Bifunctional nanotube scaffolds for diverse ligands are purified simply from Escherichia coli strains coexpressing two functionalized flagellar genes

We functionalized Escherichia coli FliC flagellin proteins to form tailored nanotubes binding single types or pairs of ligands, including divalent cations, fluorescent antibodies, or biotin-avidin-linked moieties such as ferritins. The ratio of each tag in bifunctionalized flagella could be toggled extending their sophistication as nanoscaffolds. Tobacco Etch Virus (TEV) protease site-containing FliCs were cleaved by the cognate protease without filament disintegration, potentiating their use as removable nanolithography masks to deposit attached ligands by protease cleavage.