Dynamic Events in Myosin and Actin and Their Function

细胞运动和力的产生是生物体的基本特征。肌动蛋白，最重要的 在真核细胞中保守且丰富的蛋白质在这些过程中起关键作用。长期 这项研究的目的是提供对构成力的结构和动态事件的详细了解 肌动球蛋白的产生和肌动蛋白丝的重塑以满足细胞的需要。将努力实现这一目标 通过结合肌动蛋白寡聚体及其复合物的X射线结构测定， 通过交联，动力学， 光谱、电子显微镜和诱变方法。三个项目的具体目标是： 这项研究是： I，（i-iv）通过辐解、质谱、裂解和交联方法绘制相互作用位点 肌动蛋白和cofilin，肌动蛋白和肌球蛋白在强和弱结合的复合物。 二.（i-iii）结晶并解析肌动蛋白二聚体、四聚体及其与丝切蛋白的复合物的结构， 凝溶胶蛋白片段、加帽蛋白和肌球蛋白头（S1）。 .（i-iii）为了稳定肌动蛋白丝的早期形式，并评估反平行二聚体在肌动蛋白纤维中的作用， （i）通过光谱法和诱变方法测试纤维的结构; （v）确定cofilin切断肌动蛋白丝的机制， 凝溶胶蛋白，并阐明激活cofilin功能的肌动蛋白相互作用蛋白Aip 1。 对肌动蛋白的结构、动力学和相互作用的详细了解将有助于阐明 它在肌肉收缩和细胞过程中的功能，如伤口愈合，癌症转移， 免疫细胞的趋化性和宿主-病原体相互作用。最终，这种理解应该有助于 发现了作为影响肌动蛋白相互作用的药物的治疗干预的发展。

Cell motility and force generation are fundamental features of living organisms. Actin, one of the most conserved and aboundant proteins in eukaryotic cells, plays a key role in these processes. The long-term goal of this research is to provide detailed understanding of structure and dynamic events that underlie force generation by actomyosin and the remodeling of actin filaments for cellular needs. This goal will be pursued through a combination of x-ray structure determination of actin oligomers and their complexes, and solution studies probing actin filaments structure, dynamics, interactions, and fuction via cross-linking, kinetic, spectroscopic, electron microscopy, and mutagenesis methods. The specific aims of the three projects of this study are: I, (i-iv) To map by radiolysis, mass spectrometry, cleavage, and cross-linking methods the interaction sites of actin and cofilin, and actin and myosin in strongly and weakly bound complexes. II. (i-iii) To crystallize and solve the structures of actin dimers, tetramers, and their complexes with cofilin, gelsolin fragments, capping proteins, and myosin heads (S1). . (i-iii) To stabilize the early forms of actin filaments and assess the role of anti-parallel dimers in the growth of filament branches; (iy) To test by spectroscopic and mutagenesis methods the structure of the DNase I binding loop on actin; (v) To determine the mechanism of actin filament severing by cofilin and gelsolin, and to clarify the activation of cofilin function by the actin interacting protein Aip1. Detailed understanding of the structure, dynamics and interactions of actin should clarify the mechanism of its function in muscle contraction and in cellular processes, such as wound healing, cancer metastasis, chemotaxis of immune cells and host-pathogen interactions. Ultimately, this understanding should help in the development of therapeutic interventions as drugs that influence actin interactions are discovered.