title: A Leu-Lys-rich antimicrobial peptide: activity and mechanism.
abstract: To develop novel antibiotic peptides useful as therapeutic drugs, the analogues were designed to increase not only net positive charge by Lys substitution but also hydrophobic helix region by Leu substitution from cecropin A (1-8)-magainin 2 (1-12) hybrid peptide (CA-MA). In particular, CA-MA analogue P5 (P5), designed by flexible region (GIG-->P) substitution, Lys (positions 4, 8, 14, 15) and Leu (positions 5, 6, 12, 13, 16, 17, 20) substitutions, showed an enhanced antimicrobial and antitumor activity without hemolysis. Confocal microscopy showed that P5 was located in the plasma membrane. The antibacterial effects of analogues were further confirmed by using 1,6-diphenyl-1,3,5-hexatriene as a plasma membrane probe. Flow cytometric analysis revealed that P5 acted in an energy-independent manner. This interaction is also independent of the ionic environment. Furthermore, P5 causes significant morphological alterations of the bacterial surfaces as shown by scanning electron microscopy and showed strong membrane disrupting activity when examined using liposomes (phosphatidyl choline/cholesterol; 10:1, w/w). Its potent antibiotic activity suggests that P5 is an excellent candidate as a lead compound for the development of novel antiinfective agents.
authors.affiliation: Research Center for Proteineous Materials (RCPM), Chosun University, 375 Seosuk-Dong, Dong-Ku, Kwangju, 501-759, Republic of Korea.
authors.forename: Yoonkyung
authors.initials: Y
authors.lastname: Park
authors.forename: Dong Gun
authors.initials: DG
authors.lastname: Lee
authors.forename: Seung-Hwan
authors.initials: SH
authors.lastname: Jang
authors.forename: Eun-Rhan
authors.initials: ER
authors.lastname: Woo
authors.forename: Hye Gwang
authors.initials: HG
authors.lastname: Jeong
authors.forename: Cheol-Hee
authors.initials: CH
authors.lastname: Choi
authors.forename: Kyung-Soo
authors.initials: KS
authors.lastname: Hahm
mesh_terms: D000595:Amino Acid Sequence; D000890:Anti-Infective Agents / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004161:Diphenylhexatriene; D015195:Drug Design; D005434:Flow Cytometry; D016650:Fluorescein-5-isothiocyanate; D007930:Leucine / Q000737:chemistry; D008239:Lysine / Q000737:chemistry; D008826:Microbial Sensitivity Tests; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D019810:Sodium Azide; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D000890:Anti-Infective Agents; D023181:Antimicrobial Cationic Peptides; D000970:Antineoplastic Agents; C121751:cecropin A(1-8)magainin 2(1-12); D004161:Diphenylhexatriene; D019810:Sodium Azide; D007930:Leucine; D016650:Fluorescein-5-isothiocyanate; D008239:Lysine