ATP-dependent chromatosome remodeling

Maier, Verena; Chioda, Mariacristina; Becker, Peter B.

doi:10.1515/bc.2008.040

Cited by 20 publications

(33 citation statements)

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“…ISWI can promote the assembly of nucleosome arrays containing H1 in vitro (Lusser et al 2005;Maier et al 2008), suggesting that it may be required for replication-coupled chromatin assembly in vivo. ISWI could also promote H1 incorporation via a replication-independent mechanism, since H1 undergoes rapid, ATP-dependent exchange throughout the cell cycle in other organisms (Catez et al 2006).…”

Section: Resultsmentioning

confidence: 99%

“…These abundant, basic proteins share a common structure consisting of a globular winged helix DNA-binding domain flanked by a short N-terminal segment and a C-terminal domain of 100 amino acids (Brown 2003). The winged helix domain of H1 binds the nucleosome near the site of DNA entry and exit; the flanking domains interact with core and linker DNA to promote the formation and packaging of 30-nm fibers in vitro (Robinson and Rhodes 2006;Maier et al 2008). …”

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Drosophila ISWI Regulates the Association of Histone H1 With Interphase Chromosomesin Vivo

et al. 2009

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Although tremendous progress has been made toward identifying factors that regulate nucleosome structure and positioning, the mechanisms that regulate higher-order chromatin structure remain poorly understood. Recent studies suggest that the ISWI chromatin-remodeling factor plays a key role in this process by promoting the assembly of chromatin containing histone H1. To test this hypothesis, we investigated the function of H1 in Drosophila. The association of H1 with salivary gland polytene chromosomes is regulated by a dynamic, ATP-dependent process. Reducing cellular ATP levels triggers the dissociation of H1 from polytene chromosomes and causes chromosome defects similar to those resulting from the loss of ISWI function. H1 knockdown causes even more severe defects in chromosome structure and a reduction in nucleosome repeat length, presumably due to the failure to incorporate H1 during replication-dependent chromatin assembly. Our findings suggest that ISWI regulates higher-order chromatin structure by modulating the interaction of H1 with interphase chromosomes. T HE packaging of DNA into chromatin is critical for the organization and regulation of eukaryotic genes. The basic unit of chromatin structure-the nucleosome--can be packaged in 30-nm fibers and increasingly compact structures. Higher-order chromatin structure influences many aspects of gene expression, including transcription factor binding, enhancer-promoter interactions, and the organization of chromatin into functional domains. Histone H1 and related linker histones are important determinants of higher-order chromatin structure. These abundant, basic proteins share a common structure consisting of a globular winged helix DNA-binding domain flanked by a short N-terminal segment and a C-terminal domain of 100 amino acids (Brown 2003). The winged helix domain of H1 binds the nucleosome near the site of DNA entry and exit; the flanking domains interact with core and linker DNA to promote the formation and packaging of 30-nm fibers in vitro (Robinson and Rhodes 2006;Maier et al. 2008).

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Section: Resultsmentioning

confidence: 99%

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Drosophila ISWI Regulates the Association of Histone H1 With Interphase Chromosomesin Vivo

et al. 2009

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“…Although 2-fold effects can be significant in gene expression, as is the case with dosage compensation and haploinsufficiency diseases, it seems more likely that these modifications do not singularly reposition nucleosomes in vivo. We regard it more likely that these modifications facilitate nucleosome repositioning in the presence of associated chromatin remodeling factors (16,42).…”

