Flexibility of the petunia strigolactone receptor DAD2 promotes its interaction with signaling partners
Flexibility of the petunia strigolactone receptor DAD2 promotes its interaction with signaling partners
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DOI：
10.1074/jbc.ra119.011509
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发表时间：
2020-03-27
影响因子：
4.8
通讯作者：
Snowden, Kimberley C.
中科院分区：
文献类型：
--
作者：
Lee, Hui Wen;Sharma, Prachi;Snowden, Kimberley C.
独脚金内酯 (SL) 是源自萜类化合物的植物激素，可调节各种发育过程，特别是芽分枝、根发育和叶子衰老。 SL 受体具有不寻常的作用模式。结合 SL 后，它会水解激素，然后共价结合其中一种水解产物。这些初始事件使 SL 受体 DAD2（在矮牵牛中）能够与 Skp-Cullin-F-box (SCF) 复合物的 F-box 蛋白 PhMAX2A 和/或 SL 信号传导阻遏物 PhD53A 相互作用。然而，目前尚不清楚结合和水解如何在结构上改变 SL 受体以使其与信号传导伙伴结合。在这里，我们使用诱变来改变 DAD2 并影响 SL 水解或 DAD2 与其信号传导伴侣相互作用的能力。我们鉴定了三种 DAD2 变体，其水解活性已与受体与 PhMAX2A 或 Phd53A 的相互作用分开。两个变体，DAD2(N242I) 和 DAD2(F135A)，在核心 ?/? 中进行了替换水解酶折叠结构域和发夹结构域分别与 PhMAX2A 和 PhD53A 表现出激素依赖性相互作用。相反，DAD2(D166A)变体在SL存在的情况下不能与PhMAX2A相互作用，但其与PhD53A的相互作用不受影响。 DAD2(N242I)和DAD2(D166A)的结构分析显示与WT受体的结构相比仅有很小的差异。 DAD2(N242I) 结构的分子动力学模拟结果表明，灵活性的增加可能是其与 PhMAX2A 不依赖 SL 相互作用的原因。我们的结果表明PhMAX2A和PhD53A在SL受体上具有不同的结合位点，并且其灵活性是其与这两个下游调节因子相互作用的主要决定因素。
Strigolactones (SLs) are terpenoid-derived plant hormones that regulate various developmental processes, particularly shoot branching, root development, and leaf senescence. The SL receptor has an unusual mode of action. Upon binding SL, it hydrolyzes the hormone, and then covalently binds one of the hydrolytic products. These initial events enable the SL receptor DAD2 (in petunia) to interact with the F-box protein PhMAX2A of the Skp-Cullin-F-box (SCF) complex and/or a repressor of SL signaling, PhD53A. However, it remains unclear how binding and hydrolysis structurally alters the SL receptor to enable its engagement with signaling partners. Here, we used mutagenesis to alter DAD2 and affect SL hydrolysis or DAD2's ability to interact with its signaling partners. We identified three DAD2 variants whose hydrolytic activity had been separated from the receptor's interactions with PhMAX2A or PhD53A. Two variants, DAD2(N242I) and DAD2(F135A), having substitutions in the core ?/? hydrolase-fold domain and the hairpin, exhibited hormone-independent interactions with PhMAX2A and PhD53A, respectively. Conversely, the DAD2(D166A) variant could not interact with PhMAX2A in the presence of SL, but its interaction with PhD53A remained unaffected. Structural analyses of DAD2(N242I) and DAD2(D166A) revealed only small differences compared with the structure of the WT receptor. Results of molecular dynamics simulations of the DAD2(N242I) structure suggested that increased flexibility is a likely cause for its SL-independent interaction with PhMAX2A. Our results suggest that PhMAX2A and PhD53A have distinct binding sites on the SL receptor and that its flexibility is a major determinant of its interactions with these two downstream regulators.