Oxidation and cyclization of casbene in the biosynthesis of Euphorbia factors from mature seeds of Euphorbia lathyris L.
[2];
[3];
- Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark,
- Evolva AS, CH-4153 Reinach, Switzerland,
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, DK-2100 Copenhagen, Denmark,
- Plant Biochemistry Laboratory, Department of Plant and Environmental Sciences, University of Copenhagen, DK-1871 Frederiksberg C, Denmark,, Center for Synthetic Biology “bioSYNergy,” DK-1871 Frederiksberg C, Denmark,
- Science for Life Laboratory, School of Biotechnology, Kungliga Tekniska Högskolan Royal Institute of Technology, SE-171 21 Stockholm, Sweden
The seed oil of Euphorbia lathyris L. contains a series of macrocyclic diterpenoids known as Euphorbia factors. They are the current industrial source of ingenol mebutate, which is approved for the treatment of actinic keratosis, a precancerous skin condition. Here, we report an alcohol dehydrogenase-mediated cyclization step in the biosynthetic pathway of Euphorbia factors, illustrating the origin of the intramolecular carbon–carbon bonds present in lathyrane and ingenane diterpenoids. This unconventional cyclization describes the ring closure of the macrocyclic diterpene casbene. Through transcriptomic analysis of E. lathyris L. mature seeds and in planta functional characterization, we identified three enzymes involved in the cyclization route from casbene to jolkinol C, a lathyrane diterpene. These enzymes include two cytochromes P450 from the CYP71 clan and an alcohol dehydrogenase (ADH). CYP71D445 and CYP726A27 catalyze regio-specific 9-oxidation and 5-oxidation of casbene, respectively. When coupled with these P450-catalyzed monooxygenations, E. lathyris ADH1 catalyzes dehydrogenation of the hydroxyl groups, leading to the subsequent rearrangement and cyclization. The discovery of this nonconventional cyclization may provide the key link to complete elucidation of the biosynthetic pathways of ingenol mebutate and other bioactive macrocyclic diterpenoids.
- Research Organization:
- Univ. of Wisconsin, Madison, WI (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- FC02-07ER64494
- OSTI ID:
- 1288983
- Alternate ID(s):
- OSTI ID: 1438201
- Journal Information:
- Proceedings of the National Academy of Sciences of the United States of America, Journal Name: Proceedings of the National Academy of Sciences of the United States of America Vol. 113 Journal Issue: 34; ISSN 0027-8424
- Publisher:
- Proceedings of the National Academy of SciencesCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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