title: Regulation of Polycomb group complexes by the sequence-specific DNA binding proteins Zeste and GAGA.
abstract: Repression and activation of the expression of homeotic genes are maintained by proteins encoded by the Polycomb group (PcG) and trithorax group (trxG) genes. Complexes formed by these proteins are targeted by PcG or trxG response elements (PREs/TREs), which share binding sites for several of the same factors. GAGA factor and Zeste bind specifically to PREs/TREs and have been shown to act as both activators and repressors. We have used purified proteins and complexes reconstituted from recombinant subunits to characterize the effects of GAGA and Zeste proteins on PcG function using a defined in vitro system. Zeste directly associates with the PRC1 core complex (PCC) and enhances the inhibitory activity of this complex on all templates, with a preference for templates with Zeste binding sites. GAGA does not stably associate with PCC, but nucleosomal templates bound by GAGA are more efficiently bound and more efficiently inhibited by PCC. Thus Zeste and GAGA factor use distinct means to increase repression mediated by PRC1.
authors: Department of Molecular Biology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
authors: Niveen M
authors: NM
authors: Mulholland
authors: Ian F G
authors: IF
authors: King
authors: Robert E
authors: RE
authors: Kingston
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D063150:Polycomb Repressive Complex 1; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D012097:Repressor Proteins / Q000235:genetics; D020218:Response Elements / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D002843:Chromatin; D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; C066770:Pc protein, Drosophila; D012097:Repressor Proteins; D014157:Transcription Factors; C063460:Trl protein, Drosophila; C060849:z protein, Drosophila; D063150:Polycomb Repressive Complex 1