4. ジベレリン生合成における13位水酸化反応を阻害する物質(口頭発表,植物化学調節学会第46回大会)

概要

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The 13-hydroxylation in gibberellin (GA) biosynthesis-the substrate, the enzyme, and the biological significance are still poorly understood. Although recent studies suggest that some CYP714 enzymes catalyze the 13-hydroxylation of ent-kaurenoic acid (KA) or GA_<12>, the biological significance of the 13-hydroxylation remains unclear. The GA receptor, GID1 in Arabidopsis and rice, prefers GA_4 with no hydroxy group at C13 rather than GA_1, the 13-hydroxylated GA. Nevertheless, GA_1 is the major active GA in rice. Why does the 13-hydroxylation exist in GA biosynthesis? Our goal in this study is the development of a selective inhibitor of the 13-hydroxylases in GA biosynthesis as a chemical tool for probing the biological significance of the 13-hydroxylation. We screened inhibitors for Arabidopsis KA 13-hydroxylase, CYP714A, from commercial available azole compounds, and found imazalil (IMZ), which was 30-fold stronger than uniconazole in inhibition of CYP714A. Because IMZ is a fungicide that inhibits fungal CYP51, it is not excluded the possibility that this compound inhibits plant CYP51. Hence, we are constructing the assay system of plant and fungal CYP51 to test the selectivity of IMZ. We are also modifying the structure of IMZ to raise the selectivity.
2011-10-03