Two-Dimensional Protein Arrays: De Novo Design And Applications

Thesis (Ph.D.)--University of Washington, 2015Biological building blocks that self-assemble into predetermined supramolecular structures hold enormous promise for the production of advanced materials, devices and systems. However, our ability to predict, engineer and control short- and long-range interactions in proteins is lagging and nature's most versatile building block remains underused. Two dimensional (2D) protein arrays are of considerable interest in bionanotechnology. For instance, the remarkable stability and unique photochromic properties of purple membrane patches have been exploited for optical information storage and processing, and the fact that archeal and bacterial S-layers can be patterned on surfaces or used as templates and display scaffolds has opened the door to an even broader range of applications. Yet, neither the geometry, nor the chemistry or assembly of these systems can be precisely controlled from the nano- to the mesoscale. To address these shortcomings, we computationally designed a family of proteins capable of robust self-assembly into 2D arrays by fusing monomers from symmetry-compatible oligomers and redesigning interfacial contacts between unit cells. We optimized self-assembly conditions to promote the formation of protein lattices that retain short-range order at the nanoscale but can grow over tens to hundreds of micrometers. Finally, we demonstrated that modification of the designed protomers with a C-terminal biotinylation tag does not interfere with self-assembly and supports lattice decoration with Avidin. With proof of concept established, we anticipate that these well-defined and genetically accessible arrays will prove useful for bionanotechnology applications ranging from tunable molds for inorganic mineralization to scaffolds for high-density display of enzymes and proteins