Taxonomic distribution of proteins containing H2A domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing H2A domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

DNA binding within the nucleosome core.

Luger K, Richmond TJ
Curr Opin Struct Biol. 1998; 8: 33-40

The high resolution structure of the nucleosome core particle of chromatin reveals the form of DNA that is predominant in living cells and offers a wealth of information on DNA binding and bending by the histone octamer. Recent studies imply that chromatin is highly dynamic. This propensity for unfolding and refolding stems from the structural design of the nucleosome core. The histone-fold motif, central to nucleosome structure, is also found in other proteins involved in transcriptional regulation.

Crystal structure of the nucleosome core particle at 2.8 A resolution.

Luger K, Mader AW, Richmond RK, Sargent DF, Richmond TJ
Nature. 1997; 389: 251-60

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.

Phylogenetic analysis of the core histones H2A, H2B, H3, and H4.

Thatcher TH, Gorovsky MA
Nucleic Acids Res. 1994; 22: 174-9

Despite the ubiquity of histones in eukaryotes and their important role in determining the structure and function of chromatin, no detailed studies of the evolution of the histones have been reported. We have constructed phylogenetic trees for the core histones H2A, H2B, H3, and H4. Histones which form dimers (H2A/H2B and H3/H4) have very similar trees and appear to have co-evolved, with the exception of the divergent sea urchin testis H2Bs, for which no corresponding divergent H2As have been identified. The trees for H2A and H2B also support the theory that animals and fungi have a common ancestor. H3 and H4 are 10-fold less divergent than H2A and H2B. Three evolutionary histories are observed for histone variants. H2A.F/Z-type variants arose once early in evolution, while H2A.X variants arose separately, during the evolution of multicellular animals. H3.3-type variants have arisen in multiple independent events.