Collaborative Research: Designing biomaterials through computational simulation and manipulation of phase behavior in a class of intrinsically disordered proteins

缺乏明确结构的蛋白质在生物学和材料中扮演着许多重要的角色，从细胞内部分子的组织到弹性体材料的生产，这些弹性体材料可以拉伸数倍于其原始长度而不会永久变形。尽管这些类型的蛋白质具有广泛的用途，但对定义其特性的分子特征的详细了解仍然刚刚出现，这限制了它们在高性能生物材料中的应用。该提案通过开发计算和实验方法来解决这一差距，这些方法将描述蛋白质的组成及其溶液的性质如何为制造有图案的弹性体基质提供处理，从长远来看，这将解决关键的社会挑战，如工程活材料，控制生物分子的放置以执行化学功能，和/或更有效的能量存储。该项目的研究也将影响不同年龄和经验的学生的教育活动。一系列由学生发起的活动和播客，pi将参与其中，将有助于将该计划的概念转化为中学课程和实践经验。两种不同溶液的液-液相分离（LLPS）是一个基本的热力学过程，在先进材料的开发和无膜细胞器（如核核）的组装中具有重要意义。如果更详细地了解多肽链的选择特征及其解决方案如何驱动IDPs中相分离的热力学和动力学，那么使用蛋白质LLPS有目的地设计新材料可能会取得重大进展。因此，该提案的总体目标是利用研究人员在计算机建模和重组设计树脂样IDPs （rlp）方面的独特能力来设计在中尺度上显示可调材料特性的蛋白质凝聚体。该项目将利用闭环格式，结合最先进的蛋白质LLPS模拟和广泛的rlp实验表征，提供关于氨基酸组成、序列和共溶质（盐或PEG）在LLPS中的作用的迭代反馈。实验确定的所选rlp的第二维里系数的变化及其与计算的匹配（或偏差）将使计算方法得以微调。详细的光谱和散射表征将与计算预测相关联，并进一步有助于确定凝聚体浓度和组成在水凝胶形态和性质中的作用。综上所述，这些研究将加深对IDPs的LLPS热力学和动力学的基本理解，并将允许以控制微观结构和组成为生物材料设计元素的冷凝物设计的前所未有的控制。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。

Nontechnical SummaryProteins that lack defined structures play many important roles in biology and in materials, mediating functions from the organization of molecules in the interior of cells to the production of elastomeric materials that can stretch multiple times their original length without permanent deformation. Despite the widespread utility of these types of proteins, detailed understanding of the molecular features that define their properties is still just emerging, which has limited their application in high-performance biomaterials. This proposal addresses this gap by developing computational and experimental methods that will describe how the composition of the proteins and the properties of their solutions can provide handles for making patterned elastomeric matrices, which in the long term will address critical societal challenges such as engineering living materials, controlling placement of biomolecules to conduct chemical functions, and/or more efficient energy storage. The research in this program will also impact educational activities for students of a variety of ages and experience. A series of student-initiated activities and podcasts, in which the PIs will participate, will help transfer concepts of this program into secondary school curricula and hands-on experiences.Technical summaryLiquid-liquid phase separation (LLPS) of two dissimilar solutions is a fundamental thermodynamic process with significant importance in the development of advanced materials and for the assembly of membraneless organelles such as the nucleolus. The use of protein LLPS to purposefully design new materials could be significantly advanced if finer details were known about how select features of the polypeptide chain and its solutions drive the thermodynamics and kinetics of phase separation in the IDPs. The overarching goal of this proposal, accordingly, is to leverage unique capabilities of the investigators in computer modeling and recombinant design of resilin-like IDPs (RLPs) to design protein coacervates that display tunable material properties at the mesoscale. The project will leverage a closed-loop format, combining state-of-the-art simulations of protein LLPS alongside extensive experimental characterization of RLPs to provide iterative feedback about the role of amino acid composition, sequence, and co-solutes (salt or PEG) in LLPS. Variations in the experimentally determined second virial coefficients for selected RLPs, and their match (or deviation) from computation will enable fine-tuning of computational methods. Detailed spectroscopy and scattering characterization will enable correlation with computational prediction and further serve to establish the roles of coacervate concentration and composition in hydrogel morphology and properties. Taken together, these studies will deepen fundamental understanding of thermodynamics and kinetics of the LLPS of IDPs and will allow for unprecedented control over the design of condensates with controlled microstructure and composition as elements in biomaterials design.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.