Calcium/Calmodulin-dependent Protein Kinase(s) in Plants

植物对激素、光和重力等各种信号作出反应。植物如何感知和转导这些化学和物理信号尚不清楚。越来越多的证据表明，钙在植物的信号转导中起着信使的作用。许多信号诱导的反应是由钙介导的。钙的增加可以通过钙调蛋白（一种普遍存在的钙结合蛋白）的作用影响多种生理过程。植物的这种多样性反应被认为是通过调节钙和/或钙钙调素依赖性蛋白激酶的活性来实现的。尽管钙/钙调素依赖性蛋白磷酸化参与调节植物的许多细胞过程，但对钙/钙调素依赖性蛋白激酶及其底物一无所知。Poovaiah博士利用动物钙/钙调素依赖性蛋白激酶II的α亚基序列产生的抗体对表达文库进行免疫筛选，分离出了几个cDNA克隆。首席研究员建议对编码蛋白进行生化分析，验证其蛋白激酶活性，确定其受钙和钙调蛋白调控的模式，并分析其底物特异性。此外，Poovaiah博士打算利用拟南芥的生长素抗性突变体和光响应玉米突变体分别研究钙/钙调素依赖性蛋白激酶在生长素和光信号转导中的作用。这些研究结果对了解钙/钙调素依赖性蛋白激酶在植物信号转导中的作用具有重要意义

Plants respond to various signals such as hormones, light and gravity. How plants perceive and transduce these chemical and physical signals is not clearly understood. Accumulating evidence indicates that calcium acts as a messenger in signal transduction in plants. Many of the signal-induced responses are mediated by calcium. Increased calcium can affect diverse physiological processes through the action of calmodulin, a ubiquitous calcium- binding protein. Much of this diversity in response in plants is believed to be achieved by the modulation of the activity of the calcium and/or calcium-calmodulin-dependent protein kinases. Although calcium/calmodulin-dependent protein phosphorylation is implicated in regulating a number of cellular processes in plants, nothing is known about the calcium/calmodulin-dependent protein kinase(s) and its substrates. Dr. Poovaiah has isolated several cDNA clones by immunoscreening the expression libraries with the antibody produced to the sequence corresponding to alpha subunit of animal calcium/calmodulin-dependent protein kinase II. The principal investigator proposes to perform biochemical analyses of the encoded protein to verify its protein kinase activity, determine its mode of regulation by calcium and calmodulin, and analyze its substrate specificity. Furthermore, Dr. Poovaiah intends to use auxin resistant mutants of Arabidopsis and light- responsive corn mutant to study the role of calcium/calmodulin- dependent protein kinase in auxin and light signal transduction, respectively. The information derived from these studies would be of immense value in understanding the role of calcium/calmodulin- dependent protein kinase(s) in signal transduction in plants.//