Mechanism of the Cell-Penetrating Peptide Transportan 10 Permeation of Lipid Bilayers

Abstract

The mechanism of the interaction between the cell-penetrating peptide transportan 10 (tp10) and phospholipid membranes was investigated. Tp10 induces graded release of the contents of phospholipid vesicles. The kinetics of peptide association with vesicles and peptide-induced dye efflux from the vesicle lumen were examined experimentally by stopped-flow fluorescence. The experimental kinetics were analyzed by directly fitting to the data the numerical solution of mathematical kinetic models. A very good global fit was obtained using a model in which tp10 binds to the membrane surface and perturbs it because of the mass imbalance thus created across the bilayer. The perturbed bilayer state allows peptide monomers to insert transiently into its hydrophobic core and cross the membrane, until the peptide mass imbalance is dissipated. In that transient state tp10 "catalyzes" dye efflux from the vesicle lumen. These conclusions are consistent with recent reports that used molecular dynamics simulations to study the interactions between peptide antimicrobials and phospholipid bilayers. A thermodynamic analysis of tp10 binding and insertion in the bilayer using water-membrane transfer hydrophobicity scales is entirely consistent with the model proposed. A small bilayer perturbation is both necessary and sufficient to achieve very good agreement with the model, indicating that the role of the lipids must be included to understand the mechanism of cell-penetrating and antimicrobial peptides.

Current Understanding of the Mechanisms by which Membrane-Active Peptides Permeate and Disrupt Model Lipid Membranes

“…They observed that tp10 translocation and membrane pore formation appear to be two independent processes. CF-labeled tp10 was found to rapidly translocate across the lipid bilayer, possibly via a mechanism similar to that suggested by Almeida et al [71]. However the pores, which allow this rapid translocation are small.…”

Direct Cytosolic Delivery of Polar Cargo to Cells by Spontaneous Membrane-translocating Peptides

“…The mechanism of cell entry of these peptides has been widely studied (13,(17)(18)(19)(21)(22)(23). Although there is still some disagreement on the contribution of spontaneous membrane translocation, in recent years, a consensus has begun to emerge that the highly cationic CPPs (such as Tat and polyarginine) are actively taken up into cells mostly by one or more type of endocytosis (10, 12, 13, 15, 19, 21, 24 -26).…”

The Relation Between Thermodynamic and Structural Properties and Cellular Uptake of Peptides Containing Tryptophan and Arginine

“…11, 28 The helical wheel projection for R 2 W 4 R 2 , R 3 W 4 R 3 and W 3 R 4 W 3 sequences are shown in (Figure 4). According to this projection, these peptides do not show any regular structure.…”