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The oligosaccharide binding specificities of CD22 beta, a sialic acid-specific lectin of B cells.
J Biol Chem. 1994 Apr 08; 269(14):10628-36.JB

Abstract

CD22 beta is a B cell surface glycoprotein involved in cell adhesion and activation. We previously reported that a recombinant soluble form termed CD22 beta Rg is capable of binding alpha 2-6 sialylated complex N-linked oligosaccharides purified from lymphocyte glycoprotein ligands (Powell, L. D., Sgroi, D., Sjoberg, E. R., Stamenkovic, I., and Varki, A. (1993) J. Biol. Chem. 268, 7019-7027). Here, we utilize a number of naturally and enzymatically sialylated oligosaccharides and sialoglycoproteins to further define its lectin specificity and demonstrate that the minimal structure recognized is Neu5Ac alpha 2-6Gal beta 1-4Glc(NAc). Reduction of the glucose residue of Neu5-Ac alpha 2-6Gal beta 1-4Glc diminishes the interaction, while truncation of the sialic acid side chain by mild periodate oxidation abolishes it. Branched oligosaccharides with two alpha 2-6-sialyl residues bind better, regardless of whether they were derived from N- or O-linked oligosaccharides or from gangliosides. alpha 2-3-Sialyl residues have no effect on binding, whereas increasing the number of alpha 2-6-sialyl residues on multiantennary oligosaccharides progressively improves binding. No specific feature of the core region affects binding, although the spacing of the alpha 2-6-sialyl residues on tetraantennary chains appears to have a significant effect. Of several model sialoglycoproteins examined, fetuin and transferrin had an apparent affinity no greater than that observed with free sialylated N-linked oligosaccharides. Some subfractions of these proteins displayed unexpectedly weak binding, suggesting that the protein backbone can exert a negative effect. In contrast, a subfraction of alpha 1-acid glycoprotein was identified as having a substantially higher apparent affinity than free oligosaccharides derived from it, indicating that multiple glycosylation sites may increase the apparent binding affinity. Thus, CD22 beta Rg contains a lectin activity specific for the minimal motif Neu5Ac alpha 2-6Gal beta 1-4Glc(NAc), and branched, multisialylated oligosaccharides are better ligands, regardless of the core sequences. Intact sialoglycoproteins can also interact, although with a variable affinity not directly predictable from the precise structure of their sialylated oligosaccharides chains. These data may help to explain why certain T and B cell surface sialoglycoproteins with the Neu5Ac alpha 2-6Gal beta 1-4Glc(NAc) motif are superior ligands, capable of mediating CD22 beta-mediated adhesion and activation events.

Authors+Show Affiliations

Glycobiology Program, University of California, San Diego, La Jolla 92093.No affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

8144652

Citation

Powell, L D., and A Varki. "The Oligosaccharide Binding Specificities of CD22 Beta, a Sialic Acid-specific Lectin of B Cells." The Journal of Biological Chemistry, vol. 269, no. 14, 1994, pp. 10628-36.
Powell LD, Varki A. The oligosaccharide binding specificities of CD22 beta, a sialic acid-specific lectin of B cells. J Biol Chem. 1994;269(14):10628-36.
Powell, L. D., & Varki, A. (1994). The oligosaccharide binding specificities of CD22 beta, a sialic acid-specific lectin of B cells. The Journal of Biological Chemistry, 269(14), 10628-36.
Powell LD, Varki A. The Oligosaccharide Binding Specificities of CD22 Beta, a Sialic Acid-specific Lectin of B Cells. J Biol Chem. 1994 Apr 8;269(14):10628-36. PubMed PMID: 8144652.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The oligosaccharide binding specificities of CD22 beta, a sialic acid-specific lectin of B cells. AU - Powell,L D, AU - Varki,A, PY - 1994/4/8/pubmed PY - 1994/4/8/medline PY - 1994/4/8/entrez SP - 10628 EP - 36 JF - The Journal of biological chemistry JO - J Biol Chem VL - 269 IS - 14 N2 - CD22 beta is a B cell surface glycoprotein involved in cell adhesion and activation. We previously reported that a recombinant soluble form termed CD22 beta Rg is capable of binding alpha 2-6 sialylated complex N-linked oligosaccharides purified from lymphocyte glycoprotein ligands (Powell, L. D., Sgroi, D., Sjoberg, E. R., Stamenkovic, I., and Varki, A. (1993) J. Biol. Chem. 268, 7019-7027). Here, we utilize a number of naturally and enzymatically sialylated oligosaccharides and sialoglycoproteins to further define its lectin specificity and demonstrate that the minimal structure recognized is Neu5Ac alpha 2-6Gal beta 1-4Glc(NAc). Reduction of the glucose residue of Neu5-Ac alpha 2-6Gal beta 1-4Glc diminishes the interaction, while truncation of the sialic acid side chain by mild periodate oxidation abolishes it. Branched oligosaccharides with two alpha 2-6-sialyl residues bind better, regardless of whether they were derived from N- or O-linked oligosaccharides or from gangliosides. alpha 2-3-Sialyl residues have no effect on binding, whereas increasing the number of alpha 2-6-sialyl residues on multiantennary oligosaccharides progressively improves binding. No specific feature of the core region affects binding, although the spacing of the alpha 2-6-sialyl residues on tetraantennary chains appears to have a significant effect. Of several model sialoglycoproteins examined, fetuin and transferrin had an apparent affinity no greater than that observed with free sialylated N-linked oligosaccharides. Some subfractions of these proteins displayed unexpectedly weak binding, suggesting that the protein backbone can exert a negative effect. In contrast, a subfraction of alpha 1-acid glycoprotein was identified as having a substantially higher apparent affinity than free oligosaccharides derived from it, indicating that multiple glycosylation sites may increase the apparent binding affinity. Thus, CD22 beta Rg contains a lectin activity specific for the minimal motif Neu5Ac alpha 2-6Gal beta 1-4Glc(NAc), and branched, multisialylated oligosaccharides are better ligands, regardless of the core sequences. Intact sialoglycoproteins can also interact, although with a variable affinity not directly predictable from the precise structure of their sialylated oligosaccharides chains. These data may help to explain why certain T and B cell surface sialoglycoproteins with the Neu5Ac alpha 2-6Gal beta 1-4Glc(NAc) motif are superior ligands, capable of mediating CD22 beta-mediated adhesion and activation events. SN - 0021-9258 UR - https://www.unboundmedicine.com/medline/citation/8144652/The_oligosaccharide_binding_specificities_of_CD22_beta_a_sialic_acid_specific_lectin_of_B_cells_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0021-9258(17)34106-6 DB - PRIME DP - Unbound Medicine ER -