Project description:Metriaclima estherae, Protomelas similis, Rhamphochromis "chilingali", and Astatotilapia tweddlei genomic DNA hybridized with Astatotilapia burtoni genomic DNA
Project description:Metriaclima estherae, Protomelas similis, Rhamphochromis "chilingali", and Astatotilapia tweddlei genomic DNA hybridized with Astatotilapia burtoni genomic DNA 2 Metriaclima estherae vs Astatotilapia burtoni, 2 Protomelas similis vs Astatotilapia burtoni, 2 Rhamphochromis "chilingali" vs Astatotilapia burtoni, and 2 Astatotilapia tweddlei vs Astatotilapia burtoni hybs, all in balanced dye swaps
Project description:Mediator (MED) is a conserved factor with important roles in basal and activated transcription. Here, we investigate the genome-wide roles of yeast MED by rapid depletion of its activator-binding domain (Tail) and monitoring changes in nascent transcription. Rapid Tail depletion surprisingly reduces transcription from only a small subset of genes. At most of these Tail-dependent genes, in unperturbed conditions, MED is detected at both the UASs and promoters. In contrast, at most Tail-independent genes, we find MED primarily at promoters but not at the UASs. These results suggest that MED Tail and activator-mediated MED recruitment regulate only a small subset of genes. Further, we define three classes of genes that differ in PIC assembly pathways and the requirements for MED Tail, SAGA, TFIID and BET factors Bdf1/2. Our combined results have broad implications for the roles of MED, other coactivators, and mechanisms of transcriptional regulation at different gene classes.
Project description:Mediator (MED) is a conserved factor with important roles in basal and activated transcription. Here, we investigate the genome-wide roles of yeast MED by rapid depletion of its activator-binding domain (Tail) and monitoring changes in nascent transcription. Rapid Tail depletion surprisingly reduces transcription from only a small subset of genes. At most of these Tail-dependent genes, in unperturbed conditions, MED is detected at both the UASs and promoters. In contrast, at most Tail-independent genes, we find MED primarily at promoters but not at the UASs. These results suggest that MED Tail and activator-mediated MED recruitment regulate only a small subset of genes. Further, we define three classes of genes that differ in PIC assembly pathways and the requirements for MED Tail, SAGA, TFIID and BET factors Bdf1/2. Our combined results have broad implications for the roles of MED, other coactivators, and mechanisms of transcriptional regulation at different gene classes.
Project description:Mediator is a highly conserved transcriptional coactivator organized into four modules, namely Tail, Middle, Head and Kinase (CKM). Previous work suggests regulatory roles for Tail and CKM, but an integrated model for these activities is lacking. Here, we analyzed the genome-wide distribution of Mediator subunits in wild-type and mutant yeast cells in which RNA polymerase II promoter escape is blocked allowing detection of transient Mediator forms. We found that while all modules are recruited to upstream activated regions (UAS), assembly of Mediator within the pre-initiation complex is accompanied by the release of CKM. Surprisingly, our data show that CKM regulates Mediator-UAS interaction rather than Mediator-promoter association. In addition, while Tail is required for Mediator recruitment to UAS, Tail-less Mediator nevertheless interacts with core promoters. Collectively, our data suggest that the essential function of Mediator is mediated by Head and Middle at core promoters, while Tail and CKM play regulatory roles.