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

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 malonyl-CoA 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 (thr derailed lactone after three condensations) mere 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. (C) 1999 Federation of European Biochemical Societies.