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

描述（由申请人提供）：控制CaM激酶II的激活和调节Ca[2+]频率响应Ca[2+]作为许多信号分子的第二信使，包括神经递质，激素和生长因子。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丝氨酸/苏氨酸蛋白激酶，可磷酸化细胞质溶胶、质膜和细胞核中的数十种关键细胞蛋白和酶。该激酶已成为相当关注的焦点，因为i)它具有独特的结构，具有12个激酶亚基，决定其Ca[2+]/CaM传感，细胞内靶向和底物特异性；ii)它表现出一种分子记忆形式，其中Thr残基的Ca[2+]依赖性自磷酸化和/或附近Met残基的氧化将其转换为Ca[2+]独立（自主）状态，参与神经元记忆和其他功能；iii)它可以响应Ca[2+]连接的刺激频率，如心率，并相应地改变细胞功能。因此，了解CaMKII解码Ca[2+]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。基于最近对该激酶的晶体结构和功能分析，我们假设该激酶经历了一种平衡，在一种紧凑的结构中，其催化结构域被紧密地包裹在一个由其结合结构域组成的中心枢纽中，而在一种更广泛的结构中，它更容易被CaM激活。我们将测试催化结构域和结合结构域之间的连接子序列的长度是否使激酶适应Ca[2+]峰值的不同频率，以及这是如何受到氧化的影响的。我们将进一步研究与心脏骤停风险增加相关的药理学抑制剂和SNP对自身抑制结构域的门控作用。我们建议通过确定激酶是否解码传递到心肌细胞的Ca[2+]刺激的频率来增加其自磷酸化和底物的磷酸化来测试其显着特性。最后，我们将利用我们的结构和调控见解来开发CaMKII的激活剂，该激活剂可用于评估、发现和描述不同细胞类型中新的CaMKII功能。

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.