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Distinct differences in chromatin structure at telomeric X- and Y-elements in budding yeast.

ABSTRACT: The telomeric repeat sequences (TGTGG) are the same at all chromosome ends, but the number and position of subtelomeric X and Y repeat elements vary. Using chromatin immunoprecipitation and genome-wide analyses, we here demonstrate that the subtelomeric X and Y elements have distinct structural and functional properties. Y elements are transcriptionally active and highly enriched in histones, whereas X elements are repressed and completely devoid of nucleosomes. In contrast to X elements, the Y elements lack the classical hallmarks of heterochromatin, e.g. high Sir3 and Rap1 occupancy as well as low levels of histone 4 lysine 16 acetylation, Our analyses refute the idea that subtelomeric silencing is a general phenomenon and suggest that the presence of X and Y elements govern the chromatin structure and transcription activtiy at individual chromosome ends. Keywords: nucleosome position and Histone 4 lys 16 acetylation Chip on CHIP

ORGANISM(S): Saccharomyces cerevisiae

PROVIDER: GSE13615 | GEO | 2009/07/01

SECONDARY ACCESSION(S): PRJNA110639

REPOSITORIES: GEO

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Expanding heterochromatin reveals discrete subtelomeric domains delimited by chromatin landscape transitions

Project description:The eukaryotic genome is divided into chromosomal domains of heterochromatin and euchromatin. Transcriptionally silent heterochromatin is found at subtelomeric regions, leading to the telomeric position effect (TPE) in yeast, fly and man. Heterochromatin generally initiates and spreads from defined loci, and diverse mechanisms prevent the ectopic spread of heterochromatin into euchromatin. Here, we overexpressed the silencing factor Sir3 at various levels in yeast, and found that Sir3 spreading into Extended Silent Domains (ESD) eventually reached saturation at subtelomeres. We observed that Sir3 spreading into ESDs covered zone associated with specific histone marks in wild-type cells and stopped at zones of histone mark transitions including H3K79 tri-methylation levels. The conserved enzyme Dot1 deposits H3K79 methylation, and we found that it is essential for viability upon overexpression of Sir3, but not of a spreading-defective mutant Sir3A2Q. These data suggest that H3K79 methylation actively blocks Sir3 spreading. Lastly, we demonstrate that our work uncovers previously uncharacterized discrete subtelomeric domains associated with specific chromatin features, that offers a new viewpoint on how to separate subtelomeres from the core chromosome.

2018-10-08 | GSE106499 | GEO

Dose-dependency of heterochromatin domains reveals subtelomeric structuration in budding yeast

Project description:The eukaryotic genome is divided into chromosomal domains of distinct gene activities. Transcriptionally silent chromatin is found in subtelomeric regions leading to telomeric position effect (TPE) in yeast, fly and man. Silent chromatin generally initiates at defined loci and tends to propagate from those sites by self-recruitment mechanisms implying the requirement for processes preventing ectopic spreading of silencing. Barrier elements that can block the spread of silent chromatin have been documented, but their relative efficiency is not known. Here we explore the dose-dependency of silencing factors for the extent of TPE in budding yeast. We characterized genome wide the impact of overexpressing the silencing factors Sir2 and Sir3 on the spreading of Sir3 and its impact on coding and non-coding transcription. We thus reveal that extension of silent domains can reach saturation. Analysis of published data sets enabled to uncover that the extension of Sir3 bound domains stops at zones corresponding to transitions of specific histone marks including H3K79 methylation that is deposited by the conserved enzyme Dot1. Importantly, DOT1 is essential for viability when Sir3 is in excess indicating that this transition actively blocks Sir3 spreading. Our work uncovers previously uncharacterized discrete chromosomal domains associated with specific chromatin features and demonstrates that TPE is efficiently restricted to subtelomeres by the preexisting chromatin landscape.

