scholarly journals Structural organization of DNA–protein complexes of chromatin studied by vibrational and electronic circular dichroism

2010 ◽  
Vol 24 (3-4) ◽  
pp. 239-244 ◽  
Author(s):  
Alexander Polyanichko ◽  
Helmut Wieser
Keyword(s):  
Circular Dichroism ◽  
Protein Complexes ◽  
High Mobility ◽  
Histone H1 ◽  
Cd Spectroscopy ◽  
Linker Histone ◽  
High Mobility Group ◽  
Ir Absorption ◽  
Linker Histone H1 ◽  
Circular Dichroïsm

Structure and functioning of chromatin is determined by interactions of DNA with numerous nuclear proteins. The most abundant and yet not completely understood non-histone chromosomal proteins are those belonging to a High Mobility Group (HMG) namely HMGB1. The interplay of this protein on DNA with linker histone H1 and other proteins determines both structure and functioning of the chromatin. A combination of UV and IR absorption and circular dichroism (CD) spectroscopy was applied to investigate the structure and formation of large supramolecular DNA–protein complexes. This combination of techniques was used to overcome limitations of UV-CD (ECD) spectroscopy due to considerable light scattering in such solutions. Based on the analysis of FTIR and UV circular dichroism spectra and AFM imaging the interaction of DNA with high-mobility group non-histone chromatin protein HMGB1 and linker histone H1 was studied.

scholarly journals Interaction between Nonhistone Protein HMGB1 and Linker Histone H1 Facilitates the Formation of Structurally Ordered DNA-Protein Complexes

2012 ◽  
Vol 27 ◽  
pp. 393-398 ◽  
Author(s):  
Alexander Polyanichko ◽  
Elena Chikhirzhina
Keyword(s):  
Protein Complexes ◽  
Histone H1 ◽  
Linker Histone ◽  
Chromosomal Protein ◽  
Dna Complexes ◽  
Force Microscopy ◽  
Linker Histone H1 ◽  
Nonhistone Protein ◽  
Atomic Force ◽  
Nonhistone Chromosomal Protein

The structural organization of the DNA complexes with nonhistone chromosomal protein and linker histone H1 was studied using circular dichroism spectroscopy (CD) and atomic force microscopy (AFM). It has been shown that due to the interaction between HMGB1 and H1 highly ordered DNA-protein complexes emerge in the solution. Their spectral properties are found to be similar to those of DNA/HMGB1-(AB) complexes, reported earlier. AFM images reveal the formation of fibril-like structures in the solution. We suggest that the electrostatic screening of the HMGB1 C-terminal domain by histone H1 facilitates stronger interaction of the HMGB1/H1 with DNA and the formation of the ordered supramolecular DNA-protein complexes.

scholarly journals Yeast HMO1: Linker Histone Reinvented

2016 ◽  
Vol 81 (1) ◽  
Author(s):  
Arvind Panday ◽  
Anne Grove
Keyword(s):  
Ribosomal Proteins ◽  
High Mobility ◽  
Histone H1 ◽  
Strand Break ◽  
Linker Histone ◽  
Content Type ◽  
Linker Histone H1 ◽  
Nucleosome Core ◽  
Rich Domain ◽  
Nucleosome Density

SUMMARY Eukaryotic genomes are packaged in chromatin. The higher-order organization of nucleosome core particles is controlled by the association of the intervening linker DNA with either the linker histone H1 or high mobility group box (HMGB) proteins. While H1 is thought to stabilize the nucleosome by preventing DNA unwrapping, the DNA bending imposed by HMGB may propagate to the nucleosome to destabilize chromatin. For metazoan H1, chromatin compaction requires its lysine-rich C-terminal domain, a domain that is buried between globular domains in the previously characterized yeast Saccharomyces cerevisiae linker histone Hho1p. Here, we discuss the functions of S. cerevisiae HMO1, an HMGB family protein unique in containing a terminal lysine-rich domain and in stabilizing genomic DNA. On ribosomal DNA (rDNA) and genes encoding ribosomal proteins, HMO1 appears to exert its role primarily by stabilizing nucleosome-free regions or “fragile” nucleosomes. During replication, HMO1 likewise appears to ensure low nucleosome density at DNA junctions associated with the DNA damage response or the need for topoisomerases to resolve catenanes. Notably, HMO1 shares with the mammalian linker histone H1 the ability to stabilize chromatin, as evidenced by the absence of HMO1 creating a more dynamic chromatin environment that is more sensitive to nuclease digestion and in which chromatin-remodeling events associated with DNA double-strand break repair occur faster; such chromatin stabilization requires the lysine-rich extension of HMO1. Thus, HMO1 appears to have evolved a unique linker histone-like function involving the ability to stabilize both conventional nucleosome arrays as well as DNA regions characterized by low nucleosome density or the presence of noncanonical nucleosomes.

