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PubMedDate not supplied

[Histone H1 of reptiles, homologous to histone H5 of birds].

Lysine-rich histone H1 of animals from three reptilian orders was studied. Electrophoretically pure H1 histone subfractions were cleaved at residues of tyrosine, methionine, aspartic acid and phenylalanine. The fragments obtained were studied by modified method of incomplete succinylation which permitted to determine the number of lysine residues, the positive charge and molecular length of polypeptides. The structural homology between the fastest reptilia H1 subfraction and avian H5 histone has been shown.

Amino Acid Sequence↗
PubMedDate not supplied

[Study of the structure and aggregation of histones. II. Structure of oligomers forming in mixed solutions of histones H2A and H4].

A change of light-scattering and sedimentation constant of histones H2A and H4 of monomers and oligomers has been studied. It has been shown that in salt-free solution the histone monomers are present. There is a mixture of oligomers (H2A)3, S20,w = 3,8S; (H2A)-(H4)1, S20,w = 3,8S; (H4)60, S20,w = 27S in the solution 0,6 M NaCl depending on fractions correlation. It has been shown that the molecules interactions in the composition of oligomers are cooperative and the cross interactions block the histone H4 self-aggregation.

Chemical Phenomena↗
PubMed1994

Core histone acetylation does not block linker histone binding to a nucleosome including a Xenopus borealis 5 S rRNA gene.

We demonstrate that acetylation of core histone tails does not significantly impair the ability of linker histones to bind preferentially and asymmetrically to a defined sequence mononucleosome core reconstituted in vitro. Thus a simple inhibition mechanism cannot explain models whereby acetylation is causal for the observed reduction in the linker histone content in chromatin. Other models to explain this correlation are discussed.

Acetylation↗
PubMedDate not supplied

[Structure and aggregation of histones. I. Influence of the ionic composition of the medium on the structure and effectiveness of the intermolecular relationships of histone F2a (H2A+H4)].

The investigation of fluorescence and light-scattering change of histone F2a, ribonuclease, tyrosine, N-acetyltirosinamide, methyl ether tyrosine by the concentration increasing of NaCl, MgCl2, Na2SO4 in the surrounding medium was carried out. In the case of used salts the changes of tertiary structure and histones aggregations depend on the anion type, which is presented in the environment. The tertiary structure of histones formed in the presence of salt is stabilized by weak (hydrophobic and hydrogenic) interactions.

Chemical Phenomena↗
PubMed2005

Design and synthesis of non-hydroxamate histone deacetylase inhibitors: identification of a selective histone acetylating agent.

A series of suberoylanilide hydroxamic acid (SAHA)-based non-hydroxamates was designed, synthesized, and evaluated for their histone deacetylase (HDAC) inhibitory activity. Among these, methyl sulfoxide 15 inhibited HDACs in enzyme assays and caused hyperacetylation of histone H4 while not inducing the accumulation of acetylated alpha-tubulin in HCT116 cells.

Acetylation↗
PubMed2002

Analysis of histone acetyltransferase and histone deacetylase families of Arabidopsis thaliana suggests functional diversification of chromatin modification among multicellular eukaryotes.

Sequence similarity and profile searching tools were used to analyze the genome sequences of Arabidopsis thaliana, Saccharomyces cerevisiae, Schizosaccharomyces pombe, Caenorhabditis elegans and Drosophila melanogaster for genes encoding three families of histone deacetylase (HDAC) proteins and three families of histone acetyltransferase (HAT) proteins. Plants, animals and fungi were found to have a single member of each of three subfamilies of the GNAT family of HATs, suggesting conservation of these functions. However, major differences were found with respect to sizes of gene families and multi-domain protein structures within other families of HATs and HDACs, indicating substantial evolutionary diversification. Phylogenetic analysis identified a new class of HDACs within the RPD3/HDA1 family that is represented only in plants and animals. A similar analysis of the plant-specific HD2 family of HDACs suggests a duplication event early in dicot evolution, followed by further diversification in the lineage leading to Arabidopsis. Of three major classes of SIR2-type HDACs that are found in animals, fungi have representatives only in one class, whereas plants have representatives only in the other two. Plants possess five CREB-binding protein (CBP)-type HATs compared with one to two in animals and none in fungi. Domain and phylogenetic analyses of the CBP family proteins showed that this family has evolved three distinct types of CBPs in plants. The domain architecture of CBP and TAF(II)250 families of HATs show significant differences between plants and animals, most notably with respect to bromodomain occurrence and their number. Bromodomain-containing proteins in Arabidopsis differ strikingly from animal bromodomain proteins with respect to the numbers of bromodomains and the other types of domains that are present. The substantial diversification of HATs and HDACs that has occurred since the divergence of plants, animals and fungi suggests a surprising degree of evolutionary plasticity and functional diversification in these core chromatin components.

Acetyltransferases↗
PubMed2006

Hypoxic stress induces dimethylated histone H3 lysine 9 through histone methyltransferase G9a in mammalian cells.

