Metal-Mediated Protein-Cucurbituril Crystalline Architectures

Controlled protein assembly is an enabling technology, for example, in the bottom-up fabrication of biomaterials. This paper describes the assembly of a β-propeller protein using two orthogonal interaction modes. Previously, protein assembly was directed by metal coordination or macrocycle complexation. Here, we demonstrate the combination of metal coordination and macrocycle complexation for controlled assembly. An established protein-cucurbit[7]uril (Q7) assembly, which relies on trimeric Q7 clusters, was modified by the inclusion of metal-binding sites in the protein. The application of zinc-histidine coordination to tune the Q7-induced assembly resulted in metallo-bioorganic crystalline architectures. The relative arrangement of the protein-Q7 layers was reorganized by the zinc bridging ions. One structure resulted in a different type of protein-Q7 packing that involves Q7 dimers. Apparently, Q7 is a versatile molecular glue that can be combined with metal-mediated protein assembly. This dual strategy expands significantly the toolkit for engineered assembly.