Project description:Cys2-His2 zinc finger proteins (ZFPs) are the largest group of transcription factors in higher metazoans. A complete characterization of these ZFPs and their associated target sequences is pivotal to fully annotate transcriptional regulatory networks in metazoan genomes. As a first step in this process, we have characterized the DNA-binding specificities of 130 Zinc finger sets from Drosophila melanogaster using a bacterial one-hybrid system. This data set contains the DNA-binding specificities for at least one encoded ZFP from 71 unique genes and 22 alternate splice isoforms. This represents the largest block of characterized ZFPs from any organism described to date. These recognition motifs can be used to predict genomic binding sites and potential regulatory targets for these factors within the fruit fly genome. We have characterized subsets of fingers from these ZFPs to define the correct orientation and register of the zinc fingers on their defined binding sites. By correlating individual fingers with motif subsites, we can assign finger specificity throughout each ZFP. This reveals the diversity of recognition potential within the naturally-occurring zinc fingers of a single organism, where the characterized fingers can specify 47 of the 64 possible DNA triplets. To confirm the utility of our finger recognition models, we have employed subsets of Drosophila fingers in combination with an existing archive of zinc finger modules to create ZFPs with novel DNA-binding specificity. These finger combinations can be used to create novel functional Zinc Finger Nucleases for editing vertebrate genomes. Illumina sequencing of Barcoded Binding sites obtained after B1H selection of Cys2-His2 zinc finger proteins cloned as a C-terminal fusions to the omega subunit of E. coli RNA polymerase in the B1H system.
Project description:Cys2-His2 zinc finger proteins (ZFPs) are the largest group of transcription factors in higher metazoans. A complete characterization of these ZFPs and their associated target sequences is pivotal to fully annotate transcriptional regulatory networks in metazoan genomes. As a first step in this process, we have characterized the DNA-binding specificities of 130 Zinc finger sets from Drosophila melanogaster using a bacterial one-hybrid system. This data set contains the DNA-binding specificities for at least one encoded ZFP from 71 unique genes and 22 alternate splice isoforms. This represents the largest block of characterized ZFPs from any organism described to date. These recognition motifs can be used to predict genomic binding sites and potential regulatory targets for these factors within the fruit fly genome. We have characterized subsets of fingers from these ZFPs to define the correct orientation and register of the zinc fingers on their defined binding sites. By correlating individual fingers with motif subsites, we can assign finger specificity throughout each ZFP. This reveals the diversity of recognition potential within the naturally-occurring zinc fingers of a single organism, where the characterized fingers can specify 47 of the 64 possible DNA triplets. To confirm the utility of our finger recognition models, we have employed subsets of Drosophila fingers in combination with an existing archive of zinc finger modules to create ZFPs with novel DNA-binding specificity. These finger combinations can be used to create novel functional Zinc Finger Nucleases for editing vertebrate genomes.
Project description:Histone H3K4 monomethyltransferases MLL3 and MLL4 contain a set of uncharacterized PHD fingers. By structural and biochemical assays, we found a novel function of the PHD2 and PHD3 (PHD2/3) fingers of MLL3 and MLL4, revealing their direct binding to the conserved MBH (MLL binding helix) region of ASXL1/2, components of the Polycomb repressive PR-DUB complex. In mouse embryonic stem cells, we observed that BAP1, the catalytic subunit of the PR-DUB complex, physically interacts with MLL4 in an ASXL1/2 MBH-dependent manner. Genomic studies demonstrate that the ASXL1/2 MBH is required for BAP1 binding on active enhancers and suggest that MLL4 facilitates BAP1 binding on active enhancers through ASXL1/2 MBH.
Project description:The C2H2 zinc finger is the most prevalent DNA-binding motif in the mammalian proteome, with DNA-binding domains usually containing more tandem fingers than are needed for stable sequence-specific DNA recognition. To examine the reason for the frequent presence of multiple zinc fingers, we generated mice lacking finger 1 or finger 4 of the 4-finger DNA-binding domain of Ikaros, a critical regulator of lymphopoiesis and leukemogenesis. Each mutant strain exhibited a specific subset of the phenotypes observed with Ikaros null mice. Of particular relevance, fingers 1 and 4 contributed to distinct stages of B- and T-cell development and finger 4 was selectively required for tumor suppression in thymocytes and in a new model of BCR-ABL+ acute lymphoblastic leukemia. These results, combined with transcriptome profiling (this GEO submission: RNA-Seg of whole thymus from wt and the two ZnF mutants), reveal that different subsets of fingers within multi-finger transcription factors can regulate distinct target genes and biological functions, and they demonstrate that selective mutagenesis can facilitate efforts to elucidate the functions and mechanisms of action of this prevalent class of factors. Ikaros ChIP-Seq from Whole Thymus comparing wt, Ikaros-ZnF1-/- mutant and Ikaros-ZnF4-/- mutant
Project description:Analyses of new genomic, transcriptomic or proteomic data commonly result in trashing many unidentified data escaping the ‘canonical’ DNA-RNA-protein scheme. Testing systematic exchanges of nucleotides over long stretches produces inversed RNA pieces (here named “swinger” RNA) differing from their template DNA. These may explain some trashed data. Here analyses of genomic, transcriptomic and proteomic data of the pathogenic Tropheryma whipplei according to canonical genomic, transcriptomic and translational 'rules' resulted in trashing 58.9% of DNA, 37.7% RNA and about 85% of mass spectra (corresponding to peptides). In the trash, we found numerous DNA/RNA fragments compatible with “swinger” polymerization. Genomic sequences covered by «swinger» DNA and RNA are 3X more frequent than expected by chance and explained 12.4 and 20.8% of the rejected DNA and RNA sequences, respectively. As for peptides, several match with “swinger” RNAs, including some chimera, translated from both regular, and «swinger» transcripts, notably for ribosomal RNAs. Congruence of DNA, RNA and peptides resulting from the same swinging process suggest that systematic nucleotide exchanges increase coding potential, and may add to evolutionary diversification of bacterial populations.