Functionalized protein nanotubes based on the bacteriophage vb_klem-rak2 tail sheath protein

Abstract

We report on the construction of functionalized nanotubes based on tail sheath protein 041 from vB_KleM-RaK2 bacteriophage. The truncated 041 protein (041∆200) was fused with fluorescent proteins GFP and mCherry or amidohydrolase YqfB. The generated chimeric proteins were successfully synthesized in E. coli BL21 (DE3) cells and self-assembled into tubular structures. We detected the fluorescence of the structures, which was confirmed by stimulated emission depletion microscopy. When 041∆200GFP and 041∆200mCherry were coexpressed in E. coli BL21 (DE3) cells, the formed nanotubes generated Förster resonance energy transfer, indicating that both fluorescent proteins assemble into a single nanotube. Chimeric 041∆200YqfB nanotubes possessed an enzymatic activity, which was confirmed by hydrolysis of N4-acetyl-2′-deoxycytidine. The enzymatic properties of 041∆200YqfB were similar to those of a free wild-type YqfB. Hence, we conclude that 041-based chimeric nanotubes have the potential for the development of delivery vehicles and targeted imaging and are applicable as scaffolds for biocatalysts.