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 ?
Acetylation of histone H4 plays a primary role in enhancing transcription factor binding to nucleosomal DNA in vitro.
The histone-bound DNA retains its nucleosomal structure, and it is peripherally located in the nucleus containing genes essential for early embryonic development.
Circulating fragmented nucleosomal DNA and aaspase-3 mRNA in patients with lymphoma and myeloma.
A hallmark of apoptosis is DNA degradation, in which chromosomal DNA is 1st cleaved into large fragments (50-300 kb) and subsequently into multiples of nucleosomal units (180-200 bp) (1).
Theoretically, circulating DNA is mostly released from degrading cells after cleavage by endonucleases that cut the chromatin into the basic nucleosomal elements (1,2).
Our studies have shown that circulatory DNA has apoptotic characteristics, displaying a typical ladder obtained by nucleosomal cleavage.
Previous studies have demonstrated a correlation between plasma DNA concentrations and apoptosis of tumor cells in cancer patients (14, 15), and several studies have also shown that the lengths of plasma DNA molecules in cancer patients are very short and are in multiples of nucleosomal DNA (14,16).
It has been shown that serum contains cell-free circulating DNA the size of nucleosomal DNA (3).
The authors hypothesized that this intact DNA originated from tumor cells because physiologically shed healthy mucosa cells are apoptotic, leading to nucleosomal DNA fragmentation.
High mobility group protein 1 (HMGB1) has been implicated in diverse cellular functions, including determination of nucleosomal structure and stability and binding of transcription factors to their cognate DNA sequences (1-4).
Electrophoresis of nick-translated DNA isolated from plasma of healthy controls produced autoradiographic bands at sizes equivalent to whole-number multiples (1-5X) of nucleosomal DNA (185-200 bp) (12).
Nucleosomes are made up of core nucleosomal DNA wrapped around a histone octamer (two molecules of each of the core histones, H2A, H2B, [H.