CAREER: PolyQ Proteins Phase Transition Induced by Lipid Vesicles

结构-功能范式认为蛋白质结构决定功能。然而，最近的发现挑战了这一概念，即具有重要生物学功能的真核细胞中约40%的蛋白质缺乏稳定的三维（3D）结构。许多这些内在无序的蛋白质（IDPs）可以通过称为相变的过程凝聚成无膜的液体状或凝胶状组装。这些组装的形成在一个孤立的微环境中丰富了这些蛋白质，从而调节了它们的生物活性。目前，相变组件的超微结构如何支持封闭蛋白质功能的时空控制仍然是一个谜。由于其结构的灵活性，国内流离失所者对实验结构研究提出了固有的挑战。通过应用最先进的结构方法，即低温电子断层扫描（cryoET）和先进的亚层析分析，该项目将揭示相变组件的结构，并建立这类重要蛋白质的3D结构，动力学和功能之间的联系。总的来说，这个项目将有助于基础生物学中更完整的结构-功能范式。与此同时，PI将开发一个研究驱动的教育课程，向本科生介绍跨学科研究，促进研究生的互动教学，并为年轻学者提供尖端低温低温生物结构成像的在线培训资源。cryoET教育门户网站的发展具有更广泛的影响。它将向公众展示这种新型生物成像技术在揭示自然界动态生物过程方面令人兴奋的潜力。该项目的目标是解决蛋白质相变组件的结构组织，以提供更深入地了解这些组件的生物物理和结构特性如何支持封闭IDPs的生物活性。具有延伸聚谷氨酰胺（polyQ）同源重复序列的蛋白质是最简单的IDPs之一。使用该系统，PI将在亚纳米水平上解析在生理相关实验条件下形成的相变组件的三维结构组织。该项目还将研究IDPs和脂质囊泡的序列特征如何影响相变组合的形成、稳定性和聚集倾向。这项工作将促进我们对IDP相变的分子机制的理解。更重要的是，这项工作的结果将促进调控这些亚稳态组装的策略的发展，从而调节细胞中的蛋白质稳态。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The structure-function paradigm states that protein structure dictates function. However, this concept has been challenged by recent discoveries that ~40% of proteins in eukaryotic cells with important biological functions lack a stable three-dimensional (3D) structure. Many of these intrinsically disordered proteins (IDPs) can condense into membraneless liquid-like or gel-like assemblies through a process termed phase transition. Formation of these assemblies enriches these proteins within an isolated microenvironment, and thus regulates their biological activities. At present, it remains a mystery how the ultrastructure of phase transition assemblies supports spatiotemporal control of functions of the enclosed proteins. Due to their structural flexibility, IDPs present inherent challenges for experimental structural studies. By applying state-of-the-art structural methods, namely cryo-electron tomography (cryoET) and advanced subtomogram analyses, this project will reveal the architecture of phase transition assemblies, and establish a connection between the 3D structure, dynamics, and function for this important class of proteins. Overall, this project will contribute towards a more complete structure-function paradigm in fundamental biology. In parallel, the PI will develop a research-driven education curriculum that introduces interdisciplinary research to undergraduate students, promotes interactive graduate student teaching, and provides engaging online training resources on cutting-edge cryoET biostructure imaging to young scholars. Development of the cryoET educational portal has broader impacts. It will showcase to the general public the exciting potential of this novel bioimaging technique for unraveling dynamic biological processes in nature.The goal of this project is to resolve the structural organization of protein phase transition assemblies to provide a deeper understanding of how biophysical and structural properties of these assemblies support biological activities of enclosed IDPs. Proteins with extended polyglutamine (polyQ) homo-repeats represent one of the simplest IDPs. Using this system, the PI will resolve, at the subnanometer level, the 3D structural organization of phase transition assemblies formed under physiologically relevant experimental conditions. This project will also investigate how the formation, stability, and aggregation propensity of phase transition assemblies are affected by sequence characteristics of the IDPs and lipid vesicles. This work will advance our understanding of the molecular mechanisms underlying IDP phase transitions. More importantly, results from this work will facilitate development of strategies for regulating these metastable assemblies and thereby modulating protein homeostasis in cells.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.