Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

γH2A is a component of yeast heterochromatin required for telomere elongation

ABSTRACT: Histones of heterochromatin are deacetylated in yeast and methylated in more complex eukaryotes to regulate heterochromatin structure and gene silencing. Here, we report that histone H2A phosphorylated at serine 129 (γH2A) in Saccharomyces cerevisiae is a conceptually new type of heterochromatin modification that functions downstream of silent chromatin assembly. We show that γH2A is enriched throughout yeast telomeric and silent mating locus (HM) heterochromatin where γH2A results from the action of kinases Tel1 and Mec1. Interestingly, mutation of γH2A has no apparent effect on the binding of Sir (silent information regulator) complex or on gene silencing. In contrast, deletion of SIR3 abolishes the formation of γH2A at heterochromatin. To address the function of γH2A, we used a ∆rif1 mutant strain in which telomeres are excessively elongated to show that γH2A is required for the optimal recruitment of Cdc13, a regulator of telomere elongation, and for telomere elongation itself. Thus, a histone modification that parallels Sir3 protein binding is shown here to be dispensable for the formation of a silent structure but is important for a crucial heterochromatin-specific downstream function in telomere homeostasis.

ORGANISM(S): Saccharomyces cerevisiae

PROVIDER: GSE21814 | GEO | 2011/01/05

SECONDARY ACCESSION(S): PRJNA127257

REPOSITORIES: GEO

ACCESS DATA

Json Xml

Similar Datasets

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

Elevated Levels of Aneuploidy and Chromosome Rearrangements are Separable Genome Instability Events

Project description:In Saccharomyces cerevisiae, Elevated Levels of Aneuploidy and Chromosome Rearrangements are Separable Genome Instability Events Controlled by the Tel1 and Mec1 Kinases Cancer cells often have elevated frequencies of chromosomal aberrations, and it is likely that loss of genome stability is one driving force behind tumorigenesis. Deficiencies in DNA replication, DNA repair, or cell cycle checkpoints can all contribute to increased rates of chromosomal duplications, deletions and translocations. The Saccharomyces cerevisiae proteins Tel1 and Mec1 (homologues of the human ATM and ATR proteins, respectively) are known to participate in the DNA damage response, replication checkpoint, and telomere maintenance pathways and are critical to maintain genome stability. In the absence of induced DNA damage, tel1 mec1 diploid yeast strains exhibit extremely high rates of chromosome aneuploidy. There is a significant bias towards trisomy of chromosomes II, VIII, X, and XII, whereas the smallest chromosomes I and VI are commonly monosomic. tel1 mec1 strains also demonstrate elevated levels of chromosome rearrangements, including translocations as well as interstitial duplications and deletions. Restoring wild-type telomere length with the Cdc13-Est2 fusion protein substantially reduces the amount of chromosome rearrangements in tel1 mec1 strains. This result suggests that most of the rearrangements are initiated by telomere-telomere fusions. However, the telomere defects associated with tel1 mec1 strains do not cause the high rate of aneuploidy, as restoring proper telomere function does not prevent cells from becoming aneuploid. Our data demonstrate that the same mutant genotype can produce both high levels of chromosome rearrangements and high levels of aneuploidy, and these two types of events occur through separate mechanisms.

2009-09-03 | GSE17903 | GEO

Transcription profiling of yeast strains harbouring a temperature sensitive allele of the essential telomere capping gene cdc13-1 to investigate the genome-wide response to uncapped telomeres

Project description:Telomeres are nucleoprotein complexes that protect the ends of eukaryotic chromosomes from being recognised as double strand breaks. When telomere structure is perturbed, a co-ordinated series of events to promote arrest of the cell cycle is rapidly initiated so that cells carrying damaged telomeres do not continue to divide. In order to better understand the eukaryotic response to telomere damage, we employed budding yeast strains harbouring a temperature sensitive allele of an essential telomere capping gene (cdc13-1) and conducted a transcriptomic study of the genome-wide response to uncapped telomeres. We show that telomere uncapping in cdc13-1 strains is associated with the differential expression of over 1100 genes and has features in common with the responses to DNA damage, diverse environmental stresses and, as expected, the absence of telomerase. The transcriptomic response to telomere uncapping includes many genes with known roles in telomere function and some features that appear to be unique. BNA2 is the second most highly up-regulated gene upon telomere uncapping in cdc13-1 strains and is required for the biosynthesis of NAD+. We have shown that deletion of BNA2 and other genes involved in NAD+ synthesis, suppresses the temperature sensitivity of cdc13-1 strains. NAD+ synthetic genes may therefore play previously unknown roles in the cellular response to telomere uncapping.

