Protein nanodisk assembling and intracellular trafficking powered by an arginine-rich (R9) peptide

Abstract

Aims: Arginine(R)-rich cationic peptides are powerful tools in drug delivery since, alone or when associated with polyplexes, proteins or chemicals, they confer DNA condensation, membrane translocation and blood–brain barrier crossing abilities. The unusual stability and high in vivo performance of their associated drugs suggest a particulate organization or R(n) complexes, which this study aimed to explore. Materials & methods: We have analyzed the particulate organization and biological performance in DNA delivery of a model, R9-containing green fluorescent protein by dynamic light scattering, transmission electron microscopy, atomic force microscopy, single cell confocal microscopy and flow cytometry. Results: A deep nanoscale examination of R9-powered constructs reveals a novel and promising feature of R9, that when fused to a scaffold green fluorescent protein, promote its efficient self-assembling as highly stable, regular disk-shaped nanoparticles of 20 × 3 nm. These constructs are efficiently internalized in mammalian cells and rapidly migrate through the cytoplasm towards the nucleus in a fully bioactive form. Besides, such particulate platforms accommodate, condense and deliver plasmid DNA to the nucleus and promote plasmid-driven transgene expression. Conclusion: The architectonic properties of arginine-rich peptides at the nanoscale reveal a new category of protein nanoparticles, namely nanodisks, and provide novel strategic concepts and architectonic tools for the tailored construction of new-generation artificial viruses for gene therapy and drug delivery.