Transcription Start Site data from mixed asexual blood stages of P falciparum strain 3D7
Ontology highlight
ABSTRACT:
INSTRUMENT(S): Illumina MiSeq
ORGANISM(S): Plasmodium falciparum
SUBMITTER:
PROVIDER: E-ERAD-383 | biostudies-arrayexpress |
REPOSITORIES: biostudies-arrayexpress
Similar Datasets
Project description:In eukaryotes, the chromatin architecture has a pivotal role in regulating all DNA-related processes. For P. falciparum, the causative agent of human malaria, the nucleosome landscape of the extremely AT-rich intergenic regulatory regions is largely unexplored. With the aid of a highly controlled MNase-seq procedure we reveal how positioning of nucleosomes provides a structural and regulatory framework to the transcriptional unit. We observe strong positioning of nucleosomes around splice sites that could aid co-transcriptional splicing events. In addition, nucleosome depleted regions are apparent hallmarks of transcription start sites (TSSs) and may support pre-initiation complex assembly. Moreover, we reveal nucleosome occupancy dynamics on strong TSSs during intraerythrocytic development, which correlate with gene expression changes and we observe a characteristic nucleosome architecture of functional - but not inert - TGCATGCA DNA motifs. Collectively, these findings highlight the regulatory capacity of the nucleosome landscape of this deadly human pathogen.
2015-11-25 | GSE66185 | GEO
Project description:In eukaryotes, the chromatin architecture has a pivotal role in regulating all DNA-related processes. For P. falciparum, the causative agent of human malaria, the nucleosome landscape of the extremely AT-rich intergenic regulatory regions is largely unexplored. With the aid of a highly controlled MNase-seq procedure we reveal how positioning of nucleosomes provides a structural and regulatory framework to the transcriptional unit. We observe strong positioning of nucleosomes around splice sites that could aid co-transcriptional splicing events. In addition, nucleosome depleted regions are apparent hallmarks of transcription start sites (TSSs) and may support pre-initiation complex assembly. Moreover, we reveal nucleosome occupancy dynamics on strong TSSs during intraerythrocytic development, which correlate with gene expression changes and we observe a characteristic nucleosome architecture of functional - but not inert - TGCATGCA DNA motifs. Collectively, these findings highlight the regulatory capacity of the nucleosome landscape of this deadly human pathogen. Mnase-seq during the intra-erythrocytic asexual cycle of Plasmodium falciparum var2csa-panned 3D7 parasites for 8 time-points, every 5 hours starting from 5 hours post invasion until 40 hours post-invasion (T5-T40). Cycle length of these parasites is ~43 hours, synchronicity window is ~ 8 hours. T40 has 2 technical replicates (independent digestions; T40A, T40B). Additionally, pellet control sample (T15), histone H4-ChIP control (T40A) and sonicated and amplified genomic DNA. Chromatin was digested using a combined MNase + exonuclease III treatment. Libraries were prepared according to a Plasmodium-optimized library preparation procedure including KAPA polymerase-mediated PCR amplification. Strand-specific RNA-seq for expression quantification during the intra-erythrocytic asexual cycle of Plasmodium falciparum var2csa-panned 3D7 parasites for 8 time-points every 5 hours starting from 5 hours post invasion invasion until 40 hours post-invasion (T5-T40). Cycle length of these parasites is ~43 hours, synchronicity window is ~ 8 hours. These samples are originating from the exact same batch of parasites as are the MNase-Seq libraries. Libraries were prepared according to a Plasmodium-optimized library preparation procedure including KAPA polymerase-mediated PCR amplification.
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Project description:Numerous nucleosome remodeling enzymes tightly regulate nucleosome positions in eukaryotic cells. Transcription and statistical positioning of nucleosomes may also contribute to proper nucleosome organization. Individual contributions remain controversial due to strong redundancy of processes acting on the nucleosome landscape. By incisive yeast genome engineering we radically decreased their redundancy. We find the transcriptional machinery to be disruptive of evenly spaced nucleosomes, and proper nucleosome density critical for their biogenesis. INO80 spaces nucleosomes in vivo and positions the first nucleosome covering genes. It requires its Arp8 and Ies2 subunits, but unexpectedly not the Nhp10 module, for spacing. Whereas H2A.Z stimulates INO80 in vitro, its presence is dispensable for INO80 +1 positioning function in vivo. DNA damage, recombination and transposon integration assays suggest that evenly spaced nucleosomes protect cells against genotoxic stress. We derive a unifying model of the biogenesis of the nucleosome landscape and suggest that it evolved not only to regulate but also to protect the genome.
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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.
