scholarly journals Quiescent Saccharomyces cerevisiae forms telomere hyperclusters at the nuclear membrane vicinity through a multifaceted mechanism involving Esc1, the Sir complex, and chromatin condensation

2016 ◽  
Vol 27 (12) ◽  
pp. 1875-1884 ◽  
Author(s):  
Damien Laporte ◽  
Fabien Courtout ◽  
Sylvain Tollis ◽  
Isabelle Sagot
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Nuclear Membrane ◽  
Chromatin Condensation ◽  
Histone H1 ◽  
Chromosome Condensation ◽  
Histone H4 ◽  
Microtubule Bundle ◽  
Quiescent Cells ◽  
Nuclear Reorganization ◽  
Sir Complex

Like other eukaryotes, Saccharomyces cerevisiae spatially organizes its chromosomes within the nucleus. In G1 phase, the yeast’s 32 telomeres are clustered into 6–10 foci that dynamically interact with the nuclear membrane. Here we show that, when cells leave the division cycle and enter quiescence, telomeres gather into two to three hyperclusters at the nuclear membrane vicinity. This localization depends on Esc1 but not on the Ku proteins. Telomere hypercluster formation requires the Sir complex but is independent of the nuclear microtubule bundle that specifically assembles in quiescent cells. Importantly, mutants deleted for the linker histone H1 Hho1 or defective in condensin activity or affected for histone H4 Lys-16 deacetylation are impaired, at least in part, for telomere hypercluster formation in quiescence, suggesting that this process involves chromosome condensation. Finally, we establish that telomere hypercluster formation is not necessary for quiescence establishment, maintenance, and exit, raising the question of the physiological raison d’être of this nuclear reorganization.

scholarly journals Sir3-Nucleosome Interactions in Spreading of Silent Chromatin in Saccharomyces cerevisiae

2008 ◽  
Vol 28 (22) ◽  
pp. 6903-6918 ◽  
Author(s):  
Johannes R. Buchberger ◽  
Megumi Onishi ◽  
Geng Li ◽  
Jan Seebacher ◽  
Adam D. Rudner ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Binding Activity ◽  
Chromatin Fiber ◽  
Silent Chromatin ◽  
Histone H4 ◽  
Histone Binding ◽  
Aaa Atpase ◽  
Binding Domains ◽  
Sir Complex

ABSTRACT Silent chromatin in Saccharomyces cerevisiae is established in a stepwise process involving the SIR complex, comprised of the histone deacetylase Sir2 and the structural components Sir3 and Sir4. The Sir3 protein, which is the primary histone-binding component of the SIR complex, forms oligomers in vitro and has been proposed to mediate the spreading of the SIR complex along the chromatin fiber. In order to analyze the role of Sir3 in the spreading of the SIR complex, we performed a targeted genetic screen for alleles of SIR3 that dominantly disrupt silencing. Most mutations mapped to a single surface in the conserved N-terminal BAH domain, while one, L738P, localized to the AAA ATPase-like domain within the C-terminal half of Sir3. The BAH point mutants, but not the L738P mutant, disrupted the interaction between Sir3 and nucleosomes. In contrast, Sir3-L738P bound the N-terminal tail of histone H4 more strongly than wild-type Sir3, indicating that misregulation of the Sir3 C-terminal histone-binding activity also disrupted spreading. Our results underscore the importance of proper interactions between Sir3 and the nucleosome in silent chromatin assembly. We propose a model for the spreading of the SIR complex along the chromatin fiber through the two distinct histone-binding domains in Sir3.

scholarly journals Drosophila Mcm10 Interacts with Members of the Prereplication Complex and Is Required for Proper Chromosome Condensation

2003 ◽  
Vol 14 (6) ◽  
pp. 2206-2215 ◽  
Author(s):  
Tim W. Christensen ◽  
Bik K. Tye
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Drosophila Melanogaster ◽  
Dna Replication ◽  
Dna Content ◽  
Chromatin Condensation ◽  
Chromosome Condensation ◽  
Null Mutant ◽  
Aberrant Chromosome ◽  
Initiation Of Dna Replication

Mcm10 is required for the initiation of DNA replication in Saccharomyces cerevisiae. We have cloned MCM10 from Drosophila melanogaster and show that it complements a ScMCM10 null mutant. Moreover, Mcm10 interacts with key members of the prereplication complex: Mcm2, Dup (Cdt1), and Orc2. Interactions were also detected between Mcm10 and itself, Cdc45, and Hp1. RNAi depletion of Orc2 and Mcm10 in KC cells results in loss of DNA content. Furthermore, depletion of Mcm10, Cdc45, Mcm2, Mcm5, and Orc2, respectively, results in aberrant chromosome condensation. The condensation defects observed resemble previously published reports for Orc2, Orc5, and Mcm4 mutants. Our results strengthen and extend the argument that the processes of chromatin condensation and DNA replication are linked.

