Reaction: malonyl-CoA + 5 (2S)-methylmalonyl-CoA + 5 NADPH + 5 H+ = 10-deoxymethynolide + 6 CoA + 6 CO2 + 5 NADP+ + 2 H2O
For diagram of reaction click here.
Other name(s): pikromycin PKS
Systematic name: (2S)-methylmalonyl-CoA:malonyl-CoA malonyltransferase (10-deoxymethynolide forming)
Comments: The product, 10-deoxymethynolide, contains a 12-membered ring and is an intermediate in the biosynthesis of methymycin in the bacterium Streptomyces venezuelae. The enzyme also produces narbonolide (see EC 22.214.171.124, narbonolide synthase). The enzyme has 29 active sites arranged in four polypeptides (pikAI - pikAIV) with a loading domain, six extension modules and a terminal thioesterase domain. Each extension module contains a ketosynthase (KS), keto reductase (KR), an acyltransferase (AT) and an acyl-carrier protein (ACP). Not all active sites are used in the biosynthesis.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
1. Lu, H., Tsai, S.C., Khosla, C. and Cane, D.E. Expression, site-directed mutagenesis, and steady state kinetic analysis of the terminal thioesterase domain of the methymycin/picromycin polyketide synthase. Biochemistry 41 (2002) 12590-12597. [PMID: 12379101]
2. Kittendorf, J.D., Beck, B.J., Buchholz, T.J., Seufert, W. and Sherman, D.H. Interrogating the molecular basis for multiple macrolactone ring formation by the pikromycin polyketide synthase. Chem. Biol. 14 (2007) 944-954. [PMID: 17719493]
3. Yan, J., Gupta, S., Sherman, D.H. and Reynolds, K.A. Functional dissection of a multimodular polypeptide of the pikromycin polyketide synthase into monomodules by using a matched pair of heterologous docking domains. Chembiochem 10 (2009) 1537-1543. [PMID: 19437523]
4. Whicher, J.R., Dutta, S., Hansen, D.A., Hale, W.A., Chemler, J.A., Dosey, A.M., Narayan, A.R., Hakansson, K., Sherman, D.H., Smith, J.L. and Skiniotis, G. Structural rearrangements of a polyketide synthase module during its catalytic cycle. Nature 510 (2014) 560-564. [PMID: 24965656]