Srb/mediator proteins interact functionally and physically with transcriptional repressor Sfl1.
Srb/mediator proteins that are associated with RNA polymerase II holoenzyme have been implicated in transcriptional repression in Saccharomyces cerevisiae. We show here that the defect in repression of SUC2 caused by mutation of SRB8, SRB9, SRB11, SIN4 or ROX3 is suppressed by increased dosage of the SFL1 gene, and the genetic behavior of the sfl1Delta mutation provides further evidence for a functional relationship. Sfl1 acts on SUC2 through a repression site located immediately 5' to the TATA box, and Sfl1 binds this DNA sequence in vitro. Moreover, LexA-Sfl1 represses transcription of a reporter, and repression is reduced in an srb9 mutant. Finally, we show that Sfl1 co-immunoprecipitates from cell extracts with Srb9, Srb11, Sin4 and Rox3. We propose that Sfl1, when bound to its site, interacts with Srb/mediator proteins to inhibit transcription by RNA polymerase II holoenzyme.
Departments of Genetics and Development, Columbia University, 701 W. 168th St., New York, NY 10032, USA.
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D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D018844:Cyclin-Dependent Kinases; D016213:Cyclins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D018628:Gene Dosage; D015966:Gene Expression Regulation, Fungal; D017930:Genes, Reporter; D006026:Glycoside Hydrolases / Q000096:biosynthesis* / Q000235:genetics; D056892:Mediator Complex; D008957:Models, Genetic; D009154:Mutation; D011233:Precipitin Tests; D011485:Protein Binding; D012319:RNA Polymerase II / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism; D016385:TATA Box; D015534:Trans-Activators; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D043324:beta-Fructofuranosidase; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D018844:Cyclin-Dependent Kinases; D016213:Cyclins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D006026:Glycoside Hydrolases; D056892:Mediator Complex; D012319:RNA Polymerase II; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D012697:Serine Endopeptidases; D015534:Trans-Activators; D014157:Transcription Factors; D043324:beta-Fructofuranosidase; D000099160:LexA Repressor Protein; C052130:GAL4 protein, S cerevisiae; C103856:ROX3 protein, S cerevisiae; C063404:SFL1 protein, S cerevisiae; C076878:SIN4 protein, S cerevisiae; C093967:SSN2 protein, S cerevisiae; C093345:SSN8 protein, S cerevisiae