Beta-ketoacyl-[acyl carrier protein] synthase (KAS)

Beta-ketoacyl-[acyl carrier protein] synthase is a family of enzymes essential for **fatty acid chain elongation** in the process of fatty acid biosynthesis. The enzyme catalyzes the condensation of an acyl group (commonly acetyl-CoA or propionyl-CoA) with malonyl-ACP, releasing CO₂ and forming a beta-ketoacyl-ACP intermediate, a crucial step in both prokaryotic (Type II) and eukaryotic (Type I) fatty acid synthases[1][2][3]. Multiple isoforms (KAS I, II, III) exist and play distinct roles in the fatty acid chain-length elongation cycle, with KAS III (often designated FabH in bacteria) catalyzing the initial condensation step[2][5]. Beta-ketoacyl-ACP synthase is a validated **antibacterial target**, as inhibition leads to interruption of fatty acid and cell membrane synthesis, incapacitating the pathogen[5][3]. Structural and mechanistic studies show that the active site coordinates a complex set of catalytic residues to enable precise condensation chemistry[1][4]. In plants, multiple isoforms contribute to the biosynthesis of storage and membrane lipids, influencing plant growth, development, and stress responses[4].

Other names

3-Oxoacyl-[acyl-carrier-protein] synthaseBeta-ketoacyl-ACP synthaseKAS (I, II, III)FabH (specifically the III isoform)3-Oxoacyl-ACP synthaseAcetoacetyl-ACP synthase

Inhibitors block the enzyme's condensation activity, halting fatty acid chain elongation and thereby inhibiting cell membrane synthesis in bacteria