Serine O-acetyltransferase (SAT)

Serine O-acetyltransferase (SAT) is an enzyme that catalyzes the first step in the biosynthesis of L-cysteine, converting acetyl-CoA and L-serine into CoA and O-acetyl-L-serine[1][2][3][5][8]. SAT is a member of the acyltransferase enzyme family, structurally characterized by an N-terminal alpha-helical domain and a C-terminal left-handed beta-helix domain, and commonly forms oligomeric complexes (e.g., trimers or hexamers)[1][6]. Functionally, SAT is a key regulatory point in sulfur metabolism in bacteria, plants, and some protozoa, as its activity is feedback-inhibited by the end product L-cysteine, which competes with L-serine for binding at the enzyme's active site, a mechanism well-conserved across species[1][2][7]. In plants, SAT partners with O-acetylserine thiol-lyase in a cysteine synthase complex to fine-tune cysteine production[3][6]. Owing to its absence in humans and its essential role in pathogen viability, SAT is under investigation as an antimicrobial target, particularly in drug-resistant bacterial and protozoal infections[1][7]. No approved drugs currently target SAT, but inhibitors are under preclinical study.

Other names

Serine acetyltransferaseSATaseL-serine acetyltransferaseSerine transacetylaseCysE (gene symbol in bacteria)

Competitive inhibition (by L-cysteine at the L-serine binding site); Enzymatic transfer of acetyl group from acetyl-CoA to L-serine, forming O-acetyl-L-serine