Structural determinants for the interaction of lipopolysaccharide binding protein with purified high density lipoproteins: role of apolipoprotein A-I.
The interaction of lipopolysaccharide binding protein (LBP) with apolipoprotein (apo)A-I on high density lipoproteins (HDL) was studied in solid phase ligand binding assays with a biotinylated LBP-specific antibody. The association was dependent on LBP concentration and enhanced in the presence of lipopolysaccharide (LPS). Maximal enhancement was measured at an LPS/LBP molar ratio of 6. To identify regions on apoA-I that participate directly or indirectly in the interaction between LBP and HDL, we attempted to inhibit LBP association with a panel of mapped apoA-I-specific monoclonal antibodies. Whereas some antibodies were effective inhibitors, others were not, even though they bound apoA-I. Furthermore, selected apoA-I synthetic peptides inhibited the antibody-mediated interference of the HDL/LBP interaction. Although no specific mechanism can be defined for the basis of the inhibitory effects of the antibodies on the association of LBP with HDL, we identified a role for three unique regions on apoA-I between residues 1-31, 95-164, and 178-200. These results suggested that apoA-I is a key component in the association of LBP with HDL and may play an important role in the biologic activity of LPS/LBP complexes.
Massamiri
T
T
Department of Immunology, Scripps Research Institute, La Jolla, CA 92037, USA.
Tobias
P S
PS
Curtiss
L K
LK
D000209:Acute-Phase Proteins; D000818:Animals; D000911:Antibodies, Monoclonal; D016632:Apolipoprotein A-I / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D001710:Biotin / Q000031:analogs & derivatives / Q000378:metabolism; D016466:CHO Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D006224:Cricetinae; D017077:Culture Media, Conditioned; D000939:Epitopes / Q000276:immunology; D006801:Humans; D008070:Lipopolysaccharides / Q000378:metabolism*; D008075:Lipoproteins, HDL / Q000097:blood / Q000737:chemistry / Q000378:metabolism*; D008562:Membrane Glycoproteins; D010446:Peptide Fragments / Q000494:pharmacology; D011485:Protein Binding; D011487:Protein Conformation; D000099231:Lipopolysaccharide-Binding Protein
D000209:Acute-Phase Proteins; D000911:Antibodies, Monoclonal; D016632:Apolipoprotein A-I; D001710:Biotin; D002352:Carrier Proteins; D017077:Culture Media, Conditioned; D000939:Epitopes; D008070:Lipopolysaccharides; D008075:Lipoproteins, HDL; D008562:Membrane Glycoproteins; D010446:Peptide Fragments; D000099231:Lipopolysaccharide-Binding Protein