21.イネのフィトアレキシンとジベレリン生合成に関与するent-コパリル2リン酸合成酵素の酵素的性質の比較(口頭発表)

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Gibberellins, a phytohormone, are biosynthesized from geranylgeranyl diphosphate (GGDP) via ent-kaurene. In higher plants, entkaurene was formed from GGDP via ent-copalyl diphsphate (ent-CDP) by two distinct diterpene cyclases, ent-CDP synthase and ent-kaurene synthase. Rice (Oryza sativa L.) produces diterpene phytoalexins, such as oryzalexins, momilactones and phytocassanes, of which biosynthetic hydrocarbon intermediates are converted from GGDP by the similar manner as ent-kaurene synthesis. We have shown that rice has two ent-CDP synthase genes; OsCPSl is for gibberellin biosynthesis and OsCPS2/OsCyc2 is for oryzalexins A-F and phytocassanes A-E. Although ent-CDP synthases for gibberellin biosynthesis from other plant species were well characterized, we have known little about properties of rice ent-CDP synthase for phytoalexin biosynthesis.Here, we enzymatically characterized recombinant putative mature OsCPS2/OsCyc2 as well as OsCPS4/OsCycl, syn-CDP synthase for mimilactones A and B and oryzalexin S, and compared to OsCPS1. The optima of pH (around neutral), temperature (around 30 oC), and divalent ion (0.1 mM Mg^<2+>) on OsCPS2/OsCyc2 and OsCPS4/OsCyc1 were almost the same as OsCPS1. Interestingly, the inhibition rate of activities of OsCPS2/OsCyc2 and OsCPS4/OsCyc1 by substrate, GGDP (50-60μM), and Amo-1618 (10^<-5>-10^<-4>M), a gibberellin biosynthetic inhibitor which suppresses ent-CDP synthase activity, was less than that of OsCPS1.
植物化学調節学会の論文
2007-10-05

21.イネのフィトアレキシンとジベレリン生合成に関与するent-コパリル2リン酸合成酵素の酵素的性質の比較(口頭発表)

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