β-Amyrin synthase (EsBAS) and β-amyrin 28-oxidase (CYP716A244) in oleanane-type triterpene saponin biosynthesis in Eleutherococcus senticosus

Phytochemistry. 2017 Mar;135:53-63. doi: 10.1016/j.phytochem.2016.12.011. Epub 2016 Dec 21.

Abstract

Siberian ginseng (Eleutherococcus senticosus) is a woody medical shrub belonging to the Araliaceae family. E. senticosus contains various types of saponins, including oleanane, noroleanane, lupane, and 3,4-secolupane types, depending on the aglycone structure. Oleanane-type triterpenes are the major saponin components in E. senticosus. Two enzymes (β-amyrin synthase and β-amyrin 28-oxidase) are essential for oleanane-type saponin biosynthesis from 2,3-oxidosqualene. In the present study, two full-length cDNAs encoding EsBAS and CYP716A244 were isolated based on transcriptomics analysis of plant leaves. Both β-amyrin synthase (EsBAS) and β-amyrin 28-oxidase (CYP716A244), isolated from E. senticosus, were functionally characterised. β-amyrin production was confirmed by heterologous expression of the EsBAS gene in yeast and tobacco. Oleanolic acid production was confirmed by co-expression of both EsBAS and CYP716A244 in engineered yeast and transgenic tobacco.

Keywords: Araliaceae; Eleutherococcus senticosus; Oleanolic acid synthase; Saponin biosynthesis; β-amyrin synthase.

MeSH terms

  • Amino Acid Sequence
  • Cytochrome P-450 Enzyme System / metabolism*
  • DNA, Complementary / metabolism
  • Eleutherococcus / chemistry*
  • Eleutherococcus / enzymology
  • Intramolecular Transferases / metabolism*
  • Molecular Structure
  • Oleanolic Acid / metabolism
  • Oxidoreductases / metabolism
  • Panax / genetics
  • Plants, Medicinal / chemistry
  • Saponins / metabolism
  • Squalene / analogs & derivatives
  • Squalene / metabolism
  • Triterpenes / chemistry*
  • Triterpenes / metabolism

Substances

  • DNA, Complementary
  • Saponins
  • Triterpenes
  • oxidosqualene
  • lupane
  • Oleanolic Acid
  • Squalene
  • Cytochrome P-450 Enzyme System
  • Oxidoreductases
  • Intramolecular Transferases
  • 2,3-oxidosqualene-beta-amyrin-cyclase