Database accession: MF2210001
Name: H2A-H2B histone dimer (Xenopus laevis), containing histone variants H2A type 1 and H2B 1.1
PDB ID: 1aoi
Experimental method: X-ray (2.80 Å)
Assembly: heterodimer
Source organism: Xenopus laevis
Primer publication of the structure:
Luger K, Mäder AW, Richmond RK, Sargent DF, Richmond TJ
Crystal structure of the nucleosome core particle at 2.8 A resolution.
(1997) Nature 389: 251-60
PMID: 9305837
Abstract:
The X-ray crystal structure of the nucleosome core particle of chromatin shows in atomic detail how the histone protein octamer is assembled and how 146 base pairs of DNA are organized into a superhelix around it. Both histone/histone and histone/DNA interactions depend on the histone fold domains and additional, well ordered structure elements extending from this motif. Histone amino-terminal tails pass over and between the gyres of the DNA superhelix to contact neighbouring particles. The lack of uniformity between multiple histone/DNA-binding sites causes the DNA to deviate from ideal superhelix geometry.
Molecular function:
protein heterodimerization activity Interacting selectively and non-covalently with a nonidentical protein to form a heterodimer.
Biological process: not assigned
Cellular component:
Entry contents: 2 distinct polypeptide molecules
Chains: C, D
Notes: Chains A, B, E, F, G, H, I and J have been removed to highlight the basic interaction that forms the histone dimer composed of chains C and D.
Number of unique protein segments: 2
Name: Histone H2A type 1
Source organism: Xenopus laevis
Length: 116 residues
Sequence:Sequence according to PDB SEQRESGKQGGKTRAKAKTRSSRAGLQFPVGRVHRLLRKGNYAERVGAGAPVYLAAVLEYLTAEILELAGNAARDNKKTRIIPRHLQLAVRNDEELNKLLGRVTIAQGGVLPNIQSVLLPKK
UniProtKB AC: P06897 (positions: 5-120)
Coverage: 89.2%UniRef90 AC: UniRef90_Q00728 (positions: 6-120)
Name: Histone H2B 1.1
Source organism: Xenopus laevis
Length: 99 residues
Sequence:Sequence according to PDB SEQRESKKRRKTRKESYAIYVYKVLKQVHPDTGISSKAMSIMNSFVNDVFERIAGEASRLAHYNKRSTITSREIQTAVRLLLPGELAKHAVSEGTKAVTKYTSAK
UniProtKB AC: P02281 (positions: 28-126)
Coverage: 78.6%UniRef90 AC: UniRef90_P57053 (positions: 28-126)
Complex evidence:
Histones form parts of the nucleosome particle by dimerization and subsequent multimerization (PMID: 1946434). The dimer contains both histone subunits in a highly intertwined conformation reflecting the possible domain-swapped origins of the structure (PMID: 17391511). Accordingly, this dimerization has been experimentally characterized to be coupled to the structure formation of both interacting partners (PMID: 12779337); this synergistic folding has been shown separately for H2A-H2B dimers (PMID: 15588829) and H3-H4 dimers as well (PMID: 15096635). Histones containing various types of monomeric subunits can exhibit varying stability and folding kinetics. E.g. in the case of H3-H4 histones, the dimerization is a complex process with the two monomers first adopting an intermediate state upon encounter and then reaching the classical histone fold through restructurization (PMID: 12779337). However, independent of composition and folding kinetics, all histones appear to fold in a cooperative fashion that is coupled to binding (PMID: 11669650).
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