Enzymatic formation of long-chain polyketide pyrones by plant type III polyketide synthases

Phytochemistry. 2004 Sep;65(17):2447-53. doi: 10.1016/j.phytochem.2004.08.005.

Abstract

Recombinant chalcone synthase (CHS) from Scutellaria baicalensis and stilbene synthase (STS) from Arachis hypogaea accepted CoA esters of long-chain fatty acid (CHS up to the C12 ester, while STS up to the C14 ester) as a starter substrate, and carried out sequential condensations with malonyl-CoA, leading to formation of triketide and tetraketide alpha-pyrones. Interestingly, the C6, C8, and C10 esters were kinetically favored by the enzymes over the physiological starter substrate; the kcat/KM values were 1.2- to 1.9-fold higher than that of p-coumaroyl-CoA. The catalytic diversities of the enzymes provided further mechanistic insights into the type III PKS reactions, and suggested involvement of the CHS-superfamily enzymes in the biosynthesis of long-chain alkyl polyphenols such as urushiol and ginkgolic acid in plants.

MeSH terms

  • Acyl Coenzyme A / metabolism*
  • Acyltransferases / chemistry
  • Acyltransferases / metabolism*
  • Arachis / enzymology*
  • Binding Sites
  • Kinetics
  • Molecular Structure
  • Pyrones / metabolism*
  • Scutellaria / enzymology*

Substances

  • Acyl Coenzyme A
  • Pyrones
  • 4-coumaroyl-coenzyme A
  • Acyltransferases
  • stilbene synthase
  • flavanone synthetase