title: Amorpha-4,11-diene synthase catalyses the first probable step in artemisinin biosynthesis.
abstract: The endoperoxide sesquiterpene lactone artemisinin and its derivatives are a promising new group of drugs against malaria. Artemisinin is a constituent of the annual herb Artemisia annua L. So far only the later steps in artemisinin biosynthesis--from artemisinic acid--have been elucidated and the expected olefinic sesquiterpene intermediate has never been demonstrated. In pentane extracts of A. annua leaves we detected a sesquiterpene with the mass spectrum of amorpha-4,11-diene. Synthesis of amorpha-4,11-diene from artemisinic acid confirmed the identity. In addition we identified several sesquiterpene synthases of which one of the major activities catalysed the formation of amorpha-4,11-diene from farnesyl diphosphate. This enzyme was partially purified and shows the typical characteristics of sesquiterpene synthases, such as a broad pH optimum around 6.5-7.0, a molecular mass of 56 kDa, and a K(m) of 0.6 microM. The structure and configuration of amorpha-4,11-diene, its low content in A. annua and the high activity of amorpha-4,11-diene synthase all support that amorpha-4,11-diene is the likely olefinic sesquiterpene intermediate in the biosynthesis of artemisinin.
authors.affiliation: Research Institute for Agrobiology and Soil Fertility (AB-DLO), Wageningen, Netherlands. h.j.bouwmeester@ab.dlo.nl
authors.forename: H J
authors.initials: HJ
authors.lastname: Bouwmeester
authors.forename: T E
authors.initials: TE
authors.lastname: Wallaart
authors.forename: M H
authors.initials: MH
authors.lastname: Janssen
authors.forename: B
authors.initials: B
authors.lastname: van Loo
authors.forename: B J
authors.initials: BJ
authors.lastname: Jansen
authors.forename: M A
authors.initials: MA
authors.lastname: Posthumus
authors.forename: C O
authors.initials: CO
authors.lastname: Schmidt
authors.forename: J W
authors.initials: JW
authors.lastname: De Kraker
authors.forename: W A
authors.initials: WA
authors.lastname: König
authors.forename: M C
authors.initials: MC
authors.lastname: Franssen
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000378:metabolism*; D000962:Antimalarials / Q000378:metabolism*; D019306:Artemisia / Q000201:enzymology / Q000378:metabolism; D037621:Artemisinins; D002384:Catalysis; D004365:Drugs, Chinese Herbal / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008025:Ligases / Q000378:metabolism*; D008970:Molecular Weight; D018515:Plant Leaves / Q000201:enzymology / Q000378:metabolism; D010946:Plants, Medicinal; D011106:Polyisoprenyl Phosphates / Q000378:metabolism; D012717:Sesquiterpenes / Q000378:metabolism*
chemical_list: D000962:Antimalarials; D037621:Artemisinins; D004365:Drugs, Chinese Herbal; D011106:Polyisoprenyl Phosphates; D012717:Sesquiterpenes; C004808:farnesyl pyrophosphate; C031327:artemisinin; D019883:Alkyl and Aryl Transferases; C403714:amorpha-4,11-diene synthase; D008025:Ligases