Figure2. Histone modifications
Histone modifications mainly include histone acetylation and
histone
methylation. HDACs and HATs are necessary enzymes for histone
acetylation. HATs catalyze the reversible acetylation reaction at the
ε-amino group of lysine residues. Meanwhile, HDACs can remove acetyl
groups silencing the transcriptional activity of genes and leading to
chromatin condensation. Histone methylation is catalyzed by HMTs, which
occurs mainly on lysine (K) and arginine (R) residues. Key enzymes of
histone methylation involved in HMTs and KDMs. Lysine methylation occurs
in mono-, di-, and tri-states, whereas arginine methylation only occurs
in mono-and di-states. Histone H3 methylation occurs at lysine residues
K4, K9, K27, K36, and K79 and histone H4 methylation occurs at lysine
residues K20.