Metal-Directed Design of Supramolecular Protein Assemblies

Owing to their central roles in cellular signaling, construction, and biochemistry, protein-protein interactions (PPIs) and protein self-assembly have become a major focus of molecular design and synthetic biology. In order to circumvent the complexity of constructing extensive noncovalent interfaces, which are typically involved in natural PPIs and protein self-assembly, we have developed two design strategies, metal-directed protein self-assembly (MDPSA) and metal-templated interface redesign (MeTIR). These strategies, inspired by both the proposed evolutionary roles of metals and their prevalence in natural PPIs, take advantage of the favorable properties of metal coordination (bonding strength, directionality, and reversibility) to guide protein self-assembly with minimal design and engineering. Using a small, monomeric protein (cytochrome cb562) as a model building block, we employed MDPSA and MeTIR to create a diverse array of functional supramolecular architectures which range from structurally tunable oligomers to metalloprotein complexes that can properly self-assemble in living cells into novel metalloenzymes. The design principles and strategies outlined herein should be readily applicable to other protein systems with the goal of creating new PPIs and protein assemblies with structures and functions not yet produced by natural evolution.