41.ABA受容体アンタゴニストの創出研究(口頭発表)

概要

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In this study, we tried to develop an antagonist of ABA receptors. Recently, ABA receptors were identified as PYR/PYL/RCAR family of START proteins, and ternary structures of a PYR/PYL-ABA or a PYR/PYL-ABA-PP2C complex were determined to give structural basis of ABA signaling. Interactions of ABA with the receptors in the complex crystal completely coincided with those that have been expected on the basis of the knowledge of structure-activity relationship. Therefore, now we can rationally design an ABA agonist in the view of molecular structure. In the PYR/PYL-ABA complex, the side chain carboxylate of ABA intrudes deeply into the ligand pocket to form the salt bridge with Lys, whereas the cyclohexenone ring is located near the ligand gate to induce the structural change and form an interface for accepting PP2C. An ABA antagonist needs to bind strongly to the receptor but not to induce the triad complex formation. Because the modification of the enone moiety (C2'=C3'-C4'=O) of the ring in ABA has a smaller effect on ABA bioactivities, we focused on the enone moiety in designing the antagonist and synthesized two ABA analogues with an alkyl chain at C3'. Of these, 3'-hexylsulfanyl-ABA canceled the inhibitory effect of ABA on germination of lettuce seeds and growth of the seedlings.
2010-10-01