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Geraniol dehydrogenase, the key enzyme in biosynthesis of the alarm pheromone, from the astigmatid mite Carpoglyphus lactis (Acari: Carpoglyphidae)
Author(s) -
Noge Koji,
Kato Makiko,
Mori Naoki,
Kataoka Michihiko,
Tanaka Chihiro,
Yamasue Yuji,
Nishida Ritsuo,
Kuwahara Yasumasa
Publication year - 2008
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2008.06421.x
Subject(s) - geraniol , nad+ kinase , biochemistry , cofactor , alcohol dehydrogenase , dehydrogenase , biology , nerol , stereochemistry , biosynthesis , enzyme , chemistry , botany , essential oil
Geraniol dehydrogenase (GeDH), which plays an important role in the biosynthesis of neral, an alarm pheromone, was purified from the astigmatid mite Carpoglyphus lactis . The enzyme was obtained in an apparently homogeneous and active form after 1879‐fold purification through seven steps of chromatography. Car . lactis GeDH was determined to be a monomer in its active form with a relative molecular mass of 42 800, which is a unique subunit structure in comparison with already established alcohol dehydrogenases. Car . lactis GeDH oxidized geraniol into geranial in the presence of NAD + . NADP + was ineffective as a cofactor, suggesting that Car . lactis GeDH is an NAD + ‐dependent alcohol dehydrogenase. The optimal pH and temperature for geraniol oxidation were determined to be pH 9.0 and 25 °C, respectively. The K m values for geraniol and NAD + were 51.0 μ m and 59.5 μ m , respectively. Car . lactis GeDH was shown to selectively oxidize geraniol, whereas its geometrical isomer, nerol, was inert as a substrate. The high specificity for geraniol suggests that Car . lactis GeDH specializes in the alarm pheromone biosynthesis of Car . lactis . Car . lactis GeDH is composed of 378 amino acids. Structurally, Car . lactis GeDH showed homology with zinc‐dependent alcohol dehydrogenases found in mammals and a mosquito (36.6–37.6% identical), and the enzyme was considered to be a member of the medium‐chain dehydrogenase/reductase family, in view of the highly conserved sequences of zinc‐binding and NAD + ‐binding sites. Phylogenetic analyses indicate that Car . lactis GeDH could be categorized as a new class, different from other established alcohol dehydrogenases.