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

• 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
• 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

 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某些病原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起关键作用。 必需的调节蛋白，cofilin，是四个肌动蛋白结合蛋白，精确地编排肌动蛋白组装和组织在生活系统中的一个。它通过切断细丝起作用，这增加了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网络的动态和重组。因此，了解cofilin如何使肌动蛋白丝断裂具有普遍的医学重要性。虽然cofilin与肌动蛋白丝结合的作用已经被广泛研究，但cofilin如何切断具有与商业实验室塑料相当的刚度的丝的分子机制仍然是细胞肌动蛋白细胞骨架重组的核心和未解决的谜团。阐明cofilin切断机制需要一个多学科的方法集成生物学，化学，物理学和数学建模。建议的研究工作集中在确定如何特定的阳离子结合，翻译后修饰，与其他调节蛋白的竞争，和丝形状变形调节肌动蛋白丝结构和切断脊椎动物cofilin。将检验五个一般假设。第一个是脊椎动物cofilin通过解离控制细丝结构和机械性质的特定细丝相关阳离子来切断细丝。第二是其他丝结合蛋白竞争性取代cofilin可以通过引入裸露和cofilin修饰片段的边界来促进cofilactin丝切断。第三个是磷酸化增强了协同的cofilin结合并抑制切断，不是通过降低cofilin沿丝沿着的占有率，而是通过降低可能发生切断的边界的密度。第四是收缩蛋白驱动的丝状变形增强了切丝蛋白的切割作用。第五，肌动蛋白丝可以作为张力传感器，根据丝形状变形的大小和模式招募或排除cofilin。我们将整合生物化学和生物物理学的方法，包括实验操作的单丝，数学建模和模拟开发预测的肌动蛋白丝弹性和碎片的分子模型，并直接测试假设制定从生物化学和生物物理学分析cofilin-actin相互作用在前一个奖项期间完成。拟议的研究活动将通过提供细丝力学，结构和生物功能（如切断活性）的基本调控蛋白之间的多尺度关系，推进肌动蛋白丝生理学的知识。新的实验 并且将开发容易适用于其它丝结合蛋白的分析方法。关于肌动蛋白丝弹性，构象和调节蛋白质占用之间的关系的新见解将出现从工作。