title: Metal ions control product specificity of isoprenyl diphosphate synthases in the insect terpenoid pathway.
abstract: Isoprenyl diphosphate synthases (IDSs) produce the ubiquitous branched-chain diphosphates of different lengths that are precursors of all major classes of terpenes. Typically, individual short-chain IDSs (scIDSs) make the C10, C15, and C20 isoprenyl diphosphates separately. Here, we report that the product length synthesized by a single scIDS shifts depending on the divalent metal cofactor present. This previously undescribed mechanism of carbon chain-length determination was discovered for a scIDS from juvenile horseradish leaf beetles, Phaedon cochleariae. The recombinant enzyme P. cochleariae isoprenyl diphosphate synthase 1 (PcIDS1) yields 96% C10-geranyl diphosphate (GDP) and only 4% C15-farnesyl diphosphate (FDP) in the presence of Co(2+) or Mn(2+) as a cofactor, whereas it yields only 18% C10 GDP but 82% C15 FDP in the presence of Mg(2+). In reaction with Co(2+), PcIDS1 has a Km of 11.6 μM for dimethylallyl diphosphate as a cosubstrate and 24.3 μM for GDP. However, with Mg(2+), PcIDS1 has a Km of 1.18 μM for GDP, suggesting that this substrate is favored by the enzyme under such conditions. RNAi targeting PcIDS1 revealed the participation of this enzyme in the de novo synthesis of defensive monoterpenoids in the beetle larvae. As an FDP synthase, PcIDS1 could be associated with the formation of sesquiterpenes, such as juvenile hormones. Detection of Co(2+), Mn(2+), or Mg(2+) in the beetle larvae suggests flux control into C10 vs. C15 isoprenoids could be accomplished by these ions in vivo. The dependence of product chain length of scIDSs on metal cofactor identity introduces an additional regulation for these branch point enzymes of terpene metabolism.
authors: Department of Bioorganic Chemistry, Max Planck Institute for Chemical Ecology, Beutenberg Campus, D-07745 Jena, Germany.
authors: Sindy
authors: S
authors: Frick
authors: Raimund
authors: R
authors: Nagel
authors: Axel
authors: A
authors: Schmidt
authors: René R
authors: RR
authors: Bodemann
authors: Peter
authors: P
authors: Rahfeld
authors: Gerhard
authors: G
authors: Pauls
authors: Wolfgang
authors: W
authors: Brandt
authors: Jonathan
authors: J
authors: Gershenzon
authors: Wilhelm
authors: W
authors: Boland
authors: Antje
authors: A
authors: Burse
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D003035:Cobalt / Q000737:chemistry / Q000378:metabolism*; D001517:Coleoptera / Q000201:enzymology* / Q000235:genetics; D011756:Diphosphates / Q000737:chemistry / Q000378:metabolism*; D004224:Diterpenes / Q000737:chemistry / Q000378:metabolism*; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008345:Manganese / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D011106:Polyisoprenyl Phosphates / Q000096:biosynthesis* / Q000737:chemistry; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012717:Sesquiterpenes / Q000737:chemistry
chemical_list: D011756:Diphosphates; D004224:Diterpenes; D019476:Insect Proteins; D011106:Polyisoprenyl Phosphates; D011994:Recombinant Proteins; D012717:Sesquiterpenes; C511282:geranyl diphosphate; D003035:Cobalt; D008345:Manganese; C004808:farnesyl pyrophosphate; D019883:Alkyl and Aryl Transferases