scholarly journals Chromatin-Specific Remodeling by HMGB1 and Linker Histone H1 Silences Proinflammatory Genes during Endotoxin Tolerance

2009 ◽  
Vol 29 (7) ◽  
pp. 1959-1971 ◽  
Author(s):  
Mohamed El Gazzar ◽  
Barbara K. Yoza ◽  
Xiaoping Chen ◽  
Benjamin A. Garcia ◽  
Nicolas L. Young ◽  
...  
Keyword(s):  
High Mobility ◽  
Histone H1 ◽  
Linker Histone ◽  
Mrna Levels ◽  
Transcription Activator ◽  
Blood Leukocytes ◽  
Necrosis Factor Alpha ◽  
Linker Histone H1 ◽  
Tnf Α ◽  
H3k9 Dimethylation

ABSTRACT Epigenetic silencing of tumor necrosis factor alpha (TNF-α) and interleukin 1β (IL-1β) transcription occurs in blood leukocytes of animals and humans after the initiation of severe systemic inflammation (SSI). We previously reported that the epigenetic signature requires induction of NF-κB factor RelB, which directs histone H3K9 dimethylation, disrupts assembly of transcription activator NF-κB p65, and induces a sustained switch from the euchromatin to heterochromatin. Here, we report the novel findings that intracellular high mobility group box 1 protein (HMGB1) and nucleosome linker histone H1 protein are necessary components of endotoxin-mediated silencing of TNF-α in THP-1 human promonocytes. HMGB1 binds the TNF-α promoter during transcription silencing and promotes assembly of the repressor RelB. Depletion of HMGB1 by small interfering RNA results in dissociation of RelB from the promoter and partially restores TNF-α transcription. Histone H1, which typically displaces HMGB1 from nucleosomal DNA, also binds concomitantly with HMGB1 to the heterochromatin of the silenced TNF-α promoter. Combined knockdown of HMGB1 and H1 restores binding of the transcriptionally active NF-κB p65 and reestablishes TNF-α mRNA levels. Chromatin reimmunoprecipitation experiments demonstrate that HMGB1 and H1 are likely recruited to TNF-α sequences independently and that their binding correlates with histone H3K9 dimethylation, as inhibition of histone methylation blocks HMGB1 and H1 binding. Moreover, HMGB1- and H1-mediated chromatin modifications are gene specific during endotoxin silencing in that they also bind and repress acute proinflammatory IL-1β, while no binding nor repression of antiinflammatory IκBα is observed. Finally, we find that H1 and HMGB1 bind to the TNF-α a promoter in human leukocytes obtained from patients with SSI. We conclude proinflammatory HMGB1 and structural nucleosome linker H1 couple as a component of the epigenetic complex that silences acute proinflammatory TNF-α during the assembly of heterochromatin in the SSI phenotype.

scholarly journals Loss of linker histone H1 in cellular senescence

2006 ◽  
Vol 175 (6) ◽  
pp. 869-880 ◽  
Author(s):  
Ryo Funayama ◽  
Motoki Saito ◽  
Hiroko Tanobe ◽  
Fuyuki Ishikawa
Keyword(s):  
Cellular Senescence ◽  
Fluorescent Protein ◽  
Chromatin Condensation ◽  
Ectopic Expression ◽  
High Mobility ◽  
Histone H1 ◽  
Linker Histone ◽  
Hmg Proteins ◽  
Mitotic Chromosomes ◽  
Linker Histone H1

Cellular senescence is a tumor-suppressing mechanism that is accompanied by characteristic chromatin condensation called senescence-associated heterochromatic foci (SAHFs). We found that individual SAHFs originate from individual chromosomes. SAHFs do not show alterations of posttranslational modifications of core histones that mark condensed chromatin in mitotic chromosomes, apoptotic chromatin, or transcriptionally inactive heterochromatin. Remarkably, SAHF-positive senescent cells lose linker histone H1 and exhibit increased levels of chromatin-bound high mobility group A2 (HMGA2). The expression of N-terminally enhanced green fluorescent protein (EGFP)–tagged histone H1 induces premature senescence phenotypes, including increased levels of phosphorylated p53, p21, and hypophosphorylated Rb, and a decrease in the chromatin-bound endogenous histone H1 level but not in p16 level accumulation or SAHF formation. However, the simultaneous ectopic expression of hemagglutinin-tagged HMGA2 and N-terminally EGFP-tagged histone H1 leads to significant SAHF formation (P < 0.001). It is known that histone H1 and HMG proteins compete for a common binding site, the linker DNA. These results suggest that SAHFs are a novel type of chromatin condensation involving alterations in linker DNA–binding proteins.

