title: Efficient and specific targeting of Polycomb group proteins requires cooperative interaction between Grainyhead and Pleiohomeotic.
abstract: Specific targeting of the protein complexes formed by the Polycomb group of proteins is critically required to maintain the inactive state of a group of developmentally regulated genes. Although the role of DNA binding proteins in this process has been well established, it is still not understood how these proteins target the Polycomb complexes specifically to their response elements. Here we show that the grainyhead gene, which encodes a DNA binding protein, interacts with one such Polycomb response element of the bithorax complex. Grainyhead binds to this element in vitro. Moreover, grainyhead interacts genetically with pleiohomeotic in a transgene-based, pairing-dependent silencing assay. Grainyhead also interacts with Pleiohomeotic in vitro, which facilitates the binding of both proteins to their respective target DNAs. Such interactions between two DNA binding proteins could provide the basis for the cooperative assembly of a nucleoprotein complex formed in vitro. Based on these results and the available data, we propose that the role of DNA binding proteins in Polycomb group-dependent silencing could be described by a model very similar to that of an enhanceosome, wherein the unique arrangement of protein-protein interaction modules exposed by the cooperatively interacting DNA binding proteins provides targeting specificity.
authors.affiliation: Hungarian Academy of Sciences, Biological Research Center, Institute of Genetics, Temesvari krt. 62, P.O.B. 521, H-6701 Szeged, Hungary. blastyak@nucleus.szbk.u-szeged.hu
authors.forename: András
authors.initials: A
authors.lastname: Blastyák
authors.forename: Rakesh K
authors.initials: RK
authors.lastname: Mishra
authors.forename: Francois
authors.initials: F
authors.lastname: Karch
authors.forename: Henrik
authors.initials: H
authors.lastname: Gyurkovics
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism*; D029721:Drosophila Proteins / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D018507:Gene Expression Regulation, Developmental; D020868:Gene Silencing; D017344:Genes, Insect; D008297:Male; D008954:Models, Biological; D008969:Molecular Sequence Data; D063150:Polycomb Repressive Complex 1; D063146:Polycomb-Group Proteins; D011485:Protein Binding; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C066770:Pc protein, Drosophila; D063146:Polycomb-Group Proteins; D014157:Transcription Factors; C062330:grh protein, Drosophila; C113295:pho protein, Drosophila; D004247:DNA; D063150:Polycomb Repressive Complex 1