A nucleosome turnover map reveals that the stability of histone H4 Lys20 methylation depend on histone recycling in transcribed chromatin
Ontology highlight
ABSTRACT:
OTHER RELATED OMICS DATASETS IN: PRJNA278142PRJNA255375
ORGANISM(S): Schizosaccharomyces pombe
PROVIDER: GSE66866 | GEO | 2015/03/13
SECONDARY ACCESSION(S): PRJNA278142
REPOSITORIES: GEO
Similar Datasets
Project description:Nucleosome composition actively contributes to chromatin structure and accessibility. Cells have developed mechanisms to remove or recycle histones, generating a landscape of differentially aged nucleosomes. This study aimed to create a high-resolution, genome-wide map of nucleosome turnover in Schizosaccharomyces pombe. The recombination-induced tag exchange (RITE) method was used to study replication-independent nucleosome turnover through the appearance of new histone H3 and the disappearance or preservation of old histone H3. The genome-wide location of histones was determined by chromatin immunoprecipitation-exonuclease methodology (ChIP-exo). The findings were compared with diverse chromatin marks, including histone variant H2A.Z, post-translational histone modifications, and Pol II binding. Finally, genome-wide mapping of the methylation states of H4K20 was performed to determine the relationship between methylation (mono, di, and tri) of this residue and nucleosome turnover. Our analysis showed that histone recycling resulted in low nucleosome turnover in the coding regions of active genes, stably expressed at intermediate levels. High levels of transcription resulted in the incorporation of new histones primarily at the end of transcribed units. H4K20 was methylated in low-turnover nucleosomes in euchromatic regions, notably in the coding regions of long genes that were expressed at low levels. This transcription-dependent accumulation of histone methylation was dependent on the histone chaperone complex FACT. Our data showed that nucleosome turnover is highly dynamic in the genome and that several mechanisms are at play to either maintain or suppress stability. In particular, we found that FACT-associated transcription conserves histones by recycling them and is required for progressive H4K20 methylation.
| S-EPMC4448683 | biostudies-literature
Project description:Nucleosome composition actively contribute to the chromatin structure and accessibility. To preserve chromatin state during replication, transcription and DNA repair, cells have evolved mechanisms to evict or recycle histones, generating a landscape of differentially aged nucleosomes. To map the stability of nucleosomes, we have adapted the recombination induced tag exchange (RITE) method to Schizosaccharomyces pombe histone H3. The RITE method allows us to study replication-independent protein turnover both through the occurrence of, in our case, new histone H3 and the disappearance or preservation of old histone H3. We contrast the RITE system to nucleosome turnover measured by chromatin incorporation of an epitope-tagged H3 under an inducible promoter. We confirm previous findings that stable nucleosomes are found at heterochromatin, but also at coding regions of actively transcribed genes. Genome-wide comparisons with several chromatin marks showed that high turnover nucleosomes correlate with H2A.Z, acetylated H4 and H3K4me2. The histones with high turnover are primarily found at the nucleosomes on the 5´and/or 3´ edges of the transcribed unit. In addition, in this study we have determined genome-wide maps of all three methylation marks at H4K20. All methylation of H4K20 appeared in low turnover nucleosomes and particularly in euchromatic regions. H4K20me1 marks stable nucleosomes at loci proximal to nucleosome depleted regions (NDR) and H4K20me2/3 were found further inside of transcribed units, especially at coding regions of long genes expressed at low levels. Further, this transcription-dependent accumulation of histone methylations was dependent on the histone chaperone complex FACT (Facilitates Chromatin Transcription), as predicited from its role in recycling nucleosomes during transcription.
