title: Isolation and bacterial expression of a sesquiterpene synthase cDNA clone from peppermint (Mentha x piperita, L.) that produces the aphid alarm pheromone (E)-beta-farnesene.
abstract: (E)-beta-Farnesene is a sesquiterpene semiochemical that is used extensively by both plants and insects for communication. This acyclic olefin is found in the essential oil of peppermint (Mentha x piperita) and can be synthesized from farnesyl diphosphate by a cell-free extract of peppermint secretory gland cells. A cDNA from peppermint encoding (E)-beta-farnesene synthase was cloned by random sequencing of an oil gland library and was expressed in Escherichia coli. The corresponding synthase has a deduced size of 63.8 kDa and requires a divalent cation for catalysis (Km for Mg2+ approximately 150 microM; Km for Mn2+ approximately 7 microM). The sesquiterpenoids produced by the recombinant enzyme, as determined by radio-GC and GC-MS, are (E)-beta-farnesene (85%), (Z)-beta-farnesene (8%), and delta-cadinene (5%) with the native C15 substrate farnesyl diphosphate (Km approximately 0.6 microM; Vrel = 100) and Mg2+ as cofactor, and (E)-beta-farnesene (98%) and (Z)-beta-farnesene (2%) with Mn2+ as cofactor (Vrel = 80). With the C10 analog, GDP, as substrate (Km = 1.5 microM; Vrel = 3 with Mg2+ as cofactor), the monoterpenes limonene (48%), terpinolene (15%), and myrcene (15%) are produced.
authors.affiliation: Institute of Biological Chemistry, and Department of Biochemistry and Biophysics, Washington State University, Pullman 99164-6340, USA.
authors.forename: J
authors.initials: J
authors.lastname: Crock
authors.forename: M
authors.initials: M
authors.lastname: Wildung
authors.forename: R
authors.initials: R
authors.lastname: Croteau
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001042:Aphids; D003001:Cloning, Molecular; D018076:DNA, Complementary; D004926:Escherichia coli / Q000235:genetics; D036142:Mentha piperita; D008969:Molecular Sequence Data; D010675:Pheromones / Q000096:biosynthesis*; D010936:Plant Extracts / Q000235:genetics* / Q000378:metabolism; D011755:Pyrophosphatases / Q000235:genetics*; D012717:Sesquiterpenes / Q000378:metabolism*
chemical_list: D018076:DNA, Complementary; D010675:Pheromones; D010936:Plant Extracts; D012717:Sesquiterpenes; C062671:beta-farnesene; D011755:Pyrophosphatases; C109459:beta-farnesene synthase