The interaction of the cell-penetrating peptide penetratin with heparin, heparansulfates and phospholipid vesicles investigated by ESR spectroscopy.
An ESR investigation of the interaction of spin-labelled penetratin with heparin, heparansulfates and several phospholipid vesicle formulations is reported. Penetratin is a 16-aa peptide corresponding to the third helix of the Antennapedia homeodomain and belonging to the cell-penetrating peptide family. The present study shows that ESR spectroscopy can provide specific and reliable information about the mechanism of interaction of penetratin with polysaccharides and lipids, at a molecular level. The study showed that: (i) heparin and heparansulfates specifically interact with spin-labelled penetratin and promote peptide aggregation and concentration on their molecular surface; (ii) penetratin does not interact with neutral lipids, whereas it enters negatively charged lipid bilayers; (iii) cholesterol plays a negative effect on the insertion of penetratin into the lipid membrane; (iv) the interaction of penetratin with lipid vesicles is strongly dependent on lipid concentration. In a low lipid regime, penetratin associates with the polar heads of phospholipids and aggregates on the membrane surface; once the lipid concentration attains a threshold, the peptide enters the lipid bilayer. This step is characterized by reduced peptide mobility and partial disaggregation.It has been shown that ESR spectroscopy is a valuable investigation tool in studies related to the still unclear mechanism of the internalization process.
Ghibaudi
E
E
Dipartimento Chimica I.F.M., Università di Torino, Via Giuria 7, 10125 Torino, Italia. elena.ghibaudi@unito.it
Boscolo
B
B
Inserra
G
G
Laurenti
E
E
Traversa
S
S
Barbero
L
L
Ferrari
R P
RP
D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D057846:Cell-Penetrating Peptides; D002784:Cholesterol / Q000378:metabolism; D004578:Electron Spin Resonance Spectroscopy; D006493:Heparin / Q000737:chemistry / Q000378:metabolism*; D006497:Heparan Sulfate / Q000737:chemistry / Q000378:metabolism*; D008024:Ligands; D008081:Liposomes; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding
D002352:Carrier Proteins; D057846:Cell-Penetrating Peptides; D002784:Cholesterol; D006493:Heparin; D006497:Heparan Sulfate; D008024:Ligands; D008081:Liposomes; D010743:Phospholipids; C414409:penetratin