Actin filament elasticity and actin-binding protein function

肌动蛋白丝弹性和肌动蛋白结合蛋白功能

基本信息

批准号：
9029502
负责人：
ENRIQUE M DE LA CRUZ
金额：
$ 42.43万
依托单位：
YALE UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2011
资助国家：
美国
起止时间：
2011-09-15 至 2019-08-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9029502
关键词：
Actin-Binding Protein Actins Award Binding Binding Proteins Binding Sites Biochemical Biological Process Biology Biomimetics Cations Cell Polarity Cells Chemistry Complex Computer Simulation Contractile Proteins Cryoelectron Microscopy Cytokinesis Cytoskeleton Dissociation Elasticity Endocytosis Eukaryotic Cell Filament Growth In Vitro Ions Knowledge Laboratories Link Magnetism Mechanics Medical Methods Microfilaments Molecular Molecular Conformation Molecular Models Motor Mutate Myosin ATPase Organism Phosphorylation Physics Physiology Plastics Play Post-Translational Protein Processing Probability Property Proteins Publishing Recruitment Activity Regulation Research Research Activity Resolution Role Shapes Stretching Structure System Testing Translating Work biophysical analysis biophysical techniques cell motility chemical property cofilin density experience experimental analysis genetic regulatory protein in vivo insight mathematical model models and simulation molecular modeling novel pathogenic bacteria physical property polymerization predictive modeling protein function public health relevance sensor

项目摘要

DESCRIPTION (provided by applicant): Polymerization of the protein actin into helical filaments powers the directed motility of eukaryotic cells and some pathogenic bacteria. Actin assembly also plays critical roles in endocytosis, cytokinesis, and establishment of cell polarity. The essential regulatory protein, cofilin, is one of four actin-binding proteins that precisely choreograph actin assembly and organization in living systems. It acts by severing filaments, which increases the concentration of filament ends available for subunit addition and dissociation, thereby accelerating overall actin network dynamics and reorganization. It is therefore of general medical importance to understand how cofilin fragments actin filaments. Although the effects of cofilin binding to actin filaments have been extensively studied, the molecular mechanism of how cofilin severs filaments, which have stiffness comparable to commercial laboratory plastics, remains a central and unresolved mystery of cellular actin cytoskeleton reorganization. Elucidating the cofilin severing mechanism demands a multi-disciplinary approach integrating biology, chemistry, physics and mathematical modeling. Proposed research efforts focus on identifying how specific cation binding, post-translational modification, competition with other regulatory proteins, and filament shape deformations modulate actin filament structure and severing by vertebrate cofilin. Five general hypotheses will be tested. The first is that vertebrate cofilin severs filaments by dissociating a specific filamen-associated cation that controls filament structure and mechanical properties. The second is that competitive displacement of cofilin by other filament binding proteins can promote cofilactin filament severing by introducing boundaries of bare and cofilin-decorated segments. The third is that phosphorylation enhances cooperative cofilin binding and inhibits severing, not by lowering cofilin occupancy along filaments, but by reducing the density of boundaries where severing can occur. The fourth is that contractile protein- driven deformations in filament shape enhance severing by cofilin. The fifth is that actin filaments can act as tension sensors that recruit or exclude cofilin depending on the magnitude and mode of filament shape deformation. We will integrate biochemical and biophysical approaches, including experimental manipulation of single filaments, with mathematical modeling and simulations to develop predictive molecular models of actin filament elasticity and fragmentation, and directly test hypotheses formulated from biochemical and biophysical analysis of cofilin-actin interactions completed during the prior award period. The proposed research activities will advance knowledge of actin filament physiology by providing multi-scale relationships between filament mechanics, structure, and the biological function (e.g. severing activity) of essential regulatory proteins. New experimental and methods of analysis readily applicable to other filament binding proteins will be developed. Novel insight regarding the relationship between actin filament elasticity, conformation and regulatory protein occupancy will emerge from the work.

描述（由申请人提供）：肌动蛋白聚合成螺旋丝为真核细胞和一些病原细菌的定向运动提供动力，肌动蛋白组装也在胞吞作用、胞质分裂和细胞极性的建立中发挥关键作用。重要的调节蛋白肌动蛋白丝切蛋白是四种肌动蛋白结合蛋白之一，可在生命系统中精确地编排肌动蛋白组装和组织，它通过切断细丝发挥作用，从而增加可用于亚基添加和解离的细丝末端的浓度，从而加速整体肌动蛋白。因此，了解肌丝蛋白丝切蛋白如何断裂肌动蛋白丝具有广泛的医学意义，尽管肌丝蛋白丝切蛋白与肌动蛋白丝结合的作用已被广泛研究，但其分子机制。丝切蛋白如何切断其硬度可与商业实验室塑料相媲美，仍然是细胞肌动蛋白细胞骨架重组的一个核心且未解的谜团，阐明丝切蛋白切断机制需要结合生物学、化学、物理和数学建模的多学科方法。重点研究特定阳离子结合、翻译后修饰、与其他调节蛋白的竞争以及丝形状变形如何调节肌动蛋白丝结构和切断将测试脊椎动物丝切蛋白。第一个假设是脊椎动物丝切蛋白通过解离控制丝结构和机械特性的特定丝切蛋白来切断丝丝蛋白，第二个假设是其他丝丝结合蛋白竞争性取代丝切蛋白。通过引入裸露片段和肌动蛋白丝切蛋白修饰片段的边界来切断细丝；第三个是磷酸化增强协同肌动蛋白丝切蛋白结合并抑制。切断，不是通过降低肌丝蛋白丝切蛋白沿丝的占有率，而是通过降低可能发生切断的边界的密度。第四是丝状蛋白驱动的收缩变形增强丝丝蛋白丝切蛋白的切断作用。第五是肌动蛋白丝可以充当张力传感器。根据丝形状变形的程度和模式来招募或排除丝切蛋白我们将整合生物化学和生物物理方法，包括单丝的实验操作，通过数学建模和模拟来开发肌动蛋白丝弹性和断裂的预测分子模型，并直接测试根据先前获奖期间完成的丝切蛋白-肌动蛋白相互作用的生化和生物物理分析得出的假设，拟议的研究活动将增进对肌动蛋白丝生理学的了解。通过提供必需调节蛋白的丝力学、结构和生物功能（例如切断活性）之间的多尺度关系。这项工作将开发出适用于其他丝结合蛋白的新见解，涉及肌动蛋白丝弹性、构象和调节蛋白占据之间的关系。