Search Results - (Author, Cooperation:T. Gutsmann)

2016-03-31

Nature Publishing Group (NPG)

0028-0836

1476-4687

Biology

Chemistry and Pharmacology

Medicine

Natural Sciences in General

Physics

Calcium/metabolism ; Candida albicans/immunology/*metabolism/*pathogenicity ; Candidiasis/metabolism/microbiology/pathology ; Cell Membrane Permeability/drug effects ; Cytotoxins/genetics/*metabolism/secretion/toxicity ; Epithelial Cells/drug effects/immunology/pathology ; Fungal Proteins/genetics/metabolism/secretion/*toxicity ; Host-Pathogen Interactions/immunology ; Humans ; Mucous Membrane/microbiology/pathology ; Mycotoxins/genetics/metabolism/secretion/*toxicity ; Signal Transduction/drug effects ; Virulence/drug effects ; Virulence Factors/genetics/*metabolism/toxicity

1432-1424

Key words: CAP18—Monolayer—Liposomes—Outer membrane—Lipopolysaccharide—Resistance

Springer Online Journal Archives 1860-2000

Biology

Chemistry and Pharmacology

Abstract. We have investigated the mechanism of action of the cationic antimicrobial protein (18 kDa) CAP18 on liposomes and monolayers made from phospholipids and enterobacterial lipopolysaccharides (LPS). CAP18 intercalates into lipid matrices composed of LPS from sensitive strains, weaker into those made of LPS from a resistant strain (Proteus mirabilis strain R45) or negatively charged phospholipids, but not into those composed of neutral phosphatidylcholine. From the combination of data obtained with fluorescence resonance energy transfer and Fourier-transform infrared spectroscopy and film balance measurements, it can be concluded that structural differences in the LPS determine the depth of intercalation of CAP18 into the respective lipid matrices. Thus, we identified the L-Arap4N linked to the first Kdo of the LPS of P. mirabilis strain R45 to be responsible for the CAP18 resistance of this strain. These data provide insight into CAP18-mediated effects on the integrity of the outer membrane of Gram-negative bacteria and led to an improved model for rabbit CAP18 membrane interaction.

Electronic Resource

1432-1424

Key words: Polymyxin B — Planar lipid bilayer — Outer membrane — Membrane lesions — Surface charge — Resistance

Springer Online Journal Archives 1860-2000

Biology

Chemistry and Pharmacology

Abstract. We have studied the interaction of the polycationic peptide antibiotic polymyxin B (PMB) with asymmetric planar bilayer membranes via electrical measurements. The bilayers were of different compositions, including those of the lipid matrices of the outer membranes of various species of Gram-negative bacteria. One leaflet, representing the bacterial inner leaflet, consisted of a phospholipid mixture (PL; phosphatidylethanolamine, -glycerol, and diphosphatidylglycerol in a molar ratio of 81:17:2). The other (outer) leaflet consisted either of lipopolysaccharide (LPS) from deep rough mutants of PMB-sensitive (Escherichia coli F515) or -resistant strains (Proteus mirabilis R45), glycosphingolipid (GSL-1) from Sphingomonas paucimobilis IAM 12576, or phospholipids (phosphatidylglycerol, diphytanoylphosphatidylcholine). In all membrane systems, the addition of PMB to the outer leaflet led to the induction of current fluctuations due to transient membrane lesions. The minimal PMB concentration required for the induction of the lesions and their size correlated with the charge of the lipid molecules. In the membrane system resembling the lipid matrix of a PMB-sensitive strain (F515 LPS/PL), the diameters of the lesions were large enough (d= 2.4 nm ± 8%) to allow PMB molecules to permeate (self-promoted transport), but in all other systems they were too small. A comparison of these phenomena with membrane effects induced by detergents (dodecyltriphenylphosphonium bromide, dodecyltrimethylammonium bromide, sodiumdodecylsulfate) revealed a detergent-like mechanism of the PMB-membrane interaction.

Electronic Resource