Structural basis of trimannoside recognition by concanavalin A

Area of Science:

• Biochemistry
• Structural Biology
• Glycobiology

Background:

• Protein-carbohydrate interactions are crucial for biological recognition but lack detailed molecular descriptions.
• Concanavalin A (con A), a legume lectin, selectively binds the trimannoside core of complex glycans.

Purpose of the Study:

• To elucidate the molecular interactions between concanavalin A and a trimannoside ligand.
• To provide a structural basis for con A's specificity towards N-linked glycans.

Main Methods:

• X-ray crystallography was used to determine the structure of the con A-trimannoside complex.
• Analysis of the electron density map to describe atomic interactions.

Main Results:

• The crystal structure of the con A-trimannoside complex was resolved at 2.3-Å resolution.
• All three mannose residues of the trimannoside interact with con A through hydrogen bonds and van der Waals forces.
• A conserved water molecule anchors the reducing sugar, and specific protein residues form an extended binding cleft.

Conclusions:

• The determined structure explains the high affinity of con A for N-linked glycans.
• Detailed molecular interactions, including hydrogen bonding and water-mediated contacts, stabilize the complex.