Structure and function of the histone chaperone CIA/ASF1 complexed with histones H3 and H4

Natsume, Ryo; Eitoku, Masamitsu; Akai, Yusuke; Sano, Norihiko; Horikoshi, Masami; Senda, Toshiya

doi:10.1107/s010876730808803x

Cited by 89 publications

(182 citation statements)

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“…The histone chaperones Asf1, HIR, FACT, and Spt6 are important for transcription-coupled exchange of histones H3 and H4 (16,(26)(27)(28)(29). The crystal structure of Asf1 bound to an H3-H4 dimer prompted a "strand capture" model, in which Asf1 splits H3-H4 tetramers into dimers during nucleosome disassembly by interacting with the H4 tail (30), and this mechanism is supported by biochemical analyses (3,31). Our detection of mixed tetramers at sites of dynamic chromatin provides in vivo support for such a strand capture mechanism, although the presumptive chaperone (s) mediating the observed tetramer splitting is unknown.…”

Section: Relative Ip Efficiencymentioning

confidence: 83%

Splitting of H3–H4 tetramers at transcriptionally active genes undergoing dynamic histone exchange

Katan-Khaykovich

Struhl

2011

Proc. Natl. Acad. Sci. U.S.A.

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Nucleosome deposition occurs on newly synthesized DNA during DNA replication and on transcriptionally active genes via nucleosome-remodeling complexes recruited by activator proteins and elongating RNA polymerase II. It has been long believed that histone deposition involves stable H3-H4 tetramers, such that newly deposited nucleosomes do not contain H3 and H4 molecules with their associated histone modifications from preexisting nucleosomes. However, biochemical analyses and recent experiments in mammalian cells have raised the idea that preexisting H3-H4 tetramers might split into dimers, resulting in mixed nucleosomes composed of "old" and "new" histones. It is unknown to what extent different genomic loci might utilize such a mechanism and under which circumstances. Here, we address whether tetramer splitting occurs in a locus-specific manner by using sequential chromatin immunoprecipitation of mononucleosomes from yeast cells containing two differentially tagged versions of H3 that are expressed "old" and "new" histones. At many genomic loci, we observe little or no nucleosomal cooccupancy of old and new H3, indicating that tetramer splitting is generally infrequent. However, cooccupancy is detected at highly active genes, which have a high rate of histone exchange. Thus, DNA replication largely results in nucleosomes bearing exclusively old or new H3-H4, thereby precluding the acquisition of new histone modifications based on preexisting modifications within the same nucleosome. In contrast, tetramer splitting, dimer exchange, and nucleosomes with mixed H3-H4 tetramers occur at highly active genes, presumably linked to rapid histone exchange associated with robust transcription.T he packaging of eukaryotic DNA into chromatin influences many DNA-associated processes, including transcriptional regulation. Within the chromatin fiber, each basic nucleosome unit bears important chemical and structural information. The mechanisms by which nucleosomes are assembled on DNA during replication, transcription, DNA repair, etc., can thus impact not only the integrity of chromatin structure but also patterns of gene expression and epigenetic inheritance. The H3-H4 tetramer core of each nucleosome is the more stable component and contains most of the relatively persistent and functionally important histone methylation marks. Much attention has therefore been given to the questions of how the H3-H4 tetramers are formed and maintained on chromatin.Early studies attempted to distinguish between a conservative assembly model, by which old and new histones form separate tetramers on replicating DNA, and a semiconservative assembly mechanism, by which existing tetramers are split into H3-H4 dimers, followed by association of new H3-H4 dimers to complete each nucleosome core (1-3). In the semiconservative model, the resulting tetramers would bear a mixture of old and new histones, allowing transmission of epigenetic information within the basic nucleosome unit. Though mechanistically attractive, the mixed tetramer model receiv...

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Section: Relative Ip Efficiencymentioning

confidence: 83%

Splitting of H3–H4 tetramers at transcriptionally active genes undergoing dynamic histone exchange

Katan-Khaykovich

Struhl

2011

Proc. Natl. Acad. Sci. U.S.A.

