Intrinsically Disordered Proteins as Sensors of Membrane Curvature

本质上无序的蛋白质作为膜曲率的传感器

• 批准号: 9788761
• 负责人: Wade F Zeno
• 金额: $ 6.16万
• 依托单位: UNIVERSITY OF TEXAS AT AUSTIN
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-08 至 2020-08-07
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9788761
• 关键词: Adaptor Signaling Protein; Affinity; Behavior; Binding; Biological Assay; Biological Sciences; Biophysics; C-terminal; Cell membrane; Cell physiology; Cellular biology; Chemical Engineering; Clathrin; Coupled; Cystic Fibrosis; Data; Defect; Detection; Diabetes Mellitus; Disease; Endocytosis; Ensure; Entropy; Faculty; Fluorescence Microscopy; Goals; Knowledge; Length; Lipids; Location; Mammalian Cell; Maps; Measures; Membrane; Membrane Protein Traffic; Mission; Modeling; Molecular Conformation; N-terminal; Phase; Physical Chemistry; Play; Polymers; Positioning Attribute; Process; Protein Biochemistry; Proteins; Public Health; Quantitative Microscopy; Research; Role; Site; Structure; Surface; Tertiary Protein Structure; Testing; Time; Total Internal Reflection Fluorescent; Training; United States National Institutes of Health; Vesicle; Water; Work; base; biophysical properties; experimental study; human disease; materials science; molecular modeling; physical science; post-doctoral training; preference; recruit; scaffold; sensor; skills; stoichiometry; three dimensional structure; trafficking

PROJECT SUMMARY Curved membrane structures such as endocytic pits and trafficking vesicles are essential to cellular physiology. Formation of these structures requires that the proteins involved are able to sense membrane curvature. Two structure-based mechanisms of curvature sensing are known: (i) curvature-matching by crescent-shaped BAR domains and (ii) membrane insertion by amphipathic helices. Recently, the postdoctoral applicant has discovered an additional curvature sensing mechanism that arises not from a specific structural motif, but instead from protein domains that lack a well-defined 3D structure – intrinsically disordered protein (IDP) domains. How can IDPs sense membrane curvature? Like a random polymer chain, highly water soluble IDPs seek to maximize chain entropy. Tethering polymers to flat surfaces restricts their conformation to a half-plane. In contrast, increasing the curvature of the substrate increases the polymer’s configurational entropy. As such, polymer-like IDPs should display a preference for curved membrane substrates. Because IDP domains are prevalent among endocytic proteins, their ability to sense membrane curvature could strongly impact the initiation and assembly of curved membrane structures. In addition, IDP domains involved in endocytosis are known to form interconnected protein networks, which could further amplify curvature sensing. Preliminary work shows that IDPs have 4-5 times greater affinity for highly curved membrane surfaces in comparison to flatter membranes, which is comparable to structure-based curvature sensing mechanisms. When an IDP and a structured curvature sensing domains were coupled within the same protein, an additional 4-fold increase in curvature sensitivity was observed, suggesting a synergistic relationship among the curvature sensors. The goal of the proposed work is to characterize the ability of IDPs to sense membrane curvature. Work in Aim 1 will evaluate the extent to which IDPs can sense membrane curvature, testing the working hypothesis that IDPs will partition preferentially to highly curved membrane surfaces to maximize chain entropy. Work in Aim 2 will compare curvature sensing by IDPs to sensing by structure-based mechanisms, testing the working hypothesis that entropically-driven curvature sensing by IDPs is comparable in magnitude to the mechanisms used by structured domains. Finally, work in Aim 3 will measure the role of protein networks in amplifying membrane curvature sensitivity, testing the working hypothesis that IDP-containing endocytic proteins cooperatively enhance membrane curvature sensitivity. Current understanding of membrane curvature sensing focusses on specific structural domains. In contrast, this work will be highly significant because it explores the paradigm-shifting idea that proteins lacking a defined structure, IDPs, serve as potent sensors of membrane curvature. The role IDP domains play in curvature sensing and protein network formation is an important, yet unexplored idea in membrane traffic, creating an opportunity to fill a key gap in existing knowledge.

项目摘要 弯曲的膜结构（例如内吞凹坑和运输囊泡）至关重要 这些结构的形成需要所涉及的蛋白质能够感知。 膜曲率。已知两种基于结构的曲率传感机制：(i)曲率匹配。 最近，通过新月形 BAR 结构域和 (ii) 两亲性螺旋的膜插入。 博士后申请人发现了一种额外的曲率传感机制，该机制不是由特定的 结构基序，但来自缺乏明确 3D 结构的蛋白质结构域 – 本质上是无序的 蛋白质（IDP）结构域如何感知膜曲率，就像随机的聚合物链一样，高度含水？ 可溶性 IDP 试图将链熵最大化，将聚合物束缚在平面上，从而限制其构象。 相反，增加基底的曲率会增加聚合物的构型。 因此，类聚合物 IDP 应表现出对弯曲膜基底的偏好。 结构域在内吞蛋白中普遍存在，它们感知膜曲率的能力可以强烈地影响 此外，IDP 结构域还参与弯曲膜结构的启动和组装。 众所周知，内吞作用会形成互连的蛋白质网络，这可以进一步放大曲率传感。 初步研究表明，IDP 对高度弯曲的膜表面的亲和力高出 4-5 倍。 与更平坦的膜相比，这与基于结构的曲率传感机制相当。 IDP 和结构化曲率传感域耦合在同一蛋白质内，额外增加了 4 倍 观察到曲率敏感性增加，表明曲率之间存在协同关系 拟议工作的目标是表征 IDP 感知膜曲率的能力。 目标 1 将评估 IDP 能够感知膜曲率的程度，测试工作假设 IDP 将优先分配到高度弯曲的膜表面，以最大化链熵。 目标 2 将比较 IDP 的曲率传感与基于结构的机制的传感，测试工作原理 假设 IDP 的熵驱动曲率传感在大小上与机制相当 最后，目标 3 中的工作将测量蛋白质网络在放大中的作用。 膜曲率敏感性，测试含有 IDP 的内吞蛋白的工作假设 合作增强膜曲率灵敏度的当前理解。 相比之下，这项工作将非常重要，因为它探索了特定的结构领域。 范式转变的想法，即缺乏确定结构的蛋白质（IDP）可以作为膜的有效传感器 IDP 结构域在曲率传感和蛋白质网络形成中发挥的作用非常重要。 膜交通中未经探索的想法，为填补现有知识的关键空白创造了机会。