Energy Transduction in Myosin

肌球蛋白的能量转导

• 批准号: 7921781
• 负责人: CHRISTOPHER M YENGO
• 金额: $ 19.28万
• 依托单位: PENNSYLVANIA STATE UNIV HERSHEY MED CTR
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-12-15 至 2010-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7921781
• 关键词: ATP Hydrolysis; ATP phosphohydrolase; Actins; Active Sites; Actomyosin; Actomyosin Adenosinetriphosphatase; Adopted; Affinity; Binding; Biochemical; Biological Process; Biophysics; Calmodulin; Cell division; Chemicals; Cleaved cell; Communication; Computing Methodologies; Coupled; Coupling; Data; Disease; Dissociation; Familial Hypertrophic Cardiomyopathy; Fluorescence; Fluorescence Resonance Energy Transfer; Fluorescent Probes; Future; Generations; Goals; Hereditary Disease; Intracellular Transport; Kinetics; Lead; Maps; Measures; Mechanics; Mediating; Methodology; Methods; Microfilaments; Modeling; Molecular; Molecular Conformation; Molecular Models; Monitor; Motion; Motor; Movement; Muscle; Muscle Contraction; Myosin ATPase; Myosin Phosphatase Pathway; Myosin Type II; Myosin Type V; Nucleotides; Pathway interactions; Point Mutation; Process; Production; Property; Proteins; Risk; Role; Side; Staging; Structure; System; Techniques; Testing; Tryptophan; Upper arm; Work; design; high risk; improved; inorganic phosphate; literature survey; models and simulation; molecular dynamics; molecular modeling; public health relevance; research study; simulation; tool; vacuolar H+-ATPase

DESCRIPTION (provided by applicant): The ability of myosin to generate force and motion through its interaction with actin filaments is essential to many biological processes including muscle contraction, cell division, and intracellular transport. The atomic level structures of myosin in various stages of its enzymatic cycle have provided a framework of the molecular mechanism of force generation utilized by myosin. These structures as well as other biochemical and structural data suggest that myosin generates force by coupling small conformational changes in the nucleotide-binding region to a large swing of the light-chain binding region while myosin is strongly bound to actin. However, there is a lack of information about the structural details of how myosin alters its affinity for actin throughout its ATPase cycle, and how actin-binding activates the dissociation of the products of ATP hydrolysis (ADP and phosphate), which triggers force production. The current proposal hypothesizes that the large cleft that separates the actin-binding domain changes conformation rapidly to allow binding to actin prior to phosphate release and force generation. Moreover, the switch II region in the nucleotide-binding domain is hypothesized to directly couple conformational changes to the lever arm. Myosin V, a non-muscle myosin that has unique structural and biochemical properties, will be used as a model to examine specific conformational changes in the actin- and nucleotide-binding regions of myosin. Intrinsic and extrinsic fluorescence probes will be strategically placed to measure conformational changes in the actin-, nucleotide-binding, and lever arm regions during the enzymatic cycle of myosin. In addition, transient kinetic experiments will be used to correlate the conformational changes with specific biochemical steps in the actomyosin ATPase cycle. We will use computational methods to propose a conformational pathway of the myosin ATPase cycle consistent with our experimental data. By integrating the computational and experimental data we will elucidate critical details about the structural mechanism of force generation in myosin and further our understanding of genetic diseases associated with point mutations in myosin, such as Familial Hypertrophic Cardiomyopathy. PUBLIC HEALTH RELEVANCE: The goal of this project is to determine how myosin converts chemical energy into force and motion to drive the process of muscle contraction. A combination of experimental and computational biophysical tools will be utilized to define the structural pathway of the actomyosin V ATPase cycle, which will fill in critical gaps in what is known about how myosin generates force in muscle contraction. Since point mutations in myosin are associated with genetic diseases such as Familial Hypertrophic Cardiomyopathy, elucidating the structural pathway for energy transduction in myosin may improve our understanding of and lead to future treatments for these diseases.

描述(申请人提供)：肌球蛋白通过与肌动蛋白细丝的相互作用产生力量和运动的能力对许多生物过程是必不可少的，包括肌肉收缩、细胞分裂和细胞内运输。肌球蛋白在其酶循环的不同阶段的原子级结构为肌球蛋白所利用的力产生的分子机制提供了一个框架。这些结构以及其他生化和结构数据表明，肌球蛋白通过将核苷酸结合区的小构象变化与轻链结合区的大摆动偶联而产生作用力，而肌球蛋白与肌动蛋白强烈结合。然而，关于肌球蛋白如何在其ATPase周期中改变其与肌动蛋白的亲和力，以及肌动蛋白结合如何激活ATP水解产物(ADP和磷酸)的解离从而触发力量产生的结构细节，目前还缺乏相关信息。目前的建议假设，分离肌动蛋白结合域的大裂隙迅速改变构象，使其在磷酸盐释放和力产生之前与肌动蛋白结合。此外，核苷酸结合域中的开关II区域被假设为直接将构象变化耦合到杠杆臂上。肌球蛋白V是一种非肌肉肌球蛋白，具有独特的结构和生化性质，将被用作研究肌球蛋白肌动蛋白和核苷酸结合区的特定构象变化的模型。在肌球蛋白的酶循环过程中，内源和外源荧光探针将被用于测量肌动蛋白、核苷酸结合和杠杆臂区域的构象变化。此外，瞬时动力学实验将用于将构象变化与肌动球蛋白ATPase循环中的特定生化步骤相关联。我们将使用计算方法提出与我们的实验数据一致的肌球蛋白ATPase周期的构象途径。通过结合计算和实验数据，我们将阐明肌球蛋白中力产生的结构机制的关键细节，并进一步了解与肌球蛋白点突变相关的遗传病，如家族性肥厚性心肌病。与公共健康相关：该项目的目标是确定肌球蛋白如何将化学能转化为力量和运动，以驱动肌肉收缩过程。实验和计算生物物理工具的组合将被用来确定肌动肌球蛋白V ATPase循环的结构路径，这将填补肌球蛋白如何在肌肉收缩中产生力量的关键空白。由于肌球蛋白的点突变与家族性肥厚性心肌病等遗传性疾病有关，阐明肌球蛋白能量转导的结构途径可能会加深我们对这些疾病的理解，并有助于未来的治疗。