CAREER: Surfactant Proteins that Stabilize Biomolecular Condensates: From Biophysics to Biomaterials for Biomanufacturing

Non-Technical Description:Biopolymers are large, complex molecules produced by living organisms. For millennia, humans have used biopolymer-based materials to meet their everyday needs: wood to build homes and wool to weave clothes are two well-known examples. In the modern era, how can we continue to derive inspiration from nature to develop novel biopolymeric materials for humanity’s most pressing needs? Living cells are comprised of many thousands of different biopolymers that self-organize, giving rise to biological structure and activity. The goal of this project is to learn how biopolymers self-assemble in cells and then apply those insights for the development of new biomaterials. This CAREER project will focus on proteins, a large and important class of biopolymers. The principal investigator and his team will study biomolecular condensates, which are protein-rich spherical droplets that spontaneously assemble inside cells, and surfactant proteins that coat the surface of these biomolecular condensates and impart stability and function. The investigators will first identify and engineer surfactant proteins, then determine the physical and chemical principles by which surfactants interact with and influence biomolecular condensates. Based on these studies, the investigators will develop biomaterials to address an important problem in pharmaceutical synthesis. Many proteins are enzymes, whose function is to accelerate biochemical reactions. Enzyme-catalyzed reactions are a powerful alternative to traditional chemical catalysis to enable affordable, “green” pharmaceutical manufacturing. However, purification and formulation of enzymes are major challenges that impede advancement of the biocatalysis field. The investigators propose to address these challenges by developing new bio-inspired materials based on enzymatically active, surfactant-coated biomolecular condensates. Thus, this research seeks to advance fundamental understanding of how cells build materials, then will leverage this fundamental understanding to engineer biomaterials for pharmaceutical biocatalysis. This research program will be coupled with an education program, “Ethics for Biochemical Engineers.” The goal of this education program is to train students to consider how through their careers they can address major ethical challenges, including environmental sustainability and equitable global access to affordable medications.Technical Description:Cells compartmentalize their interiors to orchestrate their biochemical processes in space and time. Biomolecular condensates are cellular compartments formed via phase separation of proteins and other biopolymers. The cytoplasm is therefore reminiscent of an emulsion, comprising droplets of one phase dispersed in another phase. Emulsions used in consumer applications require surfactants to impart stability and function, so chemical surfactants are widely used and studied. However, researchers have devoted scant attention to intracellular protein surfactants and their contribution to the emulsion-like organization of the cell. To bridge that knowledge gap, this CAREER award aims to elucidate the “surfactome” – amphiphilic proteins that self-assemble at the surface of biomolecular condensates, stabilizing the condensates and regulating their biophysical properties and functions. The investigators propose to identify the physicochemical principles governing such intracellular surfactancy, quantify the effect of such surfactant proteins on biomolecular condensate coalescence, and conduct a bioinformatics survey to map the full scope of the surfactome. This fundamental research inspires a solution to a vexing problem in biomanufacturing. In the modern pharmaceutical industry, there is keen interest in replacing traditional catalyst materials with in vitro enzyme-catalyzed reactions to synthesize medicinal compounds more sustainably, safely, and affordably. However, enzyme purification and stability are critical challenges that have hindered pharmaceutical biocatalysis. Inspired by cells’ use of biomolecular condensates to compartmentalize and regulate enzymatic reactions, the investigators propose to develop enabling technologies for pharmaceutical biosynthesis. Specifically, the investigators will engineer immobilized enzyme materials comprised of crosslinked, surfactant-coated protein condensates. The rationale is that these biomaterials will simultaneously allow facile, chromatography-free enzyme purification via phase separation, and will optimally display enzymes at the condensate surface for maximal enzyme activity. Together, this research will elucidate basic principles of “surfactome” science and develop surface-active immobilized enzyme biomaterials for pharmaceutical biomanufacturing. The education component of this project aims to train students in ethics-based decision making in biochemical engineering. This ethics program will include a summer research program for underserved undergraduates, focusing on biomaterials and sustainability; ethics training for engineering graduate students; and a course module for senior undergraduates, featuring case studies in biochemical engineering ethics.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.