InterPro: IPR013751 3-Oxoacyl-[acyl-carrier-protein (ACP)] synthase III

Fatty acid synthesis (FAS) is a vital aspect of cellular physiology which can occur by two distinct pathways. The FAS I pathway, which generally only produces palmitate, is found in eukaryotes and is performed either by a single polypeptide which contains all the reaction centres needed to form a fatty acid, or by two polypeptides which interact to form a multifunctional complex. The FAS II pathway, which is capable of producing many different fatty acids, is found in mitochondria, bacteria, plants and parasites, and is performed by many distinct proteins, each of which catalyses a single step within the pathway. The large diversity of products generated by this pathway is possible because the acyl carrier protein (ACP) intermediates are diffusible entities that can be diverted into other biosynthetic pathways [1].

3-Oxoacyl-[acyl carrier protein (ACP)] synthase III catalyses the first condensation step within the FAS II pathway, using acetyl-CoA as the primer and malonyl-ACP as the acceptor, as shown below.

Acyl-[ACP] + malonyl-[ACP] = 3-oxoacyl-[ACP] + CO(2) + [ACP]

The enzymes studied so far are homodimers, where each monomer consists of two domains (N-terminal and C-terminal) which are similar in structure, but not in sequence [2, 3]. This entry represents a conserved region within the N-terminal domain.