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A map of nucleosome positions in yeast at base-pair resolution.

ABSTRACT: The exact positions of nucleosomes along genomic DNA can influence many aspects of chromosome function. However, existing methods for mapping nucleosomes do not provide the necessary single-base-pair accuracy to determine these positions. Here we develop and apply a new approach for direct mapping of nucleosome centres on the basis of chemical modification of engineered histones. The resulting map locates nucleosome positions genome-wide in unprecedented detail and accuracy. It shows new aspects of the in vivo nucleosome organization that are linked to transcription factor binding, RNA polymerase pausing and the higher-order structure of the chromatin fibre.

SUBMITTER: Brogaard K

PROVIDER: S-EPMC3786739 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature

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A map of nucleosome positions in yeast at base-pair resolution.

Brogaard Kristin K Xi Liqun L Wang Ji-Ping JP Widom Jonathan J

Nature 20120601 7404

The exact positions of nucleosomes along genomic DNA can influence many aspects of chromosome function. However, existing methods for mapping nucleosomes do not provide the necessary single-base-pair accuracy to determine these positions. Here we develop and apply a new approach for direct mapping of nucleosome centres on the basis of chemical modification of engineered histones. The resulting map locates nucleosome positions genome-wide in unprecedented detail and accuracy. It shows new aspects ...[more]

PMID: 22722846

Similar Datasets

A map of nucleosome positions in yeast at base-pair resolution

Project description:The exact positions of nucleosomes along genomic DNA can influence many aspects of chromosome function, yet existing methods for mapping nucleosomes do not provide the necessary single base pair accuracy to determine these positions. Here we develop and apply a new approach for direct mapping of nucleosome centers based on chemical modification of engineered histones. The resulting map locates nucleosome center positions genome-wide in unprecedented detail and accuracy. It reveals novel aspects of the in vivo nucleosome organization that are linked to transcription factor binding, RNA polymerase pausing, and the higher order structure of the chromatin fiber itself. 6 samples were analyzed with high throughout parallel sequencing. All samples were created using the same chemical mapping protocol except with varying reaction times. The different reaction times did not make any significant difference in the nucleosome maps so all the data, for the 6 samples, were combined into one data set for the paper and are all considered replicates. The 6 samples are as follows: 1. 20 minute reaction time (single-end sequencing) 2. 20 minute reaction time (single-end sequencing) 3. 1 minute reaction time (single-end sequencing) 4. 1.5 minute reaction time (single-end sequencing) 5. 20 minute reaction time (paired-end sequencing) 6. 1.5 minute reaction time (paired-end sequencing)

2012-05-16 | E-GEOD-36063 | biostudies-arrayexpress

A map of nucleosome positions in yeast at base-pair resolution

2012-05-17 | GSE36063 | GEO

A computational approach to map nucleosome positions and alternative chromatin states with base pair resolution.

Project description:Understanding chromatin function requires knowing the precise location of nucleosomes. MNase-seq methods have been widely applied to characterize nucleosome organization in vivo, but generally lack the accuracy to determine the precise nucleosome positions. Here we develop a computational approach leveraging digestion variability to determine nucleosome positions at a base-pair resolution from MNase-seq data. We generate a variability template as a simple error model for how MNase digestion affects the mapping of individual nucleosomes. Applied to both yeast and human cells, this analysis reveals that alternatively positioned nucleosomes are prevalent and create significant heterogeneity in a cell population. We show that the periodic occurrences of dinucleotide sequences relative to nucleosome dyads can be directly determined from genome-wide nucleosome positions from MNase-seq. Alternatively positioned nucleosomes near transcription start sites likely represent different states of promoter nucleosomes during transcription initiation. Our method can be applied to map nucleosome positions in diverse organisms at base-pair resolution.

| S-EPMC5094857 | biostudies-literature

A DNA methylation map of human cancer at single base-pair resolution.

Project description:Although single base-pair resolution DNA methylation landscapes for embryonic and different somatic cell types provided important insights into epigenetic dynamics and cell-type specificity, such comprehensive profiling is incomplete across human cancer types. This prompted us to perform genome-wide DNA methylation profiling of 22 samples derived from normal tissues and associated neoplasms, including primary tumors and cancer cell lines. Unlike their invariant normal counterparts, cancer samples exhibited highly variable CpG methylation levels in a large proportion of the genome, involving progressive changes during tumor evolution. The whole-genome sequencing results from selected samples were replicated in a large cohort of 1112 primary tumors of various cancer types using genome-scale DNA methylation analysis. Specifically, we determined DNA hypermethylation of promoters and enhancers regulating tumor-suppressor genes, with potential cancer-driving effects. DNA hypermethylation events showed evidence of positive selection, mutual exclusivity and tissue specificity, suggesting their active participation in neoplastic transformation. Our data highlight the extensive changes in DNA methylation that occur in cancer onset, progression and dissemination.

