ChIP-exo analysis reveals novel uncharacterized transcription factors involved in the diverse regulatory functions of Escherichia coli
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PROVIDER: PRJNA670504 | ENA |
REPOSITORIES: ENA
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Project description:Bacteria regulate gene expression to adapt to changing environments through transcriptional regulatory networks (TRNs). Although extensively studied, TRNs are not fully characterized since the identity of all the transcriptional regulators that comprise a TRN are not known. Here, we experimentally evaluate 40 uncharacterized proteins in the model organism Escherichia coli K-12 MG1655, which were previously predicted to be transcription factors (TFs). First, we used myc-tagging and a multiplexed ChIP-exo assay to characterize genome-wide binding sites for these candidate TFs. We then compared those binding sites with those of RNA polymerase and sigma factors to increase the confidence in the measured DNA-binding events. Finally, we used these data to infer potential functional annotations for 13 candidate TFs. Our results revealed that these candidate TFs have a varied number of regulatory genes and are involved in E. coli’s primary cellular processes. Taken together, thes results: (1) expand the number of confirmed TFs from 249 to 276, close to the estimated total of 280 TFs in E. coli K-12 MG1655; (2) provide a roadmap for the functional characterization of the newly discovered TFs; and (3) enable the elucidation of the first comprehensive TRN in this model organism.
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Project description:Transcriptional regulation enables cells to respond to environmental changes. Yet, among the estimated 304 candidate transcription factors (TFs) in Escherichia coli K-12 MG1655, only 185 have been experimentally characterized. Here we developed an integrated workflow that contains the prediction of TFs using machine learning and comprehensive experimental validation using a suite of genome-wide experiments. Applying this workflow we: 1) computationally identified 16 candidate genes encoding uncharacterized TFs; 2) confirmed that ten of these 16 are TF candidates that showed 255 DNA binding sites; 3) found high-confidence TF-binding sequence motifs for six of the ten TFs; 4) reconstructed the regulons of the ten TFs by determining gene expression change upon deletion of each TF; and 5) further determined the regulatory roles of three TFs (YdcI, YeiE and YiaJ) to be regulating acetate metabolism, iron homeostasis under iron limited condition, and utilization of L-ascorbate, respectively. Together, these results demonstrate how the integrated workflow can be used to discover, characterize, and elucidate regulatory functions of uncharacterized TFs. This workflow can be applied to less studied bacteria for systematic discovery and characterization of their transcriptional regulatory networks.
2018-08-08 | GSE111093 | GEO
Project description:Systematic discovery of uncharacterized transcription factors in Escherichia coli K-12 MG1655 (ChIP-exo data set)
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Project description:The emerging evidences support that exosome cargo miRNAs function as important regulators in cell differentiation. Therefore, in order to figure out the mechanism that Exo-AT mediated adipogenesis, we profiled miRNAs in Exo-AT using high-throughput sequencing (miRNA-seq). After trimming low-quality reads, contaminants, adaptors, and reads smaller than 15 nt, the remaining reads were mapped to merged pre-miRNA data bases. To identify the conserved miRNAs in Exo exosomes, miRNAs were aligned to miRBase v21. 148 and 154 types of known miRNAs in Exo-ADSCs and Exo-AT, respectively, were identified in the two replicates. Among these miRNAs, 103 miRNAs were simultaneously detected in both Exo-ADSCs and Exo-AT. Compared to Exo-ADSCs, 45 conserved miRNAs were enriched (expressed ≥ 2 folds, FDR<0.05) in Exo-AT. KEGG Pathway analysis was performed for the targets of the most 20 enriched miRNAs in Exo-AT (compared with Exo-ADSCs) to determine their potential function. Data showed that pathways that regulate adipogenesis such as Wnt signaling pathway, Insulin signaling pathway, MAPK signaling pathway, TGF-ß signaling pathway were enriched significantly for targets of Exo-AT miRNAs. Furthermore, 14 of 45 enriched miRNAs in Exo-AT (31.11%, such as miR-30a-5p, miR-148a-3p) were reported to participate in regulation of adipogenesis while 8 miRNAs (17.78%, such as miR-93-5p, miR-150-3p) that negatively control osteoblastic differentiation of MSC have been described.
2018-12-01 | GSE92313 | GEO
Project description:Bacteria regulate gene expression to adapt to changing environments through transcriptional regulatory networks (TRNs). Although extensively studied, TRNs are not fully characterized since we do not know the identity of all the transcriptional regulators that comprise a TRN. Here, we experimentally evaluate 40 uncharacterized proteins in the model organisms Escherichia coli K-12 MG1655, which were previously predicted to be transcription factors (TFs). First, we used myc-tagging and a multiplexed ChIP-exo assay to characterize genome-wide binding sites for the 40 candidate TFs. Then, we compared those binding sites with those of RNA polymerase and sigma factors to increase the confidence in the measured DNA-binding events. Finally, we used these data to infer potential functional annotation for 13 candidate TFs. As a result, we characterized 570 new binding sites for 34 of 40 candidate TFs. Taken together, the study; 1) expands the number of confirmed TFs from 249 to 278, that is close to the estimated total of about 280 TFs in E. coli K-12 MG1655, 2) it provides a roadmap for functional characterization of the 34 discovered TFs, and 3) it enables the elucidation of the first comprehensive TRN.
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2021-12-23 | GSE182675 | GEO
Project description:Chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) and its ultra-high resolution cousin ChIP-exo are methods that identify where proteins bind along any genome in vivo. ChIP-exo achieves near-base pair resolution by creating exonuclease stop sites just 5’ to where formaldehyde-induced protein-DNA cross-links occur. Whereas construction of ChIP genomic libraries is straightforward and widely adopted for ChIP-seq, ChIP-exo is technically more involved which has resulted in limited adoption. Here we describe multiple ChIP-exo protocols, each with use-specific advantages and limitations. The new versions are greatly simplified through removal of multiple enzymatic steps. This is achieved in part through the use of Tn5 tagmentation and/or single-stranded DNA ligation. The result is greater library yields, lower processing time, and lower cost. A similar streamlined approach was developed for ChIP-seq, called ChIP-seq 1-step, where library construction is achieved in one-step.
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