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The amino acids involved in the distinct carbohydrate specificities between macrophage galactose-type C-type lectins 1 and 2 (CD301a and b) of mice

Authors
Journal
Biochimica et Biophysica Acta (BBA) - General Subjects
0304-4165
Publisher
Elsevier
Publication Date
Volume
1780
Issue
2
Identifiers
DOI: 10.1016/j.bbagen.2007.10.017
Keywords
  • C-Type Lectin
  • Macrophage
  • Dendritic Cells
  • Galactose
  • Carbohydrate Recognition

Abstract

Abstract Binding specificities of mouse macrophage galactose-type C-type lectin 1 (MGL1/CD301a) and 2 (MGL2/CD301b) toward various oligosaccharides were compared by frontal affinity chromatography. MGL1 preferentially bound oligosaccharides containing Lewis X (Le X) trisaccharides among 111 oligosaccharides tested, whereas MGL2 preferentially bound globoside Gb4. The important amino acids for the preferential bindings were investigated by pair-wise site-directed mutagenesis at positions 61, 89, 97, 100, 110–113, 115, 124, and 125 in the soluble recombinant carbohydrate recognition domains (CRD) prepared in Escherichia coli and purified with galactose-Sepharose. Mutations of Val, Ala, Thr, and Phe at positions 61, 89, 111 and 125 on MGL1 CRD caused reductions in Le X binding. Mutations of MGL2 CRD at Leu, Arg, Arg, and Tyr at positions 61, 89, 115 and 125 were implicated in the preference for β-GalNAc. Le X binding was observed with MGL2 mutants of Arg89Ala and Arg89Ala/Ser111Thr. MGL1 mutants of Ala89Arg and Ala89Arg/Pro115Arg showed β-GalNAc bindings. Molecular modeling illustrated potential direct molecular interactions of Leu61, Arg89, and His109 in MGL2 CRD with GalNAc.

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