The world's first wiki where authorship really matters (Nature Genetics, 2008). Due credit and reputation for authors. Imagine a global collaborative knowledge base for original thoughts. Search thousands of articles and collaborate with scientists around the globe.

wikigene or wiki gene protein drug chemical gene disease author authorship tracking collaborative publishing evolutionary knowledge reputation system wiki2.0 global collaboration genes proteins drugs chemicals diseases compound
Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

Activator Gcn4p and Cyc8p/Tup1p are interdependent for promoter occupancy at ARG1 in vivo.

The Cyc8p/Tup1p complex mediates repression of diverse genes in Saccharomyces cerevisiae and is recruited by DNA binding proteins specific for the different sets of repressed genes. By screening the yeast deletion library, we identified Cyc8p as a coactivator for Gcn4p, a transcriptional activator of amino acid biosynthetic genes. Deletion of CYC8 confers sensitivity to an inhibitor of isoleucine/valine biosynthesis and impairs activation of Gcn4p-dependent reporters and authentic amino acid biosynthetic target genes. Deletion of TUP1 produces similar but less severe activation defects in vivo. Although expression of Gcn4p is unaffected by deletion of CYC8, chromatin immunoprecipitation assays reveal a strong defect in binding of Gcn4p at the target genes ARG1 and ARG4 in cyc8Delta cells and to a lesser extent in tup1Delta cells. The defects in Gcn4p binding and transcriptional activation in cyc8Delta cells cannot be overcome by Gcn4p overexpression but are partially suppressed in tup1Delta cells. The impairment of Gcn4p binding in cyc8Delta and tup1Delta cells is severe enough to reduce recruitment of SAGA, Srb mediator, TATA binding protein, and RNA polymerase II to the ARG1 and ARG4 promoters, accounting for impaired transcriptional activation of these genes in both mutants. Cyc8p and Tup1p are recruited to the ARG1 and ARG4 promoters, consistent with a direct role for this complex in stimulating Gcn4p occupancy of the upstream activation sequence (UAS). Interestingly, Gcn4p also stimulates binding of Cyc8p/Tup1p at the 3' ends of these genes, raising the possibility that Cyc8p/Tup1p influences transcription elongation. Our findings reveal a novel coactivator function for Cyc8p/Tup1p at the level of activator binding and suggest that Gcn4p may enhance its own binding to the UAS by recruiting Cyc8p/Tup1p.[1]


  1. Activator Gcn4p and Cyc8p/Tup1p are interdependent for promoter occupancy at ARG1 in vivo. Kim, S.J., Swanson, M.J., Qiu, H., Govind, C.K., Hinnebusch, A.G. Mol. Cell. Biol. (2005) [Pubmed]
WikiGenes - Universities