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 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

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 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.

Macrocycles of Higher Ortho-Phenylenes: Assembly and Folding

2019 ◽  
Author(s):  
Zacharias Kinney ◽  
Viraj Kirinda ◽  
Scott Hartley
Keyword(s):  
Chemical Shift ◽  
Higher Order ◽  
Order Structure ◽  
Complex Geometries ◽  
Spatial Relationships ◽  
Predominant Species ◽  
Bite Angle ◽  
Direct Assembly

<p>Higher-order structure in abiotic foldamer systems represents an important but largely unrealized goal. As one approach to this challenge, covalent assembly can be used to assemble macrocycles with foldamer subunits in well-defined spatial relationships. Such systems have previously been shown to exhibit self-sorting, new folding motifs, and dynamic stereoisomerism, yet there remain important questions about the interplay between folding and macrocyclization and the effect of structural confinement on folding behavior. Here, we explore the dynamic covalent assembly of extended <i>ortho</i>-phenylenes (hexamer and decamer) with rod-shaped linkers. Characteristic <sup>1</sup>H chemical shift differences between cyclic and acyclic systems can be compared with computational conformer libraries to determine the folding states of the macrocycles. We show that the bite angle provides a measure of the fit of an <i>o</i>-phenylene conformer within a shape-persistent macrocycle, affecting both assembly and ultimate folding behavior. For the <i>o</i>-phenylene hexamer, the bite angle and conformer stability work synergistically to direct assembly toward triangular [3+3] macrocycles of well-folded oligomers. For the decamer, the energetic accessibility of conformers with small bite angles allows [2+2] macrocycles to be formed as the predominant species. In these systems, the <i>o</i>-phenylenes are forced into unusual folding states, preferentially adopting a backbone geometry with distinct helical blocks of opposite handedness. The results show that simple geometric restrictions can be used to direct foldamers toward increasingly complex geometries.</p>

Macrocycles of Higher ortho-Phenylenes: Assembly and Folding

2019 ◽  
Author(s):  
Zacharias Kinney ◽  
Viraj Kirinda ◽  
Scott Hartley
Keyword(s):  
Chemical Shift ◽  
Higher Order ◽  
Order Structure ◽  
Complex Geometries ◽  
Spatial Relationships ◽  
Predominant Species ◽  
Bite Angle ◽  
Direct Assembly

<p>Higher-order structure in abiotic foldamer systems represents an important but largely unrealized goal. As one approach to this challenge, covalent assembly can be used to assemble macrocycles with foldamer subunits in well-defined spatial relationships. Such systems have previously been shown to exhibit self-sorting, new folding motifs, and dynamic stereoisomerism, yet there remain important questions about the interplay between folding and macrocyclization and the effect of structural confinement on folding behavior. Here, we explore the dynamic covalent assembly of extended <i>ortho</i>-phenylenes (hexamer and decamer) with rod-shaped linkers. Characteristic <sup>1</sup>H chemical shift differences between cyclic and acyclic systems can be compared with computational conformer libraries to determine the folding states of the macrocycles. We show that the bite angle provides a measure of the fit of an <i>o</i>-phenylene conformer within a shape-persistent macrocycle, affecting both assembly and ultimate folding behavior. For the <i>o</i>-phenylene hexamer, the bite angle and conformer stability work synergistically to direct assembly toward triangular [3+3] macrocycles of well-folded oligomers. For the decamer, the energetic accessibility of conformers with small bite angles allows [2+2] macrocycles to be formed as the predominant species. In these systems, the <i>o</i>-phenylenes are forced into unusual folding states, preferentially adopting a backbone geometry with distinct helical blocks of opposite handedness. The results show that simple geometric restrictions can be used to direct foldamers toward increasingly complex geometries.</p>

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