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A high-resolution map of nucleosome positioning on a fission yeast centromere.

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Epigenome characterization at single base-pair resolution

Project description:We have combined standard micrococcal (MNase) digestion of nuclei with a modified protocol for construction paired-end DNA sequencing libraries to map both nucleosomes and subnucleosome-sized particles at single base-pair resolution throughout the budding yeast genome. We found that partially unwrapped nucleosomes and subnucleosome-sized particles can occupy the same position within a cell population, suggesting dynamic behavior. By varying the time of MNase digestion, we have been able to observe changes that reflect differential sensitivity of particles, including eviction of nucleosomes. Our protocol and mapping method provide a general strategy for characterizing full epigenomes. We used micrococcal nuclease mapping, chromatin immunoprecipitation and paired-end sequencing to determine the structure of yeast centromeres at single base-pair resolution.

2011-10-26 | E-GEOD-30551 | biostudies-arrayexpress

Epigenome characterization at single base-pair resolution.

Project description:We have combined standard micrococcal nuclease (MNase) digestion of nuclei with a modified protocol for constructing paired-end DNA sequencing libraries to map both nucleosomes and subnucleosome-sized particles at single base-pair resolution throughout the budding yeast genome. We found that partially unwrapped nucleosomes and subnucleosome-sized particles can occupy the same position within a cell population, suggesting dynamic behavior. By varying the time of MNase digestion, we have been able to observe changes that reflect differential sensitivity of particles, including the eviction of nucleosomes. To characterize DNA-binding features of transcription factors, we plotted the length of each fragment versus its position in the genome, which defined the minimal protected region of each factor. This process led to the precise mapping of protected and exposed regions at and around binding sites, and also determination of the degree to which they are flanked by phased nucleosomes and subnucleosome-sized particles. Our protocol and mapping method provide a general strategy for epigenome characterization, including nucleosome phasing and dynamics, ATP-dependent nucleosome remodelers, and transcription factors, from a single-sequenced sample.

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Map of nucleosome positions on the HIV DNA

Project description:This SuperSeries is composed of the SubSeries listed below.

2020-03-02 | GSE139557 | GEO

NUCLIZE for quantifying epigenome: generating histone modification data at single-nucleosome resolution using genuine nucleosome positions.

Project description:BACKGROUND:Defining histone modification at single-nucleosome resolution provides accurate epigenomic information in individual nucleosomes. However, most of histone modification data deposited in current databases, such as ENCODE and Roadmap, have low resolution with peaks of several kilo-base pairs (kb), which due to the technical defects of regular ChIP-Seq technology. RESULTS:To generate histone modification data at single-nucleosome resolution, we developed a novel approach, NUCLIZE, using synergistic analyses of histone modification data from ChIP-Seq and high-resolution nucleosome mapping data from native MNase-Seq. With this approach, we generated quantitative epigenomics data of single and multivalent histone modification marks in each nucleosome. We found that the dominant trivalent histone mark (H3K4me3/H3K9ac/H3K27ac) and others showed defined and specific patterns near each TSS, indicating potential epigenetic codes regulating gene transcription. CONCLUSIONS:Single-nucleosome histone modification data render epigenomic data become quantitative, which is essential for investigating dynamic changes of epigenetic regulation in the biological process or for functional epigenomics studies. Thus, NUCLIZE turns current epigenomic mapping studies into genuine functional epigenomics studies with quantitative epigenomic data.

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Nucleosome positions alone can be used to predict domains in yeast chromosomes.

Project description:We use molecular dynamics simulations based on publicly available micrococcal nuclease sequencing data for nucleosome positions to predict the 3D structure of chromatin in the yeast genome. Our main aim is to shed light on the mechanism underlying the formation of chromosomal interaction domains, chromosome regions of around 0.5 to 10 kbp which show enriched self-interactions, which were experimentally observed in recent MicroC experiments (importantly these are at a different length scale from the 100- to 1,000-kbp-sized domains observed in higher eukaryotes). We show that the sole input of nucleosome positioning data is already sufficient to determine the patterns of chromatin interactions and domain boundaries seen experimentally to a high degree of accuracy. Since the nucleosome spacing so strongly affects the larger-scale domain structure, we next examine the genome-wide linker-length distribution in more detail, finding that it is highly irregular and varies in different genomic regions such as gene bodies, promoters, and active and inactive genes. Finally we use our simple simulation model to characterize in more detail how irregular nucleosome spacing may affect local chromatin structure.

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