研究人员发现ATP结合盒（ABC）转运体超家族的一个成员ABCB19具有油菜素甾醇转运体的功能。研究人员展示了它在底物未结合和油菜素甾醇结合两种状态下的结构。生物活性油菜素甾醇是ABCB19 ATP水解活性的强效激活剂，转运试验表明ABCB19能转运油菜素甾醇。
在拟南芥中，ABCB19及其近缘同源物ABCB1能主动调节油菜素甾醇的反应。这些研究结果揭示了一种难以捉摸的生物活性油菜素甾醇输出机制，该机制与油菜素甾醇信号传导密切协调。
据了解，油菜素甾醇是类固醇植物激素，可调节植物的生长发育和生理机能，包括适应环境胁迫。油菜素甾醇在细胞内部合成，但与细胞表面的受体结合，因此需要一种尚未确定的输出机制。
附：英文原文
Title: Structure and function of the Arabidopsis ABC transporter ABCB19 in brassinosteroid export
Author: Wei Ying, Yaowei Wang, Hong Wei, Yongming Luo, Qian Ma, Heyuan Zhu, Hilde Janssens, Nemanja Vukainovi, Miroslav Kvasnica, Johan M. Winne, Yongxiang Gao, Shutang Tan, Jií Friml, Xin Liu, Eugenia Russinova, Linfeng Sun
Issue&Volume: 2024-03-22
Abstract: Brassinosteroids are steroidal phytohormones that regulate plant development and physiology, including adaptation to environmental stresses. Brassinosteroids are synthesized in the cell interior but bind receptors at the cell surface, necessitating a yet to be identified export mechanism. Here, we show that a member of the ATP-binding cassette (ABC) transporter superfamily, ABCB19, functions as a brassinosteroid exporter. We present its structure in both the substrate-unbound and the brassinosteroid-bound states. Bioactive brassinosteroids are potent activators of ABCB19 ATP hydrolysis activity, and transport assays showed that ABCB19 transports brassinosteroids. In Arabidopsis thaliana, ABCB19 and its close homolog, ABCB1, positively regulate brassinosteroid responses. Our results uncover an elusive export mechanism for bioactive brassinosteroids that is tightly coordinated with brassinosteroid signaling.
DOI: adj4591
Source: https://www.science.org/doi/10.1126/science.adj4591