Characterization of the Stability and Folding of H2A.Z Chromatin Particles

Abbott, D. Wade; Ivanova, Vessela S.; Wang, Xiaoying; Bonner, William M.; Ausió, Juan

doi:10.1074/jbc.m108217200

Cited by 147 publications

(120 citation statements)

References 57 publications

(65 reference statements)

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“…The increase in the stability of the (H2A.Z-H2B) dimer-(H3-H4) 2 tetramer interaction suggests that replacement of a H2A-H2B dimer with a dimer containing H2A.Z may impede elongation of transcription by RNA polymerase II, and is consistent with our proposal that H2A.Z plays an important role in establishing an architecturally distinct higher order chromatin structure at constitutive heterochromatin (22). They are, however, in disagreement with earlier studies in which structural transitions in H2A.Z NCPs were studied using analytical ultracentrifugation (53). These authors showed that the ionic strength dependence of the sedimentation coefficient of these particles exhibits a destabilization, and attribute this destabilization to the less stable binding of the (H2A.Z-H2B) dimer with the remainder of the nucleosome.…”

Section: Discussioncontrasting

confidence: 57%

A New Fluorescence Resonance Energy Transfer Approach Demonstrates That the Histone Variant H2AZ Stabilizes the Histone Octamer within the Nucleosome

Park

Dyer

Tremethick

et al. 2004

Journal of Biological Chemistry

203

200

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Nucleosomes are highly dynamic macromolecular complexes that are assembled and disassembled in a modular fashion. One important way in which this dynamic process can be modulated is by the replacement of major histones with their variants, thereby affecting nucleosome structure and function. Here we use fluorescence resonance energy transfer between fluorophores attached to various defined locations within the nucleosome to dissect and compare the structural transitions of a H2A.Z containing and a canonical nucleosome in response to increasing ionic strength. We show that the peripheral regions of the DNA dissociate from the surface of the histone octamer at relatively low ionic strength, under conditions where the dimer-tetramer interaction remains unaffected. At around 550 mM NaCl, the (H2A-H2B) dimer dissociates from the (H3-H4) 2 tetramer-DNA complex. Significantly, this latter transition is stabilized in nucleosomes that have been reconstituted with the essential histone variant H2A.Z. Our studies firmly establish fluorescence resonance energy transfer as a valid method to study nucleosome stability, and shed new light on the biological function of H2A.Z.Chromatin is built from nucleosomes, the universally repeating protein-DNA complexes in all eukaryotic cells. The crystal structure of the nucleosome core particle (NCP) 1 (1) reveals an octameric histone core around which 147 base pairs of DNA are wrapped in 1.65 tight superhelical turns. The histone octamer itself is a modular assembly of two copies each of the four histone proteins H2A, H2B, H3, and H4. Two histone pairs, composed either of H2A and H2B, or H3 and H4, form stable heterodimers. In solution, two H3-H4 dimers form a tetramer in the shape of a flat, twisted horseshoe that binds the central 60 base pairs of the nucleosomal DNA around its outside (1, 2). One (H2A-H2B) dimer is tethered to each face of the (H3-H4) 2 tetramer-DNA complex, to complete a "helical ramp" for continued DNA binding (reviewed in Ref.3).The interaction between the two histone subcomplexes occurs via two spatially distinct interaction interfaces of quite different character (Fig. 1). A four-helix bundle structure (formed by H2B and H4) is characterized mainly by hydrophobic interactions, and buries 1000 Å 2 (1). The second, larger interface (1600 Å 2 ) is characterized mostly by direct and solvent-mediated hydrogen bonds between the "docking domain" of H2A, and the histone fold extensions of H3 and H4 (4). In addition, a small interface is formed between the L1 loops of the two H2A molecules, which may contribute to holding together the two gyres of the DNA superhelix at the back of the nucleosome (Fig. 1) (5). Under physiological conditions, the (H2A-H2B) dimer associates stably with the (H3-H4) 2 tetramer only in the presence of DNA (6). Each (H2A-H2B) dimer organizes 30 base pairs toward either end of the DNA. The penultimate 10 base pairs of nucleosomal DNA on either side are organized by a region of H3 that does not form an integral part of the (H3-H4) 2 tetramer, an...

