Dynamic Regulation of the Actin Filament Barbed End

项目摘要 肌动蛋白是正常细胞功能的关键蛋白质，并且控制肌动蛋白聚合的能力是非常重要的。 肌动蛋白丝在细胞中是必需的。肌动蛋白组装成具有两个不同末端的细丝， 这种控制的大部分发生在被称为细丝的正端或倒钩端。两个关键 蛋白质在倒刺末端起作用：加帽蛋白和formins。正如它的名字所暗示的那样， 加帽蛋白“加帽”倒刺末端并防止进一步聚合，但加帽蛋白的活性 加帽蛋白也受蛋白质如肌营养因子/V-1、CARMIL和 twinfilin。形成蛋白具有与加帽蛋白相反的作用，并在蛋白质末端增强聚合。 有倒刺的一端然而，正如加帽蛋白受到调节一样，IFN-γ 2的功能也受到调节。 由环化酶相关蛋白（CAP）以及翻译后修饰调节， 肌动蛋白。 该建议的重点是了解结构，动力学和功能机制 控制着细丝的倒刺末端通过结合计算，体外 在体内研究中，我们将：（a）获得新的理解是什么定义了倒刺端，以及如何定义倒刺端。 它受肌动蛋白核苷酸状态的影响;（B）了解加帽蛋白如何与肌动蛋白相互作用。 倒钩末端以及这种相互作用如何受到V-1的空间和变构效应的影响， CARMIL和twinfilin;以及（c）确定INF 2如何与倒刺相互作用，以及CAP 肌动蛋白的赖氨酸甲基化改变了这种相互作用。

Project Summary Actin is a key protein for normal cell function, and the ability to control the polymerization of actin filaments is essential in the cell. Actin assembles into filaments with two distinct ends, and most of this control happens at what is termed the plus or barbed end of the filament. Two key proteins function at the barbed end: capping protein and formins. As suggested by its name, capping protein “caps” the barbed end and prevents further polymerization, but the activity of capping protein is also regulated by the action of proteins such as myotrophin/V-1, CARMIL and twinfilin. Formins have the opposite effect of capping protein and enhance polymerization at the barbed end. However, just as capping protein is regulated, the function of the formin INF2 is modulated by cyclase-associated protein (CAP) as well as post-translational modifications to actin. The focus of this proposal is to understand the structural, dynamical and functional mechanisms that regulate the barbed end of the filament. Through a combination of computational, in vitro and in vivo studies we will: (a) gain new understanding of what defines the barbed end and how it is affected by the nucleotide state of actin; (b) learn how capping protein interacts with the barbed end and how this interaction is affected by the steric and allosteric effects of V-1, CARMIL and twinfilin; and (c) determine how INF2 interacts with the barbed and how both CAP and lysine methylation of actin alter this interaction.