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Project description:Nucleosomes are important for gene regulation because their arrangement on the genome can control which proteins bind to DNA. Currently, few human nucleosomes are thought to be consistently positioned across cells; however, this has been difficult to assess due to the limited resolution of existing data. We performed paired-end sequencing of micrococcal nuclease-digested chromatin (MNase-seq) from seven lymphoblastoid cell lines and mapped over 3.6 billion MNase-seq fragments to the human genome to create the highest-resolution map of nucleosome occupancy to date in a human cell type. In contrast to previous results, we find that most nucleosomes have more consistent positioning than expected by chance and a substantial fraction (8.7%) of nucleosomes have moderate to strong positioning. In aggregate, nucleosome sequences have 10 bp periodic patterns in dinucleotide frequency and DNase I sensitivity; and, across cells, nucleosomes frequently have translational offsets that are multiples of 10 bp. We estimate that almost half of the genome contains regularly spaced arrays of nucleosomes, which are enriched in active chromatin domains. Single nucleotide polymorphisms that reduce DNase I sensitivity can disrupt the phasing of nucleosome arrays, which indicates that they often result from positioning against a barrier formed by other proteins. However, nucleosome arrays can also be created by DNA sequence alone. The most striking example is an array of over 400 nucleosomes on chromosome 12 that is created by tandem repetition of sequences with strong positioning properties. In summary, a large fraction of nucleosomes are consistently positioned-in some regions because they adopt favored sequence positions, and in other regions because they are forced into specific arrangements by chromatin remodeling or DNA binding proteins. MNase-seq of 7 human lymphoblastoid cell lines from the HapMap project
2012-08-01 | E-GEOD-36979 | biostudies-arrayexpress
Project description:Nucleosome positioning dictates the DNA accessibility for regulatory proteins, and thus is critical for gene expression and regulation. It has been well documented that only a subset of nucleosomes are reproducibly positioned (phased) in eukaryotic genomes. The most prominent example of phased nucleosomes is the context of genes, where phased nucleosomes flank the transcriptional starts sites (TSSs). It is unclear, however, what factors influence nucleosome phasing in regions that are not close to genes. We performed a combinational mapping of nucleosome positioning and DNase I hypersensitive sites (DHSs) across the rice genome. We discovered that DHSs located in a variety of contexts, both genic and intergenic, were flanked by strongly phased nucleosome arrays. Our results support the barrier model for nucleosome organization as a general feature of eukaryote genomes, including plant genomes, and not limited to TSSs. Specifically, regions bound with regulatory proteins, including intergenic regions, can serve as barriers that organize phased nucleosome arrays on both sides. Our results also suggest that rice DHSs often span a single, phased nucleosome, similar to the H2A.Z-containing nucleosomes observed in DHSs in the human genome. We propose that genome-wide nucleosome positioning in the eukaryotic genomes is orchestrated by genomic regions associated with regulatory proteins. Rice chromatin was digested by micrococcal nuclease (MNase) into mono-nucleosome size. Mono-nucleosomal DNA was isolated and sequenced (MNase-seq) using Illumina sequencing platforms. We obtained a total of 38 million (M) single-end reads from our first MNase-seq experiment and mapped ~26 M to unique positions in the rice genome. We also conducted pair-end sequencing of an independent MNase-seq library, obtained 274 M paired-end reads, and mapped ~231 M read pairs to unique positions in the rice genome.We applied a strategy of combinational mapping of nucleosome positioning and DHSs (GSE26610) to examine whether nucleosome positioning is associated with all cis-regulatory elements in the rice genome. All datasets used in the analysis were developed using rice leaf tissue in the same developmental stage
2014-05-01 | E-GEOD-53027 | biostudies-arrayexpress
Project description:Nucleosome positioning dictates the DNA accessibility for regulatory proteins, and thus is critical for gene expression and regulation. It has been well documented that only a subset of nucleosomes are reproducibly positioned (phased) in eukaryotic genomes. The most prominent example of phased nucleosomes is the context of genes, where phased nucleosomes flank the transcriptional starts sites (TSSs). It is unclear, however, what factors influence nucleosome phasing in regions that are not close to genes. We performed a combinational mapping of nucleosome positioning and DNase I hypersensitive sites (DHSs) across the rice genome. We discovered that DHSs located in a variety of contexts, both genic and intergenic, were flanked by strongly phased nucleosome arrays. Our results support the barrier model for nucleosome organization as a general feature of eukaryote genomes, including plant genomes, and not limited to TSSs. Specifically, regions bound with regulatory proteins, including intergenic regions, can serve as barriers that organize phased nucleosome arrays on both sides. Our results also suggest that rice DHSs often span a single, phased nucleosome, similar to the H2A.Z-containing nucleosomes observed in DHSs in the human genome. We propose that genome-wide nucleosome positioning in the eukaryotic genomes is orchestrated by genomic regions associated with regulatory proteins.
2014-05-01 | GSE53027 | GEO
Project description:Nucleosomes are important for gene regulation because their arrangement on the genome can control which proteins bind to DNA. Currently, few human nucleosomes are thought to be consistently positioned across cells; however, this has been difficult to assess due to the limited resolution of existing data. We performed paired-end sequencing of micrococcal nuclease-digested chromatin (MNase-seq) from seven lymphoblastoid cell lines and mapped over 3.6 billion MNase-seq fragments to the human genome to create the highest-resolution map of nucleosome occupancy to date in a human cell type. In contrast to previous results, we find that most nucleosomes have more consistent positioning than expected by chance and a substantial fraction (8.7%) of nucleosomes have moderate to strong positioning. In aggregate, nucleosome sequences have 10 bp periodic patterns in dinucleotide frequency and DNase I sensitivity; and, across cells, nucleosomes frequently have translational offsets that are multiples of 10 bp. We estimate that almost half of the genome contains regularly spaced arrays of nucleosomes, which are enriched in active chromatin domains. Single nucleotide polymorphisms that reduce DNase I sensitivity can disrupt the phasing of nucleosome arrays, which indicates that they often result from positioning against a barrier formed by other proteins. However, nucleosome arrays can also be created by DNA sequence alone. The most striking example is an array of over 400 nucleosomes on chromosome 12 that is created by tandem repetition of sequences with strong positioning properties. In summary, a large fraction of nucleosomes are consistently positioned-in some regions because they adopt favored sequence positions, and in other regions because they are forced into specific arrangements by chromatin remodeling or DNA binding proteins.
2012-08-01 | GSE36979 | GEO
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2018-01-12 | GSE97290 | GEO