Interactions between the antimicrobial peptide, magainin 2, and Salmonella typhimurium lipopolysaccharides.
Using FT-IR spectroscopy, the effects of magainin 2 on the thermotropic behavior of LPS isolated from wild-type (SL3770) and LPS-mutant strains of Salmonella typhimurium are characterized and compared. The mutant strains include Ra (SL3749), polymyxin-sensitive Rb2(s) (SH5014), polymyxin-resistant Rb2(r) (SH5357) and Rc (HN202) LPS chemotypes, whose polysaccharide chains differ in length but possess an identical number of phosphorylation sites. In all cases, magainin 2 causes a concentration-dependent disordering of the LPS fatty acyl chains. Differences in disordering of LPS correlate more closely with the charge on the LPS molecule (determined by high-resolution 31P NMR) rather than with the length of the LPS sugar side chain, contradicting the currently accepted model for the interaction of cationic antibiotics with the Gram-negative cell envelope.
Rana
F R
FR
Department of Chemistry, College of Osteopathic Medicine, Ohio University, Athens 45701.
Blazyk
J
J
D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology; D023181:Antimicrobial Cationic Peptides; D002236:Carbohydrate Conformation / Q000187:drug effects; D005227:Fatty Acids / Q000737:chemistry; D008070:Lipopolysaccharides / Q000737:chemistry*; D054806:Magainins; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry* / Q000494:pharmacology; D011487:Protein Conformation / Q000187:drug effects; D012486:Salmonella typhimurium / Q000737:chemistry*; D013696:Temperature; D029867:Xenopus Proteins
D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D005227:Fatty Acids; D008070:Lipopolysaccharides; D054806:Magainins; D010455:Peptides; D029867:Xenopus Proteins; C053301:magainin 2 peptide, Xenopus