This fungal enzyme system comprises a multi-functional polyketide synthase (PKS) and an enoyl reductase. The PKS catalyses many of the chain building reactions of EC 2.3.1.85, fatty-acid synthase system, as well as a reductive methylation and a Diels-Alder reaction, while the reductase is responsible for three enoyl reductions that are necessary for dihydromonacolin L acid production.