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- Title
How the Rgt1 Transcription Factor of Saccharomyces cerevisiae Is Regulated by Glucose.
- Authors
Jeffrey A. Polish; Jeong-Ho Kim; Johnston, Mark
- Abstract
Rgtl is a transcription factor that regulates expression of HXT genes encoding glucose transporters in the yeast Saccharomyces cerevisiae. Rgtl represses HXT gene expression in the absence of glucose; high levels of glucose cause Rgtl to activate expression of HXT1. We identified four functional domains of Rgtl. A domain required for transcriptional repression (amino acids 210–250) is required for interaction of Rgtl with the Ssn6 corepressor. Another region of Rgtl (320–380) is required for normal transcriptional activation, and sequences flanking this region (310–320 and 400–410) regulate this function. A central region (520–830) and a short sequence adjacent to the zinc cluster DNA-binding domain (80–90) inhibit transcriptional repression when glucose is present. We found that this middle region of Rgtl physically interacts with the N-terminal portion of the protein that includes the DNA-binding domain. This interaction is inhibited by the Rgtl regulator Mthl, which binds to Rgtl. Our results suggest that Mthl promotes transcriptional repression by Rgtl by binding to it and preventing the intramolecular interaction, probably by preventing phosphorylation of Rgtl, thereby enabling Rgtl to bind to DNA. Glucose induces HXT1 gene expression by causing Mth1 degradation, allowing Rgtl phosphorylation, and leading to the intramolecular interaction that inhibits DNA binding of Rgtl.
- Publication
Genetics, 2005, Vol 169, Issue 2, p583
- ISSN
0016-6731
- Publication type
Academic Journal
- DOI
10.1534/genetics.104.034512