InterPro domain: IPR012328

Chalcone synthases (CHS) ( 2.3.1.74 ) and stilbene synthases (STS) (formerly known as resveratrol synthases) are related plant enzymes. CHS is an important enzyme in flavanoid biosynthesis and STS is a key enzyme in stilbene-type phyloalexin biosynthesis. Both enzymes catalyse the addition of three molecules of malonyl-CoA to a starter CoA ester (a typical example is 4-coumaroyl-CoA), producing either a chalcone (with CHS) or stilbene (with STS) [ 1 ]. These enzymes have a conserved cysteine residue, located in the central section of the protein sequence, which is essential for the catalytic activity of both enzymes and probably represents the binding site for the 4-coumaryl-CoA group [ 2 , 3 ].

This domain of chalcone synthase is reported to be structurally similar to domains in thiolase and beta-ketoacyl synthase. The differences in activity are accounted for by differences in the N-terminal domain [ 4 ].

1. Stilbene and chalcone synthases: related enzymes with key functions in plant-specific pathways. Z. Naturforsch., C, J. Biosci. 45, 1-8
2. The role of cysteines in polyketide synthases. Site-directed mutagenesis of resveratrol and chalcone synthases, two key enzymes in different plant-specific pathways. J. Biol. Chem. 266, 9971-6
3. Chalcone synthase and its functions in plant resistance. Phytochem Rev 10, 397-412
4. Structure of chalcone synthase and the molecular basis of plant polyketide biosynthesis. Nat. Struct. Biol. 6, 775-84