In molecular biology, a histone octamer is the eight-protein complex found at the center of a nucleosome core particle. It consists of two copies of each of the four core histone proteins (H2A, H2B, H3, and H4). The octamer assembles when a tetramer, containing two copies of H3 and two of H4, complexes with two H2A/H2B dimers.

The nucleosome is the fundamental subunit of chromatin. Each nucleosome is composed of a little less than two turns of DNA wrapped around a set of eight proteins called histones, which are known as a histone octamer. Each histone octamer is composed of two copies each of the histone proteins H2A, H2B, H3, and H4.

Histone octamers are a complex of eight positively charged histone proteins that assist in DNA packaging. These are seen at the centre of the nucleosome core particle. Histones comprise two copies of each of the 4 core histone proteins – H2A, H2B, H3 and H4.

The DNA associates with the histone octamer such that nucleosome dyad axis passes through a single base pair at the center of the structure. The DNA helix at the dyad straddles the H3:H3 interface with the minor groove oriented directly away from the histone surface .

2017年1月20日 · Preventing octamer distortion by site-specific disulfide linkages inhibits nucleosome sliding by SNF2h while promoting octamer eviction by the SWI-SNF complex, RSC. Our findings indicate that the histone core of a nucleosome is more plastic than previously imagined and that octamer deformation plays different roles based on the type of ...

The nucleosome core particle wraps 145-147 bp of DNA around the histone octamer. The dyad of the nucleosome passes through a DNA base pair into the middle of the particle. The dyad corresponds to DNA superhelical location (SHL) 0 and the successive positions where the DNA minor groove faces the octamer are numbered -7 to +7.

In a canonical nucleosome, an octamer of two copies each of the four core histones (H3, H4, H2A and H2B) is wrapped by 145-147 base pairs (bp) of DNA in a left-handed supercoil .

Here we show that the predominant form of the CENP-A particle at human centromeres is an octameric nucleosome. CENP-A nucleosomes are very highly phased on α-satellite 171 bp monomers at normal centromeres, and also display strong positioning at neocentromeres.

2009年2月13日 · The DNA of this limiting size plus the octamer of histone molecules—two of each of histones H2A, H2B, H3, and H4—around which the DNA is wrapped up, was termed the nucleosome core particle (van Holde, 1988). The repeating unit of any chromatin—the nucleosome—was considered to be composed of two parts: the ubiquitous “core” particle ...

The structure of the octameric histone core of the nucleosome has been determined by x-ray crystallography to a resolution of 3.1 A. The histone octamer is a tripartite assembly in which a centrally located (H3-H4)2 tetramer is flanked by two ...