title: Effects of dimerization of the cell-penetrating peptide Tat analog on antimicrobial activity and mechanism of bactericidal action.
abstract: The cell-penetrating peptide Tat (48-60) (GRKKRRQRRRPPQ) derived from HIV-1 Tat protein showed potent antibacterial activity (MIC: 2-8 microM). To investigate the effect of dimerization of Tat (48-60) analog, [Tat(W): GRKKRRQRRRPWQ-NH(2)], on antimicrobial activity and mechanism of bactericidal action, its dimeric peptides, di-Tat(W)-C and di-Tat(W)-K, were synthesized by a disulfide bond linkage and lysine linkage of monomeric Tat(W), respectively. From the viewpoint of a weight basis and the monomer concentration, these dimeric peptides displayed almost similar antimicrobial activity against six bacterial strains tested but acted more rapidly against Staphylococcus aureus on kinetics of bactericidal activity, compared with monomeric Tat(W). Unlike monomeric Tat(W), these dimeric peptides significantly depolarized the cytoplasmic membrane of intact S. aureus cells at MIC and induced dye leakage from bacterial-membrane-mimicking egg yolk L-alpha-phosphatidylethanolamine/egg yolk L-alpha-phosphatidyl-DL-glycerol (7:3, w/w) vesicles. Furthermore, these dimeric peptides were less effective to translocate across lipid bilayers than monomeric Tat(W). These results indicated that the dimerization of Tat analog induces a partial change in the mode of its bactericidal action from intracellular target mechanism to membrane-targeting mechanism. Collectively, our designed dimeric Tat peptides with high antimicrobial activity and rapid bactericidal activity appear to be excellent candidates for future development as novel antimicrobial agents.
authors.affiliation: Department of Bio-Materials, Graduate School and Research Center for Proteineous Materials, Chosun University, Gwangju 501-759, Korea.
authors.forename: Wan Long
authors.initials: WL
authors.lastname: Zhu
authors.forename: Song Yub
authors.initials: SY
authors.lastname: Shin
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D002942:Circular Dichroism; D015696:Gene Products, tat / Q000737:chemistry*; D006461:Hemolysis / Q000187:drug effects*; D006801:Humans; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D055503:Protein Multimerization / Q000502:physiology*; D013211:Staphylococcus aureus / Q000187:drug effects
chemical_list: D000900:Anti-Bacterial Agents; D015696:Gene Products, tat; D008051:Lipid Bilayers; D010446:Peptide Fragments