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Section: Discussioncontrasting

confidence: 57%

A New Fluorescence Resonance Energy Transfer Approach Demonstrates That the Histone Variant H2AZ Stabilizes the Histone Octamer within the Nucleosome

Park

Dyer

Tremethick

et al. 2004

Journal of Biological Chemistry

203

200

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“…H2A.Z is also removed from promoter sequences of many yeast genes upon induction of gene transcription; it is not clear if this occurs via a passive or active mechanism (Santisteban et al 2000;Adam et al 2001;Larochelle and Gaudreau 2003;Zhang et al 2005). Since H2A.Z nucleosomes may be intrinsically unstable compared to H2A-containing nucleosomes (Suto et al 2000;Abbott 2001;Zhang et al 2005;Dion et al 2007) the dynamic changes in chromosome structure occurring at telophase may act to preferentially displace H2A.Z-containing nucleosomes. Our H3 ChIP results suggest that these nucleosomes are rapidly replaced by ones containing conventional H2A.…”

Section: Discussionmentioning

confidence: 99%

H2A.Z (Htz1) Controls the Cell-Cycle-Dependent Establishment of Transcriptional Silencing at Saccharomyces cerevisiae Telomeres

Martins-Taylor

Sharma²,

Rozario³

et al. 2011

Genetics

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The establishment of transcriptional silencing in Saccharomyces cerevisiae requires progression through the cell cycle. We have previously found that transit through M-phase is necessary and sufficient to establish silencing at telomeres following induction of the Sir3 silencing factor. In this study we find that halting cell-cycle progression in either G 1 or at the beginning of M-phase limits the ability of Sir3 to associate with a telomere-linked reporter gene and prevents the changes in histone modifications associated with gene repression. Deletion of genes coding for the histone variant H2A.Z (Htz1 in yeast) and histone acetyltransferase Sas2 abolish the cell-cycle progression requirement for the establishment of silencing. Cells blocked in telophase (but not at metaphase) are also able to establish silencing. We show that H2A.Z binds to the promoter of our telomere-linked reporter gene and that this binding diminishes in silenced cells. Finally, we observe a specific displacement of H2A.Z from chromatin in telophaseblocked cells, regardless of the silencing status of the reporter gene. These results suggest that the requirement for M-phase in the establishment of silencing may reflect a cell-cycle regulated relaxation of heterochromatin barriers.

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“…For example, the crystal structure of the variant histone H2A.Z shows specific local molecular changes that could affect the stability of the H2A.Z nucleosome particle (32). This could explain, in turn, the reported distinct properties of H2A.Z nucleosomal arrays in solution (1,15,16,32). Recent data demonstrated that a novel histone variant, H2A.Bbd, is less tightly bound both in vitro and in vivo in the nucleosome than is H2A (6,17).…”

mentioning

confidence: 92%

Weak but Uniform Enrichment of the Histone Variant macroH2A1 along the Inactive X Chromosome

Mietton

Sengupta

Molla

et al. 2009

Molecular and Cellular Biology

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We studied the enrichment and distribution of the histone variant mH2A1 in the condensed inactive X (Xi) chromosome. By using highly specific antibodies against mH2A1 and stable HEK 293 cell lines expressing either green fluorescent protein (GFP)-mH2A1 or GFP-H2A, we found that the Xi chromosome contains ϳ1.5-fold more mH2A1 than the autosomes. To determine the in vivo distribution of mH2A1 along the X chromosome, we used a native chromatin immunoprecipitation-on-chip technique. DNA isolated from mH2A1-immunoprecipitated nucleosomes from either male or female mouse liver were hybridized to tiling microarrays covering 5 kb around most promoters or the entire X chromosome. The data show that mH2A1 is uniformly distributed across the entire Xi chromosome. Interestingly, a stronger mH2A1 enrichment along the pseudoautosomal X chromosome region was observed in both sexes. Our results indicate a potential role for macroH2A in large-scale chromosome structure and genome stability.

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Characterization of the Stability and Folding of H2A.Z Chromatin Particles

Cited by 147 publications

References 57 publications

A New Fluorescence Resonance Energy Transfer Approach Demonstrates That the Histone Variant H2AZ Stabilizes the Histone Octamer within the Nucleosome

A New Fluorescence Resonance Energy Transfer Approach Demonstrates That the Histone Variant H2AZ Stabilizes the Histone Octamer within the Nucleosome

H2A.Z (Htz1) Controls the Cell-Cycle-Dependent Establishment of Transcriptional Silencing at Saccharomyces cerevisiae Telomeres

Weak but Uniform Enrichment of the Histone Variant macroH2A1 along the Inactive X Chromosome

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