Enzymatic dehydrogenation and flavin‐mediated photocatalytic skeletal rearrangement of strictosamide, a key intermediate in camptothecin biosynthesis

作者：Xinyao Li, Ziang Chen, Wenjie Xu, Longlong Gao, Qian Lou, Shijie Jin, Tianyi Xin, Aijia Ji, Ranran Gao, Jingyuan Song · 发表于：The Plant Journal · 年份：2026 · DOI：10.1111/tpj.70823 · 被引用次数：4 · 研究领域：Cancer therapeutics and mechanisms、Microbial Natural Products and Biosynthesis、Alkaloids: synthesis and pharmacology

Camptothecin is a valuable monoterpene indole alkaloid (MIA) with antitumor activity, and strictosamide represents the first specialized intermediate in camptothecin biosynthesis. The proposed camptothecin biosynthetic pathway involves several oxidation-reduction reactions, while there have been no reports on the involvement of 2-oxoglutarate-dependent dioxygenases (2OGDs) in Ophiorrhiza pumila. In this study, the genome-wide identification of 2OGDs was performed in O. pumila, and a total of 140 2OGD genes were identified. Functional characterization revealed that five Op2OGDs catalyze the dehydrogenation of the C-3 and C-14 positions of strictosamide to produce dehydrostrictosamide. Unexpectedly, strictosamide was found to undergo a rapid flavin-mediated photocatalytic skeletal rearrangement to form pumiloside. According to the chromosomal localization of functional Op2OGD genes and camptothecin biosynthetic genes, we identified an MIA gene cluster on chromosome 5 of O. pumila, including two 2OGDs identified in this study and four previously characterized genes. These findings support that camptothecin biosynthesis in O. pumila proceeds through a biosynthetic network rather than a linear pathway. This study provides important insights into the elucidation of the camptothecin biosynthetic pathway.