title: Interaction of antimicrobial peptides with bacterial polysaccharides from lung pathogens.
abstract: The interaction of two cathelicidin antimicrobial peptides, LL-37 and SMAP-29, with three bacterial polysaccharides, respectively, produced by Pseudomonas aeruginosa, Burkholderia cepacia and Klebsiella pneumoniae, was investigated to identify possible mechanisms adopted by lung pathogens to escape the action of innate immunity effectors. In vitro assays indicated that the antibacterial activity of both peptides was inhibited to a variable extent by the three polysaccharides. Circular dichroism experiments showed that these induced an alpha-helical conformation in the two peptides, with the polysaccharides from K. pneumoniae and B. cepacia showing, respectively, the highest and the lowest effect. Fluorescence measurements also indicated the presence of peptide-polysaccharide interactions. A model is proposed in which the binding of peptides to the polysaccharide molecules induces, at low polysaccharide to peptide ratios, a higher order of aggregation, due to peptide-peptide interactions. Overall, these results suggest that binding of the peptides by the polysaccharides produced by lung pathogens can contribute to the impairment of peptide-based innate defenses of airway surface.
authors.affiliation: Department of Biochemistry, Biophysics and Macromolecular Chemistry, University of Trieste, Via Licio Giorgieri 1, 34127 Trieste, Italy.
authors.forename: Yury
authors.initials: Y
authors.lastname: Herasimenka
authors.forename: Monica
authors.initials: M
authors.lastname: Benincasa
authors.forename: Maura
authors.initials: M
authors.lastname: Mattiuzzo
authors.forename: Paola
authors.initials: P
authors.lastname: Cescutti
authors.forename: Renato
authors.initials: R
authors.lastname: Gennaro
authors.forename: Roberto
authors.initials: R
authors.lastname: Rizzo
mesh_terms: D000942:Antigens, Bacterial / Q000494:pharmacology*; D000954:Antigens, Surface / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D001798:Blood Proteins / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D016956:Burkholderia cepacia / Q000472:pathogenicity; D002240:Carbohydrate Sequence; D054804:Cathelicidins; D006801:Humans; D007711:Klebsiella pneumoniae / Q000472:pathogenicity; D008168:Lung / Q000382:microbiology; D008969:Molecular Sequence Data; D018410:Pneumonia, Bacterial / Q000382:microbiology; D011135:Polysaccharides, Bacterial / Q000737:chemistry / Q000494:pharmacology*; D011550:Pseudomonas aeruginosa / Q000472:pathogenicity
chemical_list: C504509:ALG polysaccharide, Pseudomonas aeruginosa; D000942:Antigens, Bacterial; D000954:Antigens, Surface; D023181:Antimicrobial Cationic Peptides; D001798:Blood Proteins; D054804:Cathelicidins; C030659:K antigens; D011135:Polysaccharides, Bacterial; C403305:SMAP29 protein, Ovis aries; C487212:cepacian