Atomistic Molecular Simulations Suggest a Kinetic Model for Membrane Translocation by Arginine-Rich Peptides.
Arginine-rich cell penetrating peptides (ARCPPs) are known to quickly permeate cell membranes through a non-endocytotic pathway. Potential clinical applications of this facility have prompted enormous effort, both experimental and theoretical, to better understand how ARCPPs manage to overcome the prodigious thermodynamic cost of lipid bilayer permeation by these highly charged peptides. In this work we report the results of all-atom simulations, which suggest that a kinetic (rather than thermodynamic) mechanism may explain how ARCPPs are able to achieve this. Our simulations reveal that octaarginine significantly hinders the closing of membrane pores, either individually or via aggregation in the membrane pore, while octalysine (not an ARCPP) lacks this ability. Our proposed mechanism is an alternative to current attempts to explain pore-mediated translocation of ARCPPs. It asserts that ARCPPs need not lower the equilibrium thermodynamic cost of pore formation. Instead, they can achieve rapid bilayer translocation by instead slowing down the kinetics of naturally occurring thermal pores. Linking the pore lifetime to the characteristic time for peptide diffusion out of the pore, ARCPPs are able to cooperatively permeate the membrane pore.
School of Physical, Environmental and Mathematical Sciences, University of New South Wales , Canberra ACT 2600, Australia.
Delin
D
Sun
Theoretical Chemistry, Chemical Centre, Lund University , P.O. Box 124, S-221 00 Lund, Sweden.
Jan
J
Forsman
School of Physical, Environmental and Mathematical Sciences, University of New South Wales , Canberra ACT 2600, Australia.
Clifford E
CE
Woodward
D000327:Adsorption; D001120:Arginine / Q000737:chemistry*; D007700:Kinetics; D008051:Lipid Bilayers; D008956:Models, Chemical; D010455:Peptides / Q000737:chemistry*; D013816:Thermodynamics
D008051:Lipid Bilayers; D010455:Peptides; D001120:Arginine