title: Amphipathic alpha-helical peptide, HP (2-20), and its analogues derived from Helicobacter pylori: pore formation mechanism in various lipid compositions.
abstract: In a previous study, we determined that HP(2-20) (residues 2-20 of parental HP derived from the N-terminus of Helicobacter pylori Ribosomal Protein L1) and its analogue, HPA3, exhibit broad-spectrum antimicrobial activity. The primary objective of the present study was to gain insight into the relevant mechanisms of action using analogues of HP(2-20) together with model liposomes of various lipid compositions and electron microscopy. We determined that these analogues, HPA3 and HPA3NT3, exert potent antibacterial effects in low-salt buffer and antifungal activity against chitin-containing fungi, while having little or no hemolytic activity or cytotoxicity against mammalian cell lines. Our examination of the interaction of HP(2-20) and its analogues with liposomes showed that the peptides disturb both neutral and negatively-charged membranes, as demonstrated by the release of encapsulated fluorescent markers. The release of fluorescent markers induced by HP(2-20) and its analogues was inversely related to marker size. The pore created by HP(2-20) shows that the radius is approximately 1.8 nm, whereas HPA3, HPA3NT3, and melittin have apparent radii between 3.3 and 4.8 nm. Finally, as shown by electron microscopy, the liposomes and various microbial cells treated with HPA3 and HPA3NT3 showed oligomerization and blebbing similar to that seen with melittin, while HP(2-20) exhibited flabbiness. These results suggest that HP(2-20) may exert its antibiotic effects through a small pore (about 1.8 nm), whereas HPA3 and HPA3NT3 formed pores of a size consistent with those formed by melittin.
authors.affiliation: Research Center for Proteineous Materials (RCPM), Chosun University, Gwangju, Korea.
authors.forename: Seong-Cheol
authors.initials: SC
authors.lastname: Park
authors.forename: Mi-Hyun
authors.initials: MH
authors.lastname: Kim
authors.forename: Mohammed Akhter
authors.initials: MA
authors.lastname: Hossain
authors.forename: Song Yub
authors.initials: SY
authors.lastname: Shin
authors.forename: Yangmee
authors.initials: Y
authors.lastname: Kim
authors.forename: Lorenzo
authors.initials: L
authors.lastname: Stella
authors.forename: John D
authors.initials: JD
authors.lastname: Wade
authors.forename: Yoonkyung
authors.initials: Y
authors.lastname: Park
authors.forename: Kyung-Soo
authors.initials: KS
authors.lastname: Hahm
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000935:Antifungal Agents / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D001419:Bacteria / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002473:Cell Wall / Q000737:chemistry / Q000187:drug effects; D002686:Chitin / Q000378:metabolism; D002942:Circular Dichroism; D016480:Helicobacter pylori / Q000737:chemistry*; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D008055:Lipids / Q000737:chemistry*; D008070:Lipopolysaccharides / Q000378:metabolism; D008555:Melitten / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D008567:Membranes, Artificial; D008826:Microbial Sensitivity Tests; D010446:Peptide Fragments / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D010455:Peptides / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D010457:Peptidoglycan / Q000378:metabolism; D010539:Permeability / Q000187:drug effects; D020836:Protein Structure, Quaternary; D012269:Ribosomal Proteins / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D013104:Spheroplasts / Q000187:drug effects / Q000648:ultrastructure; D015003:Yeasts / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D023181:Antimicrobial Cationic Peptides; C530859:HPA3 peptide; D036341:Intercellular Signaling Peptides and Proteins; D008055:Lipids; D008070:Lipopolysaccharides; D008567:Membranes, Artificial; D010446:Peptide Fragments; D010455:Peptides; D010457:Peptidoglycan; D012269:Ribosomal Proteins; D002686:Chitin; C077195:helical erythrocyte lysing peptide; D008555:Melitten