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PsiH - Cytochrome P450 monooxygenase from Psilocybe cubensis

PsiH is a cytochrome P450 monooxygenase that catalyses the conversion of tryptamine to 4-hydroxytryptamine.

• NCBI: ASU62246.1
• UniProt: P0DPA7
• EC number: 1.14.99.59

Usage and Biology

The mechanism of psilocybin biosynthesis in Psilocybe sp. was recently elucidated by Fricke et al.^[1], demonstrating that L-tryptophan proceeds through decarboxylation (mediated by PsiD), hydroxylation (mediated by PsiH), phosphorylation (mediated by PsiK), and finally N,N-dimethylation (mediated by PsiM) to yield psilocybin.

PsiH is a native enzyme obtained from Psilocybe cubensis, which is involved in the metabolic biosynthesis of psilocybin from tryptophan. It accepts tryptamine as a substrate to yield 4-hydroxytryptamine (Fig. 1). In a native state, PsiD is a 439 amino acid protein (49.6 kDa) with a theoretical pI of 5.44 calculated with the ExPASy ProtParam tool^[2].

Fig. 1: Hydroxylation of tryptamine to 4-hydroxytryptamine, mediated by PsiH. The reaction relies on a hydrogen donor (C00030) and O₂, which results in the release of the oxidised donor (C00028) and H₂O as a by-product. Source: KEGG

Heterologous expression of PsiH has been achieved in a T7 induction system using pET-28c(+) transformed into Escherichia coli BL21(DE3), co-transformed with chaperone plasmid pGro7 (Fig. 3), resulting in a 475 amino acid polypeptide, with a computed molecular weight of 53.6 kDa.

Sequence and Features

1. ↑ Fricke, J., Blei, F. & Hoffmeister, D. Enzymatic Synthesis of Psilocybin. Angew Chem Int Ed Engl 56, 12352-12355 (2017).
2. ↑ Artimo, P. et al. ExPASy: SIB bioinformatics resource portal. Nucleic Acids Res 40, W597-603 (2012).