Comparison of the enzymatic properties of ent-copalyl diphosphate synthases in the biosynthesis of phytoalexins and gibberellins in rice.
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.
Hayashi
Yutaka
Y
Biotechnology Research Center, Toyama Prefectural University, Japan.
Toyomasu
Tomonobu
T
Hirose
Yuko
Y
Onodera
Yu
Y
Mitsuhashi
Wataru
W
Yamane
Hisakazu
H
Sassa
Takeshi
T
Dairi
Tohru
T
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
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