STRUCTURAL BASIS OF KINESIN MOTOR MOVEMENT

驱动蛋白运动的结构基础

• 批准号: 6749480
• 负责人: HERNANDO Jose SOSA
• 金额: $ 32.4万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2007-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6749480
• 关键词: adenosine diphosphate; adenosinetriphosphatase; biological signal transduction; biomechanics; conformation; cryoelectron microscopy; cytoskeleton; fluorescence microscopy; fluorescence polarization; fluorescent dye /probe; hydrolysis; intracellular transport; kinesin; mass spectrometry; microtubules; protein binding; protein structure function; proteolysis; statistics /biometry

Kinesin, dynein and myosin constitute the three superfamilies of molecular motors that generate force along cytoskeletal filaments by converting the energy from ATP hydrolysis into mechanical work. The kinesin superfamily contains more than 100 different motor proteins that move along microtubule tracks and power intracellular motile processes such as organelle transport and cell division. The long term goal of this laboratory is to elucidate the conformational changes that kinesin-superfamily members undergo as they hydrolyze ATP and translocate along microtubules. Kinesin-superfamily members contain a highly conserved catalytic domain that possesses the ATP hydrolytic and microtubule binding activities. Kinesin, the archetypal member of the superfamily, has two identical motor domains. It is a processive motor that undergoes many ATP hydrolysis cycles without dissociating from the microtubule. Despite much progress, there is limited information available on the conformational changes kinesin undergoes during ATP hydrolytic cycles and on the mechanism responsible for kinesin's processivity. This proposal addresses these two fundamental issues. The structure and configuration of the two motor domains will be characterized at different points in the ATPase cycle using cryo- electron microscopy and fluorescence polarization microscopy on kinesin molecules fluorescently labeled on the motor domain. Currently, the favored hypothesis to explain kinesin processivity is a hand over hand mechanism. We wilt investigate this hypothesis by testing structural predictions of the model such as the presence of alternating conformations for both motor domains. We will also look for direct structural evidence of the key conformational changes that are though to cause kinesin translocation. We seek to answer the following specific questions 1) Does ATP binding to kinesin moves forward one of the two motor domains? 2) Does ADP binding to kinesin cause an order disorder transition that could move the motor forward? 3) Do the two motors of kinesin alternate conformations as they walk along a microtubule? The results of these studies will contribute to elucidate at a molecular level the structural basis by which kinesins transduce ATP hydrolysis into mechanical work. Given the central role of kinesins in many cellular processes and the importance of microtubules as a target for anti-cancer therapy, this work will provide new insights into normal cellular function and may lead to the identification of new chemotherapeutic targets.

动蛋白、动力蛋白和肌球蛋白构成了分子马达的三个超家族，它们通过将ATP水解产生的能量转化为机械功，沿着细胞骨架细丝产生力。动蛋白超家族包含100多种不同的马达蛋白，它们沿着微管轨迹移动，为细胞器运输和细胞分裂等细胞内运动过程提供动力。该实验室的长期目标是阐明运动蛋白超家族成员在水解三磷酸腺苷并沿微管转运时所经历的构象变化。动蛋白超家族成员含有一个高度保守的催化结构域，具有ATP水解性和微管结合活性。动蛋白是超家族的原型成员，它有两个相同的运动域。它是一个进行性的马达，经历了许多次ATP水解循环，而不是从微管解离。尽管已经取得了很大的进展，但关于运动蛋白在ATP水解循环中所经历的构象变化以及导致运动蛋白加工的机制的信息有限。这项建议解决了这两个根本问题。利用冷冻电子显微镜和荧光偏振显微镜对运动区上荧光标记的运动蛋白分子进行研究，在ATPase循环的不同时间点表征这两个运动区的结构和构型。目前，解释动蛋白过程的最受欢迎的假说是一种移交机制。我们将通过测试模型的结构预测来研究这一假设，例如两个运动域的交替构象的存在。我们还将寻找关键构象变化的直接结构证据，这些变化可能导致运动蛋白易位。我们试图回答以下具体问题：1)与Kinesin结合的ATP是否会向前移动两个运动域中的一个？2)ADP与Kinesin的结合是否会导致有序无序转变，从而使电机向前移动？3)Kinesin的两个马达在沿着微管行走时是否会交替构象？这些研究结果将有助于在分子水平上阐明肌动蛋白将ATP水解物转化为机械功的结构基础。鉴于动蛋白在许多细胞过程中的核心作用以及微管作为抗癌治疗靶点的重要性，这项工作将为正常细胞功能提供新的见解，并可能导致识别新的化疗靶点。