title: Vertebrate homologue of Drosophila GAGA factor.
abstract: Polycomb group (PcG) and trithorax group (trxG) proteins are chromatin-mediated regulators of a number of developmentally important genes including the homeotic genes. In Drosophila melanogaster, one of the trxG members, Trithorax like (Trl), encodes the essential multifunctional DNA binding protein called GAGA factor (GAF). While most of the PcG and trxG genes are conserved from flies to humans, a Trl-GAF homologue has been conspicuously missing in vertebrates. Here, we report the first identification of c-Krox/Th-POK as the vertebrate homologue of GAF on the basis of sequence similarity and comparative structural analysis. The in silico structural analysis of the zinc finger region showed preferential interaction of vertebrate GAF with GAGA sites similar to that of fly GAF. We also show by cross-immunoreactivity studies that both fly and vertebrate GAFs are highly conserved and share a high degree of structural similarity. Electrophoretic mobility shift assays show that vertebrate GAF binds to GAGA sites in vitro. Finally, in vivo studies by chromatin immunoprecipitation confirmed that vertebrate GAF binds to GAGA-rich DNA sequences present in hox clusters. Identification of vertebrate GAF and the presence of its target sites at various developmentally regulated loci, including hox complexes, highlight the evolutionarily conserved components involved in developmental mechanisms across the evolutionary lineage and answer a long-standing question of the presence of vertebrate GAF.
authors.affiliation: Centre for Cellular and Molecular Biology Council of Scientific and Industrial Research, Uppal Road, Hyderabad-500007, India.
authors.forename: Navneet Kaur
authors.initials: NK
authors.lastname: Matharu
authors.forename: Tanweer
authors.initials: T
authors.lastname: Hussain
authors.forename: Rajan
authors.initials: R
authors.lastname: Sankaranarayanan
authors.forename: Rakesh K
authors.initials: RK
authors.lastname: Mishra
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D016000:Cluster Analysis; D019295:Computational Biology; D017124:Conserved Sequence; D003429:Cross Reactions; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000276:immunology; D029721:Drosophila Proteins / Q000235:genetics / Q000276:immunology; D024202:Electrophoretic Mobility Shift Assay; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors / Q000235:genetics* / Q000276:immunology; D015027:Zebrafish / Q000235:genetics*; D029961:Zebrafish Proteins / Q000235:genetics* / Q000276:immunology; D016335:Zinc Fingers / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; D014157:Transcription Factors; C063460:Trl protein, Drosophila; D029961:Zebrafish Proteins; D004247:DNA