Differences in DNA Condensation and Release by Lysine and Arginine Homopeptides Govern Their DNA Delivery Efficiencies

Abstract

Designing of nanocarriers that can efficiently deliver therapeutic DNA payload and allow its smooth intracellular release for transgene expression is still a major constraint. The optimization of DNA nanocarriers requires thorough understanding of the chemical and structural characteristics of the vector-nucleic acid complexes and its correlation with the cellular entry, intracellular state and transfection efficiency. L-lysine and L-arginine based cationic peptides alone or in conjugation with other vectors are known to be putative DNA delivery agents. Here we have used L-lysine and L-arginine homopeptides of three different lengths and probed their DNA condensation and release properties by using a multitude of biophysical techniques including fluorescence spectroscopy, gel electrophoresis and atomic force microscopy. Our results clearly showed that although both lysine and arginine based homopeptides condense DNA via electrostatic interactions, they follow different pattern of DNA condensation and release in vitro. While lysine homopeptides condense DNA to form both monomolecular and multimolecular complexes and show differential release of DNA in vitro depending on the peptide length, arginine homopeptides predominantly form multimolecular complexes and show complete DNA release for all peptide lengths. The cellular uptake of the complexes and their intracellular state (as observed through flow cytometry and fluorescence microscopy) seem to be controlled by the peptide chemistry. The difference in the transfection efficiency of lysine and arginine homopeptides has been rationalized in light of these observations.

Polyarginine Molecular Weight Determines Transfection Efficiency of Calcium Condensed Complexes

“…Short peptides containing only arginine have the ability to translocate through cell membranes. 1, 9, 24, 29–33 Furthermore, polymers or CPPs with some of their residues altered with arginine or the guanidine group displayed highly enhanced transfection efficiency. 32, 34 …”

Reduction-responsive cross-linked stearyl peptide for effective delivery of plasmid DNA

“…7,8 In particular, its ability to condense DNA with the positive charge and control DNA release make it possible to use polyarginine as an intracellular delivery vector for plasmid DNA (pDNA). 9 In addition, histidine has a proton sponge effect, thus making it possible to enhance the endosomal escape rate by increasing the pH of the endosomes, leading to osmotic swelling and bursting. 10,11 It was reported that stearylation could improve intracellular uptake and endosomal escape.…”

Bioreducible Polymers As a Determining Factor for Polyplex Decomplexation Rate and Transfection

“…6, 14, 15 Thus, to facilitate polyanion-induced decomplexation of polyplexes especially in intracellular environments, degradable polymers responding to acidic pHs in the endolysosomes 16 or glutathione in the cytoplasm and the nucleus 14, 17, 18 have been developed. These polyplexes resulted in improved transfection efficiency.…”