DAD2 Is an α/β Hydrolase Likely to Be Involved in the Perception of the Plant Branching Hormone, Strigolactone
DAD2 Is an α/β Hydrolase Likely to Be Involved in the Perception of the Plant Branching Hormone, Strigolactone
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DOI：
10.1016/j.cub.2012.08.007
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发表时间：
2012-11-06
期刊：
影响因子：
9.2
通讯作者：
Snowden, Kimberley C.
中科院分区：
文献类型：
--
作者：
Hamiaux, Cyril;Drummond, Revel S. M.;Snowden, Kimberley C.
独脚金内酯是最近发现的一类植物激素，参与分枝、叶衰老、根发育和植物-微生物相互作用[1-6]。它们是类胡萝卜素衍生的内酯，在根中合成并向顶运输以调节腋芽生长（即，分支）[1，2]。然而，独脚金内酯的受体尚未被鉴定。我们已经从矮牵牛中鉴定了DAD 2基因，矮牵牛是水稻和拟南芥014基因的直系同源物，并为它在独脚金内酯感知和信号传导中的作用提供了证据。DAD 2在独脚金内酯途径中起作用，并且dad 2突变体对独脚金内酯类似物GR 24不敏感。DAD 2的晶体结构揭示了包含具有能够容纳独脚金内酯的大内腔的典型催化三联体的α/β水解酶折叠。在GR 24存在下，DAD 2以GR 24浓度依赖性方式与独脚金内酯信号传导的中心组分PhMAX 2A相互作用。DAD 2可以水解GR 24，催化三联体的突变体消除了这种活性和DAD 2与PhMAX 2A相互作用的能力。水解产物既不能刺激蛋白质-蛋白质相互作用，也不能调节分支。这些观察结果表明，DAD 2的作用是结合移动的独脚金内酯信号，然后在催化过程中与PhMAX 2A相互作用，以启动SCF介导的信号转导途径。
Strigolactones are a recently discovered class of plant hormone involved in branching, leaf senescence, root development, and plant-microbe interactions [1-6]. They are carotenoid-derived lactones, synthesized in the roots and transported acropetally to modulate axillary bud outgrowth (i.e., branching) [1, 2]. However, a receptor for strigolactones has not been identified. We have identified the DAD2 gene from petunia, an ortholog of the rice and Arabidopsis 014 genes, and present evidence for its roles in strigolactone perception and signaling. DAD2 acts in the strigolactone pathway, and the dad2 mutant is insensitive to the strigolactone analog GR24. The crystal structure of DAD2 reveals an alpha/beta hydrolase fold containing a canonical catalytic triad with a large internal cavity capable of accommodating strigolactones. In the presence of GR24 DAD2 interacts with PhMAX2A, a central component of strigolactone signaling, in a GR24 concentration-dependent manner. DAD2 can hydrolyze GR24, with mutants of the catalytic triad abolishing both this activity and the ability of DAD2 to interact with PhMAX2A. The hydrolysis products can neither stimulate the protein-protein interaction nor modulate branching. These observations suggest that DAD2 acts to bind the mobile strigolactone signal and then interacts with PhMAX2A during catalysis to initiate an SCF-mediated signal transduction pathway.