Section: Discussionmentioning

confidence: 99%

Acetylation of Histone H3 at the Nucleosome Dyad Alters DNA-Histone Binding

Manohar¹,

Mooney²,

North³

et al. 2009

Journal of Biological Chemistry

122

153

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Histone post-translational modifications are essential for regulating and facilitating biological processes such as RNA transcription and DNA repair. Fifteen modifications are located in the DNA-histone dyad interface and include the acetylation of H3-K115 (H3-K115Ac) and H3-K122 (H3-K122Ac), but the functional consequences of these modifications are unknown. We have prepared semisynthetic histone H3 acetylated at Lys-115 and/or Lys-122 by expressed protein ligation and incorporated them into single nucleosomes. Competitive reconstitution analysis demonstrated that the acetylation of H3-K115 and H3-K122 reduces the free energy of histone octamer binding. Restriction enzyme kinetic analysis suggests that these histone modifications do not alter DNA accessibility near the sites of modification. However, acetylation of H3-K122 increases the rate of thermal repositioning. Remarkably, Lys 3 Gln substitution mutations, which are used to mimic Lys acetylation, do not fully duplicate the effects of the H3-K115Ac or H3-K122Ac modifications. Our results are consistent with the conclusion that acetylation in the dyad interface reduces DNA-histone interaction(s), which may facilitate nucleosome repositioning and/or assembly/disassembly.All eukaryotic genomes are organized into strings of nucleosomes, where 147 bp of DNA are tightly wrapped around a histone protein octamer (1). Many biological processes are dependent on DNA-protein interactions. However, access to DNA-binding sites is often restricted by the nucleosome structure. Alterations in nucleosome structure, dynamics, and positioning have been hypothesized to play a gatekeeper role in regulating biological processes such as DNA replication, repair, and transcription (2).The post-translational modification (PTM) 3 of core histones (3) plays a central role in regulating the biological processing of eukaryotic genomes. Until recently, known histone PTMs were almost exclusively located on the unstructured histone tail regions, which extend from the structured core of the nucleosomes. PTMs in the histone tails can function to directly alter nucleosome (4 -6) and/or chromatin structure and stability (7,8) and function as protein-binding sites (9) in the "histone code" model (10).During the past 5 years over 30 additional histone PTMs were identified within structured regions of the nucleosome (11-13). Many of these modifications are buried within the nucleosome core and thus are not readily accessible for protein binding. Fifteen of these histone PTMs are located in the DNAhistone interface, where the histone octamer contacts the phosphate backbone of the wrapped DNA (14). Studies have suggested that only mild structural perturbations occur in coremodified nucleosomes, which implies that modifications buried beneath the DNA are unlikely to provide a protein-binding site (15). This has led to two additional models for the function of nucleosome core PTMs.Modifications such as Lys acetylation that reduce the positive charge of the histone octamer surface may reduce the bindi...

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“…mpressive progress has been achieved during the last decade with regard to the functional implications of DNA methylation, histone modifications, and chromatin remodeling events for gene regulation (Fuks 2005;Kouzarides 2007;Maier et al 2008;Jiang and Pugh 2009). It has, however, also become obvious that decoding the chromatin language does not suffice to fully understand the ways in which the diploid genome contributes to the formation of the different epigenomes present in the various cell types of a multicellular organism.…”

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Chromosome Territories

Cremer¹,

Cremer²

2010

Cold Spring Harbor Perspectives in Biology

955

813

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Chromosome territories (CTs) constitute a major feature of nuclear architecture. In a brief statement, the possible contribution of nuclear architecture studies to the field of epigenomics is considered, followed by a historical account of the CT concept and the final compelling experimental evidence of a territorial organization of chromosomes in all eukaryotes studied to date. Present knowledge of nonrandom CT arrangements, of the internal CT architecture, and of structural interactions with other CTs is provided as well as the dynamics of CT arrangements during cell cycle and postmitotic terminal differentiation. The article concludes with a discussion of open questions and new experimental strategies to answer them.

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ATP-dependent chromatosome remodeling

Cited by 20 publications

References 54 publications

Drosophila ISWI Regulates the Association of Histone H1 With Interphase Chromosomesin Vivo

Drosophila ISWI Regulates the Association of Histone H1 With Interphase Chromosomesin Vivo

Acetylation of Histone H3 at the Nucleosome Dyad Alters DNA-Histone Binding

Chromosome Territories

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