Sequence-Targeted Nucleosome Sliding in vivo - Nucleosome Mapping
Ontology highlight
ABSTRACT:
ORGANISM(S): Saccharomyces cerevisiae
SUBMITTER: Jeffrey McKnight
PROVIDER: E-GEOD-72570 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
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Project description:The spore forming pathogen Bacillus anthracis is the etiologic agent of anthrax in humans and animals. It cycles through infected hosts as vegetative cells and is eventually introduced into the environment where it generates an endospore resistant to many harsh conditions. The endospores are subsequently ingested by the next host to begin the next cycle. Outbreaks of anthrax occur regularly worldwide in wildlife and livestock, and the potential for human infection exists whenever humans encounter infected animals. It is also possible to encounter intentional releases of anthrax spores, as was the case in October 2001. Consequently, it is important to be able to rapidly establish the provenance of infectious strains of B. anthracis. Here, we compare protein expression in seven low-passage wild isolates and four laboratory strains of B. anthracis grown under identical conditions using LC-MS/MS proteomic analysis. Of the 1,023 total identified proteins, 96 had significant abundance differences between wild and laboratory strains. Of those, 28 proteins directly related to sporulation were upregulated in wild isolates, with expression driven by Spo0A, CodY, and AbrB/ScoC. In addition, we observed evidence of changes in cell division and fatty acid biosynthesis between the two classes of strains, despite being grown under identical experimental conditions. These results suggest wild B. anthracis cells are more highly tuned to sporulate than their laboratory cousins, and this difference should be exploited as a method to differentiate between laboratory adapted cultures and low passage wild strains isolated during an anthrax outbreak. This knowledge should distinguish between intentional releases and exposure to strains in nature providing a basis for the type of response by public health officials and investigators.
2018-12-04 | PXD010120 | Pride
Project description:A conserved hallmark of eukaryotic chromatin architecture is the distinctive array of well-positioned nucleosomes downstream of transcription start sites (TSS). Recent studies indicate that trans-acting factors establish this stereotypical array. Here, we present the first genome-wide in vitro and in vivo nucleosome maps for the ciliate Tetrahymena thermophila. In contrast with previous studies in yeast, we find that the stereotypical nucleosome array is preserved in the in vitro reconstituted map, which is governed only by the DNA sequence preferences of nucleosomes. Remarkably, this average in vitro pattern arises from subsets of nucleosomes, rather than the whole array, being present in individual Tetrahymena genes. Variation in GC content contributes to the positioning of these sequence-directed nucleosomes, and affects codon usage and amino acid composition in genes. We propose that these ‘seed’ nucleosomes may aid the AT-rich Tetrahymena genome – which is intrinsically unfavorable for nucleosome formation – in establishing nucleosome arrays in vivo in concert with trans-acting factors, while minimizing changes to the coding sequences they are embedded within. All data are from the macronuclear genome. Datasets: 1) Log-phase cells, fixed chromatin, light MNase digest; 2) Log-phase cells, native chromatin, heavy MNase digest; 3) Starved cells, fixed chromatin, light MNase digest; 4) Starved cells, native chromatin, heavy MNase digest; 5) in vitro reconstituted chromatin, 50ul reaction, 4:10 histone:DNA ratio, light MNase digest; 6) in vitro reconstituted chromatin, 50ul reaction, 7:10 histone:DNA ratio, light MNase digest; 7) in vitro reconstituted chromatin, 150ul reaction, 4:10 histone:DNA ratio, light MNase digest; 8) in vitro reconstituted chromatin, 150ul reaction, 4:10 histone:DNA ratio, heavy MNase digest; Control dataset: 9): MNase-digested naked DNA
2015-07-30 | E-GEOD-64061 | biostudies-arrayexpress
Project description:Bacterial persister cells are phenotypic variants of regular cells that are tolerant to antibiotics. High-persister (hip) mutants of Mycobacterium tuberculosis produce 10- to 1,000-fold more persister cells than the wild type strain when challenged with various antibiotics. Comparison of gene expression pattern of the hip mutants may provide clues as to the genetic mechanisms underlying persister formation. Transcriptome analysis will provide information on what differentiates M. tuberculosis hip strains from regular strains, which will be useful in the development of anti-persister therapy for persister cell eradication. Twelve independent M. tuberculosis hip mutants and the wild type strain were grown to stationary phase in duplicate. To avoid analyzing the drug effect, total RNA was extracted from the cultures prior to the addition of antibiotic for hybridization to Affymetrix microarrays. Data analysis was performed by comparing the hip mutants to the wild type control.
