Allostery in myosins studied at the molecular level

在分子水平上研究肌球蛋白的变构

• 批准号: 8471714
• 负责人: Ronald S Rock
• 金额: $ 29.48万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-09-25 至 2016-02-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8471714
• 关键词: Actins; Affect; Amaze; Back; Biological Assay; Cadherins; Cell Polarity; Cell division; Cells; Development; Dimensions; Dimerization; Environment; Filament; Filopodia; Frequencies; Goals; Hand; Individual; Integrins; Invaded; Lead; Left; Leg; Life; Maintenance; Measures; Methods; Microfilaments; Molecular; Molecular Genetics; Molecular Machines; Monitor; Motion; Motor; Motor Activity; Movement; Muscle Contraction; Myosin ATPase; Myosin Type V; Nature; Neoplasm Metastasis; Nonmuscle Myosin Type IIB; Nucleotides; Organism; Pattern; Play; Primary Neoplasm; Proteins; Role; Rotation; Structure; System; Testing; Tissues; Torque; Travel; Walking; Work; cancer cell; cell motility; fascin; myosin VI; nanometer; neoplastic cell; netrin receptor; non-muscle myosin; programs; response; single molecule; tool; trafficking

DESCRIPTION (provided by applicant): A critical function for all living organisms is the ability to move when needed. These movements-- intracellular trafficking, cell division, muscle contraction, and cell motility-- are driven by molecular machines that exert an amazing amount of force considering that they are only a few nanometers across. Given the variety of motor proteins in the cell, a key question is how motors cooperate and compete while moving cargoes and applying forces. An emerging paradigm is the notion of "specialized" motors, or motors that are fine-tuned to perform a specific function. Despite the importance of these motor proteins, relatively little is known about their individual adaptations and how these relate to the motility patterns found in the cell. In prior studies, we discovered two myosins with new and distinct processive stepping patterns on actin. Myosin X walks along multiple filaments in a fascin-actin bundle. Nonmuscle myosin IIB (NMIIB), on the other hand, walks along the long-pitch helix of a single actin filament. Both myosins play pivotal roles in migrating cells, including metastasizing tumor cells. Myosin X delivers essential cargoes such as integrins, cadherins and netrin receptors to filopodia at the leading edge of the cell; NMIIB appears in the rear of the cell, wher it maintains cell polarity and internal organization. Thus, it is essential that we understand how both myosins operate so that we can control cell motility through these players. For both myosins, we propose that their two motor domains are synchronized through strain-sensitive gating mechanisms. For both NMIIB and myosin X, gating is tuned to accommodate their unique stepping patterns along actin tracks. We hypothesize that NMIIB has adaptations for tension maintenance, myosin X has adaptations for bundle-selection, and both may have adaptations for twisting single actin filaments. To test these gating mechanisms, we will pursue the following specific aims: Aim 1: We will determine how NMIIB takes short, processive steps along actin and maintains cytoskeletal tension. Aim 2: We will determine how myosin X is gated in the environment of an actin filament bundle. Aim 3: We will determine how both myosins twist actin filaments.

描述（由申请人提供）：所有生物体的一个关键功能是在需要时移动的能力。这些运动——细胞内运输、细胞分裂、肌肉收缩和细胞运动——是由分子机器驱动的，考虑到它们的直径只有几纳米，这些分子机器发挥着惊人的力量。鉴于细胞中马达蛋白的多样性，一个关键问题是马达在移动货物和施加力时如何合作和竞争。一个新兴的范例是“专用”电机的概念，或者经过微调以执行特定功能的电机。尽管这些运动蛋白很重要，但人们对它们的个体适应以及它们与细胞中发现的运动模式的关系知之甚少。在之前的研究中，我们发现了两种肌球蛋白，它们在肌动蛋白上具有新的、独特的进行性步进模式。肌球蛋白 X 沿着肌成束蛋白-肌动蛋白束中的多个细丝行走。另一方面，非肌肉肌球蛋白 IIB (NMIIB) 沿着单个肌动蛋白丝的长螺距螺旋行走。两种肌球蛋白在细胞迁移（包括肿瘤细胞转移）中都发挥着关键作用。肌球蛋白 X 将整合素、钙粘蛋白和 netrin 受体等必需物质递送至细胞前缘的丝状伪足； NMIIB 出现在细胞的后部，负责维持细胞极性和内部组织。因此，我们必须了解两种肌球蛋白如何运作，以便我们可以通过这些参与者控制细胞运动。对于两种肌球蛋白，我们建议它们的两个运动域通过应变敏感的门控机制进行同步。对于 NMIIB 和肌球蛋白 X，门控均经过调整，以适应其沿着肌动蛋白轨道的独特步进模式。我们假设 NMIIB 具有维持张力的适应性，肌球蛋白 X 具有束选择的适应性，并且两者都可能具有扭转单肌动蛋白丝的适应性。为了测试这些门控机制，我们将追求以下具体目标： 目标 1：我们将确定 NMIIB 如何沿着肌动蛋白采取短暂、持续的步骤并维持细胞骨架张力。目标 2：我们将确定肌球蛋白 X 在肌动蛋白丝束环境中如何门控。目标 3：我们将确定两种肌球蛋白如何扭曲肌动蛋白丝。