Integrated metabolomics identifies CYP72A67 and CYP72A68 oxidases in the biosynthesis of Medicago truncatula oleanate sapogenins

Research output: Contribution to journalJournal articleResearchpeer-review

  • Vered Tzin
  • John H. Snyder
  • Dong Sik Yang
  • David V. Huhman
  • Bonnie S. Watson
  • Stacy N. Allen
  • Yuhong Tang
  • Miettinen, Karel
  • Philipp Arendt
  • Jacob Pollier
  • Alain Goossens
  • Lloyd W. Sumner

Introduction: Triterpene saponins are important bioactive plant natural products found in many plant families including the Leguminosae. Objectives: We characterize two Medicago truncatula cytochrome P450 enzymes, MtCYP72A67 and MtCYP72A68, involved in saponin biosynthesis including both in vitro and in planta evidence. Methods: UHPLC-(-)ESI-QToF-MS was used to profile saponin accumulation across a collection of 106 M. truncatula ecotypes. The profiling results identified numerous ecotypes with high and low saponin accumulation in root and aerial tissues. Four ecotypes with significant differential saponin content in the root and/or aerial tissues were selected, and correlated gene expression profiling was performed. Results: Correlation analyses between gene expression and saponin accumulation revealed high correlations between saponin content with gene expression of β-amyrin synthase, MtCYP716A12, and two cytochromes P450 genes, MtCYP72A67 and MtCYP72A68. In vivo and in vitro biochemical assays using yeast microsomes containing MtCYP72A67 revealed hydroxylase activity for carbon 2 of oleanolic acid and hederagenin. This finding was supported by functional characterization of MtCYP72A67 using RNAi-mediated gene silencing in M. truncatula hairy roots, which revealed a significant reduction of 2β-hydroxylated sapogenins. In vivo and in vitro assays with MtCYP72A68 produced in yeast showed multifunctional oxidase activity for carbon 23 of oleanolic acid and hederagenin. These findings were supported by overexpression of MtCYP72A68 in M. truncatula hairy roots, which revealed significant increases of oleanolic acid, 2β-hydroxyoleanolic acid, hederagenin and total saponin levels. Conclusions: The cumulative data support that MtCYP72A68 is a multisubstrate, multifunctional oxidase and MtCYP72A67 is a 2β-hydroxylase, both of which function during the early steps of triterpene-oleanate sapogenin biosynthesis.

Original languageEnglish
Article number85
JournalMetabolomics
Volume15
Issue number6
ISSN1573-3882
DOIs
Publication statusPublished - 2019
Externally publishedYes

Bibliographical note

Funding Information:
Funding The Sumner lab has been graciously supported by several entities over the years for the development of natural products profiling and plant metabolomics. This project was financially supported by the Oklahoma Center for the Advancement of Science and Technology (OCAST Award#PSB10-027), the National Science Foundation Molecular and Cellular Biosciences Award#1024976, The Samuel Roberts Noble Foundation, Oklahoma EPSCoR Research Experience for Undergraduates subaward #EPSCoR-2011-15, the VIB International PhD Fellowship Program (predoctoral fellowship to P.A.), the Research Foundation Flanders (postdoctoral fellowship to J.P.), and the European Union Seventh Framework Program FP7/2007–2013 under grant agreement number 613692–TriForC.

Funding Information:
We thank Dr. Jean-Marie Prosperi and the INRA (http://institut.inra.fr/en) for providing the M. truncatula germplasm collection. We also thank Joseph Chappell for providing the WAT11 yeast strain. We thank Dr. Qiao Zhao for constructive comments on this manuscript.

Publisher Copyright:
© 2019, Springer Science+Business Media, LLC, part of Springer Nature.

    Research areas

  • CYP72A67, CYP72A68, Cytochrome P450, Integrated metabolomics, Medicago truncatula, Sapogenin, Saponin

ID: 280016644