Arabidopsis CML38, a Calcium Sensor That Localizes to Ribonucleoprotein Complexes under Hypoxia Stress
Arabidopsis CML38, a Calcium Sensor That Localizes to Ribonucleoprotein Complexes under Hypoxia Stress
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DOI：
10.1104/pp.15.01407
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发表时间：
2016-02-01
期刊：
影响因子：
7.4
通讯作者：
Roberts, Daniel M.
中科院分区：
文献类型：
--
作者：
Lokdarshi, Ansul;Conner, W. Craig;Roberts, Daniel M.
在涝渍和相关的缺氧胁迫下，植物通过诱导适应性程序做出反应，包括基因网络的重定向表达，以合成核心缺氧反应蛋白。在拟南芥（Arabidopsis thaliana）的这些核心应答蛋白中，钙传感器CML38是一种与基因沉默钙调素样蛋白（calmodulin-like protein, rgsCaMs）调控相关的蛋白。在缺氧处理6小时内，CML38转录本在根中上调300倍以上。转移DNA插入突变体CML38对低氧胁迫的敏感性增强，存活降低，根和茎的生长受到更严重的抑制。通过黄色荧光蛋白（YFP）翻译融合，发现CML38蛋白定位于与缺氧诱导的应激颗粒形态相似的胞质颗粒结构。从含有CML38pro::CML38:YFP的缺氧转基因植物的根部免疫沉淀CML38，然后进行液相色谱-串联质谱分析，发现存在与信使RNA核糖核蛋白（mRNP）复合物相关的蛋白靶点，包括应激颗粒，这些蛋白靶点在缺氧时作为信使RNA储存和分流中心积累。在共转染烟叶时，CML38与mRNP胁迫颗粒标记RNA结合蛋白47 （RBP47）共定位进一步支持了这一发现。钌红处理导致胞质颗粒中CML38信号丢失，提示钙是胁迫颗粒结合所必需的。这些结果证实了CML38是一个核心的缺氧反应钙传感器蛋白，并表明它在胁迫颗粒和其他在洪水胁迫反应中积累的mRNPs中作为潜在的钙信号靶点。
During waterlogging and the associated oxygen deprivation stress, plants respond by the induction of adaptive programs, including the redirected expression of gene networks toward the synthesis of core hypoxia-response proteins. Among these core response proteins in Arabidopsis (Arabidopsis thaliana) is the calcium sensor CML38, a protein related to regulator of gene silencing calmodulin-like proteins (rgsCaMs). CML38 transcripts are up-regulated more than 300-fold in roots within 6 h of hypoxia treatment. Transfer DNA insertional mutants of CML38 show an enhanced sensitivity to hypoxia stress, with lowered survival and more severe inhibition of root and shoot growth. By using yellow fluorescent protein (YFP) translational fusions, CML38 protein was found to be localized to cytosolic granule structures similar in morphology to hypoxia-induced stress granules. Immunoprecipitation of CML38 from the roots of hypoxia-challenged transgenic plants harboring CML38pro::CML38:YFP followed by liquid chromatography-tandem mass spectrometry analysis revealed the presence of protein targets associated with messenger RNA ribonucleoprotein (mRNP) complexes including stress granules, which are known to accumulate as messenger RNA storage and triage centers during hypoxia. This finding is further supported by the colocalization of CML38 with the mRNP stress granule marker RNA Binding Protein 47 (RBP47) upon cotransfection of Nicotiana benthamiana leaves. Ruthenium Red treatment results in the loss of CML38 signal in cytosolic granules, suggesting that calcium is necessary for stress granule association. These results confirm that CML38 is a core hypoxia response calcium sensor protein and suggest that it serves as a potential calcium signaling target within stress granules and other mRNPs that accumulate during flooding stress responses.