Vesicle membrane interactions of penetratin analogues.
Reports on serious artifacts associated with the use of cell fixation in studies of the cellular uptake of cell-penetrating peptides, also denoted protein transduction domains, have demonstrated the need for a reevaluation of the current understanding of peptide-mediated cellular delivery of large, hydrophilic molecules. In a recent study on the internalization in unfixed cells of penetratin and its analogues in which tryptophans are substituted for phenylalanines (Pen2W2F), lysines for arginines (PenArg), and arginines for lysines (PenLys), we revealed large dissimilarities in cell interactions among the peptides [Thorén et al. (2003) Biochem. Biophys. Res. Commun. 307, 100-107]. We here investigated possible correlations with their respective affinities for the lipid membranes of large unilamellar vesicles. The variations found in membrane affinity correlated qualitatively with differences in hydrophobicity among the peptides but were by far too small to account for the striking differences in cell membrane binding. Interestingly, we found that the inclusion of a small fraction of lipids conjugated to poly(ethylene glycol) (PEG) in the vesicles both stabilized the vesicle dispersion against peptide-induced aggregation and, furthermore, enhanced the binding of the peptides to the membrane. By use of PEG-conjugated lipids, it could be shown that vesicle aggregation drives an alpha-helix to beta-sheet conformational transition for these peptides. A similar transition was discovered at submicellar concentrations of sodium dodecyl sulfate in aqueous solution for all peptides except PenLys. Finally, significant changes of the contributions to CD spectra from aromatic residues due to their insertion into the membrane were observed.
Department of Chemistry and Bioscience, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden. danielp@phc.chalmers.se
Daniel
D
Persson
Per E G
PE
Thorén
Per
P
Lincoln
Bengt
B
Nordén
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D051943:Antennapedia Homeodomain Protein; D001120:Arginine / Q000378:metabolism; D002352:Carrier Proteins / Q000138:chemical synthesis / Q000378:metabolism*; D057846:Cell-Penetrating Peptides; D002942:Circular Dichroism; D029721:Drosophila Proteins / Q000138:chemical synthesis / Q000378:metabolism; D018398:Homeodomain Proteins / Q000138:chemical synthesis / Q000378:metabolism; D008081:Liposomes; D008239:Lysine / Q000378:metabolism; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000138:chemical synthesis / Q000378:metabolism; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000378:metabolism; D010715:Phosphatidylglycerols / Q000378:metabolism; D011092:Polyethylene Glycols / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D020033:Protein Isoforms / Q000138:chemical synthesis / Q000378:metabolism; D055672:Static Electricity; D014157:Transcription Factors / Q000138:chemical synthesis / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism
D051943:Antennapedia Homeodomain Protein; D002352:Carrier Proteins; D057846:Cell-Penetrating Peptides; D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D008081:Liposomes; D009687:Nuclear Proteins; D010446:Peptide Fragments; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010715:Phosphatidylglycerols; D020033:Protein Isoforms; D014157:Transcription Factors; C107570:polyethylene glycol-distearoylphosphatidylethanolamine; D011092:Polyethylene Glycols; C051388:1,2-dioleoyl-sn-glycero-3-phosphoglycerol; D014364:Tryptophan; D001120:Arginine; C414409:penetratin; C017251:1,2-oleoylphosphatidylcholine; D008239:Lysine