acetylotransferaz

Acetyltransferases, also known as acetylotransferases in some languages, are enzymes that catalyze the transfer of an acetyl group from acetyl-CoA to an acceptor molecule. The general reaction is acetyl-CoA + acceptor → CoA + acetylated product. Acceptors can be amine groups on proteins or small molecules, hydroxyl groups, or sugars, depending on the enzyme and organism.

Several families carry out acetyltransferase activity. The GNAT (GCN5-related N-acetyltransferase) superfamily is widespread and acts on various amine substrates and protein targets. Other important families include histone acetyltransferases (HATs), such as members of the GNAT and MYST families, which modify chromatin to regulate gene expression. Bacteria also have aminoglycoside N-acetyltransferases that inactivate certain antibiotics by acetylation.

Biological roles are diverse. In eukaryotes, histone acetylation by HATs generally correlates with transcriptional activation by loosening chromatin structure. Metabolic and detoxification pathways rely on acetyltransferases to modify small molecules, cofactors, and drugs, influencing enzyme activity and solubility. In microbes, acetyltransferases can contribute to antibiotic resistance by inactivating drugs.

Most acetyltransferases use acetyl-CoA as the donor of the acetyl group. The catalytic mechanism involves transfer of the acetyl moiety to the nucleophilic atom on the acceptor, with CoA released as a byproduct. Structures typically feature a conserved acetyl-CoA binding pocket and substrate-recognition elements that confer specificity.

Clinical and research relevance: human NAT1 and NAT2 enzymes show genetic polymorphism, producing fast and slow acetylator phenotypes that affect drug metabolism and toxicity for certain compounds (for example isoniazid). Dysregulation of acetyltransferase activity is also studied in cancer and metabolic diseases.