Roscovitine, a specific inhibitor of cyclin-dependent protein kinases, reversibly inhibits chromatin condensation during in vitro maturation of porcine oocytes

Zygote ◽  
2001 ◽  
Vol 9 (4) ◽  
pp. 309-316 ◽  
Author(s):  
Carsten Krischek ◽  
Burkhard Meinecke
Keyword(s):  
Map Kinase ◽  
Protein Kinases ◽  
Chromatin Condensation ◽  
Specific Inhibitor ◽  
Histone H1 ◽  
Dependent Manner ◽  
Free Medium ◽  
Concentration Dependent Manner ◽  
Dependent Protein

In the present study the effects of roscovitine on the in vitro nuclear maturation of porcine oocytes were investigated. Roscovitine, a specific inhibitor of cyclin-dependent protein kinases, prevented chromatin condensation in a concentration-dependent manner. This inhibition was reversible and was accompanied by non-activation of p34cdc2/histone H1 kinase. It also decreased enzyme activity of MAP kinase, suggesting a correlation between histone H1 kinase activation and the onset of chromatin condensation. The addition of roscovitine (50 μM) to extracts of metaphase II oocytes revealed that the MAP kinase activity was not directly affected by roscovitine, which indicates a possible link between histone H1 and MAP kinase. Chromatin condensation occurred between 20 and 28 h of culture of cumulus-oocyte complexes (COCs) in inhibitor-free medium (germinal vesicle stage I, GV1: 74.6% and 13.7%, respectively). Nearly the same proportion of chromatin condensation was detected in COCs incubated initially in inhibitor-free medium for 20-28 h and subsequently in roscovitine-supplemented medium (50 μM) for a further 2-10 h (GV I: 76.2% and 18.8%, respectively). This observation indicates that roscovitine prevents chromatin condensation even after an initial inhibitor-free cultivation for 20 h. Extending this initial incubation period to ≥22 h led to an activation of histone H1 and MAP kinase and increasing proportions of oocytes exhibiting chromatin condensation in the presence of roscovitine. It is concluded that histone H1 kinase is involved in the induction of chromatin condensation during in vitro maturation of porcine oocytes.

Chromosome condensation induced by geminivirus infection of mature plant cells

2000 ◽  
Vol 113 (7) ◽  
pp. 1149-1160 ◽  
Author(s):  
H.W. Bass ◽  
S. Nagar ◽  
L. Hanley-Bowdoin ◽  
D. Robertson
Keyword(s):  
Coat Protein ◽  
Chromatin Condensation ◽  
Nuclear Periphery ◽  
Nuclear Architecture ◽  
Plant Cells ◽  
Image Data ◽  
Chromosome Condensation ◽  
Fish Analysis ◽  
Viral Dna ◽  
Plant Dna

Tomato golden mosaic virus (TGMV) is a geminivirus that replicates its single-stranded DNA genome through double-stranded DNA intermediates in nuclei of differentiated plant cells using host replication machinery. We analyzed the distribution of viral and plant DNA in nuclei of infected leaves using fluorescence in situ hybridization (FISH). TGMV-infected nuclei showed up to a sixfold increase in total volume and displayed a variety of viral DNA accumulation patterns. The most striking viral DNA patterns were bright, discrete intranuclear compartments, but diffuse nuclear localization was also observed. Quantitative and spatial measurements of high resolution 3-dimensional image data revealed that these compartments accounted for 1–18% of the total nuclear volume or 2–45% of the total nuclear FISH signals. In contrast, plant DNA was concentrated around the nuclear periphery. In a significant number of nuclei, the peripheral chromatin was organized as condensed prophase-like fibers. A combination of FISH analysis and indirect immunofluorescence with viral coat protein antibodies revealed that TGMV virions are associated with the viral DNA compartments. However, the coat protein antibodies failed to cross react with some large viral DNA inclusions, suggesting that encapsidation may occur after significant viral DNA accumulation. Infection by a TGMV mutant with a defective coat protein open reading frame resulted in fewer and smaller viral DNA-containing compartments. Nevertheless, nuclei infected with the mutant virus increased in size and in some cases showed chromosome condensation. Together, these results established that geminivirus infection alters nuclear architecture and can induce plant chromatin condensation characteristic of cells arrested in early mitosis.

