title: Detergent-type membrane fragmentation by MSI-78, MSI-367, MSI-594, and MSI-843 antimicrobial peptides and inhibition by cholesterol: a solid-state nuclear magnetic resonance study.
abstract: Multidrug resistance against the existing antibiotics is becoming a global threat, and any potential drug that can be designed using cationic antimicrobial peptides (AMP) could be an alternate solution to alleviate this existing problem. The mechanism of action of killing bacteria by an AMP differs drastically in comparison to that of small molecule antibiotics. The main target of AMPs is to interact with the lipid bilayer of the cell membrane and disrupt it to kill bacteria. Consequently, the modes of membrane interaction that lead to the selectivity of an AMP are very important to understand. Here, we have used different membrane compositions, such as negatively charged, zwitterionic, or mixed large unilamellar vesicles (LUVs), to study the interaction of four different synthetically designed cationic, linear antimicrobial peptides: MSI-78 (commercially known as pexiganan), MSI-367, MSI-594, and MSI-843. Our solid-state nuclear magnetic resonance (NMR) experiments confirmed that the MSI peptides fragmented LUVs through a detergent-like carpet mechanism depending on the amino acid sequence of the MSI peptide and/or the membrane composition of LUVs. Interestingly, the fragmented lipid aggregates such as SUVs or micelles are sufficiently small to produce an isotropic peak in the (31)P NMR spectrum. These fragmented lipid aggregates contain only MSI peptides bestowed with lipid molecules as confirmed by NMR in conjunction with circular dichroism spectroscopy. Our results also demonstrate that cholesterol, which is present only in the eukaryotic cell membrane, inhibits the MSI-induced fragmentation of LUVs, suggesting that the MSI peptides can discriminate the bacteria and the eukaryotic cell membranes, and this selectivity could be used for further development of novel antibiotics.
authors.affiliation: †Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States.
authors.forename: Dong-Kuk
authors.initials: DK
authors.lastname: Lee
authors.affiliation: †Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States.|§Department of Biophysics, Bose Institute, P-1/12 CIT Scheme VII(M), Kolkata 700054, India.
authors.forename: Anirban
authors.initials: A
authors.lastname: Bhunia
authors.affiliation: †Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States.
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Kotler
authors.affiliation: †Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109-1055, United States.
authors.forename: Ayyalusamy
authors.initials: A
authors.lastname: Ramamoorthy
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D001419:Bacteria; D002462:Cell Membrane / Q000737:chemistry; D002784:Cholesterol / Q000737:chemistry*; D024901:Drug Resistance, Multiple, Bacterial; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry*; D053835:Unilamellar Liposomes / Q000737:chemistry*
chemical_list: D023181:Antimicrobial Cationic Peptides; C511193:MSI 594; D010455:Peptides; D053835:Unilamellar Liposomes; D002784:Cholesterol; C093828:pexiganan