Despite the fact that complex saccharides play an important role in many biological recognition processes, molecular level descriptions of protein-carbohydrate interactions are sparse. The legume lectin concanavalin A (con A), from Canavalia ensiformis, specifically recognizes the trimannoside core of many complex glycans ...
Despite the fact that complex saccharides play an important role in many biological recognition processes, molecular level descriptions of protein-carbohydrate interactions are sparse. The legume lectin concanavalin A (con A), from Canavalia ensiformis, specifically recognizes the trimannoside core of many complex glycans. We have determined the crystal structure of a con A-trimannoside complex at 2.3-A resolution now describe the trimannoside interaction with conA. All three sugar residues are in well defined difference electron density. The 1,6-linked mannose residue is bound at the previously reported monosaccharide binding site; the other two sugars bind in an extended cleft formed by residues Tyr-12, Pro-13, Asn-14, Thr-15, and Asp-16. Hydrogen bonds are formed between the protein and all three sugar residues. In particular, the 1,3-linked mannose residue makes a strong hydrogen bond with the main chain of the protein. In addition, a water molecule, which is conserved in other con A structures, plays an important role in anchoring the reducing sugar unit to the protein. The complex is further stabilized by van der Waals interactions. The structure provides a rationale for the high affinity of con A for N-linked glycans.
Related Citations:
Refined Structure of Concanavalin a Complexed with Methyl Alpha-D-Mannopyranoside at 2.0A Resolution and Comparison with the Saccharide-Free Structure Naismith, J.H., Emmerich, C., Habash, J., Harrop, S.J., Helliwell, J.R., Hunter, W.N., Raftery, J., Kalb(Gilboa), A.J., Yariv, J. (1994) Acta Crystallogr D Biol Crystallogr 50: 847
Refined Structure of Cadmium-Substituted Concanavalin a at 2.0A Resolution Naismith, J.H., Habash, J., Harrop, S.J., Helliwell, J.R., Hunter, W.N., Wan, T.C.M., Weisgerber, S., Kalb(Gilboa), A.J., Yariv, J. (1993) Acta Crystallogr D Biol Crystallogr 49: 561
Organizational Affiliation:
Centre for Biomolecular Sciences, University, St. Andrews, Scotland, United Kingdom.
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