Diels-Alderase; part of the gene cluster that mediates the biosynthesis of pyrrolocin, a bright yellow trans-fused decalin-containing tetramic acid with antimicrobial activity (PubMed:25226362, PubMed:25351193). The PKS module of prlS together with the enoylreductase prlC catalyze the formation of the polyketide unit which is then conjugated to L-serine by the condensation domain of the prlS NRPS module (PubMed:25226362). Diels-Alderase gNR600 is involved in endo-selective Diels-Alder cycloaddition to form the decalin ring (By similarity). Subsequent methylation is carried leads to pyrrolocin A (PubMed:25226362). The methyltransferase involved in that last step has not been identified yet and is probably located outside of the prl cluster (PubMed:25226362). Mycotoxin biosynthesis. Belongs to the Diels-Alderase family.