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Structural characterization of human galectin-4 C-terminal domain: Elucidating the molecular basis for recognition of glycosphingolipids, sulfated saccharides and blood group antigens

Journal Article


Abstract


  • Human galectin-4 is a lectin that is expressed mainly in the gastrointestinal tract and exhibits metastasis-promoting roles in some cancers. Its tandem-repeat nature exhibits two distinct carbohydrate recognition domains allowing crosslinking by simultaneous binding to sulfated and non-sulfated (but not sialylated) glycosphingolipids and glycoproteins, facilitating stabilization of lipid rafts. Critically, galectin-4 exerts favourable or unfavourable effects depending upon the cancer. Here we report the first X-ray crystallographic structural information on human galectin-4, specifically the C-terminal carbohydrate recognition domain of human (galectin-4C) in complex with lactose, lactose-3′-sulfate, 2′-fucosyllactose, lacto-N-tetraose and lacto-N-neotetraose. These structures enable elucidation of galectin-4C binding fine-specificity towards sulfated and non-sulfated lacto- and neolacto-series sphingolipids as well as to human blood group antigens. Analysis of the lactose-3′-sulfate complex structure shows that galectin-4C does not recognize the sulfate group using any specific amino acid, but binds the ligand nonetheless. Complex structures with lacto-N-tetraose and lacto-N-neotetraose displayed differences in binding interactions exhibited by the non-reducing-end galactose. That of lacto-N-tetraose points outward from the protein surface whereas that of lacto-N-neotetraose interacts directly with the protein. Recognition patterns of human galectin-4C towards lacto- and neolacto-series glycosphingolipids are similar to those of human galectin-3; however, detailed scrutiny revealed differences stemming from the extended binding site that offer distinction in ligand profiles of these two galectins. Structural characterization of the complex with 2′-fucosyllactose, a carbohydrate with similarity to the H antigen, and molecular dynamics studies highlight structural features that allow specific recognition of A and B antigens, whilst a lack of interaction with the 2′-fucose of blood group antigens was revealed. Database accession codes 4YLZ, 4YM0, 4YM1, 4YM2, 4YM3. Human galectin-4 exerts favourable or unfavourable effects depending upon the particular cancer. Two distinct carbohydrate recognition domains enable cross-linking by simultaneous binding to ligands including glycosphingolipids and glycoproteins. Our elucidation of the first crystal structure of human galectin-4 C-terminal carbohydrate recognition domain-ligand complexes provides insight into galectin-4C binding fine-specificity towards lacto- and neolacto-series sphingolipids and to human blood group antigens.

Publication Date


  • 2015

Citation


  • Bum-Erdene, K., Leffler, H., Nilsson, U. J., & Blanchard, H. (2015). Structural characterization of human galectin-4 C-terminal domain: Elucidating the molecular basis for recognition of glycosphingolipids, sulfated saccharides and blood group antigens. FEBS Journal, 282(17), 3348-3367. doi:10.1111/febs.13348

Scopus Eid


  • 2-s2.0-84940722610

Start Page


  • 3348

End Page


  • 3367

Volume


  • 282

Issue


  • 17

Abstract


  • Human galectin-4 is a lectin that is expressed mainly in the gastrointestinal tract and exhibits metastasis-promoting roles in some cancers. Its tandem-repeat nature exhibits two distinct carbohydrate recognition domains allowing crosslinking by simultaneous binding to sulfated and non-sulfated (but not sialylated) glycosphingolipids and glycoproteins, facilitating stabilization of lipid rafts. Critically, galectin-4 exerts favourable or unfavourable effects depending upon the cancer. Here we report the first X-ray crystallographic structural information on human galectin-4, specifically the C-terminal carbohydrate recognition domain of human (galectin-4C) in complex with lactose, lactose-3′-sulfate, 2′-fucosyllactose, lacto-N-tetraose and lacto-N-neotetraose. These structures enable elucidation of galectin-4C binding fine-specificity towards sulfated and non-sulfated lacto- and neolacto-series sphingolipids as well as to human blood group antigens. Analysis of the lactose-3′-sulfate complex structure shows that galectin-4C does not recognize the sulfate group using any specific amino acid, but binds the ligand nonetheless. Complex structures with lacto-N-tetraose and lacto-N-neotetraose displayed differences in binding interactions exhibited by the non-reducing-end galactose. That of lacto-N-tetraose points outward from the protein surface whereas that of lacto-N-neotetraose interacts directly with the protein. Recognition patterns of human galectin-4C towards lacto- and neolacto-series glycosphingolipids are similar to those of human galectin-3; however, detailed scrutiny revealed differences stemming from the extended binding site that offer distinction in ligand profiles of these two galectins. Structural characterization of the complex with 2′-fucosyllactose, a carbohydrate with similarity to the H antigen, and molecular dynamics studies highlight structural features that allow specific recognition of A and B antigens, whilst a lack of interaction with the 2′-fucose of blood group antigens was revealed. Database accession codes 4YLZ, 4YM0, 4YM1, 4YM2, 4YM3. Human galectin-4 exerts favourable or unfavourable effects depending upon the particular cancer. Two distinct carbohydrate recognition domains enable cross-linking by simultaneous binding to ligands including glycosphingolipids and glycoproteins. Our elucidation of the first crystal structure of human galectin-4 C-terminal carbohydrate recognition domain-ligand complexes provides insight into galectin-4C binding fine-specificity towards lacto- and neolacto-series sphingolipids and to human blood group antigens.

Publication Date


  • 2015

Citation


  • Bum-Erdene, K., Leffler, H., Nilsson, U. J., & Blanchard, H. (2015). Structural characterization of human galectin-4 C-terminal domain: Elucidating the molecular basis for recognition of glycosphingolipids, sulfated saccharides and blood group antigens. FEBS Journal, 282(17), 3348-3367. doi:10.1111/febs.13348

Scopus Eid


  • 2-s2.0-84940722610

Start Page


  • 3348

End Page


  • 3367

Volume


  • 282

Issue


  • 17