2015-03-06 | GSE59461 | GEO
Project description:Nucleosome composition actively contribute to the chromatin structure and accessibility. To preserve chromatin state during replication, transcription and DNA repair, cells have evolved mechanisms to evict or recycle histones, generating a landscape of differentially aged nucleosomes. To map the stability of nucleosomes, we have adapted the recombination induced tag exchange (RITE) method to Schizosaccharomyces pombe histone H3. The RITE method allows us to study replication-independent protein turnover both through the occurrence of, in our case, new histone H3 and the disappearance or preservation of old histone H3. We contrast the RITE system to nucleosome turnover measured by chromatin incorporation of an epitope-tagged H3 under an inducible promoter. We confirm previous findings that stable nucleosomes are found at heterochromatin, but also at coding regions of actively transcribed genes. Genome-wide comparisons with several chromatin marks showed that high turnover nucleosomes correlate with H2A.Z, acetylated H4 and H3K4me2. The histones with high turnover are primarily found at the nucleosomes on the 5´and/or 3´ edges of the transcribed unit. In addition, in this study we have determined genome-wide maps of all three methylation marks at H4K20. All methylation of H4K20 appeared in low turnover nucleosomes and particularly in euchromatic regions. H4K20me1 marks stable nucleosomes at loci proximal to nucleosome depleted regions (NDR) and H4K20me2/3 were found further inside of transcribed units, especially at coding regions of long genes expressed at low levels. Further, this transcription-dependent accumulation of histone methylations was dependent on the histone chaperone complex FACT (Facilitates Chromatin Transcription), as predicited from its role in recycling nucleosomes during transcription.
2015-03-13 | GSE66865 | GEO
Project description:Recent studies have indicated that nucleosome turnover is rapid, occurring several times per cell cycle. To access the effect of nucleosome turnover on the epigenetic landscape, we investigated H3K79 methylation, which is produced by a single methyltransferase (Dot1l) with no known demethylase. Using chemical-induced proximity (CIP), we find that the valency of H3K79 methylation (mono-, di-, and tri-) is determined by nucleosome turnover rates. Furthermore, propagation of this mark is predicted by nucleosome turnover simulations over the genome and accounts for the asymmetric distribution of H3K79me toward the transcriptional unit. More broadly, a meta-analysis of other conserved histone modifications demonstrates that nucleosome turnover models predict both valency and chromosomal propagation of methylation marks. Based on data from worms, flies, and mice, we propose that the turnover of modified nucleosomes is a general means of propagation of epigenetic marks and a determinant of methylation valence.
| S-EPMC6510544 | biostudies-literature
Project description:Chromatin structure is dictated by nucleosome assembly and internucleosomal interactions. The tight wrapping of nucleosomes inhibits gene expression, but modifications to histone tails modulate chromatin structure, allowing for proper genetic function. The histone H4 tail is thought to play a large role in regulating chromatin structure. Here we investigated the structure of nucleosomes assembled with a tail-truncated H4 histone using Atomic Force Microscopy. We assembled tail-truncated H4 nucleosomes on DNA templates allowing for the assembly of mononucleosomes or dinucleosomes. Mononucleosomes assembled on nonspecific DNA led to decreased DNA wrapping efficiency. This effect is less pronounced for nucleosomes assembled on positioning motifs. Dinucleosome studies resulted in the discovery of two effects- truncation of the H4 tail does not diminish the preferential positioning observed in full-length nucleosomes, and internucleosomal interaction eliminates the DNA unwrapping effect. These findings provide insight on the role of histone H4 in chromatin structure and stability.
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Project description:We employ stable-isotope labeling and quantitative mass spectrometry to track histone methylation stability. We show that H3 trimethyl K9 and K27 are slow to be established on new histones and slow to disappear from old histones, with half-lives of multiple cell divisions. By contrast, the transcription-associated marks K4me3 and K36me3 turn over far more rapidly, with half-lives of 6.8 h and 57 h, respectively. Inhibition of demethylases increases K9 and K36 methylation, with K9 showing the largest and most robust increase. We interpret different turnover rates in light of genome-wide localization data and transcription-dependent nucleosome rearrangements proximal to the transcription start site.
