Reaction: dodecanoyl-CoA + a malonyl-[acyl-carrier protein] = a 3-oxotetradecanoyl-[acyl-carrier protein] + CoA + CO2
Glossary: dodecanoyl-CoA = lauroyl-CoA
Other name(s): fabH (gene name) (ambiguous); mycobacterial 3-oxoacyl-[acyl carrier protein] synthase III
Systematic name: dodecanoyl-CoA:malonyl-[acyl-carrier protein] C-acyltransferase
Comments: The enzyme, characterized from mycobacteria, provides a link between the type I and type II fatty acid synthase systems (FAS-I and FAS-II, respectively) found in these organisms. The enzyme acts on medium- and long-chain acyl-CoAs (C12-C16) produced by the FAS-I system, condensing them with malonyl-[acyl-carrier protein] (malonyl-AcpM) and forming starter molecules for the FAS-II system, which elongates them into meromycolic acids. The enzyme has no activity with short-chain acyl-CoAs (e.g. acetyl-CoA), which are used by EC 2.3.1.180, β-ketoacyl-[acyl-carrier-protein] synthase III, or branched-chain acyl-CoAs, which are used by EC 2.3.1.300, branched-chain β-ketoacyl-[acyl-carrier-protein] synthase.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Scarsdale, J.N., Kazanina, G., He, X., Reynolds, K.A. and Wright, H.T. Crystal structure of the Mycobacterium tuberculosis β-ketoacyl-acyl carrier protein synthase III. J. Biol. Chem. 276 (2001) 20516-20522. [PMID: 11278743]
2. Musayev, F., Sachdeva, S., Scarsdale, J.N., Reynolds, K.A. and Wright, H.T. Crystal structure of a substrate complex of Mycobacterium tuberculosis β-ketoacyl-acyl carrier protein synthase III (FabH) with lauroyl-coenzyme A. J. Mol. Biol. 346 (2005) 1313-1321. [PMID: 15713483]
3. Brown, A.K., Sridharan, S., Kremer, L., Lindenberg, S., Dover, L.G., Sacchettini, J.C. and Besra, G.S. Probing the mechanism of the Mycobacterium tuberculosis β-ketoacyl-acyl carrier protein synthase III mtFabH: factors influencing catalysis and substrate specificity. J. Biol. Chem. 280 (2005) 32539-32547. [PMID: 16040614]
4. Sachdeva, S., Musayev, F.N., Alhamadsheh, M.M., Scarsdale, J.N., Wright, H.T. and Reynolds, K.A. Separate entrance and exit portals for ligand traffic in Mycobacterium tuberculosis FabH. Chem. Biol. 15 (2008) 402-412. [PMID: 18420147]