Flagellin beyond motility: exploiting flagellar filaments in biotechnology

Flagellin is the structural protein of the bacterial flagellar filament, an extracellular propeller that rotates to drive swimming in many bacteria. The structure of flagellin allows for outer domain customization, which has been the target of numerous studies for applications in biotechnology. Modified flagellin, both as monomers and in polymeric filaments, has been used in the generation of biosensors, in the formation of nanomaterials, in the attachment of cells to surfaces of interest, and in conferring motility to nanorobots. Flagellin is well characterized and provides a promising and cost-effective answer to some of the current limitations of traditional methods. This review discusses recent advances using flagellin for purposes beyond bacterial motility and new promising applications for flagellin and flagellin-derived filaments.