Histones are a family of basic, positively charged proteins that associate with DNA inside the nucleus to help condense the DNA into chromatin[1]. The nuclear DNA is wrapped around the histone in order to fit in the nucleus. Nucleosomes are chromatin beads made up of DNA wrapped around eight histone proteins, or a histone octamer[1]. The modification of histones are a type of epigenetics, where changes are made in gene expression without altering the DNA sequence. Four different examples of modifying histones including Histone acetylation, Histone deacetylation, Histone methylation and Histone demethylation[1].
Histone Deacetylases (HDACs)
ε-Amino-lysine acetylation is a type of histone modification that controls the stability of proteins and biological function in eukaryotic cells [2]. Histone Deacetylation is the reversal process for this acetylation modification. There are different classes of HDACs based on phylogenetic analysis:
•Class I - HDACs 1-3 and 8, which are homologous to yeast Rpd3
•Class II - HDACs 4-7, 9 and 10, which are homologous to yeast Hda1
HDACs 1-11 are metalloenzymes and require a zinc ion for deacetylation [2].
HDAC8
Histone Deacetylase 8 is an enzyme found in Homo sapiens. HDAC8 is 388 residues long and consists of eight-stranded parallel β-sheets surrounded by 11 α-helices [2]. HDAC8 is the only functional HDAC that is found to be a single polypeptide instead of being high-molecular-weight multi-protein complexes [2]. The substrate bound to the HDAC8 includes an acetyl group, one arginine, one histidine, two lysines and MCM, a Coumarin fluorescence tag.
↑ 2.02.12.22.32.4Vannini A, Volpari C, Gallinari P, Jones P, Mattu M, Carfi A, De Francesco R, Steinkuhler C, Di Marco S. Substrate binding to histone deacetylases as shown by the crystal structure of the HDAC8-substrate complex. EMBO Rep. 2007 Sep;8(9):879-84. Epub 2007 Aug 10. PMID:17721440
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