Dissimilar Reactions and Enzymes for Psilocybin Biosynthesis in Inocybe and Psilocybe Mushrooms

Psilocybin, the main psychoactive compound in magic mushrooms, is also produced by some Inocybe species. Researchers characterized four enzymes from Inocybe corydalina and found that none of the reactions used in Psilocybe species occur in this species. Instead, the Inocybe pathway is branched and produces baeocystin as a second end product. These results show that mushrooms evolved the ability to make psilocybin twice independently, using distantly related or entirely different enzymes.

Study at a glance

Abstract

Abstract Psilocybin (4‐phosphoryloxy‐ N , N ‐dimethyltryptamine, 1 ) is the main indolethyl‐amine natural product of psychotropic (so‐called “magic”) mushrooms. The majority of 1 ‐producing species belongs to the eponymous genus Psilocybe , for which the biosynthetic events, beginning from l ‐tryptophan ( 2 ), and the involved enzymes have thoroughly been characterized. Some Inocybe (fiber cap) species, among them Inocybe corydalina , produce 1 as well. In product formation assays, we characterized four recombinantly produced biosynthesis enzymes of this species in vitro: IpsD, a pyridoxal‐5′‐phosphate‐dependent l ‐tryptophan decarboxylase, the kinase IpsK, and two near‐identical methyltransferases, IpsM1 and IpsM2. The fifth enzyme, the insoluble monooxygenase IpsH, was analyzed in silico. Surprisingly, none of the reactions intrinsic to the 1 pathway in Psilocybe species takes place in I. corydalina . Contrasting the situation in Psilocybe , the Inocybe pathway is branched and leads to baeocystin (4‐phosphoryloxy‐ N ‐methyltryptamine, 3 ) as a second end product. Our results demonstrate that mushrooms recruited distantly or entirely unrelated enzymes to evolve the metabolic capacity for 1 biosynthesis twice independently.