title: Inhibitory effect of short cationic homopeptides against Gram-negative bacteria.
abstract: Previous work demonstrated that Lys homopeptides with an odd number of residues (9, 11 and 13) were capable of inhibiting the growth of Gram-positive bacteria in a broader spectrum and more efficiently than those with an even number of Lys residues or Arg homopeptides of the same size. Indeed, all Gram-positive bacteria tested were totally inhibited by 11-residue Lys homopeptides. In the present work, a wide variety of Gram-negative bacteria were used to evaluate the inhibitory activity of chemically synthesized homopeptides of L-Lys and L-Arg ranging from 7 to 14 residues. Gram-negative bacteria were comparatively more resistant than Gram-positive bacteria to Lys homopeptides with an odd number of residues, but exhibited a similar inhibition pattern than on Gram-positive bacteria. CD spectra for the odd-numbered Lys homopeptides in anionic lipid dimyristoylphosphatidylglycerol, and Escherichia coli membrane extract increased polyproline II content, as compared to those measured in phosphate buffer solution. Lys and Arg homopeptides were covalently linked to rhodamine to visualize the peptide interactions with E. coli cells using confocal laser scanning microscopy. Analysis of Z-stack images showed that Arg homopeptides indeed appear to be localized intracellularly, while the Lys homopeptide is localized exclusively on the plasma membrane. Moreover, these Lys homopeptides induced membrane disruption since the Sytox fluorophore was able to bind to the DNA in E. coli cultures.
authors.affiliation: Escuela de Alimentos, Facultad de Recursos Naturales, Pontificia Universidad Católica de Valparaíso, Avenida Brasil, 2950, Valparaíso, Chile.
authors.forename: Patricio
authors.initials: P
authors.lastname: Carvajal-Rondanelli
authors.affiliation: Instituto de Química, Pontificia Universidad Católica de Valparaíso, Av. Brasil, 2950, Valparaíso, Chile.
authors.forename: Mónica
authors.initials: M
authors.lastname: Aróstica
authors.affiliation: Instituto de Biología, Pontificia Universidad Católica de Valparaíso, Av. Brasil, 2950, Valparaíso, Chile.|Fraunhofer Chile Research Foundation, Santiago, Chile.
authors.forename: Sergio Hernan
authors.initials: SH
authors.lastname: Marshall
authors.affiliation: Institute for Research in Biomedicine, Barcelona, Spain.|CIBER-BBN, Networking Centre on Bioengineering, Biomaterials and Nanomedicine, Barcelona Scientific Park, Barcelona, Spain.|Department of Organic Chemistry, University of Barcelona, Barcelona, Spain.|School of Chemistry and Physics, University of KwaZulu-Natal, 4001, Durban, South Africa.
authors.forename: Fernando
authors.initials: F
authors.lastname: Albericio
authors.affiliation: Núcleo de Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Av. Brasil, 2950, Valparaíso, Chile.
authors.forename: Claudio Andrés
authors.initials: CA
authors.lastname: Álvarez
authors.affiliation: Instituto de Biología, Pontificia Universidad Católica de Valparaíso, Av. Brasil, 2950, Valparaíso, Chile.
authors.forename: Claudia
authors.initials: C
authors.lastname: Ojeda
authors.affiliation: Instituto de Química, Pontificia Universidad Católica de Valparaíso, Av. Brasil, 2950, Valparaíso, Chile.
authors.forename: Luis Felipe
authors.initials: LF
authors.lastname: Aguilar
authors.affiliation: Núcleo de Biotecnología Curauma, Pontificia Universidad Católica de Valparaíso, Av. Brasil, 2950, Valparaíso, Chile. fanny.guzman@ucv.cl.|Fraunhofer Chile Research Foundation, Santiago, Chile. fanny.guzman@ucv.cl.
authors.forename: Fanny
authors.initials: F
authors.lastname: Guzmán
mesh_terms: D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D017837:Bothrops; D002462:Cell Membrane / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects*; D003435:Crotalid Venoms / Q000737:chemistry*; D004926:Escherichia coli / Q000254:growth & development*
chemical_list: D023181:Antimicrobial Cationic Peptides; D003435:Crotalid Venoms
keywords: Antimicrobial; Arginine; Gram-negative; Homopeptides; Lysine; Membrane