The role of weak protein-protein interactions in multivalent lectin-carbohydrate binding: crystal structure of cross-linked FRIL

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Abstract:

Binding of multivalent glycoconjugates by lectins often leads to the formation of cross-linked complexes. Type I cross-links, which are one-dimensional, are formed by a divalent lectin and a divalent glycoconjugate. Type II cross-links, which are two or three-dimensional, occur when a lectin or glycoconjugate has a valence greater than two. Type II complexes are a source of additional specificity, since homogeneous type II complexes are formed in the presence of mixtures of lectins and glycoconjugates. This additional specificity is thought to become important when a lectin interacts with clusters of glycoconjugates, e.g. as is present on the cell surface. The cryst1al structure of the Glc/Man binding legume lectin FRIL in complex with a trisaccharide provides a molecular snapshot of how weak protein-protein interactions, which are not observed in solution, can become important when a cross-linked complex is formed. In solution, FRIL is a divalent dimer, but in the crystal FRIL forms a tetramer, which allows for the formation of an intricate type II cross-linked complex with the divalent trisaccharide. The dependence on weak protein-protein interactions can ensure that a specific type II cross-linked complex and its associated specificity can occur only under stringent conditions, which explains why lectins are often found forming higher-order oligomers

Notes:

DA - 20000712
IS - 0022-2836 (Print)
LA - eng
PT - Journal Article
PT - Research Support, Non-U.S. Gov't
RN - 0 (Cross-Linking Reagents)
RN - 0 (FRIL protein, Dolichos lablab)
RN - 0 (Lectins)
RN - 0 (Mannose-Binding Lectins)
RN - 0 (Plant Lectins)
RN - 0 (Trisaccharides)
RN - 11028-71-0 (Concanavalin A)
RN - 31103-86-3 (Mannose)
SB - IM