Cytochrome P450 monooxygenase; part of the gene cluster that mediates the biosynthesis of gliotoxin, a member of the epipolythiodioxopiperazine (ETP) class of toxins characterized by a disulfide bridged cyclic dipeptide (PubMed:15979823, PubMed:21612254). The first step in gliotoxin biosynthesis is the condensation of serine and phenylalanine to form the cyclo-L-phenylalanyl-L-serine diketopiperazine (DKP) by the NRPS gliP (PubMed:17154540, PubMed:21612254). GliP is also able to produce the DKP cyclo-L-tryptophanyl-L-serine, suggesting that the substrate specificity of the first adenylation (A) domain in gliP is sufficiently relaxed to accommodate both L-Phe and L-Trp (PubMed:23434416). The cytochrome P450 monooxygenase gliC has been shown to catalyze the subsequent hydroxylation of the alpha-carbon of L-Phe in cyclo-L-phenylalanyl-L-serine whereas the second cytochrome P450 enzyme, gliF, is presumably involved in the modification of the DKP side chain (PubMed:24039048, PubMed:23434416). The glutathione S-transferase (GST) gliG then forms a bis-glutathionylated biosynthetic intermediate which is responsible for the sulfurization of gliotoxin (PubMed:21513890, PubMed:21749092). This bis-glutathionylated intermediate is subsequently processed by the gamma-glutamyl cyclotransferase gliK to remove both gamma-glutamyl moieties (PubMed:22903976, PubMed:24039048). Subsequent processing via gliI yields a biosynthetic intermediate, which is N-methylated via the N-methyltransferase gliN, before the gliotoxin oxidoreductase gliT-mediated disulfide bridge closure (PubMed:20548963, PubMed:22936680, PubMed:24039048, PubMed:25062268). GliN-mediated amide methylation confers stability to ETP, damping the spontaneous formation of tri- and tetrasulfides (PubMed:25062268). Intracellular dithiol gliotoxin oxidized by gliT is subsequently effluxed by gliA (PubMed:26150413). Gliotoxin contributes to pathogenesis during invasive aspergillosis (PubMed:17601876, PubMed:18199036). In macrophages and neutrophils, gliotoxin showed inhibition of various different cell functions including cytokine production, antigen presentation, phagocytosis, and production of reactive oxygen species (PubMed:17601876). Mycotoxin biosynthesis. Belongs to the cytochrome P450 family.