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Structural basis for langerin recognition of diverse pathogen and mammalian glycans through a single binding site.

Feinberg H, Taylor ME, Razi N, McBride R, Knirel YA, Graham SA, Drickamer K, Weis WI - J. Mol. Biol. (2010)

Bottom Line: The fucose moiety of the blood group B trisaccharide Galα1-3(Fucα1-2)Gal also binds to the Ca(2+) site, and selective binding to this glycan compared to other fucose-containing oligosaccharides results from additional favorable interactions of the nonreducing terminal galactose, as well as of the fucose residue.Surprisingly, the equatorial 3-OH group and the axial 4-OH group of the galactose residue in 6SO(4)-Galβ1-4GlcNAc also coordinate Ca(2+), a heretofore unobserved mode of galactose binding in a C-type carbohydrate-recognition domain bearing the Glu-Pro-Asn signature motif characteristic of mannose binding sites.Salt bridges between the sulfate group and two lysine residues appear to compensate for the nonoptimal binding of galactose at this site.

View Article: PubMed Central - PubMed

Affiliation: Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA.

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Structure of the CRD of langerin bound to 6SO4–Gal–GlcNAc. The color scheme is the same as that described in Fig. 2. (a) Langerin carbohydrate-binding surface. Langerin CRD bound to 6SO4–Galβ1–4GlcNAc. The protein is shown in surface representation: residues not interacting with the carbohydrate (green), Ca2+ ligands (cyan), Lys299 and Lys313 (blue), and other residues interacting with the sugar (light brown). Ca2+ is with in orange. (b) Top: Chemical structure of 6SO4–Galβ1–4GlcNAc. Bottom: Fo − Fc omit map (3.0σ) of 6SO4–Galβ1–4GlcNAc (cyan). (c) 6SO4–Gal at the Ca2+ binding site. (d) Comparison of mannose binding (cyan) and 6SO4–Gal binding (yellow) at the Ca2+ site in langerin. The CRDs observed in the Man4 and 6SO4–Galβ1–4GlcNAc complexes were superimposed in order to position the mannose residue on the 6SO4–Galβ1–4GlcNAc structure. (e) Side view of the Ca2+ site bound to 6SO4–Galβ1–4GlcNAc. (f) The position of the sulfate moiety of 6SO4–Galβ1–4GlcNAc in the binding site.
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f0025: Structure of the CRD of langerin bound to 6SO4–Gal–GlcNAc. The color scheme is the same as that described in Fig. 2. (a) Langerin carbohydrate-binding surface. Langerin CRD bound to 6SO4–Galβ1–4GlcNAc. The protein is shown in surface representation: residues not interacting with the carbohydrate (green), Ca2+ ligands (cyan), Lys299 and Lys313 (blue), and other residues interacting with the sugar (light brown). Ca2+ is with in orange. (b) Top: Chemical structure of 6SO4–Galβ1–4GlcNAc. Bottom: Fo − Fc omit map (3.0σ) of 6SO4–Galβ1–4GlcNAc (cyan). (c) 6SO4–Gal at the Ca2+ binding site. (d) Comparison of mannose binding (cyan) and 6SO4–Gal binding (yellow) at the Ca2+ site in langerin. The CRDs observed in the Man4 and 6SO4–Galβ1–4GlcNAc complexes were superimposed in order to position the mannose residue on the 6SO4–Galβ1–4GlcNAc structure. (e) Side view of the Ca2+ site bound to 6SO4–Galβ1–4GlcNAc. (f) The position of the sulfate moiety of 6SO4–Galβ1–4GlcNAc in the binding site.

Mentions: Electron density in all four copies of the CRD clearly shows both 6SO4–Gal and GlcNAc residues (Fig. 5a and b). In spite of the fact that langerin binds poorly to galactose compared to mannose and fucose,6 the galactose residue is bound in the Ca2+ site (Fig. 5a and c). The Ca2+ ligands Glu293 and Asn307 form hydrogen bonds with the axial 4-OH group of 6SO4–Gal, and Glu285 and Asn287 coordinate Ca2+ and form hydrogen bonds with the equatorial 3-OH group of 6SO4–Gal. The equatorial/axial geometry of these two hydroxyl groups tilts the galactose pyranose ring relative to mannose (Fig. 5d and e) so that it packs against Ala289. The SO4 group forms salt bridges with Lys299 and Lys313, consistent with previously published results showing that Lys299Ala or Lys313Ala mutations abolish binding to the disaccharide2 (Fig. 5f). The charge–charge interactions between these lysine residues and the sulfate group must compensate for the presumably nonoptimal Ca2+ ligation of galactose at a site with an EPN signature because langerin does not bind to nonsulfated galactosides.2,6


Structural basis for langerin recognition of diverse pathogen and mammalian glycans through a single binding site.

