Cross‐reaction of chalcone synthase and stilbene synthase overexpressed in Escherichia coli

Abstract

Chalcone synthase (CHS) and stilbene synthase (STS) are related plant polyketide synthases belonging to the CHS superfamily. CHS and STS catalyze common condensation reactions of p-coumaroyl-CoA and three C 2 -units from malonylCoA but different cyclization reactions to produce naringenin chalcone and resveratrol, respectively. Using purified Pueraria lobata CHS and Arachis hypogaea STS overexpressed in Escherichia coli, bisnoryangonin (BNY, the derailed lactone after two condensations) and p-coumaroyltriacetic acid lactone (the derailed lactone after three condensations) were detected from the reaction products. More importantly, we found a crossreaction between CHS and STS, i.e. resveratrol production by CHS (2.7^4.2% of naringenin) and naringenin production by STS (1.4^2.3% of resveratrol), possibly due to the conformational flexibility of their active sites.z 1999 Federation of European Biochemical Societies.

A stilbene synthase from Japanese red pine ( Pinus densiflora ): Implications for phytoalexin accumulation and down-regulation of flavonoid biosynthesis

“…The main reaction product was pinosylvin; however, the formation of a small amount of at least three radioactive products was also found. These were probably noncyclized derailment products derived from partially formed polyketide chains (21). A GC-MS analysis confirmed that the main product was pinosylvin.…”

Physcomitrella PpORS, Basal to Plant Type III Polyketide Synthases in Phylogenetic Trees, Is a Very Long Chain 2′-Oxoalkylresorcinol Synthase

“…Even with physiological substrates, most type III PKSs produce pyrones as in vitro derailment products. For example, CHS produces bisnoryangonin (a triketide pyrone) and coumaroyltriacetic acid lactone (a tetraketide pyrone) in addition to a chalcone (33). Furthermore, type III PKS mutants often produce pyrones when their active sites are compromised.…”

Exploiting the Biosynthetic Potential of Type III Polyketide Synthases

“…Phylogenetic studies show that no ancestral STS gene was found, and STSs are likely to have evolved from CHSs independently on several occasions [29]. STSs and CHSs are structurally related and share at least 65% amino acid sequence identity [30]. These enzymes follow a similar overall reaction mechanism which involves initiation, followed by the iterative decarboxylative condensation of three units of malonyl-CoA to a starter unit, and cyclization of the linear tetraketide intermediate.…”