title: The membrane action mechanism of analogs of the antimicrobial peptide Buforin 2.
abstract: Previously, the antimicrobial peptides BF2-A and BF2-B, two analogs of Buforin 2 that was hypothesized to kill bacteria by entering cells and binding nucleic acids, had been designed based on the structure-activity analysis of Buforin 2. In the present study, BF2-A and BF2-B were chemically synthesized and their activities and lipopolysaccharide affinity were assayed. To elucidate the mechanism of action with cytoplasmic membranes, we subsequently examined the membrane permeability of both peptides in detail. Both peptides showed stronger antimicrobial activities against a broad spectrum of microorganisms than their parent peptide. Interestingly, BF2-A did not cause significant membrane permeabilization for influx of ONPG into cells, and hardly caused the leakage of intracellular macromolecules, probably BF2-A slightly disturbed cell membrane causing the K(+) leakage during peptide crossing phospholipids bilayer. Electron micrographs indicated that the cell membrane treated by BF2-A was still intact within 20min. On the contrary, BF2-B obviously increased the outer and inner membrane permeability, even induced the slight leakage of macromolecules in the cytoplasm. The leakage of cytoplasmic contents was also demonstrated by the electron micrographs. The increase of membrane permeabilization explained why BF2-B displayed better antimicrobial activity and rapid killing kinetics than BF2-A.
authors.affiliation: The State Key Laboratory of Food Science and Technology, JiangNan University, Wuxi, 214122, Jiangsu Province, China.
authors.forename: Gang
authors.initials: G
authors.lastname: Hao
authors.forename: Yong-Hui
authors.initials: YH
authors.lastname: Shi
authors.forename: Ya-Li
authors.initials: YL
authors.lastname: Tang
authors.forename: Guo-Wei
authors.initials: GW
authors.lastname: Le
mesh_terms: D000890:Anti-Infective Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure; D002463:Cell Membrane Permeability / Q000187:drug effects; D002942:Circular Dichroism; D004926:Escherichia coli / Q000187:drug effects / Q000648:ultrastructure; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D008070:Lipopolysaccharides / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D046529:Microscopy, Electron, Transmission; D011188:Potassium / Q000378:metabolism; D011485:Protein Binding; D011506:Proteins / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D000890:Anti-Infective Agents; D008070:Lipopolysaccharides; D011506:Proteins; C097849:buforin II; D011188:Potassium