Editing Nucleosome (section)

====Overview====
Pioneering structural studies in the 1980s by Aaron Klug's group provided the first evidence that an octamer of histone proteins wraps DNA around itself in about 1.7 turns of a left-handed superhelix.<ref name="pmid6482966">{{cite journal | vauthors = Richmond TJ, Finch JT, Rushton B, Rhodes D, Klug A | title = Structure of the nucleosome core particle at 7 A resolution | journal = Nature | volume = 311 | issue = 5986 | pages = 532–7 | date = 1984 | pmid = 6482966 | doi = 10.1038/311532a0 | bibcode = 1984Natur.311..532R | s2cid = 4355982 }}</ref> In 1997 the first near atomic resolution [[crystal structure]] of the nucleosome was solved by the Richmond group at the [[ETH Zurich]], showing the most important details of the particle. The human [[Centromere#Sequence|alpha satellite]] [[Palindromic sequence|palindromic DNA]] critical to achieving the 1997 nucleosome crystal structure was developed by the Bunick group at Oak Ridge National Laboratory in Tennessee.<ref>{{cite journal | vauthors = Harp JM, Palmer EL, York MH, Gewiess A, Davis M, Bunick GJ | title = Preparative separation of nucleosome core particles containing defined-sequence DNA in multiple translational phases | journal = Electrophoresis | volume = 16 | issue = 10 | pages = 1861–1864 | date = October 1995 | pmid = 8586054 | doi = 10.1002/elps.11501601305 | s2cid = 20178479 }}</ref><ref name="pmid8678288">{{cite journal | vauthors = Palmer EL, Gewiess A, Harp JM, York MH, Bunick GJ | title = Large-scale production of palindrome DNA fragments | journal = Analytical Biochemistry | volume = 231 | issue = 1 | pages = 109–114 | date = October 1995 | pmid = 8678288 | doi = 10.1006/abio.1995.1509 }}</ref><ref name="pmid15299701">{{cite journal | vauthors = Harp JM, Uberbacher EC, Roberson AE, Palmer EL, Gewiess A, Bunick GJ | title = X-ray diffraction analysis of crystals containing twofold symmetric nucleosome core particles | journal = Acta Crystallographica. Section D, Biological Crystallography | volume = 52 | issue = Pt 2 | pages = 283–288 | date = March 1996 | pmid = 15299701 | doi = 10.1107/S0907444995009139 | doi-access = free | bibcode = 1996AcCrD..52..283H }}</ref><ref name="pmid11092917">{{cite journal | vauthors = Harp JM, Hanson BL, Timm DE, Bunick GJ | title = Asymmetries in the nucleosome core particle at 2.5 A resolution | journal = Acta Crystallographica. Section D, Biological Crystallography | volume = 56 | issue = Pt 12 | pages = 1513–1534 | date = December 2000 | pmid = 11092917 | doi = 10.1107/s0907444900011847 }}</ref><ref name="pmid14870658">{{cite book | vauthors = Hanson BL, Alexander C, Harp JM, Bunick GJ | title = Chromatin and Chromatin Remodeling Enzymes, Part A | chapter = Preparation and crystallization of nucleosome core particle | series = Methods in Enzymology | volume = 375 | pages = 44–62 | year = 2004 | pmid = 14870658 | doi = 10.1016/s0076-6879(03)75003-4 | isbn = 9780121827793 }}</ref> The structures of over 20 different nucleosome core particles have been solved to date,<ref name=pmid15680970>{{cite journal | vauthors = Chakravarthy S, Park YJ, Chodaparambil J, Edayathumangalam RS, Luger K | title = Structure and dynamic properties of nucleosome core particles | journal = FEBS Letters | volume = 579 | issue = 4 | pages = 895–898 | date = February 2005 | pmid = 15680970 | doi = 10.1016/j.febslet.2004.11.030 | s2cid = 41706403 | doi-access = free | bibcode = 2005FEBSL.579..895C }}</ref> including those containing histone variants and histones from different species. The structure of the nucleosome core particle is remarkably conserved, and even a change of over 100 residues between frog and yeast histones results in electron density maps with an overall [[root mean square deviation]] of only 1.6Å.<ref name="pmid11566884">{{cite journal | vauthors = White CL, Suto RK, Luger K | title = Structure of the yeast nucleosome core particle reveals fundamental changes in internucleosome interactions | journal = The EMBO Journal | volume = 20 | issue = 18 | pages = 5207–5218 | date = September 2001 | pmid = 11566884 | pmc = 125637 | doi = 10.1093/emboj/20.18.5207 }}</ref>