are pre-have a general inhibitory effect on Mig1-VP16 activity, since deleting it causes a 60% increase in activity, even in the triple sent within the overlapping region, consistent with the notion that carbon-source control of Mig1p activity is mediated by point mutant, an effect which is independent of the carbon source and Snf1p (compare constructs 6 and 12; Fig.…”

“…A key effector in glucose of a Mig1-GFP (green fluorescent protein) fusion is regulated repression is the zinc-finger protein Mig1p [5, 6]. Mig1p binds by the carbon source and that this regulation requires a region to the sequence SYGGRG (where Y is C or T, and R is G or that largely overlaps with the R1 domain [22]. Moreover, the A), which is present in glucose-repressed promoters [7], and it protein is constitutively found in the nucleus in a snf1 ssn6 is thought that it recruits the general corepressor complex to double mutant, suggesting that Snf1p-dependent control of the target promoter [8].…”

“…Moreover, the A), which is present in glucose-repressed promoters [7], and it protein is constitutively found in the nucleus in a snf1 ssn6 is thought that it recruits the general corepressor complex to double mutant, suggesting that Snf1p-dependent control of the target promoter [8]. The corepressor complex contains two Mig1p activity may involve the same mechanism [22]. subunits, Tup1 and Cyc8p (or Ssn6p), and it is the Tup1p subunit…”

Transcription factors in eukaryotic cells can functionally regulate gene expression by acting in oligomeric assemblies formed from an intrinsically disordered protein phase transition enabled by molecular crowding

“…Here, control of gene expression is achieved by TFs which include the Zn finger DNA binding protein Mig1 [18] that acts to repress expression from targets including GAL genes involved in glucose metabolism [19]. Mig1 localizes towards the nucleus if the extracellular glucose concentration is increased [20], correlated to its own dephosphorylation by a protein called Snf1 [21,22]. …”