Histone H1 expressed in Saccharomyces cerevisiae binds to chromatin and affects survival, growth, transcription, and plasmid stability but does not change nucleosomal spacing

1994 ◽  
Vol 14 (4) ◽  
pp. 2822-2835
Author(s):  
C Linder ◽  
F Thoma
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Plasmid Stability ◽  
Apparent Molecular Weight ◽  
Histone H1 ◽  
Expression Levels ◽  
Inhibition Of Growth ◽  
Gene Coding ◽  
Gal1 Promoter ◽  
Core Histones ◽  
Low Levels

Histone H1 is proposed to serve a structural role in nucleosomes and chromatin fibers, to affect the spacing of nucleosomes, and to act as a general repressor of transcription. To test these hypotheses, a gene coding for a sea urchin histone H1 was expressed from the inducible GAL1 promoter in Saccharomyces cerevisiae by use of a YEp vector for high expression levels (strain YCL7) and a centromere vector for low expression levels (strain YCL1). The H1 protein was identified by its inducibility in galactose, its apparent molecular weight, and its solubility in 5% perchloric acid. When YCL7 was shifted from glucose to galactose for more than 40 h to achieve maximal levels of H1, H1 could be copurified in approximately stoichiometric amounts with core histones of Nonidet P-40-washed nuclei and with soluble chromatin fractionated on sucrose gradients. While S. cerevisiae tolerated the expression of low levels of H1 in YCL1 without an obvious phenotype, the expression of high levels of H1 correlated with greatly reduced survival, inhibition of growth, and increased plasmid loss but no obvious change in the nucleosomal repeat length. After an initial induction, RNA levels for GAL1 and H1 were drastically reduced, suggesting that H1 acts by the repression of galactose-induced genes. Similar effects, but to a lower extent, were observed when the C-terminal tail of H1 was expressed.

scholarly journals Local chromatin fiber folding represses transcription and loop extrusion in quiescent cells

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Sarah G Swygert ◽  
Dejun Lin ◽  
Stephanie Portillo-Ledesma ◽  
Po-Yen Lin ◽  
Dakota R Hunt ◽  
...  
Keyword(s):  
Chromatin Fiber ◽  
State Transitions ◽  
Chromatin Domain ◽  
Global Changes ◽  
Histone H4 ◽  
Mitotic Chromosomes ◽  
Quiescent Cells ◽  
Genome Wide ◽  
Dividing Cells ◽  
The Relationship

A longstanding hypothesis is that chromatin fiber folding mediated by interactions between nearby nucleosomes represses transcription. However, it has been difficult to determine the relationship between local chromatin fiber compaction and transcription in cells. Further, global changes in fiber diameters have not been observed, even between interphase and mitotic chromosomes. We show that an increase in the range of local inter-nucleosomal contacts in quiescent yeast drives the compaction of chromatin fibers genome-wide. Unlike actively dividing cells, inter-nucleosomal interactions in quiescent cells require a basic patch in the histone H4 tail. This quiescence-specific fiber folding globally represses transcription and inhibits chromatin loop extrusion by condensin. These results reveal that global changes in chromatin fiber compaction can occur during cell state transitions, and establish physiological roles for local chromatin fiber folding in regulating transcription and chromatin domain formation.

scholarly journals Histone H4 Lysine 12 Acetylation Regulates Telomeric Heterochromatin Plasticity in Saccharomyces cerevisiae

PLoS Genetics ◽  
2011 ◽  
Vol 7 (1) ◽  
pp. e1001272 ◽  
Author(s):  
Bo O. Zhou ◽  
Shan-Shan Wang ◽  
Yang Zhang ◽  
Xiao-Hong Fu ◽  
Wei Dang ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Histone H4 ◽  
Telomeric Heterochromatin

Characterization of monomeric DNA-binding protein Histone H1 inLeishmania braziliensis

Parasitology ◽  
2011 ◽  
Vol 138 (9) ◽  
pp. 1093-1101 ◽  
Author(s):  
EMMA CARMELO ◽  
GLORIA GONZÁLEZ ◽  
TERESA CRUZ ◽  
ANTONIO OSUNA ◽  
MARIANO HERNÁNDEZ ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Dna Binding ◽  
Chromatin Condensation ◽  
Histone H1 ◽  
Mass Spectrometry Analysis ◽  
Globular Domain ◽  
Mobility Shift ◽  
Aggregation State ◽  
Genome Database

SUMMARYHistone H1 inLeishmaniapresents relevant differences compared to higher eukaryote counterparts, such as the lack of a DNA-binding central globular domain. Despite that, it is apparently fully functional since its differential expression levels have been related to changes in chromatin condensation and infectivity, among other features. The localization and the aggregation state ofL. braziliensisH1 has been determined by immunolocalization, mass spectrometry, cross-linking and electrophoretic mobility shift assays. Analysis of H1 sequences from theLeishmaniaGenome Database revealed that our protein is included in a very divergent group of histones H1 that is present only inL. braziliensis.An antibody raised against recombinantL. braziliensisH1 recognized specifically that protein by immunoblot inL. braziliensisextracts, but not in otherLeishmaniaspecies, a consequence of the sequence divergences observed amongLeishmaniaspecies. Mass spectrometry analysis andin vitroDNA-binding experiments have also proven thatL. braziliensisH1 is monomeric in solution, but oligomerizes upon binding to DNA. Finally, despite the lack of a globular domain,L. braziliensisH1 is able to form complexes with DNAin vitro, with higher affinity for supercoiled compared to linear DNA.

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