scholarly journals Quercetin Affects Nucleosome Structure

2021 ◽  
Vol 27 (S1) ◽  
pp. 1740-1741
Author(s):  
Tatiana Andreeva ◽  
Alexander Lyubitelev ◽  
Elena Bondarenko ◽  
Vasily Studitsky ◽  
Alexey Feofanov
Keyword(s):  
Nucleosome Structure

Conformational characterization of nucleosome structure by Electron Microscopy

1993 ◽  
Vol 51 ◽  
pp. 194-195
Author(s):  
Gregory J. Czarnota
Keyword(s):  
Electron Microscopy ◽  
Structural Changes ◽  
Physiological State ◽  
Gene Activation ◽  
Three Dimensional ◽  
Macromolecular Complex ◽  
Ultrastructural Studies ◽  
Ionic Environment ◽  
Nucleosome Structure ◽  
Dimensional Reconstruction

Chromatin structure at the fundamental level of the nucleosome is important in vital cellular processes. Recent biochemical and genetic analyses show that nucleosome structure and structural changes are very active participants in gene expression, facilitating or inhibiting transcription and reflecting the physiological state of the cell. Structural states and transitions for this macromolecular complex, composed of DNA wound about a heterotypic octamer of variously modified histone proteins, have been measured by physico-chemical techniques and by enzyme-accessibility and are recognized to occur with various post-translational modifications, gene activation, transformation and with ionic-environment. In spite of studies which indicate various forms of nucleosome structure, all current x-ray and neutron diffraction studies have consistently resulted in only one structure, suggestive of a static conformation. In contrast, two-dimensional electron microscopy studies and three-dimensional reconstruction techniques have yielded different structures. These fundamental differences between EM and other ultrastructural studies have created a long standing quandary, which I have addressed and resolved using spectroscopic electron microscopy and statistical analyses of nucleosome images in a study of nucleosome structure with ionic environment.

scholarly journals Histone-containing subnucleosomes: possible implications to nucleosome structure

FEBS Letters ◽  
1981 ◽  
Vol 133 (1) ◽  
pp. 75-78 ◽  
Author(s):  
V.V. Bakayev ◽  
N.N. Domansky ◽  
T.G. Bakayeva
Keyword(s):  
Nucleosome Structure

Nucleosome structure

1978 ◽  
Vol 283 (997) ◽  
pp. 241-258 ◽  
Keyword(s):  
Dynamic Structure ◽  
Histone H2a ◽  
Electron Microscopic ◽  
Base Pairs ◽  
Compact Structure ◽  
Nucleosome Structure ◽  
Dna Base ◽  
Open Structures ◽  
Dna 2 ◽  
Necessary And Sufficient

Electron microscopic and biochemical results are presented supporting the following conclusions: (1) Two molecules of each histone H2A, H2B, H3 and H4 are necessary and sufficient to form a nucleosome with a diameter of 12.5± 1 nm and containing about 200 base pairs of DNA. (2) H3 plus H4 alone can compact 129 ± 8 DNA base pairs into a sub-nucleosomal particle with a diameter of 8 ± 1 nm. In such a particle the DNA duplex is under a constraint equivalent to negative superhelicity. (3) Chromatin should be viewed as a dynamic structure, oscillating between a compact structure (the nucleosome) and more open structures, depending on the environmental conditions.

scholarly journals Dispersed Mutations in Histone H3 That Affect Transcriptional Repression and Chromatin Structure of the CHA1 Promoter in Saccharomyces cerevisiae

2008 ◽  
Vol 7 (10) ◽  
pp. 1649-1660 ◽  
Author(s):  
Qiye He ◽  
Cailin Yu ◽  
Randall H. Morse
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromatin Structure ◽  
Transcriptional Repression ◽  
Histone H3 ◽  
Temperature Sensitive ◽  
Active Chromatin ◽  
Temperature Sensitive Mutants ◽  
Nucleosome Structure ◽  
Lysine Residues ◽  
Chromatin Configuration

ABSTRACT The histone H3 amino terminus, but not that of H4, is required to prevent the constitutively bound activator Cha4 from remodeling chromatin and activating transcription at the CHA1 gene in Saccharomyces cerevisiae. Here we show that neither the modifiable lysine residues nor any specific region of the H3 tail is required for repression of CHA1. We then screened for histone H3 mutations that cause derepression of the uninduced CHA1 promoter and identified six mutants, three of which are also temperature-sensitive mutants and four of which exhibit a sin − phenotype. Histone mutant levels were similar to that of wild-type H3, and the mutations did not cause gross alterations in nucleosome structure. One specific and strongly derepressing mutation, H3 A111G, was examined in depth and found to cause a constitutively active chromatin configuration at the uninduced CHA1 promoter as well as at the ADH2 promoter. Transcriptional derepression and altered chromatin structure of the CHA1 promoter depend on the activator Cha4. These results indicate that modest perturbations in distinct regions of the nucleosome can substantially affect the repressive function of chromatin, allowing activation in the absence of a normal inducing signal (at CHA1) or of Swi/Snf (resulting in a sin − phenotype).