2018-10-15 | GSE104391 | GEO

GTP-dependent regulation of heterochromatin fluctuations at subtelomeric regions in S. cerevisiae

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Analysis of a novel existence region of Sir3p in S. cerevisiae

Project description:In the budding yeast, HMR, HML, telomere and rDNA domain are known as a silencing region. Sir2 need to make it at rDNA and, HMR, HML and the telomere need to Sir2, Sir3, Sir4 complex to control internal gene repression. In this report, we found a newly Sir3 binding domain, CN domain (Chromosome New region) 1~14, by the ChIP on chip analysis on S.cerevisiae chromosome. In addition, we also performed ChIP on chip analysis with anti-Sir3 antibody using G1 phase synchronized cell to find Sir3 distribution difference of stage of cell cycle and we found CN15~CN25 which was G1 phase specific Sir3 binding region. Furthermore, we analyzed difference of gene expression at CN region in sir3 strain, and some regions did not change level of gene expression. In the conventional report, Sir3 had recruited by Sir2 and Sir4 on chromosome, but recruit of Sir3 was independent on Sir2 and Sir4 at some CN regions. These data suggested that we found a newly Sir3 function and Sir3 recruited system on chromosome.

2015-11-18 | GSE75075 | GEO

S. cerevisiae cells: control vs positive supercoiling accumulation in absence of telomere silencing after 0 and 120 min

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2009-12-01 | E-GEOD-18241 | biostudies-arrayexpress

Subtelomeric p53 Binding Prevents Accumulation of DNA Damage at Human Telomeres

Project description:Telomeres and tumor suppressor protein TP53 (p53) function in genome protection, but a direct role of p53 at telomeres has not yet been described. Here, we have identified non-canonical p53 binding sites within the human subtelomeres that suppress the accumulation of DNA damage at telomeric repeat DNA. These non-canonical subtelomeric p53 binding sites conferred transcription enhancer-like functions that include an increase in local histone H3K9 and H3K27 acetylation and stimulation of subtelomeric transcripts, including telomere-repeat containing RNA (TERRA). p53 suppressed formation of telomere-associated Î³H2AX and prevented telomere DNA degradation in response to DNA damage stress. Our findings indicate that p53 provides a direct chromatin-associated protection to human telomeres, as well as other fragile genomic sites. We propose that p53-associated chromatin modifications enhance local DNA repair or protection to provide a previously unrecognized tumor suppressor function of p53. p53 binding was analyzed by ChIP-Seq in HCT116 cells treated with camptothecin or untreated control.

2016-01-07 | E-GEOD-75528 | biostudies-arrayexpress

Telomere repeats induce domains of H3K27 methylation in Neurospora

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A genome-wide view of the expression and processing patterns of Thermus thermophilus HB8 CRISPR RNAs

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Project description:Telomeres constitute the ends of linear chromosomes and together with the shelterin complex form a structure essential for genome maintenance and stability. In addition to the constitutive binding of the shelterin complex, other direct, yet more transient interactions are mediated by the CST complex and HOT1, while subtelomeric variant repeats are recognized by NR2C/F transcription factors. Recently, the Kruppel-like zinc finger protein ZBTB48 has been described as a novel telomere-associated factor in the vertebrate lineage. Here, we show that ZBTB48 binds directly both to telomeric as well as to subtelomeric variant repeat sequences. ZBTB48 is found at telomeres of human cancer cells regardless of the mode of telomere maintenance and it acts as a negative regulator of telomere length. In addition to its telomeric function, we demonstrate through a combination of RNAseq, ChIPseq and expression proteomics experiments that ZBTB48 acts as a transcriptional activator on a small set of target genes, including mitochondrial fission process 1 (MTFP1). This discovery places ZBTB48 at the interface of telomere length regulation, transcriptional control and mitochondrial metabolism.

2017-05-11 | PXD006074 | Pride

Subtelomeric p53 Binding Prevents Accumulation of DNA Damage at Human Telomeres

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2016-01-07 | GSE75528 | GEO

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