Protein interface remodeling in a chemically induced protein dimer.

Although the development of chemically induced, self-assembled protein-based materials is rapidly expanding, methods for directing their assembly in solution are sparse, and problems of population heterogeneity remain. By exerting control over the assembly of advanced protein structures, new classes of ordered protein nanomaterials become feasible, affecting numerous applications ranging from therapeutics to nanostructural engineering. Focusing on a protein-based method for modulating the stability of a chemically induced dihydrofolate reductase (DHFR) dimer, we demonstrate the sensitivity of a methotrexate competition assay in determining the change in DHFR-DHFR binding cooperativity via interfacial mutations over a 1.3 kcal/mol range. This represents a change of more than 40% of the dimer complex binding energy conferred from protein-protein cooperativity (~3.1 kcal/mol). With the development of this investigative system and refinement of protein-based techniques for complex stability modulation, the directed assembly of protein nanomaterials into heterocomplexes and a concomitant decrease in population heterogeneity becomes a realizable goal.