Ca2+/calmodulin is critical for brassinosteroid biosynthesis and plant growth
Ca2+/calmodulin is critical for brassinosteroid biosynthesis and plant growth
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DOI：
10.1038/nature03973
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发表时间：
2005-09-29
期刊：
影响因子：
64.8
通讯作者：
Poovaiah, BW
中科院分区：
文献类型：
--
作者：
Du, LQ;Poovaiah, BW
油菜素类固醇是植物特有的类固醇激素(1，2)，在环境因素，特别是光与植物生长和发育的耦合中起着重要作用(3)。内源性油菜素类固醇如何对环境刺激做出反应在很大程度上是未知的。钙/钙调蛋白在感知和传递环境刺激中起着重要作用(4，5)。拟南芥DWARF1(DWF1)负责油菜素类固醇生物合成的早期步骤，将24-亚甲基胆固醇酯转化为油菜籽甾醇(6，7)。在这里，我们证明了DWF1是一种钙/钙调素结合蛋白，这种结合是其功能的关键。利用定点突变体和缺失突变体进行的分子遗传学分析表明，在互补性研究中，钙调蛋白结合的丢失完全取消了植物中DWF1的功能，而部分钙调蛋白结合的丢失导致了部分矮化表型。这些结果直接证明了钙/钙调蛋白介导的信号转导在调控DWF1功能中起着关键作用。此外，我们观察到来自其他植物的DWF1同源物具有相似的钙/钙调蛋白结合域，这意味着植物中普遍存在对DWF1及其同源物的钙/钙调蛋白调节。这些结果提高了通过改变其DWF1同源物的钙/钙调素结合特性来生产尺寸工程作物的可能性。
Brassinosteroids are plant-specific steroid hormones(1,2) that have an important role in coupling environmental factors, especially light, with plant growth and development(3). How the endogenous brassinosteroids change in response to environmental stimuli is largely unknown. Ca2+/calmodulin has an essential role in sensing and transducing environmental stimuli(4,5). Arabidopsis DWARF1 (DWF1) is responsible for an early step in brassinosteroid biosynthesis that converts 24-methylenecholesterol to campesterol(6,7). Here we show that DWF1 is a Ca2+/calmodulin-binding protein and this binding is critical for its function. Molecular genetic analysis using site-directed and deletion mutants revealed that loss of calmodulin binding completely abolished the function of DWF1 in planta, whereas partial loss of calmodulin binding resulted in a partial dwarf phenotype in complementation studies. These results provide direct proof that Ca2+/calmodulin-mediated signalling has a critical role in controlling the function of DWF1. Furthermore, we observed that DWF1 orthologues from other plants have a similar Ca2+/calmodulin-binding domain, implying that Ca2+/calmodulin regulation of DWF1 and its homologues is common in plants. These results raise the possibility of producing size-engineered crops by altering the Ca2+/calmodulin-binding property of their DWF1 orthologues.