Molecular basis of the differences in binding properties of the highly related C-type lectins DC-SIGN and L-SIGN to Lewis X trisaccharide and Schistosoma mansoni egg antigens.
The dendritic cell-specific C-type lectin DC-SIGN functions as a pathogen receptor that recognizes Schistosoma mansoni egg antigens through its major glycan epitope Galbeta1,4(Fucalpha1,3)GlcNAc (Lex). Here we report that L-SIGN, a highly related homologue of DC-SIGN found on liver sinusoidal endothelial cells, binds to S. mansoni egg antigens but not to the Lex epitope. L-SIGN does bind the Lewis antigens Lea, Leb, and Ley, similar as DC-SIGN. A specific mutation in the carbohydrate recognition domain of DC-SIGN (V351G) abrogates binding to all Lewis antigens. In L-SIGN Ser363 is present at the corresponding position of Val351 in DC-SIGN. Replacement of this Ser into Val resulted in a "gain of function" L-SIGN mutant that binds to Lex, and shows increased binding to the other Lewis antigens. These data indicate that Val351 is important for the fucose specificity of DC-SIGN. Molecular modeling and docking of the different Lewis antigens in the carbohydrate recognition domains of L-SIGN, DC-SIGN, and their mutant forms, demonstrate that Val351 in DC-SIGN creates a hydrophobic pocket that strongly interacts with the Fucalpha1,3/4-GlcNAc moiety of the Lewis antigens. The equivalent amino acid residue Ser363 in L-SIGN creates a hydrophilic pocket that prevents interaction with Fucalpha1,3-GlcNAc in Lex but supports interactions with the Fucalpha1,4-GlcNAc moiety in Lea and Leb antigens. These data demonstrate for the first time that DC-SIGN and L-SIGN differ in their carbohydrate binding profiles and will contribute to our understanding of the functional roles of these C-type lectin receptors, both in recognition of pathogen and self-glycan antigens.
Van Liempt
Ellis
E
Department of Molecular Cell Biology and Immunology, VU University Medical Center, van der Boechorststraat 7, 1081BT Amsterdam, The Netherlands.
Imberty
Anne
A
Bank
Christine M C
CM
Van Vliet
Sandra J
SJ
Van Kooyk
Yvette
Y
Geijtenbeek
Teunis B H
TB
Van Die
Irma
I
D000595:Amino Acid Sequence; D000818:Animals; D000947:Antigens, Helminth / Q000378:metabolism*; D001665:Binding Sites; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D042783:Endothelial Cells / Q000737:chemistry; D005643:Fucose / Q000378:metabolism; D006801:Humans; D037181:Lectins, C-Type / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016256:Lewis X Antigen / Q000378:metabolism*; D008099:Liver / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D009844:Oligosaccharides / Q000378:metabolism; D010063:Ovum / Q000276:immunology; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012550:Schistosoma mansoni / Q000276:immunology*; D012694:Serine / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D014162:Transfection; D014633:Valine / Q000737:chemistry / Q000378:metabolism; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin
D000947:Antigens, Helminth; D015815:Cell Adhesion Molecules; D005643:Fucose; D037181:Lectins, C-Type; D016256:Lewis X Antigen; D009844:Oligosaccharides; D011956:Receptors, Cell Surface; D012694:Serine; D014633:Valine; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin; C433029:CLEC4M protein, human