title: Antimicrobial activity and interactions of cationic peptides derived from Galleria mellonella cecropin D-like peptide with model membranes.
abstract: Antimicrobial peptides are effector molecules of the innate immune system against invading pathogens. The cationic charge in their structures has a strong correlation with antimicrobial activity, being responsible for the initial electrostatic interaction between peptides and the anionic microbial surface. This paper contains evidence that charge modification in the neutral peptide Gm cecropin D-like (WT) improved the antimicrobial activity of the modified peptides. Two cationic peptides derived from WT sequence named as ΔM1 and ΔM2, with net charge of +5 and +9, respectively, showed at least an eightfold increase in their antimicrobial activity in comparison to WT. The mechanism of action of these peptides was investigated using small unilamellar vesicles (SUVs) as model membranes. To study permeabilization effects of the peptides on cell membranes, entrapped calcein liposomes were used and the results showed that all peptides induced calcein release from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) SUVs, whereas in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), POPC/POPG and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine (POPE)/POPG SUVs, only ΔM1 and ΔM2 induced a notable permeabilization. In addition, interactions of these peptides with phospholipids at the level of the glycerol backbone and hydrophobic domain were studied through observed changes in generalized polarization and fluorescence anisotropy using probes such as Laurdan and DPH, respectively. The results suggest that peptides slightly ordered the bilayer structure at the level of glycerol backbone and on the hydrophobic core in 1,2-dimyristoyl-sn-glycero-3-phosphoglycerol (DMPG) SUVs, whereas in 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/DMPG SUVs, only ΔM1 and ΔM2 peptides increased the order of bilayers. Thus, peptides would be inducing clustering of phospholipids creating phospholipid domains with a higher phase transition temperature.
authors.affiliation: Instituto de Química, Department of Chemistry, Universidad de Antioquia, Grupo de Bioquímica Estructural de Macromoléculas, Medellín, Colombia.
authors.forename: José
authors.initials: J
authors.lastname: Oñate-Garzón
authors.affiliation: Instituto de Química, Department of Chemistry, Universidad de Antioquia, Grupo de Bioquímica Estructural de Macromoléculas, Medellín, Colombia.
authors.forename: Marcela
authors.initials: M
authors.lastname: Manrique-Moreno
authors.affiliation: Departamento de Física, Universidad de los Andes, Grupo de Biofísica, Bogotá, Colombia.
authors.forename: Steven
authors.initials: S
authors.lastname: Trier
authors.affiliation: Departamento de Física, Universidad de los Andes, Grupo de Biofísica, Bogotá, Colombia.
authors.forename: Chad
authors.initials: C
authors.lastname: Leidy
authors.affiliation: Escuela de Química, Facultad de Ciencias, Universidad Industrial de Santander, Santander, Colombia.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Torres
authors.affiliation: Instituto de Química, Department of Chemistry, Universidad de Antioquia, Grupo de Bioquímica Estructural de Macromoléculas, Medellín, Colombia.
authors.forename: Edwin
authors.initials: E
authors.lastname: Patiño
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects; D005452:Fluoresceins / Q000378:metabolism; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D008081:Liposomes; D008560:Membrane Fluidity; D008567:Membranes, Artificial; D008826:Microbial Sensitivity Tests; D009036:Moths / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D010713:Phosphatidylcholines / Q000737:chemistry; D010715:Phosphatidylglycerols / Q000737:chemistry; D010743:Phospholipids / Q000737:chemistry
chemical_list: D023181:Antimicrobial Cationic Peptides; D005452:Fluoresceins; D008081:Liposomes; D008567:Membranes, Artificial; D010455:Peptides; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D010743:Phospholipids; C000618140:cecropin D-like peptide; C060037:1-palmitoyl-2-oleoylglycero-3-phosphoglycerol; C028694:1-palmitoyl-2-oleoylphosphatidylcholine; C007740:fluorexon