Triterpene Functional Genomics in Licorice for Identification of CYP72A154 Involved in the Biosynthesis of Glycyrrhizin

Plant Cell. 2011 Nov;23(11):4112-23. doi: 10.1105/tpc.110.082685. Epub 2011 Nov 29.

Abstract

Glycyrrhizin, a triterpenoid saponin derived from the underground parts of Glycyrrhiza plants (licorice), has several pharmacological activities and is also used worldwide as a natural sweetener. The biosynthesis of glycyrrhizin involves the initial cyclization of 2,3-oxidosqualene to the triterpene skeleton β-amyrin, followed by a series of oxidative reactions at positions C-11 and C-30, and glycosyl transfers to the C-3 hydroxyl group. We previously reported the identification of a cytochrome P450 monooxygenase (P450) gene encoding β-amyrin 11-oxidase (CYP88D6) as the initial P450 gene in glycyrrhizin biosynthesis. In this study, a second relevant P450 (CYP72A154) was identified and shown to be responsible for C-30 oxidation in the glycyrrhizin pathway. CYP72A154 expressed in an engineered yeast strain that endogenously produces 11-oxo-β-amyrin (a possible biosynthetic intermediate between β-amyrin and glycyrrhizin) catalyzed three sequential oxidation steps at C-30 of 11-oxo-β-amyrin supplied in situ to produce glycyrrhetinic acid, a glycyrrhizin aglycone. Furthermore, CYP72A63 of Medicago truncatula, which has high sequence similarity to CYP72A154, was able to catalyze C-30 oxidation of β-amyrin. These results reveal a function of CYP72A subfamily proteins as triterpene-oxidizing enzymes and provide a genetic tool for engineering the production of glycyrrhizin.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cytochrome P-450 Enzyme System / genetics
  • Cytochrome P-450 Enzyme System / metabolism*
  • Glycyrrhetinic Acid / metabolism
  • Glycyrrhiza / genetics*
  • Glycyrrhiza / metabolism*
  • Glycyrrhizic Acid / metabolism*
  • Medicago truncatula / enzymology
  • Molecular Sequence Data
  • Oleanolic Acid / analogs & derivatives
  • Oleanolic Acid / metabolism
  • Triterpenes / metabolism*
  • Yeasts / genetics

Substances

  • Triterpenes
  • Glycyrrhizic Acid
  • Oleanolic Acid
  • Cytochrome P-450 Enzyme System
  • beta-amyrin
  • Glycyrrhetinic Acid

Associated data

  • GENBANK/AB558144
  • GENBANK/AB558145
  • GENBANK/AB558146
  • GENBANK/AB558147
  • GENBANK/AB558148
  • GENBANK/AB558149
  • GENBANK/AB558150
  • GENBANK/AB558152
  • GENBANK/AB558153
  • GENBANK/AB558154