HATs and HDACs

Abstract

DNA in eukaryotes is arranged into higher order structures termed chromatin. Chromatin poses an obstacle for gene transcription because it is not readily accessible to DNA binding transcription factors. Chromatin also provides the structural basis for gene regulation, keeping most genes in a default state of repression. The regulation of gene expression involves dynamic chromatin remodeling associated with reversible histone acetylation. The enzymes that catalyze histone acetylation (HAT) and deacetylation (HDAC) are critical elements that regulate chromatin dynamics and gene expression. These chromatin-modifying enzymes are recruited to the genome by DNA binding transcription factors and are the key effectors that control chromatin structure. HAT and HDAC proteins are important in both normal cellular physiology and disease states. The recent identification of a large number of non-histone substrates for HATs and HDACs suggest even broader biological functions for these versatile enzymes.