Allosterically Activated Protein Self-Assembly for the Construction of Helical Microfilaments with Tunable Helicity.

Protein allostery, a chemical-to-mechanical effect that can precisely regulate protein structure, exists in many proteins. Herein, we demonstrate that protein allostery can be used to drive self-assembly for the construction of tunable protein architectures. Calmodulin (CaM) was chosen as a model allosteric protein. Ca2+ -mediated contraction of CaM to a closed state can activate CaM and its ligand to self-assemble into a 1D protein helical microfilament. Conversely, relaxation of CaM to the open state can unwind and further dissociate the helical assemblies. Fine regulation of the protein conformation by tuning the external Ca2+ level allows us to obtain various protein helical nanostructures with tunable helicity. This study offers a new approach toward chemomechanically controlled protein self-assembly.