The homeodomain derived peptide Penetratin induces curvature of fluid membrane domains.
BACKGROUND
Protein membrane transduction domains that are able to cross the plasma membrane are present in several transcription factors, such as the homeodomain proteins and the viral proteins such as Tat of HIV-1. Their discovery resulted in both new concepts on the cell communication during development, and the conception of cell penetrating peptide vectors for internalisation of active molecules into cells. A promising cell penetrating peptide is Penetratin, which crosses the cell membranes by a receptor and metabolic energy-independent mechanism. Recent works have claimed that Penetratin and similar peptides are internalized by endocytosis, but other endocytosis-independent mechanisms have been proposed. Endosomes or plasma membranes crossing mechanisms are not well understood. Previously, we have shown that basic peptides induce membrane invaginations suggesting a new mechanism for uptake, "physical endocytosis".


RESULTS
Herein, we investigate the role of membrane lipid phases on Penetratin induced membrane deformations (liquid ordered such as in "raft" microdomains versus disordered fluid "non-raft" domains) in membrane models. Experimental data show that zwitterionic lipid headgroups take part in the interaction with Penetratin suggesting that the external leaflet lipids of cells plasma membrane are competent for peptide interaction in the absence of net negative charges. NMR and X-ray diffraction data show that the membrane perturbations (tubulation and vesiculation) are associated with an increase in membrane negative curvature. These effects on curvature were observed in the liquid disordered but not in the liquid ordered (raft-like) membrane domains.


CONCLUSIONS
The better understanding of the internalisation mechanisms of protein transduction domains will help both the understanding of the mechanisms of cell communication and the development of potential therapeutic molecular vectors. Here we showed that the membrane targets for these molecules are preferentially the fluid membrane domains and that the mechanism involves the induction of membrane negative curvature. Consequences on cellular uptake are discussed.
Lamazière
Antonin
A
INSERM, UMR538, CHU Saint Antoine, Paris, France.
Wolf
Claude
C
Lambert
Olivier
O
Chassaing
Gérard
G
Trugnan
Germain
G
Ayala-Sanmartin
Jesus
J
D001703:Biophysics / Q000379:methods; D002352:Carrier Proteins / Q000494:pharmacology*; D002462:Cell Membrane / Q000378:metabolism*; D057846:Cell-Penetrating Peptides; D004705:Endocytosis; D008055:Lipids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008563:Membrane Lipids / Q000737:chemistry; D021962:Membrane Microdomains / Q000378:metabolism; D008954:Models, Biological; D010455:Peptides / Q000737:chemistry; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D012542:Scattering, Radiation; D014961:X-Ray Diffraction; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000378:metabolism
D002352:Carrier Proteins; D057846:Cell-Penetrating Peptides; D008055:Lipids; D008563:Membrane Lipids; D010455:Peptides; D054322:tat Gene Products, Human Immunodeficiency Virus; C414409:penetratin