Reaction: a medium-chain acyl-CoA + 5 malonyl-CoA + 5 (S)-methylmalonyl-CoA + 22 NADPH + 22 H+ = a mycoketide-CoA + 10 CO2 + 10 CoA + 22 NADP+ + 11 H2O
Glossary: a mycoketide-CoA = a 4,8,12,16,20-pentamethyl-(long-chain fatty acyl)-CoA
Other name(s): pks12 (gene name)
Systematic name: malonyl-CoA/(S)-methylmalonyl-CoA:heptanoyl-CoA malonyltransferase (mycoketide-CoA-forming)
Comments: The enzyme, found in mycobacteria, is involved in the synthesis of β-D-mannosyl phosphomycoketides. It is a very large polyketide synthase that contains two complete sets of FAS-like fatty acid synthase modules. It binds an acyl-CoA with 5-9 carbons as a starter unit, and extends it by five rounds of alternative additions of malonyl-CoA and methylmalonyl-CoA extender units. Depending on the starter unit, the enzyme forms mycoketide-CoAs of different lengths.
1. Matsunaga, I., Bhatt, A., Young, D.C., Cheng, T.Y., Eyles, S.J., Besra, G.S., Briken, V., Porcelli, S.A., Costello, C.E., Jacobs, W.R., Jr. and Moody, D.B. Mycobacterium tuberculosis pks12 produces a novel polyketide presented by CD1c to T cells. J. Exp. Med. 200 (2004) 1559-1569. [PMID: 15611286]