Exploring the cross‐reactivity of S25‐2: complex with a 5,6‐dehydro‐Kdo disaccharide
The near‐germline antibody S25‐2 exhibits a remarkable cross‐reactivity for oligosaccharides containing the bacterial lipopolysaccharide carbohydrate 3‐deoxy‐D‐manno‐oct‐2‐ulosonic acid (Kdo). The recent synthesis of a variety of Kdo analogues permits a detailed structural analysis of the importance of specific interactions in antigen recognition by S25‐2. The Kdo disaccharide analogue Kdo‐(2→4)‐5,6‐dehydro‐Kdo lacks a 5‐OH group on the second Kdo residue and has been cocrystallized with S25‐2. The structure reveals that the modification of the Kdo residue at position 5 results in a rearrangement of intramolecular hydrogen bonds in the antigen that allows it to assume a novel conformation in the antibody‐combining site. The cross‐reactive binding of S25‐2 to this synthetic ligand highlights the adaptability of this antibody to non‐natural synthetic analogues.
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Document Type: Research Article
Publication date: January 1, 2013