title: Comparison of the enzymatic properties of ent-copalyl diphosphate synthases in the biosynthesis of phytoalexins and gibberellins in rice.
abstract: The rice genome contains two ent-copalyl diphosphate synthase genes: OsCPS1 acts in gibberellin (phytohormone) biosynthesis, and OsCPS2/OsCyc2 acts in the synthesis of oryzalexins A-F and phytocassanes A-E (phytoalexins). We characterized the enzymatic properties of recombinant OsCPS2/OsCyc2 fused with a tag-protein at the N-terminus, and compared them to those of OsCPS1. Several enzymatic properties of OsCPS2/OsCyc2, including the optimal pH, optimal temperature, divalent cation requirement, and kinetic values for the geranylgeranyl diphosphate (GGDP) substrate, were almost the same as those of OsCPS1. However, OsCPS2/OsCyc2 activity was not inhibited by 50-60 muM GGDP substrate, by which the OsCPS1 activity was inhibited. Furthermore, the OsCPS1 activity exhibited approximately 70% inhibition by 100 muM Amo-1618 (a gibberellin biosynthetic inhibitor), whereas the OsCPS2/OsCyc2 activity exhibited approximately 10% inhibition. These results indicate that the properties of OsCPS2/OsCyc2 were partially different from those of OsCPS1, although OsCPS2/OsCyc2 catalyzes the same reaction step as OsCPS1.
authors.affiliation: Biotechnology Research Center, Toyama Prefectural University, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Tomonobu
authors.initials: T
authors.lastname: Toyomasu
authors.forename: Yuko
authors.initials: Y
authors.lastname: Hirose
authors.forename: Yu
authors.initials: Y
authors.lastname: Onodera
authors.forename: Wataru
authors.initials: W
authors.lastname: Mitsuhashi
authors.forename: Hisakazu
authors.initials: H
authors.lastname: Yamane
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sassa
authors.forename: Tohru
authors.initials: T
authors.lastname: Dairi
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000378:metabolism*; D001483:Base Sequence; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D005875:Gibberellins / Q000096:biosynthesis*; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D012275:Oryza / Q000201:enzymology / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012717:Sesquiterpenes; D013379:Substrate Specificity; D013696:Temperature; D013729:Terpenes / Q000378:metabolism*; D000094162:Phytoalexins
chemical_list: D017931:DNA Primers; D005875:Gibberellins; D010940:Plant Proteins; D011994:Recombinant Proteins; D012717:Sesquiterpenes; D013729:Terpenes; D019883:Alkyl and Aryl Transferases; C090963:ent-kaurene synthetase A; D000094162:Phytoalexins