A de novo designed protein–protein interface

As an approach to both explore the physical/chemical parameters that drive molecular self‐assembly and to generate novel protein oligomers, we have developed a procedure to generate protein dimers from monomeric proteins using computational protein docking and amino acid sequence design. A fast Fourier transform‐based docking algorithm was used to generate a model for a dimeric version of the 56‐amino‐acid β1 domain of streptococcal protein G. Computational amino acid sequence design of 24 residues at the dimer interface resulted in a heterodimer comprised of 12‐fold and eightfold variants of the wild‐type protein. The designed proteins were expressed, purified, and characterized using analytical ultracentrifugation and heteronuclear NMR techniques. Although the measured dissociation constant was modest (∼300 μM), 2D‐[1H,15N]‐HSQC NMR spectra of one of the designed proteins in the absence and presence of its binding partner showed clear evidence of specific dimer formation.