InterPro: IPR000182 GCN5-related N-acetyltransferase

Histone acetylation is carried out by a class of enzymes known as histone acetyltransferases (HATs), which catalyze the transfer of an acetyl group from acetyl-CoA to the lysine E-amino groups on the N-terminal tails of histones[1]. Early indication that HATs were involved in transcription came from the observation that in actively transcribed regions of chromatin, histones tend to be hyperacetylated, whereas in transcriptionally silent regions histones are hypoacetylated. The histone acetyltransferases are divided into five families. These include the Gcn5-related acetyltransferases (GNATs); the MYST (for `MOZ, Ybf2/Sas3, Sas2 and Tip60)-related HATs; p300/CBP HATs; the general transcription factor HATs, which include the TFIID subunit TAF250; and the nuclear hormone-related HATs SRC1 and ACTR (SRC3). The GCN5-related N-acetyltransferase superfamily includes such enzymes as the histone acetyltransferases GCN5 and Hat1, the elongator complex subunit Elp3, the mediator-complex subunit Nut1, and Hpa2 [2].

Many GNATs share several functional domains, including an N-terminal region of variable length, an acetyltransferase domain that encompasses the conserved sequence motifs described above, a region that interacts with the coactivator Ada2, and a C-terminal bromodomain that is believed to interact with acetyl-lysine residues. Members of the GNAT family are important for the regulation of cell growth and development. In mice, knockouts of Gcn5L are embryonic lethal. Yeast Gcn5 is needed for normal progression through the G2-M boundary and mitotic gene expression. The importance of GNATs is probably related to their role in transcription and DNA repair.

The yeast GCN5 (yGCN5) transcriptional coactivator functions as a histone acetyltransferase (HAT) to promote transcriptional activation. The crystal structure of the yeast histone acetyltransferase Hat1-acetyl coenzyme A (AcCoA) shows that Hat1 has an elongated, curved structure, and the AcCoA molecule is bound in a cleft on the concave surface of the protein, marking the active site of the enzyme. A channel of variable width and depth that runs across the protein is probably the binding site for the histone substrate [3]. The central protein core associated with AcCoA binding that appears to be structurally conserved among a superfamily of N-acetyltransferases, including yeast histone acetyltransferase 1 and Serratia marcescens aminoglycoside 3-N-acetyltransferase [4].