Molecular actions of two synthetic brassinosteroids, iso-carbaBL and 6-deoxoBL, which cause altered physiological activities between Arabidopsis and rice.
Molecular actions of two synthetic brassinosteroids, iso-carbaBL and 6-deoxoBL, which cause altered physiological activities between Arabidopsis and rice.
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DOI：
10.1371/journal.pone.0174015
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发表时间：
2017
期刊：
影响因子：
3.7
通讯作者：
Nakano T
中科院分区：
文献类型：
--
作者：
Nakamura A;Tochio N;Fujioka S;Ito S;Kigawa T;Shimada Y;Matsuoka M;Yoshida S;Kinoshita T;Asami T;Seto H;Nakano T
油菜素内酯（BR）是一种重要的植物激素，由油菜素内酯不敏感1（BRI 1）受体感知。BRI 1在双子叶植物和单子叶植物物种中是保守的;然而，单子叶植物中BR感知的分子机制尚未完全了解。我们合成了两个BR，异卡巴素（iso-carbabrassinsulate，iso-carbabBL）和6-deoxoBL，它们在拟南芥（Arabidopsis thaliana，Arabidopsis）和水稻中具有不同的BR活性。我们的生物测定表明，iso-carbBL在拟南芥中具有相对较强的BR活性，但在水稻中是无活性的，并且竞争性地抑制BR活性。6-deoxoBL在拟南芥中的生物活性与BL相似，但在水稻中的生物活性要低得多。使用重组拟南芥和水稻BRI 1蛋白片段的结合实验表明，iso-carbBL和6-deoxoBL结合两种受体。这些结果表明，异卡巴BL和6-脱氧BL分别对水稻BR具有拮抗和激动作用。对接模拟分析表明，iso-carbBL适合更深的结合口袋，以阻止活性BR与水稻BRI 1的结合。6-deoxoBL与水稻BRI 1的结合能远低于与拟南芥BRI 1的结合能。根据拟南芥和水稻中异卡巴基（iso-carbBL）和6-脱氧卡巴基（6-deoxoBL）BR活性的差异，确定了水稻BRI 1可能的结构特征。
Brassinosteroid (BR) is an important plant hormone that is perceived by the BRASSINOSTEROID INSENSITIVE 1 (BRI1) receptor. BRI1 is conserved among dicot and monocot species; however, the molecular mechanism underlying BR perception in monocots is not fully understood. We synthesised two BRs, iso-carbabrassinolide (iso-carbaBL) and 6-deoxoBL, which have different BR activities in Arabidopsis thaliana (Arabidopsis) and rice. Our bioassay indicated that iso-carbaBL has relatively strong BR activity in Arabidopsis, but is inactive in rice and competitively inhibits BR activity. The bioactivity of 6-deoxoBL was similar to that of BL in Arabidopsis, but was much lower in rice. Binding experiments using recombinant Arabidopsis and rice BRI1 protein fragments suggested that iso-carbaBL and 6-deoxoBL bind to both receptors. These results showed that iso-carbaBL and 6-deoxoBL act as an antagonist and agonist, respectively, of BRs in rice. A docking simulation analysis suggested that iso-carbaBL fits deeper in the binding pocket to block the binding of active BR to rice BRI1. The simulated binding energy of 6-deoxoBL with rice BRI1 is much lower than that with Arabidopsis BRI1. The possible structural characteristics of rice BRI1 were determined based on the difference in the BR activities of iso-carbaBL and 6-deoxoBL in Arabidopsis and rice.