Structural insights into the mechanism of abscisic acid signaling by PYL proteins
Structural insights into the mechanism of abscisic acid signaling by PYL proteins
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DOI：
10.1038/nsmb.1730
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发表时间：
2009-12-01
影响因子：
16.8
通讯作者：
Yan, Nieng
中科院分区：
文献类型：
--
作者：
Yin, Ping;Fan, He;Yan, Nieng
脱落酸（阿坝）是一种重要的植物激素，调节植物的逆境反应。来自PYR-PYL-RCAR家族的蛋白质最近被鉴定为阿坝受体。在与阿坝结合后，PYL蛋白与2C型蛋白磷酸酶（PP 2C）如ABI 1和ABI 2结合，抑制它们的活性;然而，PYL介导阿坝信号传导的分子机制仍然未知。在这里，我们报告了三种晶体结构：apo-PYL 2，（+）-ABA结合的PYL 2和（+）-ABA结合的PYL 1与磷酸酶ABI 1的复合物。Apo-PYL 2包含一个由四个高度保守的表面环包围的口袋。响应阿坝结合，环CL 2闭合到口袋上，产生识别ABI 1的表面。在三元复合物中，CL 2环位于ABI 1的活性位点附近，阻断底物蛋白的进入。总之，我们的数据揭示了阿坝调节PYL介导的PP 2Cs抑制的机制。
Abscisic acid (ABA) is an important phytohormone that regulates plant stress responses. Proteins from the PYR-PYL-RCAR family were recently identified as ABA receptors. Upon binding to ABA, a PYL protein associates with type 2C protein phosphatases (PP2Cs) such as ABI1 and ABI2, inhibiting their activity; the molecular mechanisms by which PYLs mediate ABA signaling remain unknown, however. Here we report three crystal structures: apo-PYL2, (+)-ABA-bound PYL2 and (+)-ABA-bound PYL1 in complex with phosphatase ABI1. Apo-PYL2 contains a pocket surrounded by four highly conserved surface loops. In response to ABA binding, loop CL2 closes onto the pocket, creating a surface that recognizes ABI1. In the ternary complex, the CL2 loop is located near the active site of ABI1, blocking the entry of substrate proteins. Together, our data reveal the mechanisms by which ABA regulates PYL-mediated inhibition of PP2Cs.