title: Cloning of a cDNA probably encoding oxidosqualene cyclase associated with asiaticoside biosynthesis from Centella asiatica (L.) Urban.
abstract: 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.
authors.affiliation: Department of Biology, Chonnam National University, Gwangju, 500-757, South Korea.
authors.forename: Ok Tae
authors.initials: OT
authors.lastname: Kim
authors.forename: Min Young
authors.initials: MY
authors.lastname: Kim
authors.forename: Sun Mi
authors.initials: SM
authors.lastname: Huh
authors.forename: Dong Gyu
authors.initials: DG
authors.lastname: Bai
authors.forename: Jun Cheul
authors.initials: JC
authors.lastname: Ahn
authors.forename: Baik
authors.initials: B
authors.lastname: Hwang
mesh_terms: D000085:Acetates / Q000494:pharmacology; D000595:Amino Acid Sequence; D028041:Centella / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D003517:Cyclopentanes / Q000494:pharmacology; D018076:DNA, Complementary / Q000737:chemistry; D019751:Intramolecular Transferases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D054883:Oxylipins; D010802:Phylogeny; D018515:Plant Leaves / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014315:Triterpenes / Q000378:metabolism*; D015854:Up-Regulation
chemical_list: D000085:Acetates; D003517:Cyclopentanes; D018076:DNA, Complementary; D054883:Oxylipins; D012333:RNA, Messenger; D014315:Triterpenes; C072239:methyl jasmonate; D019751:Intramolecular Transferases; C039924:2,3-oxidosqualene-beta-amyrin-cyclase; C021924:lanosterol synthase; C004446:asiaticoside