Two O-Methyltransferases Mediate Multiple Methylation Steps in the Biosynthesis of Coumarins in Cnidium monnieri

Abstract

Coumarins with methoxy groups such as osthole (1), xanthotoxin (2), bergapten (3), and isopimpinellin (4) are typical bioactive ingredients of many medicinal plants. The methylation steps remain widely unknown. Herein, we report the discovery of two methyltransferases in the biosynthesis of O-methyl coumarins in Cnidium monnieri by transcriptome mining, heterologous expression, and in vitro enzymatic assays. The results reveal that (i) CmOMT1 catalyzes the methylation of osthenol (8) as the final step in the biosynthesis of 1, (ii) CmOMT2 shows the highest efficiency and preference for methylating xanthotoxol (11) to form 2, and (iii) CmOMT1 and CmOMT2 also efficiently transform bergaptol (10) and 8-hydroxybergapten (13) into 3 or 4, suggesting the CmOMTs mediate multistep methylations in the biosynthesis of linear furanocoumarins in C. monnieri.

Biosynthesis of the Plant Coumarin Osthole by Engineered Saccharomyces cerevisiae

“…Recently, Zhang et al characterized a novel OMT, CmOMT1, from C. monnieri that exhibited high activity when catalyzing the formation of OSE from OSN . Therefore, we synthesized and expressed this gene using E.…”

“…Recently, Zhang et al characterized a novel OMT, CmOMT1, from C. monnieri that exhibited high activity when catalyzing the formation of OSE from OSN. 11 Therefore, we synthesized and expressed this gene using E. coli. In vitro assays to assess the enzymatic activity of CmOMT1 toward OSN confirmed its function in OSE biosynthesis (Figure 3b).…”

“…Until recently, Zhang et al characterized two OMTs from C. monnieri, one of which, CmOMT1, catalyzes the C7−OH methylation of osthenol (OSN) to produce OSE. 11 Although the PT that participates in the biosynthesis of OSN remains unknown in C. monnieri, a complete biosynthetic pathway for OSE could be feasible because a PT from Pastinaca sativa (PsPT2) could fulfill the C8 prenylation of UMB to produce OSN. 12 Here, using the baker's yeast species Saccharomyces cerevisiae as a host, we explored the potential for the complete biosynthesis of OSE from a simple carbon source via microbial fermentation.…”

“…Until recently, Zhang et al characterized two OMTs from C. monnieri, one of which, CmOMT1, catalyzes the C7–OH methylation of osthenol (OSN) to produce OSE . Although the PT that participates in the biosynthesis of OSN remains unknown in C.…”

Osthole Activates the Cholinergic Anti‐Inflammatory Pathway via α7nAChR Upregulation to Alleviate Inflammatory Responses

“…[1] The dried fruits of C. monnieri, known as Fructus Cnidii (She-Chuang-Zi in Chinese), are well known as a traditional Chinese medicine used for the treatment of diverse inflammatory-related diseases, such as fungal or becterial skin infection, asthma, cough, and male sexual dysfunction. [2,3] As the dominant secondary metabolite of C. monnieri, Osthole (Figure 1) was regarded as the main active ingredient responsible for the anti-inflammation activity of the title herb and serves as the exclusive quality-controlled component according the Chinese Pharmacopoeia. [4,5] Interestingly, although Osthole has been demonstrated to possess potential immunoregulation activity against different diseases, its anti-inflammation modeof-action remain unexplored.…”