scholarly journals The higher-order structure of chromatin: evidence for a helical ribbon arrangement.

1984 ◽  
Vol 99 (1) ◽  
pp. 42-52 ◽  
Author(s):  
C L Woodcock ◽  
L L Frado ◽  
J B Rattner
Keyword(s):  
Ionic Strength ◽  
Electron Scattering ◽  
Helical Structure ◽  
Histone H1 ◽  
Higher Order ◽  
Order Structure ◽  
Helical Ribbon ◽  
Double Helical Structure ◽  
Scattering Measurements ◽  
Preparation Techniques

Both intact and nuclease-isolated chromatin fibers have been examined at different degrees of salt-induced compaction, using a variety of preparation techniques. The results suggest that the initial folding step in nucleosome packing involves the formation of a zig-zag ribbon as has been proposed by others (Thoma F., T. Koller, and A. Klug, 1979, J. Cell Biol., 83:403-427; Worcel A., S. Strogartz, and D. Riley, 1981, Proc. Natl. Acad. Sci. USA, 78:1461-1465), and that subsequent compaction occurs by coiling of the ribbon to form a double helical structure. This type of folding generates a fiber in which the nucleosome-nucleosome contacts established in the zig-zag ribbon are maintained and in which the histone H1 molecules occupy equivalent sites. The diameter of the fiber is not dependent upon the nucleosome repeat length. Direct mass values for individual isolated fibers obtained from electron scattering measurements showed that the mass per length was dependent on ionic strength, and ranged from 6.0 X 10(4) daltons/nm at 10 mM NaCl to 27 X 10(4) daltons/nm at 150 mM salt. These values are equivalent to 2.5 nucleosomes/11 nm at 10 mM NaCl and to 11.6 nucleosomes/11 nm at 150 mM salt and are consistent with the range of packing ratios for the proposed helical ribbon.

scholarly journals Regulation of the higher-order structure of chromatin by histones H1 and H5.

1981 ◽  
Vol 90 (2) ◽  
pp. 279-288 ◽  
Author(s):  
J Allan ◽  
G J Cowling ◽  
N Harborne ◽  
P Cattini ◽  
R Craigie ◽  
...  
Keyword(s):  
Spatial Organization ◽  
Single Species ◽  
Histone H1 ◽  
Higher Order ◽  
Linker Histone ◽  
Micrococcal Nuclease ◽  
Order Structure ◽  
Chicken Erythrocyte ◽  
Base Pairs ◽  
Native Chicken

Chicken erythrocyte chromatins containing a single species of linker histone, H1 or H5, have been prepared, using reassembly techniques developed previously. The reconstituted complexes possess the conformation of native chicken erythrocyte chromatin, as judged by chemical and structural criteria; saturation is reached when two molecules of linker histone are bound per nucleosome, as in native erythrocyte chromatin, which the resulting material resembles in its appearance in the electron microscope and quantitatively in its linear condensation factor relative to free DNA. The periodicity of micrococcal nuclease-sensitive sites in the linker regions associated with histone H1 or H5 is 10.4 base pairs, suggesting that the spatial organization of the linker region in the higher-order structure of chromatin is similar to that in isolated nucleosomes. The susceptible sites are cut at differing frequencies, as previously found for the nucleosome cores, leading to a characteristic distribution of intensities in the digests. The scission frequency of sites in the linker DNA depends additionally on the identity of the linker histone, suggesting that the higher-order structure is subject to secondary modulation by the associated histones.

Histone H1 and chromatin higher order structure does histone H1 exhibit specific self-association?

1983 ◽  
Vol 15 (4) ◽  
pp. 487-493 ◽  
Author(s):  
E. Russo ◽  
V. Giancotti ◽  
C. Crane-Robinson ◽  
G. Geraci
Keyword(s):  
Histone H1 ◽  
Higher Order ◽  
Order Structure ◽  
Self Association

The Higher Order Structure of Chromatin and Histone H1

1984 ◽  
Vol 1984 (Supplement 1) ◽  
pp. 1-20 ◽  
Author(s):  
J. O. THOMAS
Keyword(s):  
Histone H1 ◽  
Higher Order ◽  
Order Structure

scholarly journals Hydrogen bonding investigation of poly(3-hydroxybutyrate) / glycol chitosan blends studied by infrared and terahertz spectroscopies

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Dian Marlina ◽  
Harumi Sato
Keyword(s):  
Hydrogen Bonding ◽  
Crystalline Structure ◽  
Low Frequency ◽  
Helical Structure ◽  
Higher Order ◽  
Order Structure ◽  
Glycol Chitosan ◽  
Structure Deformation ◽  
Structure And Bonding ◽  
Chitosan Blends

