Substructure and Communication in Myosin and Actin

[9630997] Reisler骨骼肌、平滑肌和心肌的收缩是由ATP的水解促进的，ATP的水解与两种主要肌肉蛋白（肌球蛋白和肌动蛋白）之间的循环相互作用相结合。这些蛋白与其他运动蛋白一起参与非肌肉细胞的多种功能，包括运动、分裂、细胞器运输等。根据流行的观点，在肌凝蛋白水解ATP的不同步骤中，肌凝蛋白和肌动蛋白的相互作用和结构发生循环变化，从而产生运动和力。我们研究的一个主要目标是阐明这些事件的分子基础。为了实现这一目标，我们将绘制肌动蛋白上在ATP存在下与肌球蛋白结合的位点，并分析它们在ATP水解和力和运动产生的特定步骤中的作用。将用于绘制ATP水解过程中肌球蛋白与肌动蛋白结合动态变化的实验材料包括工程肌动蛋白突变体和化学修饰的肌动蛋白。这些材料将用于肌动蛋白丝运动的体外测量以及肌凝蛋白和ATP产生的力，以及肌动蛋白相互作用的生化、生物物理和动力学分析。在本课程的另一部分中，将阐明肌动蛋白丝结构在基于肌动球蛋白的细胞功能中的作用。该项目的具体目的是确定肌动蛋白与肌凝蛋白的功能相互作用与肌动蛋白丝组织的动态变化之间的关系。蛋白水解裂解肌动蛋白、化学交联肌动蛋白和肌动蛋白突变体将在本项目中通过功能和结构分析方法、肌动球蛋白相互作用测定和光谱方法进行研究。这项工作的结果将为肌动球蛋白相互作用在这些蛋白质产生力和运动过程中的演变提供结构描述。这些信息将有助于理解生物系统中化学能转化为机械事件的基本分子机制。在更广泛的范围内，这样的理解将有助于设计产生力或运动的仿生装置。肌肉收缩涉及肌动蛋白和肌球蛋白之间的相互作用，这一过程依赖于ATP水解形式的能量。该项目将研究肌动蛋白-肌球蛋白相互作用以及这些相互作用在肌肉和非肌肉细胞中产生力和运动的机制。各种方法将被使用，包括在体外运动测定，力测量，荧光光谱，和肌动球蛋白相互作用的生化表征。这些研究将提高对肌肉收缩和生物系统中化学能转化为功的理解。***…__,

9630997 Reisler The contraction of skeletal, smooth, and cardiac muscles is fueled by the hydrolysis of ATP which is coupled to cyclic interactions between the two main muscle proteins, myosin and actin. These proteins, along with other motor proteins, are involved also in diverse functions of non-muscle cells including their locomotion, division, organelle transport, etc. According to prevalent views, motion and force are generated by myosin and actin as a result of cyclic changes in their interaction and structures during the different steps of ATP hydrolysis by myosin. A major goal of our research is to clarify the molecular basis of these events. To achieve this goal we will map those sites on actin which bind myosin in the presence of ATP and will analyze their role in specific steps of ATP hydrolysis and force and motion generation. The experimental materials that will be used in the mapping of the dynamic changes in myosin binding to actin during ATP hydrolysis include engineered actin mutants and chemically modified actins. These materials will be used in the in vitro measurements of actin filament motion and the force generated with myosin and ATP, and in biochemical, biophysical, and kinetic assays of actomyosin interactions. In another part of this program, the role of actin filament structure in actomyosin-based cellular functions will be clarified. The specific aim of this project is to determine the relationship between the functional interactions of actin with myosin and the dynamic changes in the organization of actin filaments. Proteolytically cleaved actin, chemically crosslinked actin, and actin mutants will be studied in this project by functional and structural analysis methods, by assays of actomyosin interactions, and by spectroscopic methods. The results of the proposed work will provide a structural description of the evolution of actomyosin interactions during force and motion generation by these proteins. This information will lead to the understanding of the basic molecular mechanisms by which chemical energy is converted into mechanical events in biological systems. On a broader scope, such an understanding will be instrumental in the design of biomimetic devices that will generate force or motion. %%% Muscle contraction involves the interaction between actin and myosin in a process that is dependent upon energy in the form of ATP hydrolysis. This project will investigate actin-myosin interactions and the mechanism by which these interactions contribute to the generation of force and motion in muscle as well as non-muscle cells. A variety of methods will be used including in vitro motility assays, force measurements, fluorescence spectroscopy, and biochemical characterization of the actomyosin interactions. These studies will improve the understanding of muscle contraction and the transduction of chemical energy into work in biological systems. *** .. . __,