title: Frontalin pheromone biosynthesis in the mountain pine beetle, Dendroctonus ponderosae, and the role of isoprenyl diphosphate synthases.
abstract: The mountain pine beetle (Dendroctonus ponderosae Hopkins) is the most destructive pest of western North American pine forests. Adult males produce frontalin, an eight-carbon antiaggregation pheromone, via the mevalonate pathway, as part of several pheromones that initiate and modulate the mass attack of host trees. Frontalin acts as a pheromone, attractant, or kairomone in most Dendroctonus species, other insects, and even elephants. 6-Methylhept-6-en-2-one, a frontalin precursor, is hypothesized to originate from 10-carbon geranyl diphosphate (GPP), 15-carbon farnesyl diphosphate (FPP), or 20-carbon geranylgeranyl diphosphate (GGPP) via a dioxygenase- or cytochrome P450-mediated carbon-carbon bond cleavage. To investigate the role of isoprenyl diphosphate synthases in pheromone biosynthesis, we characterized a bifunctional GPP/FPP synthase and a GGPP synthase in the mountain pine beetle. The ratio of GPP to FPP produced by the GPP/FPP synthase was highly dependent on the ratio of the substrates isopentenyl diphosphate and dimethylallyl diphosphate used in the assay. Transcript levels in various tissues and life stages suggested that GGPP rather than GPP or FPP is used as a precursor to frontalin. Reduction of transcript levels by RNA interference of the isoprenyl diphosphate synthases identified GGPP synthase as having the largest effect on frontalin production, suggesting that frontalin is derived from a 20-carbon isoprenoid precursor rather than from the 10- or 15-carbon precursors.
authors.affiliation: Michael Smith Laboratories, University of British Columbia, Vancouver, BC, Canada V6T 1A4.
authors.forename: Christopher I
authors.initials: CI
authors.lastname: Keeling
authors.forename: Christine C
authors.initials: CC
authors.lastname: Chiu
authors.forename: Tidiane
authors.initials: T
authors.lastname: Aw
authors.forename: Maria
authors.initials: M
authors.lastname: Li
authors.forename: Hannah
authors.initials: H
authors.lastname: Henderson
authors.forename: Claus
authors.initials: C
authors.lastname: Tittiger
authors.forename: Hong-Biao
authors.initials: HB
authors.lastname: Weng
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Blomquist
authors.forename: Joerg
authors.initials: J
authors.lastname: Bohlmann
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001483:Base Sequence; D053898:Biosynthetic Pathways / Q000502:physiology*; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000378:metabolism*; D003001:Cloning, Molecular; D001517:Coleoptera / Q000201:enzymology / Q000378:metabolism*; D019295:Computational Biology; D051231:Farnesyltranstransferase / Q000235:genetics*; D008401:Gas Chromatography-Mass Spectrometry; D020869:Gene Expression Profiling / Q000379:methods; D023281:Genomics / Q000379:methods; D008969:Molecular Sequence Data; D010675:Pheromones / Q000096:biosynthesis* / Q000378:metabolism; D011106:Polyisoprenyl Phosphates / Q000378:metabolism*; D011487:Protein Conformation; D034622:RNA Interference; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D010675:Pheromones; D011106:Polyisoprenyl Phosphates; C012327:frontalin; D051231:Farnesyltranstransferase; C002963:geranylgeranyl pyrophosphate
keywords: bark beetle; midgut; semiochemistry