Allostery in myosins studied at the molecular level

在分子水平上研究肌球蛋白的变构

基本信息

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
项目类别：
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

项目摘要

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）：所有生物体的关键功能是在需要时移动的能力。这些运动 - 细胞内贩运，细胞分裂，肌肉收缩和细胞运动性 - 由分子机器驱动，这些机器考虑到它们只是少数纳米的含量，它们施加了惊人的力量。鉴于细胞中各种运动蛋白的多样性，一个关键问题是电动机在移动货物和施加力时如何合作和竞争。新兴范式是“专业”电动机的概念，也是对执行特定功能进行微调的电动机的概念。尽管这些运动蛋白很重要，但对它们的个体适应性以及这些与细胞中的运动模式的关系相对较少。在先前的研究中，我们发现了两种具有肌动蛋白上新颖而独特的遗传踏脚模式的肌动物。肌球蛋白X沿着fascin-actin束的多个细丝行走。另一方面，非肌肌球蛋白IIB（NMIIB）沿着单个肌动蛋白细丝的长螺旋螺旋行走。两种肌动物在迁移细胞中起关键作用，包括转移肿瘤细胞。肌球蛋白X提供基本货物，例如整联蛋白，钙粘蛋白和Netrin受体，以在细胞的前缘处于丝状上。 NMIIB出现在细胞的后部，它保持细胞极性和内部组织。因此，我们必须了解两种肌球蛋白的操作是至关重要的，以便我们可以通过这些玩家控制细胞运动。对于这两种肌球蛋白，我们都建议它们的两个运动结构域通过应变敏感的门控机制进行了同步。对于NMIIB和肌球蛋白X，门控均可调整其沿肌动蛋白轨道的独特垫子图案。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，并且两者都可能适应扭曲单肌动蛋白丝。为了测试这些门控机制，我们将追求以下特定目的：目标1：我们将确定NMIIB如何沿肌动蛋白沿肌动蛋白进行短暂的遗传步骤并保持细胞骨架张力。 AIM 2：我们将确定在肌动蛋白丝束环境中肌球蛋白X的门控。目标3：我们将确定两种肌球蛋白如何扭曲肌动蛋白丝。