Article open access publication

Oxidation and cyclization of casbene in the biosynthesis of Euphorbia factors from mature seeds of Euphorbia lathyris L.

Proceedings of the National Academy of Sciences of the United States of America, Proceedings of the National Academy of Sciences, ISSN 0027-8424

Volume 113, 34, 2016

DOI:10.1073/pnas.1607504113, Dimensions: pub.1023992201, PMC: PMC5003294, PMID: 27506796,

Affiliations

Organisations

  1. (1) University of Copenhagen, grid.5254.6, KU
  2. (2) Evolva (Switzerland), grid.476330.5
  3. (3) Center for Synthetic Biology “bioSYNergy,” DK-1871 Frederiksberg C, Denmark;
  4. (4) Royal Institute of Technology, grid.5037.1

Countries

Denmark

Sweden

Switzerland

Continents

Europe

Description

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.

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NORA University Profiles

University of Copenhagen

Danish Open Access Indicator

2016: Unused

Research area: Science & Technology

Danish Bibliometrics Indicator

2016: Level 2

Research area: Science & Technology

Dimensions Citation Indicators

Times Cited: 37

Field Citation Ratio (FCR): 5.97

Relative Citation ratio (RCR): 2.17

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