title: Biophysical analysis of the interaction of granulysin-derived peptides with enterobacterial endotoxins.
abstract: To combat infections by Gram-negative bacteria, it is not only necessary to kill the bacteria but also to neutralize pathogenicity factors such as endotoxin (lipopolysaccharide, LPS). The development of antimicrobial peptides based on mammalian endotoxin-binding proteins is a promising tool in the fight against bacterial infections, and septic shock syndrome. Here, synthetic peptides derived from granulysin (Gra-pep) were investigated in microbiological and biophysical assays to understand their interaction with LPS. We analyzed the influence of the binding of Gra-pep on (1) the acyl chain melting of the hydrophobic moiety of LPS, lipid A, by Fourier-transform spectroscopy, (2) the aggregate structure of LPS by small-angle X-ray scattering and cryo-transmission electron microscopy, and 3) the enthalpy change by isothermal titration calorimetry. In addition, the influence of Gra-pep on the incorporation of LPS and LPS-LBP (lipopolysaccharide-binding protein) complexes into negatively charged liposomes was monitored. Our findings demonstrate a characteristic change in the aggregate structure of LPS into multilamellar stacks in the presence of Gra-pep, but little or no change of acyl chain fluidity. Neutralization of LPS by Gra-pep is not due to a scavenging effect in solution, but rather proceeds after incorporation into target membranes, suggesting a requisite membrane-bound step.
authors.affiliation: Division of Immunology and Transplantation Biology, Department of Pediatrics, CCSR 2105, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
authors.forename: Jörg
authors.initials: J
authors.lastname: Howe
authors.forename: Jörg
authors.initials: J
authors.lastname: Andrä
authors.forename: Manfred
authors.initials: M
authors.lastname: Rössle
authors.forename: Walter
authors.initials: W
authors.lastname: Richter
authors.forename: Ana Paula Galvão
authors.initials: AP
authors.lastname: da Silva
authors.forename: Alan M
authors.initials: AM
authors.lastname: Krensky
authors.forename: Carol
authors.initials: C
authors.lastname: Clayberger
authors.forename: Klaus
authors.initials: K
authors.lastname: Brandenburg
mesh_terms: D000595:Amino Acid Sequence; D000945:Antigens, Differentiation, T-Lymphocyte / Q000737:chemistry*; D001427:Bacterial Toxins / Q000737:chemistry*; D016207:Cytokines / Q000096:biosynthesis; D004731:Endotoxins / Q000737:chemistry*; D006801:Humans; D008070:Lipopolysaccharides / Q000737:chemistry*; D008081:Liposomes / Q000737:chemistry; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry*
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D001427:Bacterial Toxins; D016207:Cytokines; D004731:Endotoxins; C075005:GNLY protein, human; D008070:Lipopolysaccharides; D008081:Liposomes; D010455:Peptides; C027952:salmonella toxin