title: N-terminal aromatic residues closely impact the cytolytic activity of cupiennin 1a, a major spider venom peptide.
abstract: Cupiennins are small cationic α-helical peptides from the venom of the ctenid spider Cupiennius salei which are characterized by high bactericidal as well as hemolytic activities. To gain insight into the determinants responsible for the broad cytolytic activities, two analogues of cupiennin 1a with different N-terminal hydrophobicities were designed. The insecticidal, bactericidal and hemolytic activities of these analogues were assayed and compared to the native peptide. Specifically, substitution of two N-terminal Phe residues by Ala results in less pronounced insecticidal and cytolytic activity, whereas a substitution by Lys reduces strongly its bactericidal activity and completely diminishes its hemolytic activity up to very high tested concentrations. Biophysical analyses of peptide/bilayer membrane interactions point to distinct interactions of the analogues with lipid bilayers, and dependence upon membrane surface charge. Indeed, we find that lower hemolytic activity was correlated with less surface association of the analogues. In contrast, our data indicate that the reduced bactericidal activity of the two cupiennin 1a analogues likely correspond to greater bilayer-surface localization of the peptides. Overall, ultimate insertion and destruction of the host cell membrane is highly dependent on the presence of Phe-2 and Phe-6 (Cu 1a) or Leu-6 (Cu 2a) in the N-terminal sequences of native cupiennins.
authors.affiliation: Institute of Ecology and Evolution, University of Bern, Baltzerstrasse 6, CH-3012 Bern, Switzerland. Electronic address: lucia.kuhn@iee.unibe.ch.
authors.forename: Lucia
authors.initials: L
authors.lastname: Kuhn-Nentwig
authors.forename: Tania
authors.initials: T
authors.lastname: Sheynis
authors.forename: Sofiya
authors.initials: S
authors.lastname: Kolusheva
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Nentwig
authors.forename: Raz
authors.initials: R
authors.lastname: Jelinek
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides; D001419:Bacteria / Q000187:drug effects; D001681:Biological Assay; D002462:Cell Membrane / Q000187:drug effects; D002942:Circular Dichroism; D004331:Drosophila melanogaster / Q000187:drug effects; D006461:Hemolysis; D006801:Humans; D007306:Insecticides / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology; D008051:Lipid Bilayers / Q000737:chemistry; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D013111:Spider Venoms / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology; D013112:Spiders
chemical_list: D000596:Amino Acids; D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D007306:Insecticides; D008051:Lipid Bilayers; D010455:Peptides; D013111:Spider Venoms; C453880:cupiennin 1a
keywords: Biomimetic membranes; Cupiennin 1a; Cytolytic peptides; Peptide-membrane interactions; Polydiacetylene vesicles