Membrane interactions of two arginine-rich peptides with different cell internalization capacities

Abstract

Cell penetrating peptides (CPPs) can cross cell membranes in a receptor independent manner and transport cargo molecules inside cells. These peptides can internalize through two independent routes: energy dependent endocytosis and energy independent translocation across the membrane, but the exact mechanisms are still unknown. The interaction of the CPP with different membrane components is certainly a preliminary key point that triggers internalization, such as the interaction with lipids to lead to the translocation process. In this study, we used two arginine-rich peptides, RW9 (RRWWRRWRR-NH2), which is a potent CPP, and RL9 (RRLLRRLRR-NH2) that, although binding tightly and accumulating on membranes, does not enter into cells. Using a set of experimental and theoretical techniques, we studied the binding, insertion and orientation of the peptides into different model membranes as well as the subsequent membrane reorganization. Herein we show that although the two peptides had rather similar behavior regarding lipid membrane interaction, subtle differences were found concerning the depth of peptide insertion, effect on the lipid chain ordering and kinetics of peptide insertion in the membrane, which altogether might explain their different cell internalization capacities. Molecular dynamics simulation studies show that some peptide molecules flipped their orientation over the course of the simulation such that the hydrophobic residues penetrated deeper in the lipid core region while Arg-residues maintained H-bonds with the lipid headgroups, serving as a molecular hinge in a conformation that appeared to correspond to the equilibrium one.

The role of tryptophans on the cellular uptake and membrane interaction of arginine-rich cell penetrating peptides

“…Green 3]. 48 They found that the Tat protein from HIV-1 was internalized into 49 cells and Vives et al, found in 1997 the minimal sequence that was 50 responsible for the protein internalization [4]. Following this finding, 51 penetratin was discovered in 1994 by the group of Alain Prochiantz 52 [5].…”

Cationic amphipathic peptides KT2 and RT2 are taken up into bacterial cells and kill planktonic and biofilm bacteria

“…290ability to bury deeper in lipid bilayers however would not imply better 291 translocation of a peptide[23,24]. Indeed peptides with higher 292 hydrophobicity might have weaker penetrating ability since peptides 293 interact more strongly with the lipid core of the liposome[25].…”

“…At 23 their minimal inhibitory concentrations (MICs), these peptides completely killed cells of multidrug-resistant, 24 enterohemorrhagic pathogen Escherichia coli O157:H7 within 1-5 min. In addition, both peptides exhibited 25 anti-biofilm activity at sub-MIC levels.…”

A Virus-Mimicking, Endosomolytic Liposomal System for Efficient, pH-Triggered Intracellular Drug Delivery

“…1B) is in agreement with the results of other researchers demonstrating that a deep polymer insertion into the bilayer is not always required for membrane destabilization. 30 When increasing the cholesterol proportion in the liposomal formulation, the enhancement of membrane rigidity and elasticity as well as the adsorption of polymer on the liposomal surface lead to a lower leakage at pH 7.4. …”