Construction of robust bio-nanotubes using the controlled self-assembly of component proteins of bacteriophage T4

Achieving control over the structures of artifi cial protein and peptide assemblies is a worthwhile goal because it would provide a powerful approach for the construction of nanomaterials.^[1-4] Artifi cial self-assembled proteins obtained using protein engineering techniques could then be obtained by designing quaternary structures that include modifi ed protein-protein interfaces,^[5-9] fusion proteins,^[10-13] chemical conjugations,^[14,15] and self-assembly of short peptides. ^[16,17] The resulting protein assembly structures in the form of tubes,^[6,10] cages,^[5,7,9,11] rings ^[18] and 2D layers ^[12,14,15] could serve as nanoreactors and nanotemplates. In particular, tube structures offer great promise as building blocks of nanomaterials designed for applications such as molecular sensing, drug delivery, imaging, catalysis, and the synthesis of new materials. ^{[2,4,10,13,19-23]} Although several studies showed that tubular protein assemblies have been adopted as protein-based platforms for catalytic reactions promoted by enzymes or fl uorescent molecules displayed on the surfaces,^{[2,4,10,13,19-23]} it is diffi cult to control the reactivity of these systems by fixation of functional molecules at appropriate sites. Thus, it has remained challenging to obtain tube structures with high stability and well-defi ned nanoscale lengths for properly aligning synthetic molecules on the surfaces of the nanotubes.