Distribution of cannabinoid synthase genes in non-Cannabis organisms

Abstract

The discovery of phytocannabinoid synthesizing enzymes, tetrahydrocannabinolic acid synthase (THCAs) and cannabidiolic acid synthase (CBDAs) was a breakthrough in Cannabis research. However, their evolutionary aspects and distribution across organisms has not been adequately studied. We searched for THCAs and CBDAs genes in organisms other than Cannabis plants using the database available in NCBI. Both cannabinoid synthases seem to be widely distributed in the plant kingdom. Of several complete or partial sequences of cannabinoid synthases-likes, CBDAs-like from Morus notabilis matched closely to CsCBDAs and CsTHCAs. When amino acid sequences of CsTHCAs, CsCBDAs and MnCBDAs-like were compared to each other, and to the motif database stored in Expasy, all three proteins contained the FAD_PCMH (PCMH-type FAD-binding) domain indicating the conservation of this domain in cannabinoid synthases. Apart from FAD binding, Berberine Bridge Enzyme (BBE-likes), which catalyzes the synthesis of isoquinoline alkaloids in many plants such as mulberry, poplas and citrus, were the other most closely related enzymes to CsTHCAs and CsCBDAs. We also searched for THCAs and CBDAs in fungal and bacterial kingdom but could not find any notably similar sequence. However, partial mRNA from FAD binding enzyme from Trametes versicolor and 6-hydroxy D nicotine oxidase from Aspergillus saccharolyticus matched the CsTHCA sequence and a partial mRNA from a hypothetical protein in Pneumocystis carinii was the most closely matched fungal enzyme to the CsCBDA. Our database search showed that Morus notabilis from mulberry family could be the candidate plant for further studies. Comparative transcriptomic and metabolomic studies for mulberry and Cannabis plants could provide a much clear concepts on the co-evolution of these syanthases. Moreover, the understanding of cannabinoid synthesis pathway is still evolving, in-depth bioinformatics and functional analysis of the enzymes involved are required for pharmaceutical research and industrial advancement.