Analyses and Identification of molecular mechanisms underlying Calcium-sensor function and priming in guard cells

许多实验室的研究表明，ABA诱导的气孔关闭的转导过程依赖于胞质Ca ~（2+）。然而，最近的研究表明，细胞质Ca 2+的升高可以自发地发生，甚至在气孔开放刺激，如低CO2。这些观察结果表明，需要额外的分子机制来“启动”钙传感器，以允许钙信号。最近在宿主实验室中鉴定了阿坝信号通路的两种钙传感器（CPK 3和CPK 6）（1）。我将调查的工作假设，在钙依赖性信号，钙2+传感器蛋白，如CPK 3和CPK 6和钙调神经磷酸酶B样蛋白（CBL的），可以“引发”的翻译后修饰，如磷酸化，或通过改变其细胞内定位，以使他们能够响应钙转换（1，2）。为了确定钙信号的调节剂，我想确定阿坝信号的进一步组成部分。在阿坝信号传导过程中被修饰或诱导的蛋白质将通过质谱法进行鉴定，CPK 6和CPK 3的底物将使用生物化学方法和肽阵列进行分析。这一Ca 2+传感器启动假说也可能有助于理解植物基因组中编码的众多Ca 2+感觉蛋白如何介导植物中许多Ca 2+依赖性信号传导过程的特异性。

Studies in a number of laboratories have shown cytosolic Ca2+ dependent processes in the transduction of ABA-induced stomatal closing. However, recent studies indicated that cytosolic Ca2+ elevations can occur spontaneously and even during stomatal opening stimuli, such as low CO2. These observations suggest that additional molecular mechanisms are required to “prime” calcium sensors in order to allow calcium signalling. Two calcium sensors (CPK3 and CPK6) of the ABA signalling pathway have recently been identified in the host laboratory (1). I will investigate the working hypothesis, that during Ca2+-dependent signalling, Ca2+ sensor proteins, such as CPK3 and CPK6 and Calcineurin B-like proteins (CBL’s), could be “primed” by posttranslational modifications, such as phosphorylations, or by changing their intracellular localization, in order to allow them to respond to calcium transitions (1, 2). To identify modulators of calcium signalling I want to identify further components of ABA signalling. Proteins that are modified or induced during ABA signalling will be identified by mass spectrometry and substrates of CPK6 and CPK3 will be analyzed using biochemical methods and peptide arrays. This Ca2+ sensor priming hypothesis may also contribute basic knowledge and a new perspective to understanding how the numerous Ca2+ sensory proteins encoded in plant genomes can mediate specificity in the many Ca2+-dependent signaling processes in plants.