Poly(3-hydroxybutyrate) (PHB)/glycol chitosan (GC) polymer blend was developed as one of the new biopolymer materials. Effects of different PHB / GC concentrations were analysed as a function of the blend compositions by using Fourier transform infrared (FTIR) and terahertz (THz) spectroscopies to investigate the changes in the higher-order structure and bonding of hydrogen. The higher-order structure and hydrogen bonding monitored in this study include the crystalline structure and (C=O…H-C) hydrogen bonding of PHB. The FTIR and THz spectra showed that PHB's higher-order structure transforms into the less-order structure by adding GC without altering the crystalline structure and PHB's intramolecular (C = O ... H-C) hydrogen bonding with increasing GC concentration. Because of the addition of GC, the intensity ratio of THz bands figure out the crystalline dynamics of PHB, the helical structure deformation occurs first followed by the weakening of intramolecular (C = O ... H-C) hydrogen bonding within PHB-PHB molecules. Keywords: Chitosan, higher-order structure, hydrogen bonding, low-frequency vibrational spectroscopy

scholarly journals Highly disordered histone H1−DNA model complexes and their condensates

2018 ◽  
Vol 115 (47) ◽  
pp. 11964-11969 ◽  
Author(s):  
Abigail L. Turner ◽  
Matthew Watson ◽  
Oscar G. Wilkins ◽  
Laura Cato ◽  
Andrew Travers ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Chromatin Condensation ◽  
Bound State ◽  
Histone H1 ◽  
Higher Order ◽  
Disordered Proteins ◽  
Order Structure ◽  
Dependent Manner ◽  
Model Complexes

Disordered proteins play an essential role in a wide variety of biological processes, and are often posttranslationally modified. One such protein is histone H1; its highly disordered C-terminal tail (CH1) condenses internucleosomal linker DNA in chromatin in a way that is still poorly understood. Moreover, CH1 is phosphorylated in a cell cycle-dependent manner that correlates with changes in the chromatin condensation level. Here we present a model system that recapitulates key aspects of the in vivo process, and also allows a detailed structural and biophysical analysis of the stages before and after condensation. CH1 remains disordered in the DNA-bound state, despite its nanomolar affinity. Phase-separated droplets (coacervates) form, containing higher-order assemblies of CH1/DNA complexes. Phosphorylation at three serine residues, spaced along the length of the tail, has little effect on the local properties of the condensate. However, it dramatically alters higher-order structure in the coacervate and reduces partitioning to the coacervate phase. These observations show that disordered proteins can bind tightly to DNA without a disorder-to-order transition. Importantly, they also provide mechanistic insights into how higher-order structures can be exquisitely sensitive to perturbation by posttranslational modifications, thus broadening the repertoire of mechanisms that might regulate chromatin and other macromolecular assemblies.

Nucleosomes are assembled into discrete size structures by histone H1 in vitro

1986 ◽  
Vol 64 (5) ◽  
pp. 463-473 ◽  
Author(s):  
Teni Boulikas
Keyword(s):  
Ionic Strength ◽  
Histone H1 ◽  
Higher Order ◽  
Third Order ◽  
Calf Thymus ◽  
Exogenous Histone ◽  
Structural Subunit ◽  
Chromatin Structural ◽  
Low Ionic Strength

The involvement of histone H1 in the formation and maintenance of higher order chromatin structures in vitro was investigated biochemically. Addition of exogenous histone H1 to isolated calf thymus mononucleosomes in low ionic strength buffer resulted in the formation of electrophoretically distinct mononucleosome assemblies (supernucleosomes). The smaller super-nucleosomes were composed of about 12, 18, 24, or 30 nucleosomes and one to two molecules of histone H1 per nucleosome. It was difficult to determine accurately the size of the larger supernucleosomes, but their bands from native gels contained probably between 60 and 300 nucleosomes or more. Similar supemucleosome size classes were also obtained when oligonucleosomes instead of mononucleosomes were employed. When the assembly of mono- and oligo-nucleosomes with histone H1 took place in 0.15 M NaCl, discrete supernucleosomes containing only mono- or di-nucleosomes, but not a mixture of both, were formed. It is proposed that the small supernucleosomes containing oligomers of 6 nucleosomes may represent integral multiples of the second-order chromatin structural subunit, whereas the larger supernucleosomes containing about 60 to 300 or more nucleosomes may correspond to chromatin domains or third-order chromatin structures observed by other techniques.

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