Proteins 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.
Liquid-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.
