Interaction between Lipopolysaccharide (LPS), LPS-Binding Protein (LBP), and Planar Membranes

• Published in: Biological chemistry Vol. 382; no. 3; pp. 425 - 434
• Main Authors: Gutsmann, Thomas, Haberer, Niels, Carroll, Stephen F., Seydel, Ulrich, Wiese, Andre
• Format: Journal Article
• Language: English
• Published: Germany Walter de Gruyter 01.03.2001
• Subjects: Acute-Phase Proteins; Antibodies - metabolism; Carrier Proteins - chemistry; Carrier Proteins - immunology; Carrier Proteins - metabolism; Cell Membrane - chemistry; Cell Membrane - metabolism; Humans; Immune Sera; Lipid A - chemistry; Lipid A - immunology; Lipid A - metabolism; Lipid Bilayers - chemistry; Lipopolysaccharides - chemistry; Lipopolysaccharides - metabolism; Membrane Glycoproteins
• ISSN: 1431-6730; 1437-4315
• DOI: 10.1515/BC.2001.052

The mechanism of interaction of the lipopolysaccharide (LPS)binding protein, LBP, with differently composed symmetric and asymmetric planar lipid bilayers was investigated in electrical measurements (membrane current, potential, capacitance). From a change of the inner membrane potential difference, binding of LBP to membranes was deduced. After addition of LBP to one side of the membrane, binding of antiLBP antibodies and LPS to LBP on both sides of the bilayer was observed. Effects resulting from an interaction of antiLBP antiserum with membranebound LBP depend on the side of addition of the antiserum, indicating a directed intercalation of LBP into the membrane. Addition of LPS to the same side as LBP may induce a change of the conformation of LBP or its orientation in the membrane. Based on these observations, we propose that LBP intercalates in a directed orientation into negativelycharged membranes and assumes a transmembrane configuration. Moreover, preincubated complexes of LPS and LBP do not interact with membranes. These experiments show that reconstituted planar membranes are a suitable tool for investigations of the interaction of non poreforming proteins that are involved in signal transduction.