Nucleosome Structure Modulates Benzo[a]pyrenediol Epoxide Adduct Formation

Biochemistry ◽  
1994 ◽  
Vol 33 (8) ◽  
pp. 2210-2216 ◽  
Author(s):  
Brian D. Thrall ◽  
David B. Mann ◽  
Michael J. Smerdon ◽  
David L. Springer
Keyword(s):  
Adduct Formation ◽  
Nucleosome Structure

scholarly journals Structural and biochemical analyses of monoubiquitinated human histones H2B and H4

Open Biology ◽  
2016 ◽  
Vol 6 (6) ◽  
pp. 160090 ◽  
Author(s):  
Shinichi Machida ◽  
Satoshi Sekine ◽  
Yuuki Nishiyama ◽  
Naoki Horikoshi ◽  
Hitoshi Kurumizaka
Keyword(s):  
Histone H4 ◽  
Core Particle ◽  
Post Translational Modification ◽  
Nucleosome Core Particle ◽  
Active Chromatin ◽  
Histone H2b ◽  
Nucleosome Core ◽  
Nucleosome Structure ◽  
Biochemical Analyses ◽  
Nucleosome Stability

Monoubiquitination is a major histone post-translational modification. In humans, the histone H2B K120 and histone H4 K31 residues are monoubiquitinated and may form transcriptionally active chromatin. In this study, we reconstituted nucleosomes containing H2B monoubiquitinated at position 120 (H2Bub 120 ) and/or H4 monoubiquitinated at position 31 (H4ub 31 ). We found that the H2Bub 120 and H4ub 31 monoubiquitinations differently affect nucleosome stability: the H2Bub 120 monoubiquitination enhances the H2A–H2B association with the nucleosome, while the H4ub 31 monoubiquitination decreases the H3–H4 stability in the nucleosome, when compared with the unmodified nucleosome. The H2Bub 120 and H4ub 31 monoubiquitinations both antagonize the Mg 2+ -dependent compaction of a poly-nucleosome, suggesting that these monoubiquitinations maintain more relaxed conformations of chromatin. In the crystal structure, the H2Bub 120 and H4ub 31 monoubiquitinations do not change the structure of the nucleosome core particle and the ubiquitin molecules were flexibly disordered in the H2Bub 120 /H4ub 31 nucleosome structure. These results revealed the differences and similarities of the H2Bub 120 and H4ub 31 monoubiquitinations at the mono- and poly-nucleosome levels and provide novel information to clarify the roles of monoubiquitination in chromatin.

Chromatin from the unicellular red alga Porphyridium has a nucleosome structure

1982 ◽  
Vol 57 (1) ◽  
pp. 151-160
Author(s):  
K.L. Barnes ◽  
R.A. Craigie ◽  
P.A. Cattini ◽  
T. Cavalier-Smith
Keyword(s):  
Sodium Dodecyl ◽  
Red Alga ◽  
Repeat Length ◽  
Micrococcal Nuclease ◽  
Nucleosome Structure ◽  
Dna Repeat ◽  
Micrococcal Nuclease Digestion ◽  
Nuclease Digestion ◽  
Core Histones ◽  
Higher Eukaryotes

We have isolated a crude nuclear preparation from the unicellular red alga Porphyridium aerugineum and investigated the structure of Porphyridium chromatin. Electrophoresis of deproteinized DNA fragments produced by micrococcal nuclease digestion of Porphyridium nuclei gives a typical ladder pattern, indicative of a repeating structure. The DNA repeat-length, calculated from plots of multimer length against multimer number, varies somewhat between different digestions, ranging from 160 to 180 base-pairs (average 173). We interpret this as evidence of heterogeneity in repeat-length; the calculated repeat-length depends on the extent of digestion because chromatin sub-populations with longer repeat-lengths are on average digested earlier. Polyacrylamide/sodium dodecyl sulphate gel electrophoresis of basic proteins purified from Porphyridium nuclear preparations gives a pattern characteristic of core histones. Although our interpretation is complicated by some degradation, the result strongly suggests that Porphyridium chromatin contains each of the four core histones and that they are similar to those of higher eukaryotes. This, together with the micrococcal nuclease digestion results, demonstrates that Porphyridium chromatin is not fundamentally different from that of higher eukaryotes.

Na+ and K+ Ions Differently Affect Nucleosome Structure, Stability, and Interactions with Proteins

2021 ◽  
pp. 1-11
Author(s):  
Tatyana V. Andreeva ◽  
Natalya V. Maluchenko ◽  
Anastasiia L. Sivkina ◽  
Oleg V. Chertkov ◽  
Maria E. Valieva ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Rna Polymerase Ii ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Inorganic Ions ◽  
Structure Stability ◽  
Ion Concentrations ◽  
Nucleosome Structure ◽  
Nucleosomal Dna ◽  
Stabilizing Effect

Inorganic ions are essential factors stabilizing nucleosome structure; however, many aspects of their effects on DNA transactions in chromatin remain unknown. Here, differential effects of K+ and Na+ on the nucleosome structure, stability, and interactions with protein complex FACT (FAcilitates Chromatin Transcription), poly(ADP-ribose) polymerase 1, and RNA polymerase II were studied using primarily single-particle Förster resonance energy transfer microscopy. The maximal stabilizing effect of K+ on a nucleosome structure was observed at ca. 80–150 mM, and it decreased slightly at 40 mM and considerably at >300 mM. The stabilizing effect of Na+ is noticeably lower than that of K+ and progressively decreases at ion concentrations higher than 40 mM. At 150 mM, Na+ ions support more efficient reorganization of nucleosome structure by poly(ADP-ribose) polymerase 1 and ATP-independent uncoiling of nucleosomal DNA by FACT as compared with K+ ions. In contrast, transcription through a nucleosome is nearly insensitive to K+ or Na+ environment. Taken together, the data indicate that K+ environment is more preserving for chromatin structure during various nucleosome transactions than Na+ environment.

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