Acetylation and deacetylation of histone plays a vital role in maintaining active profile and repressed version of genes.
Gene regulation in eukaryotes is carried out by acetylation and deacetylation of histone proteins. Histones contain lysine residues in the N-terminal tail; these lysine residues are acetylated and deacetylated as a part of gene regulation.
Histone acetyltransferase (HAT) is the enzyme that catalyzes acetylation, whereas Histone deacetylase (HDAC) is the enzyme that catalyzes deacetylation. Positive charge on the histones is removed by acetylation; as a result condensed chromatin is relaxed for further transcription of gene. Deacetylation process reverses this process, thus reduces the gene expression.