Genetically engineered protein nanowires: unique features in site-specific functionalization and multi-dimensional self-assembly

Abstract

Protein nanowires possess promising features, including their site-specific genetic functionalization and multi-dimensional self-assembly with biomolecular recognition-based specificity for bottom-up material synthesis. Previously, a variety of rod-shaped inorganic and amphiphile-mimic nanowires have been studied for their controlled aggregation in nanotechnology and their assembled structures are sensitive to the molecular structures of the monomers. Protein nanowires are expected to be assembled in more diverse structures with the unique features of genetically-directed site-specific functionalization and conformational changes of proteins. These advantages lead to the creation of 2D and 3D assemblies in various structures and geometries, which is difficult to achieve from other molecular building blocks. In this review article, after a list of the practical protein nanowires including the flagellar protein (FliC), cell division protein (FtsZ), yeast amyloid protein (Sup35), collagen, and virus coat proteins is introduced, their functional designs and the methodologies of their functionalization via genetic engineering are explained. Finally, their assembled structures from functionalized proteins are discussed with some practical applications. Highly ordered hierarchical superstructures assembled from protein nanowires are highlighted as one of the unique features of protein nanowires for future bottom-up nanotechnological science and engineering. To accomplish the precise assembly of complex 3D superstructures from proteins and nanomaterials, controlling the interactions between the as-prepared protein nanowires is critical, and biorecognition sites on the nanowires need to be properly designed. Additionally, other fine interactions also play important roles in determining the final 3D superstructures and it is desirable to understand these effects in order to better predict complex 3D assembled structures.