title: Effect of drastic sequence alteration and D-amino acid incorporation on the membrane binding behavior of lytic peptides.
abstract: The amphipathic alpha-helix is a common motif found in many cell lytic peptides including antimicrobial peptides. We have recently shown that significantly altering the amphipathic structure of a lytic peptide by reshuffling its sequence and/or replacing a few l-amino acids with their D-enantiomers did not significantly affect the antimicrobial activity of the peptides nor their ability to bind and permeate negatively charged (PE/PG) membranes. However, a pronounced effect was observed regarding their hemolytic activity and their ability to bind and permeate zwitterionic (PC/Cho) membranes. To shed light on these findings, here we used surface plasmon resonance (SPR) with mono- and bilayer membranes. We found that the L-amino acid (aa) peptides bound 10-25-fold stronger to PC/Cho bilayers compared with monolayers, whereas the diastereomers bound similarly to both membranes. A two-state reaction model analysis of the data indicated that this difference is due to the insertion of the L-aa peptides into the PC/Cho bilayers, whereas the diastereomers are surface-localized. In contrast, only an approximately 2-fold difference was found with negatively charged membranes. Changes in the amphipathicity markedly affected only the insertion of the L-aa peptides into PC/Cho bilayers. Furthermore, whereas the all-L-aa peptides bound similarly to the PC/Cho and PE/PG membranes, the diastereomers bound approximately 100-fold better to PE/PG compared with PC/Cho membranes, and selectivity was determined only in the first binding step. The effect of the peptides on the lipid order determined by using ATR-FTIR studies supported these findings. Besides shedding light on the mode of action of these peptides, the present study demonstrates SPR as a powerful tool to differentiate between non-cell-selective compared with bacteria-selective peptides, based on differences in their membrane binding behavior.
authors.affiliation: Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Niv
authors.initials: N
authors.lastname: Papo
authors.forename: Yechiel
authors.initials: Y
authors.lastname: Shai
mesh_terms: D000595:Amino Acid Sequence; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D002784:Cholesterol / Q000737:chemistry; D008051:Lipid Bilayers; D008956:Models, Chemical; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D010713:Phosphatidylcholines / Q000737:chemistry / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000737:chemistry / Q000378:metabolism; D010715:Phosphatidylglycerols / Q000737:chemistry / Q000378:metabolism; D010743:Phospholipids / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D017550:Spectroscopy, Fourier Transform Infrared; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D020349:Surface Plasmon Resonance
chemical_list: D008051:Lipid Bilayers; D010455:Peptides; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010715:Phosphatidylglycerols; D010743:Phospholipids; C483858:phosphatidylethanolamine; D002784:Cholesterol