Editing Histone octamer (section)

== History of research==

[[Histone]] [[post-translational modifications]] were first identified and listed as having a potential regulatory role on the synthesis of [[RNA]] in 1964.<ref name="allfrey">{{cite journal|last=Allfrey|first=VG|author2=Mirsky, AE|title=Structural Modifications of Histones and their Possible Role in the Regulation of RNA Synthesis.|journal=Science|date=May 1, 1964|volume=144|issue=3618|pages=559|pmid=17836360|doi=10.1126/science.144.3618.559}}</ref>   Since then, over several decades, [[chromatin]] theory has evolved.  Chromatin subunit models as well as the notion of the nucleosome were established in 1973 and 1974, respectively.<ref name="history 2">{{cite journal|last=Hewish|first=Dean R.|last2=Burgoyne|first2=Leigh A.|author-link2=Leigh Burgoyne|title=Chromatin sub-structure. The digestion of chromatin DNA at regularly spaced sites by a nuclear deoxyribonuclease|journal=Biochem. Biophys. Res. Commun.|year=1973|volume=52|issue=2|pages=504–510|doi=10.1016/0006-291x(73)90740-7|pmid=4711166}}</ref> Richmond and his research group has been able to elucidate the crystal structure of the histone octamer with DNA wrapped up around it at a resolution of 7 Å in 1984.<ref name="klug">{{cite journal|last=Klug|author2=Richmond|title=Structure of the nucleosome core particle at 7 Å resolution|journal=Nature|year=1984|volume=311|pages=532–537|doi=10.1038/311532a0|issue=5986|pmid=6482966|bibcode=1984Natur.311..532R|s2cid=4355982}}</ref>  The structure of the octameric core complex was revisited seven years later and a resolution of 3.1 Å was elucidated for its crystal at a high salt concentration.  Though sequence similarity is low between the core histones, each of the four have a repeated element consisting of a helix-loop-helix called the [[histone fold]] motif.<ref name="arents">{{cite journal|last=Arents|author2=Burlingame|title=The nucleosomal core histone octamer at 3.1 ˚A resolution: a tripartite protein assembly and a left-handed superhelix|journal=PNAS|year=1991|volume=88|issue=22|pages=10148–52|doi=10.1073/pnas.88.22.10148|pmid=1946434|pmc=52885|bibcode=1991PNAS...8810148A|doi-access=free}}</ref>  Furthermore, the details of protein-protein and protein-DNA interactions were fine-tuned by X-ray crystallography studies at 2.8 and 1.9 Å, respectively, in the 2000s.<ref name="Solvent Mediated Interactions in the Structure of the Nucleosome Core Particle at 1.9Å Resolution">{{cite journal|last=Davey|first=Curt A.|author2=Sargent, David F. |author3=Luger, Karolin |author4=Maeder, Armin W. |author5= Richmond, Timothy J. |title=Solvent Mediated Interactions in the Structure of the Nucleosome Core Particle at 1.9Å Resolution|journal=Journal of Molecular Biology|date=June 2002|volume=319|issue=5|pages=1097–1113|doi=10.1016/S0022-2836(02)00386-8|pmid=12079350}}</ref>
<!-- Deleted image removed: [[File:Histone Octamer x-ray structure.jpg|thumb|right|Histone Octamer Structure]] -->