title: The lantibiotic nisin induces lipid II aggregation, causing membrane instability and vesicle budding.
abstract: The antimicrobial peptide nisin exerts its activity by a unique dual mechanism. It permeates the cell membranes of Gram-positive bacteria by binding to the cell wall precursor Lipid II and inhibits cell wall synthesis. Binding of nisin to Lipid II induces the formation of large nisin-Lipid II aggregates in the membrane of bacteria as well as in Lipid II-doped model membranes. Mechanistic details of the aggregation process and its impact on membrane permeation are still unresolved. In our experiments, we found that fluorescently labeled nisin bound very inhomogeneously to bacterial membranes as a consequence of the strong aggregation due to Lipid II binding. A correlation between cell membrane damage and nisin aggregation was observed in vivo. To further investigate the aggregation process of Lipid II and nisin, we assessed its dynamics by single-molecule microscopy of fluorescently labeled Lipid II molecules in giant unilamellar vesicles using light-sheet illumination. We observed a continuous reduction of Lipid II mobility due to a steady growth of nisin-Lipid II aggregates as a function of time and nisin concentration. From the measured diffusion constants of Lipid II, we estimated that the largest aggregates contained tens of thousands of Lipid II molecules. Furthermore, we observed that the formation of large nisin-Lipid II aggregates induced vesicle budding in giant unilamellar vesicles. Thus, we propose a membrane permeation mechanism that is dependent on the continuous growth of nisin-Lipid II aggregation and probably involves curvature effects on the membrane.
authors.affiliation: Institute for Physical and Theoretical Chemistry, Pharmaceutical Microbiology Unit, Rheinische Friedrich-Wilhelms University Bonn, Bonn, Germany. Electronic address: kscherer@uni-bonn.de.
authors.forename: Katharina M
authors.initials: KM
authors.lastname: Scherer
authors.affiliation: Institute for Physical and Theoretical Chemistry, Pharmaceutical Microbiology Unit, Rheinische Friedrich-Wilhelms University Bonn, Bonn, Germany.
authors.forename: Jan-Hendrik
authors.initials: JH
authors.lastname: Spille
authors.affiliation: Institute for Medical Microbiology, Immunology and Parasitology, Pharmaceutical Microbiology Unit, Rheinische Friedrich-Wilhelms University Bonn, Bonn, Germany.
authors.forename: Hans-Georg
authors.initials: HG
authors.lastname: Sahl
authors.affiliation: Institute for Medical Microbiology, Immunology and Parasitology, Pharmaceutical Microbiology Unit, Rheinische Friedrich-Wilhelms University Bonn, Bonn, Germany.
authors.forename: Fabian
authors.initials: F
authors.lastname: Grein
authors.affiliation: Institute for Physical and Theoretical Chemistry, Pharmaceutical Microbiology Unit, Rheinische Friedrich-Wilhelms University Bonn, Bonn, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Kubitscheck
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001412:Bacillus subtilis / Q000187:drug effects / Q000378:metabolism; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism; D022162:Cytoplasmic Vesicles / Q000187:drug effects* / Q000378:metabolism; D008563:Membrane Lipids / Q000737:chemistry / Q000378:metabolism; D009561:Nisin / Q000494:pharmacology*; D053835:Unilamellar Liposomes / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D008563:Membrane Lipids; D053835:Unilamellar Liposomes; D009561:Nisin