Identification of a secondary binding site in human macrophage galactose-type lectin by microarray studies: Implications for the molecular recognition of its ligands.
| Autor: | Marcelo F; Departamento de Química, Faculdade de Ciências e Tecnologia, UCIBIO, REQUIMTE, 2829-516 Caparica, Portugal., Supekar N; Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602., Corzana F; Departamento de Química, Universidad de La Rioja, Centro de Investigación en Síntesis Química, E-26006 Logroño, Spain., van der Horst JC; Department of Molecular Cell Biology and Immunology, Cancer Center Amsterdam, Amsterdam Infection and Immunity Institute, Amsterdam UMC, Vrije Universiteit Amsterdam, 1081 HZ Amsterdam, The Netherlands., Vuist IM; Department of Molecular Cell Biology and Immunology, Cancer Center Amsterdam, Amsterdam Infection and Immunity Institute, Amsterdam UMC, Vrije Universiteit Amsterdam, 1081 HZ Amsterdam, The Netherlands., Live D; Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602., Boons GPH; Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602., Smith DF; Department of Biochemistry, Emory Comprehensive Glycomics Center, Emory University School of Medicine, Atlanta, Georgia 30322., van Vliet SJ; Department of Molecular Cell Biology and Immunology, Cancer Center Amsterdam, Amsterdam Infection and Immunity Institute, Amsterdam UMC, Vrije Universiteit Amsterdam, 1081 HZ Amsterdam, The Netherlands. Electronic address: s.vanvliet@vumc.nl. |
|---|---|
| Jazyk: | angličtina |
| Zdroj: | The Journal of biological chemistry [J Biol Chem] 2019 Jan 25; Vol. 294 (4), pp. 1300-1311. Date of Electronic Publication: 2018 Nov 30. |
| DOI: | 10.1074/jbc.RA118.004957 |
| Abstrakt: | The human macrophage galactose-type lectin (MGL) is a C-type lectin characterized by a unique specificity for terminal GalNAc residues present in the tumor-associated Tn antigen (αGalNAc-Ser/Thr) and its sialylated form, the sialyl-Tn antigen. However, human MGL has multiple splice variants, and whether these variants have distinct ligand-binding properties is unknown. Here, using glycan microarrays, we compared the binding properties of the short MGL 6C (MGL short ) and the long MGL 6B (MGL long ) splice variants, as well as of a histidine-to-threonine mutant (MGL short H259T). Although the MGL short and MGL long variants displayed similar binding properties on the glycan array, the MGL short H259T mutant failed to interact with the sialyl-Tn epitope. As the MGL short H259T variant could still bind a single GalNAc monosaccharide on this array, we next investigated its binding characteristics to Tn-containing glycopeptides derived from the MGL ligands mucin 1 (MUC1), MUC2, and CD45. Strikingly, in the glycopeptide microarray, the MGL short H259T variant lost high-affinity binding toward Tn-containing glycopeptides, especially at low probing concentrations. Moreover, MGL short H259T was unable to recognize cancer-associated Tn epitopes on tumor cell lines. Molecular dynamics simulations indicated that in WT MGL short , His 259 mediates H bonds directly or engages the Tn-glycopeptide backbone through water molecules. These bonds were lost in MGL short H259T, thus explaining its lower binding affinity. Together, our results suggest that MGL not only connects to the Tn carbohydrate epitope, but also engages the underlying peptide via a secondary binding pocket within the MGL carbohydrate recognition domain containing the His 259 residue. (© 2019 Marcelo et al.) |
| Databáze: | MEDLINE |
| Externí odkaz: |
|