Virus-like particles (VLPs) consist of repeating units of viral structural proteins that spontaneously self-assemble into particles structurally identical or very similar to their native viruses. Due to the absence of viral genetic material they are non-infectious and can be used in a wide range of applications in the field of biomedicine and bionanomaterials. We focused on potato virus Y (PVY) VLPs that form flexible filaments, which can reach up to 3 µm in length and have a diameter of 13 nm. PVY VLPs are assembled from octameric coat protein (CP) rings stacked along the longitudinal axis of filaments. CP unit is comprised of globular core domain and extended N- and C-terminal regions. N-terminal region is located on the surface of the viral filament whereas C-terminal region is buried in the lumen. Using E. coli as an expressions system, we prepared PVY CPs with different peptide sequences introduced in the N-terminal region via genetic fusion, thus achieving the presentation of foreign peptides on the surface of the filaments. With shorter pentapeptide amino acid sequences (Asp5, Asn5, Leu5, and His5), we have shown that by adding “MGND” sequence to the beginning of the N-terminal region, the different chemical nature of the peptide does not affect the self-assembly of CPs. When 26 amino acids residues long melittin was added to the N-terminal region, the protein was present in the insoluble fraction of the cell lysate. But we were successful at introducing 13 amino acids residues long peptide SpyTag (ST) to the N-terminal region of CP. Using SpyTag/SpyCatcher (ST/SC) system we were able to attach the target protein to the surface of the filament composed of ST_CP units. With our results, we have shown that PVY VLPs are a suitable system for displaying heterologous peptides and proteins on the surface of flexible VLP filaments.
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