Repression and Activation Domains of Rme1p Structurally Overlap, but Differ in Genetic Requirements

Columbia University, New York, New York, United States
Molecular Biology of the Cell (Impact Factor: 4.47). 06/2002; 13(5):1709-21. DOI: 10.1091/mbc.01-09-0468
Source: PubMed


Rme1p, a repressor of meiosis in the yeast Saccharomyces cerevisiae, acts as both a transcriptional repressor and activator. Rme1p is a zinc-finger protein with no other homology to any protein of known function. The C-terminal DNA binding domain of Rme1p is essential for function. We find that mutations and progressive deletions in all three zinc fingers can be rescued by fusion of RME1 to the DNA binding domain of another protein. Thus, structural integrity of the zinc fingers is not required for the Rme1p-mediated effects on transcription. Using a series of mutant Rme1 proteins, we have characterized domains responsible for repression and activation. We find that the minimal transcriptional repression and activation domains completely overlap and lie in an 88-amino-acid N-terminal segment (aa 61-148). An additional transcriptional effector determinant lies in the first 31 amino acids of the protein. Notwithstanding the complete overlap between repression and activation domains of Rme1p, we demonstrated a functional difference between repression and activation: Rgr1p and Sin4p are absolutely required for repression but dispensable for activation.

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Available from: Anna Blumental-Perry
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    • "Ash1 similarly has both repressive and activating functions (Chandarlapaty and Errede 1998; Maxon and Herskowitz 2001). The Rme1 repressor is unusual in that it has overlapping repression and activation domains and no apparent requirement for specific DNA binding (Blumental-Perry et al. 2002). All known TRs recruit complexes that maintain chromatin in a generally repressive state that may inhibit the binding of an activator and the recruitment of coactivators and prevent chromatin remodeling or block a subsequent step in transcription. "
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    • "The repressor binds directly to two sites within the IME1 promoter and modifies chromatin structure to prevent the binding of transcriptional activators (Schimizu et al., 1997). Rme1p also interacts with two subunits of the RNA polymerase II Mediator Complex, Rgr1p and Sin4p, which maintain a repressive chromatin structure at the IME1 promoter (Blumental-Perry et al., 2002). In haploid yeast cells and in artificially created diploids of inappropriate mating type, e.g., MATα/MATα, RME1 is expressed constitutively at a high level. "
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    • "Additional data suggest that Rme1p interacts with the yeast Mediator complex, 1999a,b, 2003; Rupp et al. 1999; Pan and Heitman 2000; Kö hler et al. 2002). required for various aspects of transcriptional regulation , and in particular with the subunits Rgr1p and Here we show that RME1 acts as a central switch between nutrient-induced cellular differentiation path- Sin4p (Blumental-Perry et al. 2002). "
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