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==The hypothesis==
The hypothesis is that [[chromatin]]-DNA interactions are guided by combinations of histone modifications. While it is accepted that modifications (such as [[methylation]], [[acetylation]], [[ADP-ribosylation]], [[ubiquitination]], [[citrullination]], [[SUMO protein|SUMO]]-ylation <ref>{{cite https://wwwjournal |last1=Shiio |first1=Yuzuru |last2=Eisenman |first2=Robert N.pnas.org/content/100/23/13225 |title=Histone sumoylation is associated with transcriptional repression |journal=Proceedings of the National Academy of Sciences |date=11 November 2003 |volume=100 |issue=23 |pages=13225–13230 |doi=10.1073/pnas.1735528100 }}</ref> and [[phosphorylation]]) to [[histone]] tails alter chromatin structure, a complete understanding of the precise mechanisms by which these alterations to histone tails influence DNA-histone interactions remains elusive. However, some specific examples have been worked out in detail. For example, phosphorylation of [[serine]] residues 10 and 28 on [[histone H3]] is a marker for chromosomal condensation. Similarly, the combination of phosphorylation of [[serine]] residue 10 and acetylation of a [[lysine]] residue 14 on histone H3 is a tell-tale sign of active [[Transcription (genetics)|transcription]].
, by Yuzuru Shiio and Robert N. Eisenman</ref> and [[phosphorylation]]) to [[histone]] tails alter chromatin structure, a complete understanding of the precise mechanisms by which these alterations to histone tails influence DNA-histone interactions remains elusive. However, some specific examples have been worked out in detail. For example, phosphorylation of [[serine]] residues 10 and 28 on [[histone H3]] is a marker for chromosomal condensation. Similarly, the combination of phosphorylation of [[serine]] residue 10 and acetylation of a [[lysine]] residue 14 on histone H3 is a tell-tale sign of active [[Transcription (genetics)|transcription]].
[[File:Histone modifications.png|thumb|center|640px|Schematic representation of histone modifications. Based on Rodriguez-Paredes and Esteller, Nature, 2011]]
===Modifications===
*[[Phosphorylation]]
*[[Ubiquitination]]
* SUMOylation <ref>https://www{{cite journal |last1=Shiio |first1=Yuzuru |last2=Eisenman |first2=Robert N.pnas.org/content/100/23/13225 |title=Histone sumoylation is associated with transcriptional repression Yuzuru|journal=Proceedings Shiioof andthe RobertNational NAcademy of Sciences |date=11 November 2003 |volume=100 |issue=23 |pages=13225–13230 |doi=10.1073/pnas.1735528100 Eisenman}}</ref>
However, there are many more histone modifications, and sensitive [[mass spectrometry]] approaches have recently greatly expanded the catalog.<ref name="pmid21925322">{{cite journal |vauthors=Tan M, Luo H, Lee S, Jin F, Yang JS, Montellier E, etal | title=Identification of 67 histone marks and histone lysine crotonylation as a new type of histone modification. | journal=Cell | year= 2011 | volume= 146 | issue= 6 | pages= 1016–28 | pmid=21925322 | doi=10.1016/j.cell.2011.08.008 | pmc=3176443 }}</ref>
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