Energy Transduction in Myosin

肌球蛋白的能量转导

• 批准号: 7589312
• 负责人: CHRISTOPHER M YENGO
• 金额: $ 1.22万
• 依托单位: UNIVERSITY OF NORTH CAROLINA CHARLOTTE
• 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 2009-05-15
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7589312
• 关键词: ATP Hydrolysis; ATP phosphohydrolase; Actins; Active Sites; Actomyosin; Actomyosin Adenosinetriphosphatase; Adopted; Affinity; Algorithms; Binding; Biochemical; Biological Process; Biophysics; Calmodulin; Cell division; Chemicals; Cleaved cell; Communication; Computing Methodologies; Coupled; Coupling; DNA Sequence Rearrangement; Data; Disease; Dissociation; Doctor of Philosophy; Familial Hypertrophic Cardiomyopathy; Fluorescence; Fluorescence Resonance Energy Transfer; Fluorescent Probes; Future; Generations; Goals; Hereditary Disease; Intracellular Transport; Kinetics; Lead; Measures; Mechanics; Mediating; Methods; Microfilaments; Modeling; Molecular; Molecular Conformation; Monitor; Monte Carlo Method; 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; Role; Side; Simulate; Staging; Structure; System; Techniques; Testing; Tryptophan; Upper arm; Work; base; design; flexibility; improved; inorganic phosphate; insight; literature survey; models and simulation; molecular dynamics; 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（由申请人提供）：肌球蛋白通过与肌动蛋白丝相互作用产生力和运动的能力对于许多生物过程（包括肌肉收缩、细胞分裂和细胞内转运）是必不可少的。肌球蛋白在其酶循环的各个阶段的原子水平结构提供了肌球蛋白利用的力产生的分子机制的框架。这些结构以及其他生物化学和结构数据表明，肌球蛋白产生的力量耦合小的构象变化的核苷酸结合区的轻链结合区的大摆动，而肌球蛋白强烈结合到肌动蛋白。然而，缺乏关于肌球蛋白如何在其ATP酶循环中改变其对肌动蛋白的亲和力的结构细节的信息，以及肌动蛋白结合如何激活ATP水解产物（ADP和磷酸盐）的解离，从而触发力的产生。目前的提议假设，分隔肌动蛋白结合结构域的大裂缝迅速改变构象，以便在磷酸盐释放和力产生之前与肌动蛋白结合。此外，在核苷酸结合域的开关II区域被假设为直接耦合的杠杆臂的构象变化。肌球蛋白V，非肌肉肌球蛋白，具有独特的结构和生化特性，将被用作一个模型来检查特定的构象变化的肌动蛋白和核苷酸结合区的肌球蛋白。内在和外在的荧光探针将被战略性地放置，以测量肌动蛋白，核苷酸结合，和杠杆臂区域的肌球蛋白的酶循环过程中的构象变化。此外，瞬态动力学实验将被用来关联的构象变化与特定的生化步骤中的肌动球蛋白ATP酶循环。我们将使用计算方法提出一个与我们的实验数据一致的肌球蛋白ATP酶循环的构象途径。通过整合的计算和实验数据，我们将阐明关键的细节，肌球蛋白的力产生的结构机制，并进一步了解与点突变相关的遗传性疾病，如家族性肥厚性心肌病。公共卫生关系：该项目的目标是确定肌球蛋白如何将化学能转化为力和运动，以驱动肌肉收缩的过程。将利用实验和计算生物物理工具的组合来定义肌动球蛋白V ATP酶循环的结构途径，这将填补已知肌球蛋白如何在肌肉收缩中产生力的关键空白。由于肌球蛋白的点突变与家族性肥厚性心肌病等遗传疾病有关，因此阐明肌球蛋白中能量转导的结构途径可能会提高我们对这些疾病的理解并导致未来的治疗方法。