Soraya Omardien1, Jan W Drijfhout2, Frédéric M Vaz3, Michaela Wenzel4, Leendert W Hamoen4, Sebastian A J Zaat5, Stanley Brul6. 1. Swammerdam Institute for Life Sciences, Department of Molecular Biology and Microbial Food Safety, University of Amsterdam, Amsterdam, The Netherlands. 2. Leiden University Medical Centre (LUMC), Leiden University, Leiden, The Netherlands. 3. Laboratory Genetic Metabolic Diseases, Academic Medical Centre, Amsterdam, The Netherlands. 4. Swammerdam Institute for Life Sciences, Department of Bacterial Cell Biology and Physiology, University of Amsterdam, Amsterdam, The Netherlands. 5. Department of Medical Microbiology, Amsterdam Infection and Immunity Institute, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands. 6. Swammerdam Institute for Life Sciences, Department of Molecular Biology and Microbial Food Safety, University of Amsterdam, Amsterdam, The Netherlands. Electronic address: s.brul@uva.nl.
Abstract
BACKGROUND: Amphipathic cationic antimicrobial peptides (AMPs) TC19 and TC84, derived from the major AMPs of human blood platelets, thrombocidins, and Bactericidal Peptide 2 (BP2), a synthetic designer peptide showed to perturb the membrane of Bacillus subtilis. We aimed to determine the means by which the three AMPs cause membrane perturbation in vivo using B. subtilis and to evaluate whether the membrane alterations are dependent on the phospholipid composition of the membrane. METHODS: Physiological analysis was employed using Alexa Fluor 488 labelled TC84, various fluorescence dyes, fluorescent microscopy techniques and structured illumination microscopy. RESULTS: TC19, TC84 and BP2 created extensive fluidity domains in the membrane that are permeable, thus facilitating the entering of the peptides and the leakage of the cytosol. The direct interaction of the peptides with the bilayer create the fluid domains. The changes caused in the packing of the phospholipids lead to the delocalization of membrane bound proteins, thus contributing to the cell's destruction. The changes made to the membrane appeared to be not dependent on the composition of the phospholipid bilayer. CONCLUSIONS: The distortion caused to the fluidity of the membrane by the AMPs is sufficient to facilitate the entering of the peptides and leakage of the cytosol. GENERAL SIGNIFICANCE: Here we show in vivo that cationic AMPs cause "membrane leaks" at the site of membrane insertion by altering the organization and fluidity of the membrane. Our findings thus contribute to the understanding of the membrane perturbation characteristic of cationic AMPs.
BACKGROUND: Amphipathic cationic antimicrobial peptides (AMPs) TC19 and TC84, derived from the major AMPs of human blood platelets, thrombocidins, and Bactericidal Peptide 2 (BP2), a synthetic designer peptide showed to perturb the membrane of Bacillus subtilis. We aimed to determine the means by which the three AMPs cause membrane perturbation in vivo using B. subtilis and to evaluate whether the membrane alterations are dependent on the phospholipid composition of the membrane. METHODS: Physiological analysis was employed using Alexa Fluor 488 labelled TC84, various fluorescence dyes, fluorescent microscopy techniques and structured illumination microscopy. RESULTS: TC19, TC84 and BP2 created extensive fluidity domains in the membrane that are permeable, thus facilitating the entering of the peptides and the leakage of the cytosol. The direct interaction of the peptides with the bilayer create the fluid domains. The changes caused in the packing of the phospholipids lead to the delocalization of membrane bound proteins, thus contributing to the cell's destruction. The changes made to the membrane appeared to be not dependent on the composition of the phospholipid bilayer. CONCLUSIONS: The distortion caused to the fluidity of the membrane by the AMPs is sufficient to facilitate the entering of the peptides and leakage of the cytosol. GENERAL SIGNIFICANCE: Here we show in vivo that cationic AMPs cause "membrane leaks" at the site of membrane insertion by altering the organization and fluidity of the membrane. Our findings thus contribute to the understanding of the membrane perturbation characteristic of cationic AMPs.