The enzyme is responsible for initiating straight-chain fatty acid biosynthesis by the dissociated (or type II) fatty-acid biosynthesis system that occurs in plants and bacteria. In contrast to EC
2.3.1.41, beta-ketoacyl-[acyl-carrier-protein] synthase I, and EC
2.3.1.179, beta-ketoacyl-[acyl-carrier-protein] synthase II, this enzyme specifically uses short-chain acyl-CoA thioesters (preferably acetyl-CoA) rather than acyl-[acp] as its substrate [1]. The enzyme can also catalyse the reaction of EC
2.3.1.38, [acyl-carrier-protein] S-acetyltransferase, but to a much lesser extent [1]. The enzymes from some organisms (e.g. the Gram-positive bacterium Streptococcus pneumoniae) can accept branched-chain acyl-CoAs in addition to acetyl-CoA [5] (cf. EC
2.3.1.300, branched-chain beta-ketoacyl-[acyl-carrier-protein] synthase).