2014-04-07 | E-GEOD-55647 | biostudies-arrayexpress
Project description:Altered chromatin structure is a hallmark of cancer, and inappropriate regulation of chromatin structure may represent the origin of transformation. Several important studies have mapped human nucleosome distributions genome wide, but the genome-wide role of chromatin structure in cancer progression has not been addressed. We developed a MNase-Sequence Capture method, mTSS-seq, to map genome-wide nucleosome distribution in primary human lung and colon adenocarcinoma tissue. Here, we confirm that nucleosome redistribution is an early, widespread event in lung (LAC) and colon (CRC) adenocarcinoma. These altered nucleosome architectures are consistent between LAC and CRC patient samples indicating that they may serve as important early adenocarcinoma markers. We demonstrate that the nucleosome alterations are driven by the underlying DNA sequence and potentiate transcription factor binding. We conclude that DNA-directed nucleosome redistributions are widespread early in cancer progression. We have proposed an entirely new hierarchical model for chromatin-mediated genome regulation. â Nucleosome distribution mapping in primary patient tissue at all transcription start sites in the human genome Please note that two processed data files '4137N_ALLcombined.bed' and '4137T_ALLcombined.bed' (linked as Series supplementary file) are processed bed files combined from three 4137N_*_hiseq samples (total 6 raw data files) and three 4137T_*_hiseq samples (total 6 raw data files), respectively.
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2012-11-22 | E-GEOD-34207 | biostudies-arrayexpress
Project description:The capacity to sense and transduce temperature signals pervades all aspects of biology, and temperature exerts powerful control over the development and virulence of diverse pathogens. In the leading fungal pathogen of humans, Candida albicans, temperature has a profound impact on morphogenesis, a key virulence trait. Many cues that induce the transition from yeast to filamentous growth are contingent on a minimum temperature of 37ºC, while further elevatation to 39ºC serves as an independent inducing cue. The molecular chaperone Hsp90 is a key regulator of C. albicans temperature-dependent morphogenesis, as induction of filamentous growth requires relief from Hsp90-mediated repression of the morphogenetic program. Compromise of Hsp90 function genetically, pharmacologically, or by elevated temperature induces filamentation in a manner that depends on protein kinase A (PKA) signaling, but is independent of the terminal transcription factor, Efg1. Here, we determine that despite morphological and regulatory differences, inhibition of Hsp90 induces a transcriptional profile similar to that induced by other filamentation cues, and does so in a manner that is independent of Efg1. Further, we identify Hms1 as a transcriptional regulator required for morphogenesis induced by elevated temperature or compromise of Hsp90 function. Hms1 functions downstream of the cyclin Pcl, and the cyclin-dependent kinase Pho85, both of which are required for temperature-dependent filamentation. Upon Hsp90 inhibition, Hms1 binds to DNA elements involved in filamentous growth, including UME6 and RBT5, and regulates their expression, providing a mechanism through which Pho85, Pcl1, and Hms1 govern morphogenesis. Consistent with the importance of morphogenetic flexibility with virulence, deletion of C. albicans HMS1 attenuates virulence in a metazoan model of infection. Thus, we establish a new mechanism through which Hsp90 orchestrates C. albicans morphogenesis, and define novel regulatory circuitry governing a temperature-dependent developmental program, with broad implications for temperature sensing and virulence of microbial pathogens. Two-color experimental design testing the effect of geldanamycin on wild type of delta-efg1 cells. RNA from each replicate came from independent cultures.
