Structure–activity relationships of DNA nanocarriers based on the amphipathic cell penetrating peptide transportan 10

Abstract

Cell penetrating peptides (CPPs) have emerged as promising materials for the fabrication of synthetic nanovectors endowed with potential for improving the future landscape of gene therapy. A group of well-studied CPPs includes the transportan family, comprised of chimeric molecules combining segments derived from the antimicrobial wasp-venom mastoporan and the neuropeptide galanin. The success of these CPPs is supported by their effective use as the base for commercial peptide-based transfection reagents. Herein, we present a comprehensive study of the structure of peptiplexes formed between DNA fragments and transportan 10, a prototype example of amphipathic CPP. We conducted a thorough analysis of the self-aggregation of TP10, its secondary structure, and revealed details of its interaction with DNA. We employed atomic force microscopy-based nanospectroscopy to obtain single-particle data that revealed details of the conformations assumed by the peptide and DNA in the inner structure of nanoassemblies with different morphologies. Our structural results showed that TP10 exhibits self-aggregation capabilities and a strong propensity to assume α-helical conformations upon association with DNA strands. This behavior contrasts with that of prototype CPPs such as TAT-HIV and penetratin, potentially explaining why peptiplexes based on transportans demonstrate increased uptake compared to their cationic counterparts. Also, single-particle spectroscopy indicated that the secondary structure in peptiplexes is strongly dependent on the size and shape, reinforcing that controlled self-assembly is crucial for optimizing CPP-based nanotherapeutics. The peptiplexes were also evaluated for cell uptake efficiency and kinetics, revealing a logistic time–response increase in permeability, suggestive of cooperativeness. We anticipate that the findings presented here might contribute to refining structure–activity relationships of peptiplexes based on amphipathic CPPs, assisting the optimization of products based on this relevant class of CPPs with potential applications in therapeutic delivery systems.