2010-02-24 | E-MEXP-1551 | biostudies-arrayexpress

Histone H3 N-terminus Regulates Higher Order Structure of Yeast Heterochromatin

Project description:In budding yeast, telomeres and the mating type (HM) loci are found in a heterochromatin-like silent structure initiated by Rap1 and extended by the interaction of Sir (Silencing Information Regulator) proteins with histones. Binding data demonstrate that both the H3 and H4 N terminal domains required for silencing in vivo interact directly with Sir3 and Sir4 in vitro. The role of H4 lysine 16 deacetylation is well established in Sir3 protein recruitment, however that of the H3 N terminal tail has remained unclear. In order to characterize the role of H3 in silent chromatin formation and compare it to H4 we have generated comprehensive high resolution genome-wide binding maps of heterochromatin proteins. We find that H4 lysine 16 deacetylation is required for the recruitment and spreading of heterochromatin proteins at all telomeres and HM loci. In contrast the H3 N terminus is required for neither recruitment nor spreading of Sir proteins. Instead, deletion of the H3 tail leads to increased accessibility within heterochromatin of an ectopic bacterial dam methylase and the decreased mobility of an HML heterochromatic fragment in sucrose gradients. These findings indicate an altered chromatin structure. We propose that Sir proteins recruited by the H4 tail then interact with the H3 tail to form a higher order silent chromatin structure.

2009-08-01 | GSE16742 | GEO

SESAME-catalyzed H3T11 phosphorylation inhibits Dot1-catalyzed H3K79me3 to regulate autophagy and telomere silencing

Project description:The glycolytic enzyme, pyruvate kinase Pyk1 maintains telomere heterochromatin by phosphorylating histone H3T11 (H3pT11), which promotes SIR (silent information regulator) complex binding at telomeres and prevents autophagy-mediated Sir2 degradation. However, the exact action mechanism of H3pT11 is poorly understood. Here, we report that H3pT11 directly inhibits Dot1-catalyzed H3K79 tri-methylation (H3K79me3) and uncover how this histone crosstalk regulates autophagy and telomere silencing. Mechanistically, Pyk1-catalyzed H3pT11 directly reduces the binding of Dot1 to chromatin and inhibits Dot1-catalyzed H3K79me3, which leads to transcriptional repression of autophagy genes and reduced autophagy. Despite the antagonism between H3pT11 and H3K79me3, they work together to promote the binding of SIR complex at telomeres to maintain telomere silencing. Furthermore, we identify Reb1 as a telomere-associated factor that recruits Pyk1-containing SESAME (Serine-responsive SAM36 taining Metabolic Enzyme) complex to telomere regions to phosphorylate H3T11 and prevent the invasion of H3K79me3 from euchromatin into heterochromatin to maintain telomere silencing. Together, these results uncover a novel histone crosstalk and provide insights into dynamic regulation of silent heterochromatin and autophagy in response to cell metabolism.

2023-02-07 | PXD038138 | Pride

Chip-chip of Sir3 and of Sir2, and ChAP-chip of AAR from budding yeast cells

Project description:O-acetyl-ADP-ribose (AAR) is a small metabolic molecule that is generated during NAD-dependent deacetylation by Sir2. Sir2 regulates gene expression, DNA repair, and genome stability. chromatin affinity-precipitation (ChAP) method was used to detect the chromatin fragments at which small molecules interact with binding partners. Chromatin immunoprecipitation of Sir3 and of Sir2, respectively, applied with tilling array chip (ChIP on chip of Sir3 and of Sir2, respectively) and Chromatin affinity-precipitation of AAR applied with tilling array chip (ChAP on chip of AAR ) analysis demonstrated that an extended spreading of Sir3 and of AAR, but not Sir2 in Saccharomyces cerevisiae Ysa1 deleted cells compared with those in wild type cells Comparison the distributions of Sir3, of Sir2 and of AAR on silent heterochromatin of Ysa1 deletion cells vs those of wild type cells

2015-12-31 | E-GEOD-65672 | biostudies-arrayexpress

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

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

Metabolic regulation of telomere silencing by SESAME complex-catalyzed H3T11 phosphorylation

Project description:Telomeres are organized into a heterochromatin structure and maintenance of silent heterochromatin is required for chromosome stability. How telomere heterochromatin is dynamically regulated in response to stimuli remains unknown. Pyruvate kinase Pyk1 forms a complex, named SESAME (Serine-responsive SAM-containing Metabolic Enzyme complex) to regulate gene expression by phosphorylating histone H3T11 (H3pT11). Here, we identified a novel function of SESAME in regulating telomere heterochromatin structure. SESAME phosphorylates H3T11 at telomeres, which promotes SIR (silent information regulator) complex assembly at telomeres and protects Sir2 from degradation by autophagy. Moreover, SESAMEcatalyzed H3pT11 directly represses autophagy-related gene expression to further prevent autophagy-mediated Sir2 degradation. By promoting H3pT11, serine increases Sir2 protein levels and enhances telomere silencing. Loss of H3pT11 leads to reduced Sir2 and compromised telomere silencing during chronological aging. Together, our study provides insights into dynamic regulation of silent heterochromatin by histone modifications and autophagy in response to cell metabolism and aging.

2020-12-04 | GSE147050 | GEO

Saccharomyces cerevisiae

Project description:γH2A is a component of yeast heterochromatin required for telomere elongation

| PRJNA127257 | ENA