Molecular basis of cytochalasan biosynthesis in fungi:: Gene cluster analysis and evidence for the involvement of a PKS-NRPS hybrid synthase by RNA silencing

Analysis of the first gene cluster encoding cytochalasan biosynthesis and targeted RNA silencing in Penicillium expansum revealed that these complex tricyclic natural products are assembled by a fungal PKS-NRPS hybrid synthase, CheA. A biosynthetic Diels-Alder macrocyclization can be rationalized on the basis of the deduced enzyme functions.