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      Maculatin 1.1 disrupts Staphylococcus aureus lipid membranes via a pore mechanism.

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          Abstract

          Maculatin 1.1 (Mac1) showed potent activity against Staphylococcus aureus with an MIC of 7 μM. The mode of action of Mac1 was investigated by combining assays with S. aureus cells and lipid vesicles mimicking their membrane composition. A change in Mac1 conformation was monitored by circular dichroism from random coil to ca. 70% α-helix structure in contact with vesicles. Electron micrographs of S. aureus incubated with Mac1 showed rough and rippled cell surfaces. An uptake of 65% of small (FD, 4 kDa [FD-4]) and 35% of large (RD, 40 kDa [RD-40]) fluorescent dextrans by S. aureus was observed by flow cytometry and indicate that Mac1 formed a pore of finite size. In model membranes with both dyes encapsulated together, the full release of FD-4 occurred, but only 40% of RD-40 was reached, supporting the flow cytometry results, and indicating a pore size between 1.4 and 4.5 nm. Finally, solid-state nuclear magnetic resonance showed formation of an isotropic phase signifying highly mobile lipids such as encountered in a toroidal pore structure. Overall, Mac1 is a promising antimicrobial peptide with the potent capacity to form pores in S. aureus membranes.

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          Author and article information

          Journal
          Antimicrob. Agents Chemother.
          Antimicrobial agents and chemotherapy
          American Society for Microbiology
          1098-6596
          0066-4804
          Aug 2013
          : 57
          : 8
          Affiliations
          [1 ] School of Chemistry, Bio21 Institute, The University of Melbourne, Melbourne, Victoria, Australia. msani@unimelb.edu.au
          Article
          AAC.00195-13
          10.1128/AAC.00195-13
          3719708
          23689707
          5c9d9a8e-86f4-4c14-8904-d1ffd5b861a6
          History

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