Harnessing synthetic biology to create novel protein materials for applications on the nano and macro scales

While the field of synthetic biology has been historically dominated by developments on the genetic level, interest has recently grown for advancing the production and engineering of proteins. In nature, proteins play a wide variety of roles across dimensional scales, ranging from functional roles in enzyme catalysis, metabolism, and signaling to structural roles in creating or protecting from mechanical forces. Synthetic biology enables an expansion upon these natural roles through precise sequence control and the integration of defined and interchangeable biochemical parts, yielding proteins with improved capabilities or even entirely new capabilities altogether. This thesis further explores the application of synthetic biology in the production of novel protein-based materials on the nano and macro scales. By combining split intein ligation domains and the rod-shaped, computationally designed three-helix bundle protein, we constructed ultrastable nanostructures and demonstrated that they could be used as scaffolds for assembling molecular entities with precise control. Using the flexible linker from dragline spider silk to connect several copies of the zipper-forming sequence from natural amyloidogenic proteins, we created block polypeptides that rapidly assemble into nanofibrils with high thermodynamic stability. On the macro scale, we manufactured fibers with desirable mechanical properties such as high toughness by polymerizing the immunoglobulin domains from animal muscle titin and processing those through aqueous wet-spinning. Finally, we applied the same aqueous wet-spinning approach to produce fibers from the three-helix bundle that are not only tough and highly extensible but are made of a unique α-helical molecular structure. Together, these projects demonstrate the diversity of novel applications for protein materials that can be achieved through synthetic biology strategies by integrating different biological parts and processing those proteins on multiple dimensional scales. These novel materials could be applied in addressing challenges found in a range of fields including biomedicine and the manufacture of renewable and sustainable materials