title: The interaction of an antimicrobial decapeptide with phospholipid vesicles.
abstract: Previously, by using combinatorial peptide libraries, we have identified activity-optimized decapeptide (KSL, KKVVFKVKFK-NH(2)), which exhibited a broad spectrum of the activity against bacteria and fungi without hemolytic activity. In order to examine lipid requirements and to understand the mode of KSL action, we investigated interactions of the peptide with vesicles consisting of various lipid compositions. KSL increased the permeability of negatively charged but not zwitterionic phospholipid membranes, and the leakage was independent on the size of encapsulated molecules (calcein, 1-aminonaphthalene-3,6,8-trisulfonic acid (ANTS)/N,N'-p-xylene bis(pyridinium) bromide (DPX), and fluorescein isothiocyanate (FITC)-dextran with different molecular weight), indicating that the peptide did not form pores or channels in this leakage process. KSL ability to permeabilize vesicles with negatively charged surface was dramatically reduced upon the addition of zwitterionic phospholipid rather than cholesterol, which revealed that the surface charge of lipid membranes played a major role in the activity and selectivity of KSL. Moreover, KSL diastereomer did not increase the permeability of negatively charged vesicles, indicating that the secondary structure of KSL was also required for membrane perturbation activity. Interestingly, KSL had an ability to cause aggregation and subsequent fusion of the acidic vesicles, which seemed to be related to the biological action. Structural studies performed by circular dichroism (CD) spectroscopy indicated that in the presence of acidic vesicles, the beta sheet structure of KSL must be required for the ability to (1) induce a leakage of dye from the acidic vesicles (2) to fuse the acidic vesicles.
authors.affiliation: Charmzone Biomaterial Research Center, #607 Byucsan Technopia, 434-6 Sangdaewon-dong, Jungwon-gu, Seongnam, Kyeonggi-do, South Korea.
authors.forename: Myeong-Jun
authors.initials: MJ
authors.lastname: Choi
authors.forename: Sun Hee
authors.initials: SH
authors.lastname: Kang
authors.forename: Seunghee
authors.initials: S
authors.lastname: Kim
authors.forename: Jin-Soo
authors.initials: JS
authors.lastname: Chang
authors.forename: Sung Soo
authors.initials: SS
authors.lastname: Kim
authors.forename: Hyeongjin
authors.initials: H
authors.lastname: Cho
authors.forename: Keun-Hyeung
authors.initials: KH
authors.lastname: Lee
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D000935:Antifungal Agents / Q000737:chemistry*; D002942:Circular Dichroism; D047630:Depsipeptides / Q000737:chemistry*; D007700:Kinetics; D008081:Liposomes / Q000737:chemistry*; D008561:Membrane Fusion; D019151:Peptide Library; D010539:Permeability; D010743:Phospholipids / Q000737:chemistry*; D017433:Protein Structure, Secondary; D013329:Structure-Activity Relationship
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D047630:Depsipeptides; D008081:Liposomes; D019151:Peptide Library; D010743:Phospholipids; C119235:lysyl-lysyl-valyl-valyl-phenylalanyl-lysyl-valyl-lysyl-phenylalanyl-lysine