Structural dynamics of CaMKII activation

描述（由申请人提供）：钙（Ca 2+）（可以说是细胞信号传导中最常用的第二信使）浓度的增加激活普遍存在的Ca 2+传感器钙调蛋白，然后钙调蛋白继续结合并激活多种酶，包括Ca 2 +/钙调蛋白依赖性蛋白激酶II（CaMKII）。CaMKII作为由细胞内钙瞬变的幅度、持续时间和频率传达的信息的解释器发挥作用。钙信号的读出是由一系列复杂的构象变化介导的，这些构象变化发生在独特的十二聚体CaMKII低聚物的范围内。在钙浓度通过自磷酸化恢复到基础水平后，激活持续良好。激活的构象记忆对于酶的生理功能是必不可少的，并且是学习和记忆的组成部分。激活和构象记忆的潜在结构和动力学基础定义不清。虽然最近已经解决了单体催化结构域的X射线结构，它的一些功能似乎与生物化学数据不兼容。本研究的长期目标是通过映射明确定义的催化中间体CaMKII的构象变化来弥合结构差距。具体的目标将测试的假设，即无活性的CaMKIl的自抑制广泛的催化调节相互作用和Ca 2 +/CaM结合和自磷酸化破坏自抑制脱离调节和催化结构域。我们将利用现场定向自旋标记和电子顺磁共振（SDSL-EPR），以获得当地的环境约束和全球的距离约束。这种方法的可行性建立在我们的初步结果，挑战单体晶体结构的许多功能。SDSL-EPR研究将扩展到全酶，以获得新的洞察合作钙调素结合和自我调节的基础上，通过自磷酸化。CaMKII在学习和记忆中起关键作用，并且还可以用作自调节的结构支架以在关键的细胞内位置组装蛋白质复合物，例如神经元突触后密度或心脏T-小管膜上。它涉及许多疾病，包括帕金森病和精神分裂症，使其成为药物开发的有吸引力的目标。确定CaMKII机制具有基本的生物化学重要性，并且可以很好地促进具有更好的治疗作用和最小副作用的新化合物的开发。

DESCRIPTION (provided by applicant): Increase in concentration of Calcium (Ca2+), arguably the most utilized second messenger in cellular signaling, activates the ubiquitous Ca2+sensor calmodulin which then proceeds to bind and activate numerous enzymes including Ca2+/calmodulin-dependent protein kinase II (CaMKIl). CaMKIl functions as an interpreter of information conveyed by the amplitude, duration and frequency of intracellular calcium transients. The readout of the calcium signal is mediated by a complex series of conformational changes that occur in the confines of the unique dodecameric CaMKIl oligomer. Activation persists well after return of calcium concentration to basal levels through autophosphorylation. The conformational memory of activation is essential for the enzyme's physiological function and is integral for learning and memory. The underlying structural and dynamic basis of activation and of conformational memory is poorly defined. Although an X-ray structure of a monomeric catalytic domain has recently been solved, some of its features seem incompatible with biochemical data. The long term goal of this research is to bridge the structural gap by mapping conformational changes in well defined catalytic intermediates of CaMKIl. The specific aims will test the hypothesis that inactive CaMKIl is autoinhibited by extensive catalytic-regulatory interaction and that Ca2+/CaM binding and autophosphorylation disrupt autoinhibition by disengaging regulatory and catalytic domains. We will utilize site directed spin labeling and electron paramagnetic resonance (SDSL-EPR) to derive local environmental constraints and global distance restraints. The feasibility of this approach is established in our preliminary results which challenge many features of the monomer crystal structure. The SDSL-EPR studies will be extended to the holoenzyme to gain novel insight into the basis of cooperative calmodulin binding and self regulation by autophosphorylation. CaMKIl plays a critical role in learning and memory and may also serve as an autoregulated structural scaffold to assemble protein complexes at key intracellular locations, such as neuronal postsynaptic densities or on cardiac T-tubule membranes. It is implicated in a number of diseases including Parkinson's disease and Schizophrenia making it an attractive target for drug development. Determining CaMKIl mechanisms is of fundamental biochemical importance and may well facilitate development of new compounds with better therapeutic action and minimal side effects.