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 ?
Professor Holdenrieder is an expert in the field of circulating nucleosomes and currently serves as secretary of the International Society of Oncological BioMarkers, External Quality Assessment consultant for tumor marker ring trials at INSTAND e.
sup][23] As core epigenetic regulators, a well-known alternative target of HDACs is “histone protein,” HDACs are capable of removing acetyl groups from histone lysine tails, stabilizing nucleosome structure and compacting chromatin, thereby blocking access of transcriptional activators to the DNA template and repressing gene transcription.
The protein "reads" various signals displayed on the nucleosome surface by adopting a shape that fits various modifications on the nucleosome complex, like the different shaped pieces of a jigsaw puzzle.
It can help load histones onto DNA during nucleosome assembly in vitro (Laskey et al.
The first step in that direction is to make an initial nucleosome map to serve as a reference.
Involvement of histone H1 in the organization of the nucleosome and of the salt-dependent superstructures of chromatin.
Most importantly, they found that the nucleosomes are assembled in irregular groups across the chromatin and nucleosome-free-DNA regions separate these groups.
Also Anti-ENA (Extractable Nuclear Antigen) assay was performed with commercial kits (Euroline ANA Profile 1 Euroimmun) based on Immunblotting method with each strip containing nRNP/Sm (U1-nRNP) Sm SS-A Recombinant Ro-52 (Ro-52 52kDa) SS-B DNA- Topoisomerase I (Scl-70) PM-Scl Histidyl-tRNA synthetase (Jo-1) Centromer protein B (CENP B) Double stranded DNA (dsDNA) and Nucleosome Histone antigens.
In a molecular level the modification of cytosine and histone alkaline modification and changes in nucleosome location are known as the typical mechanisms of epigenetic.
Each nucleosome contains two copies of four different histone proteins (H2A, H2B, H3, and H4) as well as around 141 base pairs of DNA.
Among the topics are DNA repair by reversal of DNA damage, the maintenance of mitochondrial DNA integrity, nucleosome dynamics as modular systems that integrate DNA damage and repair, trans-lesion DNA synthesis and mutagenesis in prokaryotes, and Deinococcus radiodurans and the biology of extreme radiation resistance.