Computational design of a homotrimeric metalloprotein with a trisbipyridyl core

Significance This article reports the computational design of a threefold symmetric, self-assembling protein homotrimer containing a highly stable noncanonical amino acid-mediated metal complex within the protein interface. To achieve this result, recently developed protein–protein interface design methods were extended to include a metal-chelating noncanonical amino acid containing a bipyridine functional group in the design process. Bipyridine metal complexes can give rise to photochemical properties that would be impossible to achieve with naturally occurring amino acids alone, suggesting that the methods reported here could be used to generate novel photoactive proteins.