Dimethylated histone H3 lysine 9 (H3K9me2) is a critical epigenetic mark for gene repression and silencing and plays an essential role in embryogenesis and carcinogenesis. Here, we investigated the effects of hypoxic stress on H3K9me2 at both global and gene-specific level. We found that hypoxia increased global H3K9me2 in several mammalian cell lines. This hypoxia-induced H3K9me2 was temporally correlated with an increase in histone methyltransferase G9a protein and enzyme activity. The increase in H3K9me2 was significantly mitigated in G9a-/- mouse embryonic stem cells following hypoxia challenge, indicating that G9a was involved in the hypoxia-induced H3K9me2. In addition to the activation of G9a, our results also indicated that hypoxia increased H3K9me2 by inhibiting H3K9 demethylation processes. Hypoxic mimetics, such as deferoxamine and dimethyloxalylglycine, were also found to increase H3K9me2 as well as G9a protein and activity. Finally, hypoxia increased H3K9me2 in the promoter regions of the Mlh1 and Dhfr genes, and these increases temporally correlated with the repression of these genes. Collectively, these results indicate that G9a plays an important role in the hypoxia-induced H3K9me2, which would inhibit the expression of several genes that would likely lead to solid tumor progression.

Acetylation↗
PubMed1976

Basic polypeptides as histone models. Effect of conformation, base composition and methylation of nucleic acids on the interaction with H1 and histone models and on the circular dichroism of complexes.

Interaction of histone H 1 and models simulating histone chains was followed by monitoring the melting curves of supernatants after the sedimentation of aggregated complexes. In a mixture of two DNAs the histones reacted selectively with (A+T)-rich and non-methylated DNA, respectively. H 1 and (Ala-Lys-Pro)n also interacted preferentially with DNA in a mixture with double stranded RNA whereas (Lys30,Ala70)n did not show any selectivity. (G+C)-rich DNA in complexes showed CD spectra the intensity of which decreased with increasing DNA methylation to values comparable with these of complexes of (A+T)-rich DNA. In complexed with double stranded RNA only the polymer (Lys30,Ala70) displayed CD pattern similar to spectra of complexes with DNA. It was concluded that formation and structure of complexes depend selectively on the DNA conformation and base composition.

Binding Sites↗
PubMed2026

Regulation of the histone H3K36 methyltransferase Set2 by the histone chaperone Spt6.

Histone H3 lysine 36 methylation is a conserved histone modification that is critical for maintaining eukaryotic transcriptional fidelity and genomic stability. In Saccharomyces cerevisiae, this modification is catalyzed by Set2, an ortholog of the mammalian H3K36 methyltransferase SETD2. Previous genetic, biochemical, and structural studies showed that Set2 activity is repressed by a Set2 autoinhibitory domain (AID) and that activation requires the direct binding of the histone chaperone Spt6. To study the role of Spt6 and Set2 autoinhibition in vivo, we have isolated and analyzed multiple classes of Spt6 and Set2 mutants. Our results suggest an autoinhibited form of Set2 in which the catalytic domain is bound by the AID. In strong agreement with our genetic results, biophysical experiments demonstrate that the catalytic domain and AID physically interact, and that the autoinhibition mutants disrupt this interaction. Finally, RNA-seq and ChIP-seq studies show the importance of the Set2-Spt6 interaction for transcription and H3K36 methylation genome-wide. Taken together, our results support a model in which Set2 exists in an inactive, autoinhibited state in vivo through direct catalytic domain-AID interactions, with binding by Spt6 required to release this autoinhibited state.

Journal Article↗
PubMed1980

Histochemical determination of histone and non-histone protein content in rat liver nuclei.

The purpose of this study is to compare the protein content of parenchymal and non-parenchymal nuclei, as isolated from rat liver. The nuclei have been separated by means of a 1 g-sedimentation technique. The protein content of the separated nuclei has been determined cytophotometrically using the Naphthol Yellow S staining procedure after TCA-extraction (corresponding with the total protein content) and directly (corresponding with the non-histone proteins). The ratio of the total protein content of non-parenchymal, parenchymal diploid and parenchymal tetraploid nuclei respectively was found to be 0.65:100:1.90. The ratio of non-histone protein a total protein was the same for all types of nuclei investigated, namely about 55%.

Animals↗
PubMed1984

Phosphorylation of histones and non-histone nuclear proteins in liver cells stimulated by glucagon and cyclic AMP.

Phosphorylation of a characteristic subset of nuclear proteins is increased in rat liver cells stimulated with glucagon. Regulated proteins include histones H1 and H3, an HMG 14-like protein and a previously unidentified 23-kDa basic protein. The effect of glucagon is mimicked by forskolin and exogenous cAMP. Insulin and dexamethasone have no effect. In a cell-free system containing purified hepatocyte nuclei, addition of cAMP-dependent protein kinase results in phosphorylation of histone H3, an HMG 14-like protein and a 23-kDa basic protein similar or identical to the protein phosphorylated in vivo.

