Chimeric CA2+/Calmodulin-Dependent Protein Kinase in Plants

Poovaiah蛋白磷酸化是细胞外信号转导到细胞内反应的主要机制之一。钙在介导许多信号通路中发挥重要作用，钙离子/钙调蛋白（CM）调节的蛋白磷酸化放大和修饰钙介导的信号。一些Ca/CaM依赖性蛋白激酶已经在哺乳动物系统中得到了很好的表征，但对植物中的Ca/CaM依赖性蛋白激酶知之甚少。PI实验室从发育中的花药中克隆了Ca/CaM依赖的嵌合蛋白激酶基因。该CCaMk在一个多肽中包含催化结构域、CaM结合结构域和视觉样Ca结合结构域。这种蛋白不同于其他已知的植物和动物激酶，它的结构表明它可能是从两个功能和系统发育不同的基因融合而来的。这是植物中Ca/CaM依赖性蛋白激酶存在的第一个证据。在这项拨款中，将研究CCaMK的结构功能关系以及植物中CCaMK水平改变的影响。将研究缺失和点突变体以确定调控域的功能，并使用位点定向突变体确认自磷酸化位点的作用。合成肽将用于识别和研究自抑制结构域。CCaMK基因表达改变的影响将在具有CCaMK基因正义或反义结构的转基因植物中观察。这些研究将确定这种重要酶在植物中的存在和作用。* * * * * *

Abstract 9630337 Poovaiah Protein phosphorylation is one of the major mechanisms for transducing extracellular signals to intracellular responses. Calcium is important in mediating a number of signaling pathways, and Ca+/Calmodulin (CM) regulated protein phosphorylation amplifies and modifies Ca mediated signals. Several Ca/CaM dependent protein kinases have been well characterized in mammalian systems, but little is known about Ca/CaM dependent protein kinases in plants. The laboratory of the PI has cloned a chimeric Ca/CaM dependent protein kinase gene from developing anthers. This CCaMk contains a catalytic domain, a CaM binding domain and a visin-like Ca binding domain in one polypeptide. This protein is distinct form other known plant and animal kinases, and its structure suggests it may have evolved from the fusion of two genes that are functionally and phylogenetically diverse. This is the first evidence for a Ca/CaM dependent protein kinase in plants. In this grant the structure function relationships of CCaMK as well as the effects of altered levels in the plant, will be examined. Deletion and point mutants will be studied to determine the function of the regulatory domain, and the role of autophosphorylation sites will be confirmed using site directed mutants. Synthetic peptides will be used to identify and study the autoinhibitory domain. The effect of altered expression of CCaMK will be observed in transgenic plants with sense or antisense constructs of the CCaMK gene. These studies should establish the presence and the role of this important enzyme in plants. *** ***