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Project description:BackgroundThe protein anti-silencing function 1 (Asf1) chaperones histones H3/H4 for assembly into nucleosomes every cell cycle as well as during DNA transcription and repair. Asf1 interacts directly with H4 through the C-terminal tail of H4, which itself interacts with the docking domain of H2A in the nucleosome. The structure of this region of the H4 C-terminus differs greatly in these two contexts.ResultsTo investigate the functional consequence of this structural change in histone H4, we restricted the available conformations of the H4 C-terminus and analyzed its effect in vitro and in vivo in Saccharomyces cerevisiae. One such mutation, H4 G94P, had modest effects on the interaction between H4 and Asf1. However, in yeast, flexibility of the C-terminal tail of H4 has essential functions that extend beyond chromatin assembly and disassembly. The H4 G94P mutation resulted in severely sick yeast, although nucleosomes still formed in vivo albeit yielding diffuse micrococcal nuclease ladders. In vitro, H4G4P had modest effects on nucleosome stability, dramatically reduced histone octamer stability, and altered nucleosome sliding ability.ConclusionsThe functional consequences of altering the conformational flexibility in the C-terminal tail of H4 are severe. Interestingly, despite the detrimental effects of the histone H4 G94P mutant on viability, nucleosome formation was not markedly affected in vivo. However, histone octamer stability and nucleosome stability as well as nucleosome sliding ability were altered in vitro. These studies highlight an important role for correct interactions of the histone H4 C-terminal tail within the histone octamer and suggest that maintenance of a stable histone octamer in vivo is an essential feature of chromatin dynamics.
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Project description:Histone proteins play essential structural and functional roles in the transition between active and inactive chromatin states. Although histones have a high degree of conservation due to constraints to maintain the overall structure of the nucleosomal octameric core, variants have evolved to assume diverse roles in gene regulation and epigenetic silencing. Histone variants, post-translational modifications and interactions with chromatin remodeling complexes influence DNA replication, transcription, repair and recombination. The authors review recent findings on the structure of chromatin that confirm previous interparticle interactions observed in crystal structures.
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Project description:Regulation of Set1-COMPASS-mediated H3K4 methylation and Dot1-mediated H3K79 methylation by H2BK123 ubiquitination (H2Bub1) is an evolutionarily conserved trans-histone crosstalk mechanism. How H2Bub1 impacts chromatin structure and affects Set1-COMPASS/Dot1 functions has not been fully defined. Ubiquitin was proposed to bind proteins to physically bridge H2Bub1 with Set1-COMPASS/Dot1. Alternatively, the bulky ubiquitin was thought to be a "wedge" that loosens the nucleosome for factor access. Contrary to the latter possibility, recent discoveries provide evidence for nucleosome stabilization by H2Bub1 via preventing the constant H2A-H2B eviction. Recent data has also uncovered a "docking-site" on H2B for Set1-COMPASS. Collectively, these findings invoke a model, where ubiquitin acts as a "glue" to bind the nucleosome together for supporting Set1-COMPASS/Dot1 functions. This review provides an overview of these novel findings. Additionally, how H2Bub1 and its deubiquitination might alter the chromatin dynamics during transcription is discussed. Possible models for nucleosome stabilization by ubiquitin are also provided.
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Project description:The yeast histone chaperone Rtt106 is involved in de novo assembly of newly synthesized histones into nucleosomes during DNA replication and plays a role in regulating heterochromatin silencing and maintaining genomic integrity. The interaction of Rtt106 with H3-H4 is modulated by acetylation of H3 lysine 56 catalyzed by the lysine acetyltransferase Rtt109. Using affinity purification strategies, we demonstrate that Rtt106 interacts with (H3-H4)(2) heterotetramers in vivo. In addition, we show that Rtt106 undergoes homo-oligomerization in vivo and in vitro, and mutations in the N-terminal homodimeric domain of Rtt106 that affect formation of Rtt106 oligomers compromise the function of Rtt106 in transcriptional silencing and response to genotoxic stress and the ability of Rtt106 to bind (H3-H4)(2). These results indicate that Rtt106 deposits H3-H4 heterotetramers onto DNA and provide the first description of a H3-H4 chaperone binding to (H3-H4)(2) heterotetramers in vivo.
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