Programmable 2- and 3-Dimensional Protein Assemblies

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Nontechnical SummaryWhether for constructing complex biological devices like enzymes or for building sophisticated materials with advanced physical properties like skeletal muscles, proteins have been nature’s premier building blocks throughout the course of evolution. Yet, the ability of laboratory scientists to control the self-assembly of proteins or to use them as synthetic building blocks to generate new functions has been severely limited. The overarching goal of the proposed research program is to overcome this limitation by developing new protein design tools based on metal coordination chemistry and DNA nanotechnology. In one project goal, the PI’s group will construct complex, cage-like protein architectures which can ultimately be used to encapsulate and release molecular cargo in a stimuli-dependent fashion. In a second project goal, they will exploit the programmability of DNA self-assembly to generate multicomponent protein architectures and elucidate the complex energy landscape of protein-DNA interactions. In terms of the broader impacts, the proposed effort will not only provide fundamental insights into biological self-assembly processes, but also lend access to novel protein-based functionalities and materials with potential applications in bio/nano-technology and basic sciences (e.g., separations, catalysis, delivery, sensing, X-ray or electron-diffraction-based structure determination). Due to its highly interdisciplinary nature, this project will provide an expansive training ground for graduate, undergraduate, and high school researchers, and help them tackle complex scientific problems later in their careers. As a new educational activity, the PI’s lab will start hosting STEM activities designed for Junior Reserve Officers’ Training Corps from San Diego-area high schools. These activities collectively will enhance the students’ understanding of proteins as biomolecules and their self-assembly/crystallization as well as their novel uses as building blocks for novel catalysts and materials. Importantly, the students will be exposed to daily activities that are taking place in a research laboratory. Technical SummaryWhile natural evolution has produced remarkable protein-based machines and materials over the course of billions of years, it has only explored an infinitesimally small fraction of the design/self-assembly space that could be achieved with the available protein folds. Therefore, it would be highly desirable to have the ability to craft ordered protein assemblies from scratch using building blocks of choice, which would greatly broaden the structural and functional scope of naturally existing protein assemblies and bioinspired materials. Previous findings from the PI’s indicate that the tools and principles of supramolecular/inorganic/polymer chemistry and protein engineering can be combined in new ways to address outstanding issues in protein self-assembly and to create novel biomaterials. In the proposed research, these efforts will be expanded under two Objectives. Under Objective 1, the PI’s group will expand their inorganic chemical toolkit through the use of unnatural metal chelating functionalities and combine them with computational design to access complex, stimuli-responsive polyhedral architectures that were previously out of reach. Objective 2 will exploit the programmability of DNA self-assembly to generate heteromeric/multicomponent protein architectures and to better understand the complex energy landscape of protein-DNA co-assembly. The Objectives will take advantage of two protein building blocks (cytochrome cb562 and Rop) to access a multitude of oligomeric and polymeric protein assemblies in a modular fashion, probe their structures and structural dynamics using state-of-the-art tools (e.g., cryoEM, X-ray diffraction and scattering), and examine their emergent functions (e.g., nucleic acid encapsulation).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.