Part of the gene cluster that mediates the biosynthesis of paspalitrems, indole-diterpene (IDT) mycotoxins that are potent tremorgens in mammals (PubMed:23468653, PubMed:29457197, PubMed:32077051). The geranylgeranyl diphosphate (GGPP) synthase idtG is proposed to catalyze the first step in IDT biosynthesis via catalysis of a series of iterative condensations of isopentenyl diphosphate (IPP) with dimethylallyl diphosphate (DMAPP), geranyl diphosphate (GPP), and farnesyl diphosphate (FPP), to form GGPP (Probable). Condensation of indole-3-glycerol phosphate with GGPP by the prenyltransferase idtC then forms 3-geranylgeranylindole (3-GGI) (Probable). Epoxidation of the two terminal alkenes of the geranylgeranyl moiety by the FAD-dependent monooxygenase idtM, and cyclization by the terpene cyclase idtB then leads to the production of paspaline (Probable). The cytochrome P450 monooxygenase idtP then catalyzes oxidative elimination of the pendant methyl group at C-12 of paspaline and generates the C-10 ketone to yield 13-desoxypaxilline (PubMed:32077051). The cytochrome P450 monooxygenase idtQ may catalyze the C-13 oxidation of 13-desoxypaxilline to afford paxilline (Probable). Considering that both paspalicine and paxilline were detected in C.paspali, idtQ also catalyzes the formation of paspalinine from 13-desoxypaxilline via paspalicine as an intermediate (Probable). Finally, the alpha-prenyltransferase idtF prenylates paspalinine at the C-20 or the C-21 positions to yield paspalitrems A and C, respectively (PubMed:32077051). The hydroxylation of paspalitrem A at C-32 by a still unknown oxidase affords paspalitrem B (Probable). Belongs to the ltmS family.