The animal lectin galectin-3 interacts with bacterial lipopolysaccharides via two independent sites.
Galectin-3 is a beta-galactoside binding protein expressed by activated macrophages, epithelial cells, and certain other cell types. Galectin-3 has a C-terminal carbohydrate binding domain, an N-terminal part consisting of a proline- and glycine-rich repetitive domain, and a small N-terminal domain. Two independent LPS binding sites on galectin-3 were demonstrated by binding of biotinylated LPS to immobilized recombinant galectin-3. One appears to be the carbohydrate binding site in the C-terminal domain that confers binding of LPS from Klebsiella pneumoniae that has a beta-galactoside-containing polysaccharide chain. This binding is best demonstrated using galectin-3 immunocaptured by a mAb to the N-terminal part (M3/38) and is inhibited by lactose. In contrast, Salmonella minnesota R7 LPS (Rd mutant), which is devoid of beta-galactosides, appears to bind to a site within the N-terminal part of galectin-3. This interaction is best demonstrated using galectin-3 directly immobilized in wells, and it is inhibited by the Ab M3/38, but not by lactose. Binding inhibition by polymyxin B and the profile of inhibition by a panel of LPSs with different amounts of the inner and outer cores present indicate that this second binding site recognizes the lipid A/inner core region of LPSs.
Mey
A
A
INSERM Unit 80, E. Herriot Hospital, Lyon, France.
Leffler
H
H
Hmama
Z
Z
Normier
G
G
Revillard
J P
JP
D000943:Antigens, Differentiation / Q000378:metabolism*; D001665:Binding Sites; D037502:Galectin 3; D006801:Humans; D007711:Klebsiella pneumoniae; D037102:Lectins / Q000378:metabolism*; D008050:Lipid A / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins; D012475:Salmonella
D000943:Antigens, Differentiation; D037502:Galectin 3; D037102:Lectins; D008050:Lipid A; D008070:Lipopolysaccharides; D011994:Recombinant Proteins