Gating the activation and tuning the Ca2+ frequency response of CaM kinase II

描述（由申请人提供）：门控激活和调节CaM激酶II的Ca[2+]频率响应Ca[2+]作为许多信号分子（包括神经递质、激素和生长因子）的第二信使发挥作用。Ca[2+]/CaM作用的中心介质之一是多功能CaM激酶II（CaMKII），这是一种普遍存在的Ser/Thr蛋白激酶，其磷酸化细胞溶质、质膜和细胞核中的数十种关键细胞蛋白和酶。该激酶已经成为相当多的关注的焦点，因为i）它具有由12个激酶亚基组成的独特结构，这些亚基决定其Ca[2+]/CaM传感、细胞内靶向和底物特异性; ii）它显示一种形式的分子记忆，其中Thr残基处的Ca[2+]依赖性自磷酸化和/或附近Met残基处的氧化将其转换为Ca[2+]非依赖性自磷酸化。（iii）它可以对Ca[2+]相关刺激的频率（如心率）作出反应，并相应地改变细胞功能。因此，理解CaMKII解码Ca[2+]尖峰频率的机制和结构基础对于理解其生理和病理功能至关重要。基于最近的晶体结构和功能分析的激酶，我们假设，激酶经历了一个紧凑的结构之间的平衡，其中它的催化结构域被紧紧地包装成一个中心枢纽组成的它的关联域和一个更扩展的结构，更容易激活钙调素。我们将测试催化结构域和结合结构域之间的接头序列的长度是否将激酶调节到不同频率的Ca[2+]尖峰，以及这如何受到氧化的影响。我们将进一步研究通过药理学抑制剂和与心脏骤停风险增加相关的SNP对自抑制结构域进行门控的影响。我们建议测试其显着的性能，确定是否激酶解码的频率Ca[2+]刺激传递到心肌细胞，以增加其自身磷酸化和磷酸化的底物。最后，我们将利用我们的结构和监管的见解，开发一种激活剂的CaMKII，可用于评估和发现和描绘新的CaMKII功能，在不同的细胞类型。

DESCRIPTION (provided by applicant): Gating the activation and tuning the Ca[2+] frequency response of CaM kinase II Ca[2+] functions as a second messenger for many signaling molecules, including neurotransmitters, hormones and growth factors. One of the central mediators of Ca[2+]/CaM action is the multifunctional CaM kinase II (CaMKII), a ubiquitous Ser/Thr protein kinase that phosphorylates dozens of key cellular proteins and enzymes in the cytosol, plasma membrane, and nucleus. The kinase has been the focus of considerable attention because i) it has a unique architecture with 12 kinase subunits that determine its Ca[2+]/CaM sensing, intracellular targeting, and substrate specificity; ii) it displays a form of molecular memory in which Ca[2+]-dependent autophosphorylation at a Thr residue and/or oxidation at a nearby Met residue switches it to a Ca[2+]-independent (autonomous) state that participates in neuronal memory and other functions; iii) it can respond to the frequency of Ca[2+]-linked stimulation, such as heart rate, and modifies cell function accordingly. Understanding the mechanism and structural basis by which CaMKII decodes the frequency of Ca[2+] spikes is therefore critical to understanding both its physiological and pathological functions. Based on a recent crystal structure and functional analysis of the kinase we hypothesize that the kinase undergoes an equilibrium between a compact structure where its catalytic domains are tightly packed into a central hub composed of its association domain and a more extended structure that is more readily activated by CaM. We will test whether the length of linker sequences between the catalytic and association domains tune the kinase to different frequencies of Ca[2+] spikes and how this is affected by oxidation. We will further examine the effects of gating of the autoinhibitory domain by a pharmacological inhibitor and by a SNP that is associated with increased risk of sudden cardiac arrest. We propose to test its remarkable properties by determining whether the kinase decodes the frequency of Ca[2+] stimuli delivered to cardiomyocytes to increase its autophosphorylation and phosphorylation of its substrates. Finally, we will use our structural and regulatory insights to develop an activator of CaMKII that can be used to evaluate and discover and delineate new CaMKII functions in diverse cell types.