The dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) is an innate immune C-type lectin receptor that recognizes carbohydrate-based pathogen associated with molecular patterns of various bacteria, fungi, viruses and protozoa. Although a range of highly mannosylated glycoproteins have been shown to induce signaling via DC-SIGN, precise structure of the recognized oligosaccharide epitope is still unclear. Using the array of oligosaccharides related to selected fragments of main fungal antigenic polysaccharides we revealed a highly specific pentamannoside ligand of DC-SIGN, consisting of α-(1→2)-linked mannose chains with one inner α-(1→3)-linked unit. This structural motif is present in Candida albicans cell wall mannan and corresponds to its antigenic factors 4 and 13b. This epitope is not ubiquitous in other yeast species and may account for the species-specific nature of fungal recognition via DC-SIGN. The discovered highly specific oligosaccharide ligands of DC-SIGN are tractable tools for interdisciplinary investigations of mechanisms of fungal innate immunity and anti-Candida defense. Ligand- and receptor-based NMR data demonstrated the pentasaccharide-to-DC-SIGN interaction in solution and enabled the deciphering of the interaction topology.

DC-SIGN, glycoarray, Candida albicans mannan, NMR binding and conformational studies, oligomannoside ligand

SMILES errors: -6)aDManp(1-6)[aDManp(1-2)]aDManp(1-6)[aDManp(1-2)aDManp(1-2)]aDManp(1-6)[/aDManp(1-2)/n=2/aDManp(1-2)]aDManp(1-6)[aDManp(1-3)/aDManp(1-2)/n=2/aDManp(1-2)]aDManp(1-6)[aDManp(1-2)aDManp(1-3)/aDManp(1-2)/n=2/aDManp(1-2)]aDManp(1-6)[aDManp(1-3)[aDManp(1-6)]aDManp(1-2)aDManp(1-2)aDManp(1-2)]aDManp(1-6)[aDManp(1-2)aDManp(1-3)[aDManp(1-6)]aDManp(1-2)aDManp(1-2)aDManp(1-2)]aDManp(1-6)[bDManp(1-2)/aDManp(1-2)/n=2/aDManp(1-2)]aDManp(1-6)[/bDManp(1-2)/n=2//aDManp(1-2)/n=2/aDManp(1-2)]aDManp(1-6)[/bDManp(1-2)/n=3//aDManp(1-2)/n=2/aDManp(1-2)]aDManp(1-6)[/bDManp(1-2)/n=4//aDManp(1-2)/n=2/aDManp(1-2)]aDManp(1-6)[aDManp(1-2)[bDManp(1-2)/bDManp(1-2)/n=0-2/aDManp(1-P-6)]aDManp(1-2)aDManp(1-2)]aDManp(1-:
SMILES error: number of atoms (~741) exceeds a structural formula limit (500)

Mannans are polysaccharide antigens expressed on the cell wall of different fungal species including Saccharomyces cerevisiae and Candida spp. These fungi are components of the normal intestinal microflora, and the presence of antibodies to fungal antigens is known to reflect the features of the patient's immune system. Thus, titers of IgG and IgA antibodies against Saccharomyces cerevisiae mannan (ASCA) are markers for clinical diagnostics of inflammatory bowel diseases. The complex organization and heterogeneity of cell-wall mannans may reduce the quality and reproducibility of ELISA results due to interference by different antigenic epitopes. In this research, we analyzed the levels of IgG antibodies in the sera of healthy donors and patients with colorectal cancer using an array of synthetic oligosaccharides related to distinct fragments of fungal mannan. This study aimed to establish the influence of oligosaccharide structure on their antigenicity. Variations in the structure of the previously established ASCA epitope (changing type of linkage, chain length, and the presence of branches) significantly modified the ability of ligands to bind to circulating antibodies in blood sera. The study showed that surface presentation density of the ligand critically affects the results of enzyme immunoassay. The transition from natural coating antigens to their corresponding synthetic mimetics with a defined structure opens new opportunities for improving existing ELISA test systems, as well as developing diagnostic kits with new properties.

antibodies, IgG, mannan, Candida albicans, fungi, Saccharomyces cerevisiae, human sera, colorectal cancer

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

Warning = sub-repeat ending at bDManp: variable unit count (0-2) was assumed to be 0
Warning = sub-repeat ending at bDManp: variable unit count (0-2) was assumed to be 0
[*]OC[C@H]1O[C@H](OC[C@H]2O[C@H](OC[C@H]3O[C@H](OC[C@H]4O[C@H](OC[C@H]5O[C@H](OC[C@H]6O[C@H](OC[C@H]7O[C@H]([*])[C@@H](O[C@H]8O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]8O[C@H]8O[C@H](COP(=O)(O)O[C@H]9O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]9O[C@@H]9O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]9O[C@@H]9O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]9O)[C@@H](O)[C@H](O)[C@@H]8O[C@H]8O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]8O)[C@@H](O)[C@@H]7O)[C@@H](O[C@H]7O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]7O[C@H]7O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]7O[C@H]7O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]7O[C@@H]7O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]7O[C@@H]7O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]7O)[C@@H](O)[C@@H]6O)[C@@H](O[C@H]6O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]6O[C@H]6O[C@H](CO)[C@@H](O)[C@H](O[C@H]7O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]7O[C@H]7O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]7O)[C@@H]6O)[C@@H](O)[C@@H]5O)[C@@H](O[C@H]5O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]5O[C@H]5O[C@H](CO)[C@@H](O)[C@H](O[C@H]6O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]6O)[C@@H]5O)[C@@H](O)[C@@H]4O)[C@@H](O[C@H]4O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]4O[C@H]4O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]4O)[C@@H](O)[C@@H]3O)[C@@H](O[C@H]3O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]3O)[C@@H](O)[C@@H]2O)[C@@H](O)[C@@H](O)[C@@H]1O