2012-03-20 | E-GEOD-34255 | biostudies-arrayexpress
Project description:Determining how facultative anaerobic organisms sense and direct cellular responses to electron acceptor availability has been a subject of intense study. However, even in the model organism Escherichia coli, established mechanisms only explain a small fraction of the hundreds of genes that are regulated during shifts in electron acceptor availability. Here we propose a qualitative model that accounts for the full breadth of regulated genes by detailing how two global transcription factors (TFs), ArcA and Fnr of E. coli, sense key metabolic redox ratios and act on a genome-wide basis to regulate anabolic, catabolic, and energy generation pathways. We first fill gaps in our knowledge of this transcriptional regulatory network by carrying out ChIP-chip and gene expression experiments to identify 463 regulatory events. We then interfaced this reconstructed regulatory network with a highly curated genome-scale metabolic model to show that ArcA and Fnr regulate > 80% of total metabolic flux and 96% of differential gene expression across fermentative and nitrate respiratory conditions. Finally, based on the data we propose a feedforward with feedback trim regulatory scheme by showing extensive repression of catabolic genes by ArcA and extensive activation of chemiosmotic genes by Fnr. We further corroborated this regulatory scheme by showing a 0.71 r2 (p < 1e-6) correlation between changes in metabolic flux and changes in regulatory activity across fermentative and nitrate respiratory conditions. We also are able to relate the proposed model to a wealth of previously generated data by contextualizing the existing transcriptional regulatory network. Biological replicates were performed in triplicate for M-NM-^Tfnr, M-NM-^TarcA, and wild type Escherichia coli K12 MG1655 strains under both fully fermentative and nitrate respiratory conditions. An 18 chip study with three different strains under two different culture conditions.
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Project description:RNA-directed DNA methylation (RdDM) is a small interfering RNA (siRNA)-mediated epigenetic modification that contributes to transposon silencing in plants. RdDM requires a complex transcriptional machinery that includes specialized RNA polymerases, named Pol IV and Pol V, as well as chromatin remodelling proteins, transcription factors, RNA binding proteins, and other plant-specific proteins whose functions are not yet clarified. In Arabidopsis thaliana, DICER-LIKE3 and members of the ARGONAUTE4 group of AROGONAUTE (AGO) proteins are involved, respectively, in generating and using 24-nt siRNAs that trigger methylation and transcriptional gene silencing (TGS) of homologous promoter sequences. AGO proteins act in silencing effector complexes by anchoring the 3â and 5â ends of the guide siRNAs at their N-terminal PAZ domain and MID domain, respectively. In addition, many AGO proteins cleave complementary target RNAs through an endonuclease (âslicerâ) activity in their C-terminal PIWI domain. AGO4 is the main AGO protein implicated in the RdDM pathway. Here we report the identification of the related AGO6 in a forward genetic screen for mutants defective in RdDM and TGS in shoot and root apical meristems in Arabidopsis thaliana. The identification of AGO6, and not AGO4, in our screen is consistent with the primary expression of AGO6 in shoot and root growing points and the preferential association of Pol V with AGO6. Examination of siRNA abundance in the trasngenic wild type plant (contains trigger and silencer transgenes) and the ago6-4 mutant.
2011-12-01 | E-GEOD-28537 | biostudies-arrayexpress
Project description:Early meiotic genes (EMGs) encompass an important subset within the developmental program of gametogenesis. Regulation of EMGs is achieved through the recognition of a common regulatory element in their promoters by the transcription factor Ume6. Proper meiotic execution requires the timely expression of EMGs, which is achieved through the adoption of the meiotic regulator Ime1 by Ume6. While it is known that Ime1’s binding to Ume6 promotes EMG expression, the mechanism of EMG activation remains unclear. Two competing models have been proposed: (1) Ime1 converts Ume6 to a coactivator complex, and (2) Ime1 binding targets Ume6 for degradation. Using a combination of tools including meiotic synchronization, temporally controlled protein depletion, protein-protein interaction engineering, and transcriptomics, here we address this conundrum. We identify 160 genes that are directly regulated by Ime1-Ume6, including UME6 itself. Removal of Ume6 shortly before meiotic entry is detrimental to EMG activation and gamete formation, whereas tethering of Ume6 to a heterologous activation domain is sufficient to trigger EMG expression and to generate viable gametes in the absence of Ime1. We conclude that Ime1-Ume6 functions as a coactivator complex. While Ume6 is indispensable for EMGs expression, Ime1 primarily serves as an evolutionarily tuned activation domain for Ume6.
2023-06-30 | GSE226769 | GEO