7. オーキシン生合成阻害剤KOK1169の作用機構解析(口頭発表,植物化学調節学会第46回大会)

概要

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Indole-3-acetic acid (IAA), the most important member of the auxin family, has been reported to play an important role in plant development and growth. TRYPTOPHAN AMINOTRANSFERASE of ARABIDOPSIS 1 (TAA1) is involved in IAA biosynthesis. We reported that L-aminooxy-phenylpropionic acid (AOPP) is an inhibitor of TAA1. However AOPP has side effects, such as inhibition of phenylalanine ammonia-lyase and 1-Aminocyclopropane-l-carboxylic acid synthase (ACS). Here, we developed more stable and specific auxin-biosynthesis inhibitor, KOK1169, using AOPP as a lead compound. We examined the inhibitor activity of KOK1169 for AtACS8. The K, value of KOK1169 is 246 nM, and it was lower than that of AOPP (847 nM). While, the K, value of KOK1169 is higher than that of L-α-(2-Aminoethoxyvinyl)glyeine (AVG), which is a typical inhibitor of the ACS (37 nM). Although KOK1169 showed an inhibitor activity for ACS in enzyme assay, ethylene biosynthesis of Arabidopsis seedling was scarcely affected by KOK1169. Furthermore, the K_i value of KOK1169 for TAA1 is 76 nM, and it was superior to that of KOK1169 for AtACS8. Therefore, we concluded that KOK1169 has the higher specificity for IAA biosynthesis than AOPP. This work was supported by the Program for Promotion of Basic and Applied Researches for Innovations in Bio-oriented Industry (BRAIN).
2011-10-03