Psilocybin is the psychotropic tryptamine-derived natural product of Psilocybe carpophores, the so-called "magic mushrooms". Although its structure has been known for 60 years, the enzymatic basis of its biosynthesis has remained obscure. We characterized four psilocybin biosynthesis enzymes, namely i) PsiD, which represents a new class of fungal l-tryptophan decarboxylases, ii) PsiK, which catalyzes the phosphotransfer step, iii) the methyltransferase PsiM, catalyzing iterative N-methyl transfer as the terminal biosynthetic step, and iv) PsiH, a monooxygenase. In a combined PsiD/PsiK/PsiM reaction, psilocybin was synthesized enzymatically in a step-economic route from 4-hydroxy-l-tryptophan. Given the renewed pharmaceutical interest in psilocybin, our results may lay the foundation for its biotechnological production.

Interaction between microbes affects the growth, metabolism and differentiation of members of the microbial community. While direct and indirect competition, like antagonism and nutrient consumption have a negative effect on the interacting members of the population, microbes have also evolved in nature not only to fight, but in some cases to adapt to or support each other, while increasing the fitness of the community. The presence of bacteria and fungi in soil results in various interactions including mutualism. Bacilli attach to the plant root and form complex communities in the rhizosphere. Bacillus subtilis, when grown in the presence of Aspergillus niger, interacts similarly with the fungus, by attaching and growing on the hyphae. Based on data obtained in a dual transcriptome experiment, we suggest that both fungi and bacteria alter their metabolism during this interaction. Interestingly, the transcription of genes related to the antifungal and putative antibacterial defence mechanism of B. subtilis and A. niger, respectively, are decreased upon attachment of bacteria to the mycelia. Analysis of the culture supernatant suggests that surfactin production by B. subtilis was reduced when the bacterium was co-cultivated with the fungus. Our experiments provide new insights into the interaction between a bacterium and a fungus.

The psychotropic effectso fPsilocybe "magic" mushroomsa re caused by the l-tryptophan-derived alkaloid psilocybin.D espite their significance,t he secondary metabolome of these fungi is poorly understood in general. Our analysis of four Psilocybe speciesi dentified harmane, harmine, and ar ange of other l-tryptophan-derived b-carbolines as their natural products,w hichw as confirmed by 1D and 2D NMR spectroscopy.S table-isotope labeling with 13 C 11 -l-tryptophan verifiedt he b-carbolines as biosynthetic products of these fungi. In addition, MALDI-MS imaging showedt hat b-carbolines accumulate toward the hyphal apices.A sp otent inhibitors of monoamine oxidases, b-carbolines are neuroactive compounds and interfere with psilocybin degradation. Therefore, our findings represent an unprecedented scenario of natural product pathways that diverge from the same buildingb lock and produce dissimilar compounds, yet contribute directlyo ri ndirectly to the same pharmacological effects.