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“…However, expectations for the H3-H4 tetramer split model revived in the past few years, after the discoveries that H3-H4 histones deposit onto chromatin as dimers rather than tetramers [28][29][30], and that the histone chaperone Asf1 blocks H3-H4 tetramer formation [31,32] and even disrupts pre-assembled H3-H4 tetramers to form H3-H4/Asf1 heterotrimers [32]. Although without direct evidence, these studies certainly offered a possibility for the H3-H4 tetramer splitting events.…”

Section: Bing Zhu and Danny Reinberg 437mentioning

confidence: 99%

Epigenetic inheritance: Uncontested?

Reinberg

2011

Cell Res

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"Epigenetics" is currently defined as "the inheritance of variation (-genetics) above and beyond (epi-) changes in the DNA sequence". Despite the fact that histones are believed to carry important epigenetic information, little is known about the molecular mechanisms of the inheritance of histone-based epigenetic information, including histone modifications and histone variants. Here we review recent progress and discuss potential models for the mitotic inheritance of histone modifications-based epigenetic information.

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“…GST-Asf1b(1-169) was purified using affinity and gel filtration chromatography. GST-Asf1b(1-169)-H3/H4 complexes were assembled by mixing purified GST-Asf1b and H3/H4 in a 1:5 molar ratio followed gel filtration chromatography as described previously (9). Concentrations of purified proteins were determined by measuring absorbance at 280 nm using a Thermo Fisher Genesys 10S UV-visible spectrometer and by Bradford assays.…”

Section: Methodsmentioning

confidence: 99%

Recognition Elements in the Histone H3 and H4 Tails for Seven Different Importins

Soniat

Çağatay

Chook

2016

Journal of Biological Chemistry

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N-terminal tails of histones H3 and H4 are known to bind several different Importins to import the histones into the cell nucleus. However, it is not known what binding elements in the histone tails are recognized by the individual Importins. Biochemical studies of H3 and H4 tails binding to seven Importins, Imp␤, Kap␤2, Imp4, Imp5, Imp7, Imp9, and Imp␣, show the H3 tail binding more tightly than the H4 tail. The H3 tail binds Kap␤2 and Imp5 with K D values of 77 and 57 nM, respectively, and binds the other five Importins more weakly. Mutagenic analysis shows H3 tail residues 11-27 to be the sole binding segment for Imp␤, Kap␤2, and Imp4. However, Imp5, Imp7, Imp9, and Imp␣ bind two separate elements in the H3 tail: the segment at residues 11-27 and an isoleucine-lysine nuclear localization signal (IK-NLS) motif at residues 35-40. The H4 tail also uses either one or two basic segments to bind the same set of Importins with a similar trend of relative affinities as the H3 tail, albeit at least 10-fold weaker. Of the many lysine residues in the H3 and H4 tails, only acetylation of the H3 Lys 14 substantially decreased binding to several Importins. Lastly, we show that, in addition to the N-terminal tails, the histone fold domains of H3 and H4 and/or the histone chaperone Asf1b are important for Importin-histone recognition.New nucleosomes are assembled in the nucleus during S phase as new core histones H2A, H2B, H3, and H4 are synthesized, assembled into H2A/H2B and H3/H4 dimers in the cytoplasm, and then imported into the nucleus for deposition onto replicating chromatin (1-8). Little is known about cytoplasmic assembly/processing of H2A and H2B, but assembly/processing of H3 and H4 are better understood. In the cytoplasm, H3 and H4 are passed from one histone chaperone to another for folding, assembly into H3/H4 dimers, and acetylation.

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Structure and function of the histone chaperone CIA/ASF1 complexed with histones H3 and H4

Cited by 89 publications

References 0 publications

Splitting of H3–H4 tetramers at transcriptionally active genes undergoing dynamic histone exchange

Splitting of H3–H4 tetramers at transcriptionally active genes undergoing dynamic histone exchange

Epigenetic inheritance: Uncontested?

Recognition Elements in the Histone H3 and H4 Tails for Seven Different Importins

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