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.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
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]