| Autor: |
Torrens-Spence MP; Whitehead Institute for Biomedical Research , 455 Main Street , Cambridge , Massachusetts 02142 , United States., Liu CT; Whitehead Institute for Biomedical Research , 455 Main Street , Cambridge , Massachusetts 02142 , United States.; Department of Biology , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States.; Department of Chemistry , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States., Pluskal T; Whitehead Institute for Biomedical Research , 455 Main Street , Cambridge , Massachusetts 02142 , United States., Chung YK; Whitehead Institute for Biomedical Research , 455 Main Street , Cambridge , Massachusetts 02142 , United States.; Division of Life Science , Hong Kong University of Science & Technology , Clear Water Bay , Hong Kong , China., Weng JK; Whitehead Institute for Biomedical Research , 455 Main Street , Cambridge , Massachusetts 02142 , United States.; Department of Biology , Massachusetts Institute of Technology , Cambridge , Massachusetts 02139 , United States. |
| Abstrakt: |
Aromatic l-amino acid decarboxylases (AAADs) are a phylogenetically diverse group of enzymes responsible for the decarboxylation of aromatic amino acid substrates into their corresponding aromatic arylalkylamines. AAADs have been extensively studied in mammals and plants as they catalyze the first step in the production of neurotransmitters and bioactive phytochemicals, respectively. Unlike mammals and plants, the hallucinogenic psilocybin mushroom Psilocybe cubensis reportedly employs an unrelated phosphatidylserine-decarboxylase-like enzyme to catalyze l-tryptophan decarboxylation, the first step in psilocybin biosynthesis. To explore the origin of this chemistry in psilocybin mushroom, we generated the first de novo transcriptomes of P. cubensis and investigated several putative l-tryptophan-decarboxylase-like enzymes. We report the biochemical characterization of a noncanonical AAAD from P. cubensis ( PcncAAAD) that exhibits substrate permissiveness toward l-phenylalanine, l-tyrosine, and l-tryptophan, as well as chloro-tryptophan derivatives. The crystal structure of PcncAAAD revealed the presence of a unique C-terminal appendage domain featuring a novel double-β-barrel fold. This domain is required for PcncAAAD activity and regulates catalytic rate and thermal stability through calcium binding. PcncAAAD likely plays a role in psilocybin production in P. cubensis and offers a new tool for metabolic engineering of aromatic-amino-acid-derived natural products. |