Analysis of the secondary structure of linker histone H1 based on IR absorption spectra

2014 ◽  
Vol 8 (4) ◽  
pp. 352-358 ◽  
Author(s):  
A. M. Polyanichko ◽  
N. M. Romanov ◽  
T. Yu. Starkova ◽  
E. I. Kostyleva ◽  
E. V. Chikhirzhina
Keyword(s):  
Secondary Structure ◽  
Absorption Spectra ◽  
Histone H1 ◽  
Linker Histone ◽  
Ir Absorption ◽  
Linker Histone H1 ◽  
Ir Absorption Spectra

scholarly journals Synthesis of a sucrose dimer with enone tether; a study on its functionalization

2014 ◽  
Vol 10 ◽  
pp. 1246-1254 ◽  
Author(s):  
Zbigniew Pakulski ◽  
Norbert Gajda ◽  
Magdalena Jawiczuk ◽  
Jadwiga Frelek ◽  
Piotr Cmoch ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Double Bond ◽  
Carbonyl Group ◽  
Osmium Tetroxide ◽  
Cd Spectroscopy ◽  
Allylic Alcohol ◽  
Circular Dichroïsm

The reaction of appropriately functionalized sucrose phosphonate with sucrose aldehyde afforded a dimer composed of two sucrose units connected via their C6-positions (‘the glucose ends’). The carbonyl group in this product (enone) was stereoselectively reduced with zinc borohydride and the double bond (after protection of the allylic alcohol formed after reduction) was oxidized with osmium tetroxide to a diol. Absolute configurations of the allylic alcohol as well as the diol were determined by circular dichroism (CD) spectroscopy using the in situ dimolybdenum methodology.

scholarly journals Site-specific ubiquitylation acts as a regulator of linker histone H1

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Eva Höllmüller ◽  
Simon Geigges ◽  
Marie L. Niedermeier ◽  
Kai-Michael Kammer ◽  
Simon M. Kienle ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Histone H1 ◽  
Linker Histone ◽  
Active Chromatin ◽  
Site Specific ◽  
Linker Histone H1 ◽  
Fundamental Process ◽  
Core Histones ◽  
Wide Scale

AbstractDecoding the role of histone posttranslational modifications (PTMs) is key to understand the fundamental process of epigenetic regulation. This is well studied for PTMs of core histones but not for linker histone H1 in general and its ubiquitylation in particular due to a lack of proper tools. Here, we report on the chemical synthesis of site-specifically mono-ubiquitylated H1.2 and identify its ubiquitin-dependent interactome on a proteome-wide scale. We show that site-specific ubiquitylation of H1 at position K64 modulates interactions with deubiquitylating enzymes and the deacetylase SIRT1. Moreover, it affects H1-dependent chromatosome assembly and phase separation resulting in a more open chromatosome conformation generally associated with a transcriptionally active chromatin state. In summary, we propose that site-specific ubiquitylation plays a general regulatory role for linker histone H1.

scholarly journals The histone variant H2A.W and linker histone H1 co-regulate heterochromatin accessibility and DNA methylation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Pierre Bourguet ◽  
Colette L. Picard ◽  
Ramesh Yelagandula ◽  
Thierry Pélissier ◽  
Zdravko J. Lorković ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Histone H1 ◽  
Epigenetic Modifications ◽  
Flowering Plants ◽  
Linker Histone ◽  
Histone Variant ◽  
Null Mutant ◽  
Chromatin Compaction ◽  
Linker Histone H1

AbstractIn flowering plants, heterochromatin is demarcated by the histone variant H2A.W, elevated levels of the linker histone H1, and specific epigenetic modifications, such as high levels of DNA methylation at both CG and non-CG sites. How H2A.W regulates heterochromatin organization and interacts with other heterochromatic features is unclear. Here, we create a h2a.w null mutant via CRISPR-Cas9, h2a.w-2, to analyze the in vivo function of H2A.W. We find that H2A.W antagonizes deposition of H1 at heterochromatin and that non-CG methylation and accessibility are moderately decreased in h2a.w-2 heterochromatin. Compared to H1 loss alone, combined loss of H1 and H2A.W greatly increases accessibility and facilitates non-CG DNA methylation in heterochromatin, suggesting co-regulation of heterochromatic features by H2A.W and H1. Our results suggest that H2A.W helps maintain optimal heterochromatin accessibility and DNA methylation by promoting chromatin compaction together with H1, while also inhibiting excessive H1 incorporation.

Sign in / Sign up

Export Citation Format

Share Document