CD14 employs hydrophilic regions to "capture" lipopolysaccharides.
CD14 participates in the host innate inflammatory response to bacterial LPS obtained from Escherichia coli and other Gram-negative bacteria. Evidence from several laboratories suggests that different regions of the amino-terminal portion of the molecule may be involved in LPS binding. In this report a series of single-residue serine replacement and charge reversal mutations were generated to further elucidate the mechanism by which this protein may bind a multitude of different LPS ligands. Single-residue CD14 mutation proteins were examined for their ability to bind LPS obtained from E. coli, Porphyromonas gingivalis, and Helicobacter pylori and facilitate the activation of E-selectin from human endothelial cells. In addition, the single-residue CD14 mutation proteins were employed to perform monoclonal epitope-mapping studies with three LPS-blocking Abs that bound tertiary epitopes. Evidence that several different hydrophilic regions of the amino-terminal region of CD14 are involved in LPS binding was obtained. Epitope-mapping studies revealed that these hydrophilic regions are located on one side of the protein surface. These studies suggest that CD14 employs a charged surface in a manor similar to the macrophage scavenger receptor to "capture" LPS ligands and "present" them to other components of the innate host defense system.
Cunningham
M D
MD
Bristol-Myers Squibb Pharmaceutical Research Institute, Lawrenceville, NJ 08543, USA.
Shapiro
R A
RA
Seachord
C
C
Ratcliffe
K
K
Cassiano
L
L
Darveau
R P
RP
D000595:Amino Acid Sequence; D019138:Antibodies, Blocking / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D001666:Binding Sites, Antibody; D002460:Cell Line; D004730:Endothelium, Vascular / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D018604:Epitope Mapping; D004926:Escherichia coli / Q000378:metabolism; D016480:Helicobacter pylori / Q000378:metabolism; D006801:Humans; D016209:Interleukin-8 / Q000378:metabolism; D018950:Lipopolysaccharide Receptors / Q000737:chemistry / Q000235:genetics* / Q000276:immunology / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016966:Porphyromonas gingivalis / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D017434:Protein Structure, Tertiary
D019138:Antibodies, Blocking; D000911:Antibodies, Monoclonal; D016209:Interleukin-8; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides