Project description:PUF proteins have become a leading scaffold for designing RNA-binding proteins to contact and control RNAs at will. We analyze the effects of that reengineering across the transcriptome in vivo for the first time. We show, by HITS-CLIP and PAR-CLIP, that S. cerevisiae Puf2p, a non-canonical PUF protein, binds more than 1000 mRNA targets. Puf2p binds multiple UAAU elements, unlike canonical PUF proteins. We also perform CLIP-seq on truncations of Puf2p, showing that its prion domain is dispensable for WT binding. We design a modified Puf2p to bind UAAG rather than UAAU, which allows us to align the protein with the binding site. In vivo, the redesigned protein binds UAAG sites. Its altered specificity redistributes the protein away from 3âUTRs, such that the protein tracks with its sites and binds throughout the mRNA. We use RNA-seq to determine that R1 SNE Puf2p represses a novel RNA network. CLIP-seq was performed in BY4742 S. cerevisiae grown in log phase, and using 2 replicates of TAP-tagged proteins. RNA-seq was performed to determine the regulatory effect of WT or mutant Puf2p, using 4 replicates of the control (no Puf2p), 3 of WT Puf2p and 4 of R1 SNE Puf2p.
Project description:PUF proteins have become a leading scaffold for designing RNA-binding proteins to contact and control RNAs at will. We analyze the effects of that reengineering across the transcriptome in vivo for the first time. We show, by HITS-CLIP and PAR-CLIP, that S. cerevisiae Puf2p, a non-canonical PUF protein, binds more than 1000 mRNA targets. Puf2p binds multiple UAAU elements, unlike canonical PUF proteins. We also perform CLIP-seq on truncations of the Puf2p, showing that its prion domain is dispensable for WT binding. We design a modified Puf2p to bind UAAG rather than UAAU, which allows us to align the protein with the binding site. In vivo, the redesigned protein binds UAAG sites. Its altered specificity redistributes the protein away from 3âUTRs, such that the protein tracks with its sites, binds throughout the mRNA. We use RNA-seq to determine that R1 SNE Puf2p represses a novel RNA network. CLIP-seq was performed in BY4742 S. cerevisiae grown in log phase, and using 2 replicates of TAP-tagged proteins.
Project description:PUF proteins have become a leading scaffold for designing RNA-binding proteins to contact and control RNAs at will. We analyze the effects of that reengineering across the transcriptome in vivo for the first time. We show, by HITS-CLIP and PAR-CLIP, that S. cerevisiae Puf2p, a non-canonical PUF protein, binds more than 1000 mRNA targets. Puf2p binds multiple UAAU elements, unlike canonical PUF proteins. We also perform CLIP-seq on truncations of Puf2p, showing that its prion domain is dispensable for WT binding. We design a modified Puf2p to bind UAAG rather than UAAU, which allows us to align the protein with the binding site. In vivo, the redesigned protein binds UAAG sites. Its altered specificity redistributes the protein away from 3’UTRs, such that the protein tracks with its sites and binds throughout the mRNA. We use RNA-seq to determine that R1 SNE Puf2p represses a novel RNA network.
Project description:PUF proteins have become a leading scaffold for designing RNA-binding proteins to contact and control RNAs at will. We analyze the effects of that reengineering across the transcriptome in vivo for the first time. We show, by HITS-CLIP and PAR-CLIP, that S. cerevisiae Puf2p, a non-canonical PUF protein, binds more than 1000 mRNA targets. Puf2p binds multiple UAAU elements, unlike canonical PUF proteins. We also perform CLIP-seq on truncations of the Puf2p, showing that its prion domain is dispensable for WT binding. We design a modified Puf2p to bind UAAG rather than UAAU, which allows us to align the protein with the binding site. In vivo, the redesigned protein binds UAAG sites. Its altered specificity redistributes the protein away from 3’UTRs, such that the protein tracks with its sites, binds throughout the mRNA. We use RNA-seq to determine that R1 SNE Puf2p represses a novel RNA network.
Project description:Transcription factors (TFs) play a central role in regulating gene expression by interacting with cis regulatory DNA elements associated with their target genes. Recent surveys have examined the DNA binding specificities of most Saccharomyces cerevisiae transcription factors but a comprehensive evaluation of their data has been lacking. Results: We analyzed in vitro and in vivo TF-DNA binding data reported in previous large-scale studies to generate a comprehensive, curated resource of DNA binding specificity data for all characterized S. cerevisiae transcription factors. Our collection comprises DNA binding site motifs and comprehensive in vitro DNA binding specificity data for all possible 8 bp sequences. Included in this database is DNA binding specificity data for 27 TFs independently generated by PBM analysis in this current study. Investigation of the DNA binding specificities within the basic leucine zipper (bZIP) and VHR transcription factor families revealed unexpected plasticity in TF-DNA recognition: intriguingly, the VHR transcription factors, newly characterized by protein binding microarrays in this study, recognize bZIP like DNA motifs, while the bZIP transcription factor Hac1 recognizes a motif highly similar to the canonical E-box motif of basic helix-loop-helix (bHLH) transcription factors. We identified several transcription factors with distinct primary and secondary motifs, which might be associated with different regulatory functions. Finally, integrated analysis of in vivo transcription factor binding data with protein binding microarray data lends further support for indirect DNA binding in vivo by sequence-specific transcription factors.
