Biophysics of Phase Separation in Protein-RNA Systems

该项目将开发和使用新的工具，研究细胞材料是如何组织起来的，以促进支持生命的化学和生物功能，同时将更广泛的影响纳入教学、培训和宣传。人类和其他生物的生物学在很大程度上依赖于大量细胞分子的相互作用和化学作用。在其他分子的巨大背景下，这些正确的相互作用的一个关键机制是选择性地将分子组织到不同的隔室中。事实上，几十年来，人们已经详细研究了周围膜对细胞的分隔作用。相比之下，另一种没有膜的细胞室很常见，但研究较少。这些无膜或“液滴”细胞器是通过相变自发形成的(称为液-液相分离，类似于水包油液滴的形成过程)。在这个项目中，将开发新的方法来解决我们对这一过程背后的物理原理的理解中尚未填补的空白。这项工作有望产生广泛适用于细胞生物学的新工具、见解和预测原则。该项目还将在教学、培训和宣传方面产生更广泛的影响，旨在扩大对科学的参与。这项工作将被用作学生在前沿和及时的研究领域进行跨学科研究的极好培训基础。这项研究的多学科性质也将促进研究生课程的加强，以及研究领域与更广泛社区的延伸和交流。细胞中的几个无膜细胞器含有蛋白质和RNA，这两种细胞大分子都参与了广泛的细胞过程。理解这些分子的分子级结构和相互作用如何与液滴形成和无膜细胞器的生物物理学联系起来继续构成挑战。该项目将开发和使用新的单分子和系综方法相结合的方法来研究这一领域的一系列重要问题。单分子方法可以提供访问关键信息的途径，这些信息通常通过对大量分子进行平均来隐藏。将开发一种方法，通过使用多色单分子检测来探测比目前通常可检测到的液滴更小的液滴的大小和构象分布。将开发另一种方法，使用单分子和化学生物学工具来探测分子间相互作用和构象性质。这些新的工具和现有的方法将被用于探索蛋白质-RNA液滴的复杂相变、非平衡亚结构形成和构象模式的决定因素。该项目预计将揭示细胞相变及其功能后果的这些方面的新见解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The project will develop and use novel tools to study how cellular materials are organized to facilitate chemical and biological functions that support life, while integrating broader impacts in teaching, training and outreach. The biology of humans and other organisms is critically dependent on interactions and chemistry of a host of cellular molecules. A key mechanism that underlies these correct interactions in a huge background of other molecules is the selective organization of molecules into different compartments. Indeed, cellular compartmentalization by a surrounding membrane has been studied in detail for decades. In contrast, another type of cellular compartment that lacks a membrane is common but less well-studied. These membraneless or "droplet" organelles are spontaneously formed by a phase transition (referred to as liquid-liquid phase separation, a process similar to oil-in-water droplet formation). In this project, novel methods to address unfilled gaps in our understanding of the physical principles underlying this process will be developed. The work is expected to result in new tools, insights and predictive principles that are broadly applicable in cell biology. The project will also integrate broader impacts in teaching, training and outreach, and aim to broaden participation in science. The work will be used as an excellent training ground for students in performing interdisciplinary research in a cutting-edge and timely area of research. The multidisciplinary nature of the research will also facilitate enhancement of graduate student curriculum, as well as outreach and communication of the research area to the broader community.Several membraneless organelles in cells contain proteins and RNA, both cellular macromolecules that are involved in a wide range of cellular processes. Understanding how molecular-level structure and interactions of these molecules link to the biophysics of droplet formation and membraneless organelles continues to pose challenges. The project will develop and use a combination of novel single-molecule and ensemble methods to study a series of important questions in this area. Single-molecule methods can provide access to critical information that is normally hidden by averaging over a large number of molecules. A method will be developed to probe size and conformational distributions in droplets smaller than typically detectable currently, by use of multicolor single-molecule detection. Another method will be developed to probe intermolecular interactions and conformational properties using single-molecule and chemical biology tools. These new tools and existing methods will be used to probe the determinants of complex phase transitions, non-equilibrium substructure formation and conformational patterning of protein-RNA droplets. The project is expected to reveal new insight in these aspects of cellular phase transitions and their functional consequenceThis 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.