ChIP-chip of LeuO, H-NS and RNA Polymerase (RNAP) in Salmonella enterica serovar Typhimurium strain SL1344
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ABSTRACT: The LysR family transcription factor LeuO is believed to antagonize the global repressor H-NS. ChIP-on-chip analysis of LeuO, H-NS and RNAP binding to the Salmonella enterica serovar Typhimurium chromosome demonstrated a high degree of overlap between LeuO and H-NS regulated genes. Furthermore LeuO binding was associated with RNA polymerase recruitment, indicating a role for LeuO in activating transcription. Analysis of LeuO, H-NS and RNA Polymerase binding in Low-phosphate media (LPM)
Project description:The global regulator H-NS represses transcription in gram negative bacteria. Sfh is a homologue of H-NS and is encoded by plasmid pSfR27. Sfh provides a 'stealth' function that allows pSfR27 to be transmitted to a new host without disrupting the competitive fitness of the new host We used ChIP-on-chip to profile Sfh (3xFLAG-tagged) and H-NS binding sites in Salmonella Typhimurium strain SL1344 and found that Sfh provides its 'stealth' function by targeting a sub-set of H-NS bound genes that display reduced levels of H-NS occupancy with the SL1344 chromosome upon acquisition of plasmid pSfR27 Identification of Sfh binding sites in strains SL1344 (pSfR27) and SL1344 hns (pSfR27) as well as identification of H-NS binding sites in strains SL1344, SL1344 (pSfR27), and SL1344 (pSfR27) sfh
Project description:This SuperSeries is composed of the following subset Series: GSE19230: The effect of sfh deletion on Salmonella Typhimurium gene expression GSE19231: Identification of Sfh and H-NS binding sites in the Salmonella Typhimurium genome Refer to individual Series
Project description:ChIP-on-chip analysis of RNAP and RpoD binding to the Salmonella enterica serovar Typhimurium chromosome demonstrated a high degree of overlap between RNAP and RpoD binding and provided us with important insights into the global distribution of these factors. Furthermore this data was correlated with information on the location of 1873 transcription start sites identified by RNA-Seq technology, thereby providing a detailed transcriptional map of Salmonella Typhimurium. Analysis of RNAP, RNAP-Rifampicin and and RpoD binding in Luria Broth (LB)
Project description:We performed Chromatin Immunoprecipitation (ChIP) and microarray hybridization analysis of CspC binding in Salmonella Typhimurium strain SL1344 which has been genetically engineered to express a 3xFLAG tagged CspC protein. Chromatin samples were prepared from SL1344 CspC 3xFLAG grown to exponential phase (OD600nm = 0.2). CspC FLAG ChIP and mock normal mouse IgG ChIP reactions were carried out. The purified ChIP DNA samples were hybridized to SL1344 tiling microarrays.
Project description:Despite the prevalence of antisense transcripts in bacterial transcriptomes, little is known about how their synthesis is controlled. We report that a major function of the Escherichia coli termination factor Rho and its co-factor NusG is suppression of ubiquitous antisense transcription genome-wide. Rho binds C-rich unstructured nascent RNA (high C/G ratio) prior to its ATP-dependent dissociation of transcription complexes. NusG is required for efficient termination at minority subsets (~20%) of both antisense and sense Rho-dependent terminators with lower C/G ratio sequences. In contrast, a widely studied nusA deletion proposed to compromise Rho-dependent termination had no effect on antisense or sense Rho-dependent terminators in vivo. Global co-localization of the nucleoid-associated protein H-NS with Rho-dependent terminators and genetic interactions between hns and rho suggest that H-NS aids Rho in suppression of antisense transcription. The combined actions of Rho, NusG, and H-NS appear to be analogous to the Sen1-Nrd1-Nab3 and nucleosome systems that suppress antisense transcription in eukaryotes. Chromatin immunoprecipitation (ChIP) experiments were performed using antibodies against RNA polymerase (RNAP; Beta subunit) in wild-type cells or cells deleted for hns, nusG, or a partial deletion of nusA. Differentially labeled ChIP DNA and genomic DNA were competitively hybridized to an E. coli K-12 MG1655 tiling array with overlapping probes at ~12bp spacing across the entire genome. The series contains 12 datasets.
Project description:Mixed Lineage Leukemia (MLL) and its metazoan Trithorax orthologs have been linked with the epigenetic maintenance of transcriptional activity. To identify mechanisms by which MLL perpetuates active transcription in dividing cells, we investigated its role during M-phase of the cell cycle. Unlike other chromatin modifying enzymes examined, we found that MLL associates with gene promoters packaged within condensed mitotic chromosomes. Genome-wide location analysis identified a globally rearranged pattern of MLL occupancy during mitosis in a manner favoring genes that were highly transcribed during interphase. Knockdown experiments revealed that MLL retention at gene promoters during mitosis accelerates transcription reactivation following mitotic exit. MLL tethers Menin, RbBP5, and ASH2L to its occupied sites during mitosis, but is dispensable for preserving histone H3K4 methylation. These findings implicate mitotic bookmarking as a component of Trithorax-based gene regulation which may facilitate inheritance of active gene expression states during cell division. anti-MLL ChIP (antibody 456) and anti-pol2 chip (sc-899) in chromatin prepared from interphase and mitotic HeLa cells
Project description:Transcriptionally active loci are particularly prone to breakage and mounting evidence suggest that DNA Double-Strand Breaks arising in active genes are handled by a dedicated repair pathway, Transcription-Coupled DSB Repair (TC-DSBR), that entails R-loop accumulation and dissolution. Here, we uncovered a function for the Bloom RecQ DNA helicase (BLM) in TC-DSBR in human cells. BLM is recruited in a transcription dependent-manner at DSBs where it fosters resection, RAD51 binding and accurate Homologous Recombination repair. However, in an R-loop dissolution-deficient background, we found that BLM promotes cell death. We report that upon excessive R-loop accumulation, DNA synthesis is enhanced at DSBs, in a anner that depends on BLM and POLD3. Altogether our work unveils a role for BLM at DSBs in active chromatin, and highlights the toxic potential of RNA:DNA hybrids that accumulate at transcription-associated DSBs.
Project description:ENCODE ChIP/chip study using human lymphoblastoid cell line GM06990; human cervix carcinoma cell line HeLaS3; human fetal lung fibroblast cell line HFL1; human T cell line MOLT4; chimpanzee lymphoblastoid cell line PTR8; and anti Histone H3K4me1 (Abcam; ab8895); H3K4me2 (Abcam; ab7766); H3K4me3 (Abcam; ab8580); H3ac (Upstate; 06-599) and H4ac (Upstate; 06-866) antibodies. The experiment was conducted in three biological replicates (1;2;3) with up to two technical duplicates (a;b).