4619.927 g/mol (C₁₆₈H₂₈₁R₂O₁₄₃P, R = next and previous repeats, not counted in mol weight)

The dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN) is an innate immune C-type lectin receptor that recognizes carbohydrate-based pathogen associated with molecular patterns of various bacteria, fungi, viruses and protozoa. Although a range of highly mannosylated glycoproteins have been shown to induce signaling via DC-SIGN, precise structure of the recognized oligosaccharide epitope is still unclear. Using the array of oligosaccharides related to selected fragments of main fungal antigenic polysaccharides we revealed a highly specific pentamannoside ligand of DC-SIGN, consisting of α-(1→2)-linked mannose chains with one inner α-(1→3)-linked unit. This structural motif is present in Candida albicans cell wall mannan and corresponds to its antigenic factors 4 and 13b. This epitope is not ubiquitous in other yeast species and may account for the species-specific nature of fungal recognition via DC-SIGN. The discovered highly specific oligosaccharide ligands of DC-SIGN are tractable tools for interdisciplinary investigations of mechanisms of fungal innate immunity and anti-Candida defense. Ligand- and receptor-based NMR data demonstrated the pentasaccharide-to-DC-SIGN interaction in solution and enabled the deciphering of the interaction topology.

DC-SIGN, glycoarray, Candida albicans mannan, NMR binding and conformational studies, oligomannoside ligand

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

OC[C@H]1O[C@H](O)[C@@H](O[C@H]2O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]2O[C@H]2O[C@H](CO)[C@@H](O)[C@H](O[C@H]3O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]3O[C@H]3O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]3O)[C@@H]2O)[C@@H](O)[C@@H]1O

828.72 g/mol (C₃₀H₅₂O₂₆)

Mannans are polysaccharide antigens expressed on the cell wall of different fungal species including Saccharomyces cerevisiae and Candida spp. These fungi are components of the normal intestinal microflora, and the presence of antibodies to fungal antigens is known to reflect the features of the patient's immune system. Thus, titers of IgG and IgA antibodies against Saccharomyces cerevisiae mannan (ASCA) are markers for clinical diagnostics of inflammatory bowel diseases. The complex organization and heterogeneity of cell-wall mannans may reduce the quality and reproducibility of ELISA results due to interference by different antigenic epitopes. In this research, we analyzed the levels of IgG antibodies in the sera of healthy donors and patients with colorectal cancer using an array of synthetic oligosaccharides related to distinct fragments of fungal mannan. This study aimed to establish the influence of oligosaccharide structure on their antigenicity. Variations in the structure of the previously established ASCA epitope (changing type of linkage, chain length, and the presence of branches) significantly modified the ability of ligands to bind to circulating antibodies in blood sera. The study showed that surface presentation density of the ligand critically affects the results of enzyme immunoassay. The transition from natural coating antigens to their corresponding synthetic mimetics with a defined structure opens new opportunities for improving existing ELISA test systems, as well as developing diagnostic kits with new properties.

antibodies, IgG, mannan, Candida albicans, fungi, Saccharomyces cerevisiae, human sera, colorectal cancer

There is only one chemically distinct structure:

SVGMWSMILES3D molIonize

 

[*]OC[C@H]1O[C@H](OC[C@H]2O[C@H](OC[C@H]3O[C@H](OC[C@H]4O[C@H](OC[C@H]5O[C@H]([*])[C@@H](O[C@H]6O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]6O[C@H]6O[C@H](COP(=O)(O)O[C@H]7O[C@H](CO)[C@@H](O)[C@H](O[C@H]8O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]8O)[C@@H]7O)[C@@H](O)[C@H](O[C@H]7O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]7O)[C@@H]6O)[C@@H](O)[C@@H]5O)[C@@H](O[C@H]5O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]5O[C@H]5O[C@H](CO)[C@@H](O)[C@H](O[C@H]6O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]6O)[C@@H]5O)[C@@H](O)[C@@H]4O)[C@@H](O[C@H]4O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]4O[C@H]4O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]4O)[C@@H](O)[C@@H]3O)[C@@H](O[C@H]3O[C@H](CO)[C@@H](O)[C@H](O)[C@@H]3O)[C@@H](O)[C@@H]2O)[C@@H](O)[C@@H](O)[C@@H]1O

2674.235 g/mol (C₉₆H₁₆₁R₂O₈₃P, R = next and previous repeats, not counted in mol weight)