Cloning of a cDNA probably encoding oxidosqualene cyclase associated with asiaticoside biosynthesis from Centella asiatica (L.) Urban

• Published in: Plant cell reports Vol. 24; no. 5; pp. 304 - 311
• Main Authors: Kim, O.T, Kim, M.Y, Huh, S.M, Bai, D.G, Ahn, J.C, Hwang, B
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.07.2005; Springer Nature B.V
• Subjects: Acetates - pharmacology; Amino Acid Sequence; amino acid sequences; Amino acids; asiaticoside; Bacteria; beta-amyrin synthase; Biological and medical sciences; Biosynthesis; Biotechnology; Centella - enzymology; Centella - genetics; Centella - metabolism; Centella asiatica; Cloning; Cloning, Molecular; complementary DNA; Cyclopentanes - pharmacology; DNA, Complementary - chemistry; Eukaryotic cell cultures; Fundamental and applied biological sciences. Psychology; Genes; glycosides; Intramolecular Transferases - genetics; Intramolecular Transferases - metabolism; isomerases; Leaves; Methods. Procedures. Technologies; Miscellaneous; Molecular Sequence Data; nucleotide sequences; oxidosqualene cyclase; Oxylipins; Phylogeny; Plant cells and fungal cells; Plant Leaves - enzymology; Plant Leaves - genetics; Plant Leaves - metabolism; Plant tissues; RNA, Messenger - metabolism; sequence analysis; Sequence Homology, Amino Acid; Triterpenes - metabolism; triterpenoid saponins; triterpenoids; Up-Regulation; Oxidosqualene cyclases; Complementary DNA; Triterpene saponins; β-Amyrin synthase; Triterpene; Centella asiatica; Biosynthesis; Molecular cloning; Saponin
• ISSN: 0721-7714; 1432-203X
• DOI: 10.1007/s00299-005-0927-y

A homology-based PCR method was used to clone a cDNA encoding oxidosqualene cyclase from Centella asiatica, which produces a large quantity of triterpene saponins such as asiaticoside and madecassoside. Sequence analysis of one clone found sequences related to beta-amyrin synthase. An open reading frame in the full-length clone was named CabAS (Centella asiatica putative beta-amyrin synthase). On the basis of amino acid sequence, CabAS appears to be an enzyme (beta-amyrin synthase) that synthesizes beta-amyrin. Southern analysis showed that the C. asiatica genome contains one copy of the CabAS gene. Northern blot analysis demonstrated that the CabAS gene is expressed in leaves with no detectable transcript in other plant tissues, consistent with the organ-specific accumulation of the asiaticoside. Up-regulation of expression of CabAS by methyl jasmonate in leaves was also demonstrated.