Mediator as a general transcription factor.
Others have shown that yeast strains bearing a ts mutation in the Srb4 subunit of Mediator cease transcription of all mRNA at the restrictive temperature, in a manner virtually indistinguishable from a strain bearing a ts mutation in the largest subunit of RNA polymerase II. We find that srb4ts Mediator is defective for the stimulation of basal RNA polymerase II transcription at the restrictive temperature in vitro. Taken together, these findings lead to the suggestion that Mediator is required for basal RNA polymerase II transcription in vivo. On this basis, Mediator is identified as a general transcription factor, comparable in importance to RNA polymerase II and other general factors for the initiation of transcription. The possibility that Mediator serves as an anti-inhibitor, opposing the effects of global negative regulators, is largely excluded.
Pubmed ID: 16263706 RIS Download
Gene Expression Regulation, Fungal | Mediator Complex | Mutagenesis | Phenotype | RNA Polymerase II | Saccharomyces cerevisiae | Saccharomyces cerevisiae Proteins | Temperature | Transcription Factors | Transcription, Genetic