Interaction between lipopolysaccharide (LPS), LPS-binding protein (LBP), and planar membranes.
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 anti-LBP antibodies and LPS to LBP on both sides of the bilayer was observed. Effects resulting from an interaction of anti-LBP antiserum with membrane-bound 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 negatively-charged membranes and assumes a transmembrane configuration. Moreover, pre-incubated 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 pore-forming proteins that are involved in signal transduction.
Gutsmann
T
T
Research Center Borstel, Center for Medicine and Biosciences, Division of Biophysics, Germany.
Haberer
N
N
Carroll
S F
SF
Seydel
U
U
Wiese
A
A
D000209:Acute-Phase Proteins; D000906:Antibodies / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D007106:Immune Sera; D008050:Lipid A / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D008051:Lipid Bilayers / Q000737:chemistry*; D008070:Lipopolysaccharides / Q000737:chemistry / Q000378:metabolism*; D008562:Membrane Glycoproteins; D000099231:Lipopolysaccharide-Binding Protein
D000209:Acute-Phase Proteins; D000906:Antibodies; D002352:Carrier Proteins; D007106:Immune Sera; D008050:Lipid A; D008051:Lipid Bilayers; D008070:Lipopolysaccharides; D008562:Membrane Glycoproteins; D000099231:Lipopolysaccharide-Binding Protein