title: High substrate specificity of ipsdienol dehydrogenase (IDOLDH), a short-chain dehydrogenase from Ips pini bark beetles.
abstract: Ips spp. bark beetles use ipsdienol, ipsenol, ipsdienone and ipsenone as aggregation pheromone components and pheromone precursors. For Ips pini, the short-chain oxidoreductase ipsdienol dehydrogenase (IDOLDH) converts (-)-ipsdienol to ipsdienone, and thus likely plays a role in determining pheromone composition. In order to further understand the role of IDOLDH in pheromone biosynthesis, we compared IDOLDH to its nearest functionally characterized ortholog with a solved structure: human L-3-hydroxyacyl-CoA dehydrogenase type II/ amyloid-β binding alcohol dehydrogenase (hHADH II/ABAD), and conducted functional assays of recombinant IDOLDH to determine substrate and product ranges and structural characteristics. Although IDOLDH and hHADH II/ABAD had only 35% sequence identity, their predicted tertiary structures had high identity. We found IDOLDH is a functional homo-tetramer. In addition to oxidizing (-)-ipsdienol, IDOLDH readily converted racemic ipsenol to ipsenone, and stereo-specifically reduced both ketones to their corresponding (-)-alcohols. The (+)-enantiomers were never observed as products. Assays with various substrate analogs showed IDOLDH had high substrate specificity for (-)-ipsdienol, ipsenol, ipsenone and ipsdienone, supporting that IDOLDH functions as a pheromone-biosynthetic enzyme. These results suggest that different IDOLDH orthologs and or activity levels contribute to differences in Ips spp. pheromone composition.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557, USA.
authors.forename: Rubi
authors.initials: R
authors.lastname: Figueroa-Teran
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557, USA.
authors.forename: Heidi
authors.initials: H
authors.lastname: Pak
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557, USA.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Blomquist
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557, USA crt@unr.edu.
authors.forename: Claus
authors.initials: C
authors.lastname: Tittiger
mesh_terms: D000080462:Acyclic Monoterpenes; D000818:Animals; D001517:Coleoptera / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D019476:Insect Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D039821:Monoterpenes / Q000737:chemistry* / Q000378:metabolism; D000442:Octanols / Q000737:chemistry* / Q000378:metabolism; D010088:Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010675:Pheromones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity / Q000502:physiology
chemical_list: D000080462:Acyclic Monoterpenes; D019476:Insect Proteins; D039821:Monoterpenes; D000442:Octanols; D010675:Pheromones; D010088:Oxidoreductases; C515391:ipsdienol
keywords: ipsdienol; ipsenol; monoterpene; pheromone; short-chain dehydrogenase