APA<i>n</i>, a Class of ABA Receptor Agonism/Antagonism Switching Probes
Chuanliang Che, Yuejuan Zeng, Yefei Xu, Huizhe Lu, Yan-Jun Xu, Xueqin Zhang, Yumei Xiao, Jiaqi Li, Zhaohai Qin
Abstract
In plants, biosynthesized ABA undergoes two important physiological processes of signal transduction and metabolism simultaneously. In this study, we described a class of ABA receptor agonist/antagonist switching probes APAn, which can regulate the agonistic activity or antagonistic activity according to the length of a 6′-alkoxyl chain. From APA1 to APA6, with the extension of the alkoxyl chain, it showed a gradually increased receptor-binding potential and decreased HAB1 inhibition activity. Theoretical analysis based on molecular docking and molecular dynamics simulation revealed that some factors outside the ligand-binding pocket in receptors could also affect the binding of the ligand to the receptor, for example, the van der Waals interaction between the alkyl chain in APAn and the 3′-tunnel of ABA receptors made it bind more tightly than iso-PhABA. This enhanced binding made it an antagonist rather than a weakened agonist.