Animals↗
PubMed2005

Peptide mass mapping of acetylated isoforms of histone H4 from mouse lymphosarcoma cells treated with histone deacetylase (HDACs) inhibitors.

The acetylated isoforms of histone H4 from mouse lymphosarcoma cells treated with HDAC inhibitors trichostatin A (TSA) and depsipeptide (DDP) were separated by acetic acid urea-polyacrylamide gel electrophoresis (AU-PAGE), in-gel digested, and analyzed by matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and liquid chromatography tandem mass spectrometry (LC-MS/MS). The acetylation pattern of histone H4 in mouse lymphosarcoma cells induced by TSA was established in which acetylation initially occurred at K16 followed by K12 and then K8 and/or K5. An identical order of acetylation was found for cells treated with DDP.

Acetylation↗
PubMed2006

Functional genomics of histone modification and non-histone chromosomal proteins using the polytene chromosomes of Drosophila.

Knowing the genomic distribution of chromosomal proteins and of histone modifications provides essential insight into function. The giant polytene chromosomes of the Drosophila larval salivary glands provide a high-resolution genomic map with a resolution exceeded only by chromatin immunoprecipitation. Immunofluorescence localization of chromosomal proteins and specific post-translational modifications of histones is a simple and rapid tool for the functional genomics of chromosomal proteins.

Animals↗
PubMed2002

A second catalytic domain in the Elp3 histone acetyltransferases: a candidate for histone demethylase activity?

A new subfamily of two-domain histone acetyltransferases (HATs) related to Elp3 has been identified. In addition to a HAT domain in the C terminus, these proteins have an N-terminal domain similar to the catalytic domain of S-adenosylmethionine radical enzymes. Two-domain organization is preserved in evolution, suggesting that both enzymatic activities are functionally or mechanistically coupled and directed towards highly conserved substrates. The functional implications of this similarity and a possible role for Elp3-related proteins as histone demethylases are discussed.

Acetyltransferases↗
PubMed2004

On the function of the 14 A long internal cavity of histone deacetylase-like protein: implications for the design of histone deacetylase inhibitors.

Histone deacetylases (HDACs) play an important role in gene transcription. Inhibitors of HDACs induce cell differentiation and suppress cell proliferation in tumor cells. AutoDock calculations of known and novel HDAC inhibitors as well as of several probe molecules to histone deacetylase-like protein (HDLP), using a modified scoring function for metalloproteins, demonstrate excellent agreement (R = 0.92) between experimental and computed binding constants. Analysis of the docked structures allows a determination of the different binding motifs in known inhibitors. Such calculations are a useful tool for the prediction of binding constants for new HDAC inhibitors. Exploration of the 14 A long internal cavity adjacent to the active site by docking of small molecular probes suggest that it plays a crucial role by accepting the cleaved acetate and releasing it at the far side of the cavity. The importance of the findings for the design of new inhibitors is discussed.

Binding Sites↗
PubMed2000

The structural basis for the recognition of acetylated histone H4 by the bromodomain of histone acetyltransferase gcn5p.

The bromodomain is an approximately 110 amino acid module found in histone acetyltransferases and the ATPase component of certain nucleosome remodelling complexes. We report the crystal structure at 1.9 A resolution of the Saccharomyces cerevisiae Gcn5p bromodomain complexed with a peptide corresponding to residues 15-29 of histone H4 acetylated at the zeta-N of lysine 16. We show that this bromodomain preferentially binds to peptides containing an N:-acetyl lysine residue. Only residues 16-19 of the acetylated peptide interact with the bromodomain. The primary interaction is the N:-acetyl lysine binding in a cleft with the specificity provided by the interaction of the amide nitrogen of a conserved asparagine with the oxygen of the acetyl carbonyl group. A network of water-mediated H-bonds with protein main chain carbonyl groups at the base of the cleft contributes to the binding. Additional side chain binding occurs on a shallow depression that is hydrophobic at one end and can accommodate charge interactions at the other. These findings suggest that the Gcn5p bromodomain may discriminate between different acetylated lysine residues depending on the context in which they are displayed.

Acetylation↗
PubMed1993

Two non-histone proteins are associated with the promoter region and histone HI with the transcribed region of active hsp-70 genes as revealed by UV-induced DNA-protein crosslinking in vivo.

We described here an approach for mapping proteins on any sequence of genomic DNA. UV-induced DNA-protein crosslinking within whole cells and the 'protein image' hybridization technique (1) were applied to test the proteins bound to different regions of the D. melanogaster hsp-70 gene. The histone H1-DNA association with the coding region is shown to be maintained, even during very intensive transcription, but is absent in the promoter. Two non-histone proteins with apparent molecular masses of 50 kD (p50) and 100 kD (p100) are crosslinked only to the active hsp-70 gene regulatory region and preferentially bind to its complementary and coding DNA strands, respectively.

Animals↗