Feinberg H, Taylor ME, Razi N, McBride R, Knirel YA, Graham SA, Drickamer K, Weis WI - J. Mol. Biol. (2010)

Structure of the CRD of langerin bound to 6SO4–Gal–GlcNAc. The color scheme is the same as that described in Fig. 2. (a) Langerin carbohydrate-binding surface. Langerin CRD bound to 6SO4–Galβ1–4GlcNAc. The protein is shown in surface representation: residues not interacting with the carbohydrate (green), Ca2+ ligands (cyan), Lys299 and Lys313 (blue), and other residues interacting with the sugar (light brown). Ca2+ is with in orange. (b) Top: Chemical structure of 6SO4–Galβ1–4GlcNAc. Bottom: Fo − Fc omit map (3.0σ) of 6SO4–Galβ1–4GlcNAc (cyan). (c) 6SO4–Gal at the Ca2+ binding site. (d) Comparison of mannose binding (cyan) and 6SO4–Gal binding (yellow) at the Ca2+ site in langerin. The CRDs observed in the Man4 and 6SO4–Galβ1–4GlcNAc complexes were superimposed in order to position the mannose residue on the 6SO4–Galβ1–4GlcNAc structure. (e) Side view of the Ca2+ site bound to 6SO4–Galβ1–4GlcNAc. (f) The position of the sulfate moiety of 6SO4–Galβ1–4GlcNAc in the binding site.
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Related In: Results  -  Collection

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Show All Figures
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f0025: Structure of the CRD of langerin bound to 6SO4–Gal–GlcNAc. The color scheme is the same as that described in Fig. 2. (a) Langerin carbohydrate-binding surface. Langerin CRD bound to 6SO4–Galβ1–4GlcNAc. The protein is shown in surface representation: residues not interacting with the carbohydrate (green), Ca2+ ligands (cyan), Lys299 and Lys313 (blue), and other residues interacting with the sugar (light brown). Ca2+ is with in orange. (b) Top: Chemical structure of 6SO4–Galβ1–4GlcNAc. Bottom: Fo − Fc omit map (3.0σ) of 6SO4–Galβ1–4GlcNAc (cyan). (c) 6SO4–Gal at the Ca2+ binding site. (d) Comparison of mannose binding (cyan) and 6SO4–Gal binding (yellow) at the Ca2+ site in langerin. The CRDs observed in the Man4 and 6SO4–Galβ1–4GlcNAc complexes were superimposed in order to position the mannose residue on the 6SO4–Galβ1–4GlcNAc structure. (e) Side view of the Ca2+ site bound to 6SO4–Galβ1–4GlcNAc. (f) The position of the sulfate moiety of 6SO4–Galβ1–4GlcNAc in the binding site.
Mentions: Electron density in all four copies of the CRD clearly shows both 6SO4–Gal and GlcNAc residues (Fig. 5a and b). In spite of the fact that langerin binds poorly to galactose compared to mannose and fucose,6 the galactose residue is bound in the Ca2+ site (Fig. 5a and c). The Ca2+ ligands Glu293 and Asn307 form hydrogen bonds with the axial 4-OH group of 6SO4–Gal, and Glu285 and Asn287 coordinate Ca2+ and form hydrogen bonds with the equatorial 3-OH group of 6SO4–Gal. The equatorial/axial geometry of these two hydroxyl groups tilts the galactose pyranose ring relative to mannose (Fig. 5d and e) so that it packs against Ala289. The SO4 group forms salt bridges with Lys299 and Lys313, consistent with previously published results showing that Lys299Ala or Lys313Ala mutations abolish binding to the disaccharide2 (Fig. 5f). The charge–charge interactions between these lysine residues and the sulfate group must compensate for the presumably nonoptimal Ca2+ ligation of galactose at a site with an EPN signature because langerin does not bind to nonsulfated galactosides.2,6

Bottom Line: The fucose moiety of the blood group B trisaccharide Galα1-3(Fucα1-2)Gal also binds to the Ca(2+) site, and selective binding to this glycan compared to other fucose-containing oligosaccharides results from additional favorable interactions of the nonreducing terminal galactose, as well as of the fucose residue.Surprisingly, the equatorial 3-OH group and the axial 4-OH group of the galactose residue in 6SO(4)-Galβ1-4GlcNAc also coordinate Ca(2+), a heretofore unobserved mode of galactose binding in a C-type carbohydrate-recognition domain bearing the Glu-Pro-Asn signature motif characteristic of mannose binding sites.Salt bridges between the sulfate group and two lysine residues appear to compensate for the nonoptimal binding of galactose at this site.

View Article: PubMed Central - PubMed

Affiliation: Department of Structural Biology, Stanford University School of Medicine, Stanford, CA, USA.

Show MeSH
Related in: MedlinePlus