Methyllysine

{{Short description|Derivative of the amino acid residue lysine}}

Methyllysine is derivative of the amino acid residue lysine where the sidechain ammonium group has been methylated one or more times.{{cite journal|doi=10.1038/emm.2017.11|pmid=28450737|pmc=6130214|title=Writing, erasing and reading histone lysine methylations|journal=Experimental & Molecular Medicine|volume= 49|issue=4|pages=e324|year=2017|last1=Hyun|first1= Kwangbeom|last2=Jeon|first2=Jongcheol|last3= Park|first3=Kihyun|last4 =Kim|first4=Jaehoon}}

Such methylated lysines play an important role in epigenetics; the methylation of specific lysines of certain histones in a nucleosome alters the binding of the surrounding DNA to those histones, which in turn affects the expression of genes on that DNA.{{cite journal | vauthors = Ruthenburg AJ, Allis CD, Wysocka J | title = Methylation of lysine 4 on histone H3: intricacy of writing and reading a single epigenetic mark | journal = Molecular Cell | volume = 25 | issue = 1 | pages = 15–30 | date = January 2007 | pmid = 17218268 | doi = 10.1016/j.molcel.2006.12.014 | doi-access = free }}{{cite journal | vauthors = Fischle W, Wang Y, Jacobs SA, Kim Y, Allis CD, Khorasanizadeh S | title = Molecular basis for the discrimination of repressive methyl-lysine marks in histone H3 by Polycomb and HP1 chromodomains | journal = Genes & Development | volume = 17 | issue = 15 | pages = 1870–81 | date = August 2003 | pmid = 12897054 | pmc = 196235 | doi = 10.1101/gad.1110503 }} The binding is affected because the effective radius of the positive charge is increased (methyl groups are larger than the hydrogen atoms they replace), reducing the strongest potential electrostatic attraction with the negatively charged DNA.

It is thought that the methylation of lysine (and arginine) on histone tails does not directly affect their binding to DNA. Rather, such methyl marks recruit other proteins that modulate chromatin structure.{{cite journal | vauthors = Arrowsmith CH, Bountra C, Fish PV, Lee K, Schapira M | title = Epigenetic protein families: a new frontier for drug discovery | journal = Nature Reviews. Drug Discovery | volume = 11 | issue = 5 | pages = 384–400 | date = April 2012 | pmid = 22498752 | doi = 10.1038/nrd3674 | doi-access = free }}

In Protein Data Bank files, methylated lysines are indicated by the MLY or MLZ acronyms.

Image:L-Lysine.svg|Unmethylated lysine

Image:N6-methyllysine.svg|Monomethylated: 6-N-methyllysine

Image:N6,N6-dimethyllysine.svg|Dimethylated: (6-N,6-N)dimethyllysine

Image:Trimethyllysine.svg|Trimethylated: (6-N,6-N,6-N)trimethyllysine