Starter substrate specificities of wild-type and mutant polyketide synthases from Rutaceae

Chalcone and acridone synthases catalyse similar condensations of 4-coumaroyl-CoA and N-methylanthraniloyl-CoA, respectively, with three malonyl-CoAs, and the enzyme polypeptides show 75-85% sequence homology. Mutant chalcone synthases were generated from Ruta CHS1 with the aim to confer acridone synthase activity. Homology modeling and docking studies suggested that a Phe267Val and further conformational changes in the periphery of the polypeptide backbone are essentially required.