Project description:Transcription factors (TFs) play a central role in regulating gene expression by interacting with cis regulatory DNA elements associated with their target genes. Recent surveys have examined the DNA binding specificities of most Saccharomyces cerevisiae transcription factors but a comprehensive evaluation of their data has been lacking. Results: We analyzed in vitro and in vivo TF-DNA binding data reported in previous large-scale studies to generate a comprehensive, curated resource of DNA binding specificity data for all characterized S. cerevisiae transcription factors. Our collection comprises DNA binding site motifs and comprehensive in vitro DNA binding specificity data for all possible 8 bp sequences. Included in this database is DNA binding specificity data for 27 TFs independently generated by PBM analysis in this current study. Investigation of the DNA binding specificities within the basic leucine zipper (bZIP) and VHR transcription factor families revealed unexpected plasticity in TF-DNA recognition: intriguingly, the VHR transcription factors, newly characterized by protein binding microarrays in this study, recognize bZIP like DNA motifs, while the bZIP transcription factor Hac1 recognizes a motif highly similar to the canonical E-box motif of basic helix-loop-helix (bHLH) transcription factors. We identified several transcription factors with distinct primary and secondary motifs, which might be associated with different regulatory functions. Finally, integrated analysis of in vivo transcription factor binding data with protein binding microarray data lends further support for indirect DNA binding in vivo by sequence-specific transcription factors. 27 Protein binding microarray (PBM) experiments of Saccharomyces cerevisiae transcription factors were performed. Briefly, the PBMs involved binding GST-tagged yeast transcription factors to double-stranded 44K Agilent microarrays in order to determine their sequence preferences. The method is described in Berger et al., Nature Biotechnology 2006 (PMID 16998473). A key feature is that the microarrays are composed of de Bruijn sequences that contain each 10-base sequence once and only once, providing an evenly balanced sequence distribution. Individual de Bruijn sequences have different properties, including representation of gapped patterns. The array probe sequences on the custom array design used in this study were reported previously in Berger et al., Cell 2008 (PMID 18585359) and are available via an academic research use license. Here we provide the data transformed into median signal intensities (after normalization and detrending of the original array data) for all 32,896 8-base sequences, Z-scores for these intensities, and E-scores. E-scores are a modified version of AUC and describe how well each 8-mer ranks the intensities of the spots. In general, the E-scores are slightly more reproducible than Z-scores, but contain less information about relative binding affinity. Additional experimental details are found in Berger et al., Nature Biotechnology 2006, Gordan et al., Genome Biology (in press), and the accompanying Supplementary information.
Project description:The type II nuclear receptors (NRs) function as heterodimeric transcription factors with the retinoid X receptor (RXR) to regulate diverse biological processes in response to endogenous ligands and therapeutic drugs. DNA-binding specificity has been proposed as a primary mechanism for NR gene regulatory specificity. We use protein-binding microarrays (PBMs) to comprehensively analyze the DNA binding of 12 NR:RXRα heterodimers. We find more promiscuous NR-DNA binding than has been reported, challenging the view that NR binding specificity is defined by half-site spacing. We show that NRs bind DNA using two distinct modes, explaining widespread NR binding to half-sites in vivo. Finally, we show that the current models of NR specificity better reflect binding-site activity rather than binding-site affinity. Our rich dataset and revised NR binding models provide a framework for understanding NR regulatory specificity and will facilitate more accurate analyses of genomic datasets.
Project description:Floral organ identities in plants are specified by the combinatorial action of homeotic master regulatory transcription factors (TFs). How these factors achieve their regulatory specificities is however still largely unclear. Genome-wide in vivo DNA binding data show that homeotic MADS-domain proteins recognize partly distinct genomic regions, suggesting that DNA binding specificity contributes to functional differences of homeotic protein complexes. We used in vitro systematic evolution of ligands by exponential enrichment followed by high throughput DNA sequencing (SELEX-seq) on several floral MADS-domain protein homo- and heterodimers to measure their DNA-binding specificities. We show that specification of reproductive organs is associated with distinct binding preferences of a complex formed by SEPALLATA3 (SEP3) and AGAMOUS (AG). Binding specificity is further modulated by different binding site (BS) spacing preferences. Combination of SELEX-seq and genome-wide DNA binding data allows to differentiate between targets in specification of reproductive versus perianth organs in the flower. We validate the importance of DNA-binding specificity for organ-specific gene regulation by modulating promoter activity through targeted mutagenesis. Our study shows that intrafamily protein interactions affect DNA-binding specificity of floral MADS-domain proteins. DNA-binding specificity of individual dimers, as well as DNA-binding preferences of higher-order complexes differ between floral homeotic protein complexes. Differential DNA-binding of MADS-domain protein complexes plays a role in the specificity of target gene regulation.