Molecular mechanisms of muscle contraction

肌肉收缩的分子机制

• 批准号: RGPIN-2016-05317
• 负责人: Rassier, Dilson
• 金额: $ 5.25万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=615623
• 关键词: Molecular; mechanisms; muscle; contraction

Background. Muscle contraction is driven by the molecular motor myosin II while attached to actin filaments. Myosin molecules transform chemical energy extracted from adenosine tri-phosphate (ATP) into mechanical work. After an initial attachment between myosin and actin, ATP is hydrolyzed, and phosphate (Pi) and subsequently ADP are released from myosin. The molecule undergoes a conformational change - the power stroke - producing force and sliding the actin filament. The molecular mechanisms behind the conversion of chemical energy released from ATP into the myosin power stroke, and its amplification into muscle contraction is not well understood. Long-term objective. The long-term objective of this research program is to understand the molecular and cellular mechanisms of muscle contraction and force generation. The specific goals of this proposal are: 1 - To determine the relation between myosin structures and actin sliding 2 - To determine the sub-structures of myosin responsible for converting chemical energy into mechanical work 3 - To determine the emerging properties of myosin molecules when working cooperatively in filaments. Methods. This research program will use a variety of experimental systems and techniques developed in my laboratory. There are domains and sub-domains of the myosin molecule that have been hypothesized to define the power stroke. In specific aim (1) we will experiment with native myosin molecules and also myosin mutants in which some of these sub-domains have been depleted. Molecules will be tested with a motility essay, that allows for measurements of velocity of actin sliding. In specific aim (2) the molecules (native and mutants) will be tested under a High-Speed Atomic Force Microscope (HS-AFM), that allows measurements of force while visualizing structural changes in the myosin-actin system. In specific aim (3) molecules (native and mutants) will be polymerized into filaments in different concentrations, to evaluate the emerging properties of myosins working cooperatively. The filaments will be tested for force measurements using a system of nanofabricated cantilevers. Significance. Understanding the myosin power stroke - the most fundamental step of muscle contraction - is essential for understanding muscle contraction, a basic function of life. Beyond the mechanisms of contraction, myosin II is one among many molecular motors (e.g. kinesin, dynein, myosin V), with a variety of physiological functions. Molecular motors share several similarities, including a power-stroke induced motility and force production. Therefore, understanding myosin II mechanisms will provide insight into the functioning of molecular motors in general, with far-reaching implications for biology.

背景肌肉收缩是由分子马达肌球蛋白II驱动，同时连接到肌动蛋白丝。肌球蛋白分子将从三磷酸腺苷（ATP）中提取的化学能转化为机械功。在肌球蛋白和肌动蛋白之间的初始附着之后，ATP被水解，并且磷酸盐（Pi）和随后的ADP从肌球蛋白释放。这个分子经历了一个构象的变化--动力冲程--产生力并使肌动蛋白丝滑动。从ATP释放的化学能转化为肌球蛋白动力冲程，并将其放大为肌肉收缩的分子机制尚未完全了解。 长期目标。这项研究计划的长期目标是了解肌肉收缩和力量产生的分子和细胞机制。该提案的具体目标是： 1 -确定肌球蛋白结构和肌动蛋白滑动之间的关系 2 -确定负责将化学能转化为机械功的肌球蛋白的亚结构 3 -确定肌球蛋白分子在细丝中协同工作时的新兴特性。 方法.该研究计划将使用我实验室开发的各种实验系统和技术。肌球蛋白分子的结构域和亚结构域被假设为定义动力冲程。在具体的目标（1）中，我们将用天然肌球蛋白分子和肌球蛋白突变体进行实验，其中这些亚结构域中的一些已经耗尽。分子将用运动试验进行测试，该试验允许测量肌动蛋白滑动的速度。在具体目标（2）中，将在高速原子力显微镜（HS-AFM）下测试分子（天然和突变体），该显微镜允许测量力，同时可视化肌球蛋白-肌动蛋白系统中的结构变化。在特定目标（3）中，分子（天然的和突变体）将以不同浓度聚合成细丝，以评估协同工作的肌球蛋白的新兴特性。将使用纳米制造的杠杆系统测试细丝的力测量。 意义了解肌球蛋白动力冲程-肌肉收缩的最基本步骤-对于了解肌肉收缩是至关重要的，肌肉收缩是生命的基本功能。除了收缩机制之外，肌球蛋白II是许多分子马达（例如驱动蛋白、动力蛋白、肌球蛋白V）之一，具有多种生理功能。分子马达有几个相似之处，包括动力冲程诱导的运动和力的产生。因此，了解肌球蛋白II的机制将提供深入了解一般的分子马达的功能，对生物学具有深远的影响。