nucleosome

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Nucleosome

The fundamental histone-containing structural subunit of eukaryotic chromosomes. In most eukaryotic organisms, nuclear deoxyribonucleic acid (DNA) is complexed with an approximately equal mass of histone protein. The nucleosome is organized so that the DNA is exterior and the histones interior. The DNA makes two turns around a core of eight histone molecules, thus forming a squat cylinder 11 nanometers in diameter and 5.5 nm in height. A short length of linker or spacer DNA connects one nucleosome to the next, forming a nucleosomal chain that has been likened to a beaded string. This basic structure is found in all forms of chromatin. Nucleosomes have been found in all eukaryotic organisms examined, the only exceptions being some sperm nuclei and the dinoflagellate algae.

A chain of adjacent nucleosomes is approximately sixfold shorter than the DNA it contains. Moreover, chains of nucleosomes have the property of self-assembling into thicker fibers in which the DNA packing ratio approaches 35:1. These observations, and the lack of any obvious catalytic activity, have led to the assumption that the primary function of the nucleosome consists of organizing and packing DNA. See Chromosome, Deoxyribonucleic acid (DNA), Gene

nucleosome

[′nü·klē·ə‚sōm]
(cell and molecular biology)
A morphologically repeating unit of deoxyribonucleic acid (DNA) containing 190 base pairs of DNA folded together with eight histone molecules. Also known as v-body.
References in periodicals archive ?
S-nitrosylation, one of the above-mentioned NO-derived protein posttranslational modifications, affects direct chromatin modification, namely, tyrosine nitration of nucleosomal core histones [115].
Disruption of higher-order folding by core histone acetylation dramatically enhances transcription of nucleosomal arrays by RNA polymerase III.
We observed that EGCG induced apoptosis in human lymphoma U937 cells as evidenced by the events including formation of apoptotic bodies and degradation of DNA into nucleosomal units.
EBV induced cell death in vitro, and the cell death was associated with nucleosomal cleavage of cellular DNA and expression of phosphatidylserines on cell surface, an early event of apoptosis occurring before membrane disruption.
Such a pattern corresponded to inter nucleosomal cleavage, which was characteristic of apoptosis.
The nucleosomal DNA was extracted according to the protocol provided with the apoptosis kit, (G.
Acetylation of the e amino lysines weakens the electrostatic attraction for the (negatively charged) nucleic acids and disassembles the nucleosomal histones, further the DNA sequence is accessible for various transcriptional factors and activates the gene transcription whereas deacetylation results in chromatin condensation and gene repression (30,31).
Formation of the nucleosomal DNA ladder is the hallmark of apoptosis so analysis of the pattern of DNA isolated from the cells exposed to different stress inducers was done.
The hallmark diagnostic sign is the presence of auto-antibodies against nucleosomal antigens.
Third, the nucleosomal structural alterations have the potential to transform helper T lymphocytes in such a way that they cannot distinguish self from non-self antibodies (Berden, 1997).
In some cancer cells, there is an overexpression of HDACs, or an aberrant recruitment of HDACs to oncogenic transcription factors causing hypoacetylation of core nucleosomal histones.
The nucleosomal surface as a docking station for Kaposi's sarcoma herpesvirus LANA," Science, vol.