Fig. 5. Proposed mechanism of the formation of the C₆–C₅–C₆ scaffold by PECPS.

a Decarboxylative condensation of malonyl-CoA with the enzyme-bound 4-hydroxyphenylpropionyl unit. b Formation of the 4-hydroxyphenylpropionyl-β-diketide-CoA intermediate. c Decarboxylative condensation of phenylpropionyl-β-diketide acid nonenzymatically derived from phenylpropionyl-β-diketide-CoA with the enzyme-bound benzoyl unit. d Formation of the C₆–C₅–C₆ scaffold product. e Schematic representation of the proposed mechanism of the formation of the C₆–C₅–C₆ scaffold by PECPS. The entrances to the catalytic cavities are indicated with red arrows.