Weak protein-protein interactions in lectins: the crystal structure of a vegetative lectin from the legume Dolichos biflorus
| Autor: | Marilynn E. Etzler, Lode Wyns, Lieven Buts, Thomas Hamelryck, Remy Loris, M.-H. Dao-Thi |
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| Přispěvatelé: | Department of General Biology, Department of Bio-engineering Sciences |
| Rok vydání: | 2001 |
| Předmět: |
Models
Molecular Stereochemistry Dimer Molecular Sequence Data Crystallography X-Ray Ligands Antiparallel (biochemistry) legume lectins Protein Structure Secondary Protein–protein interaction Structure-Activity Relationship chemistry.chemical_compound Tetramer Structural Biology Lectins Amino Acid Sequence Soybean agglutinin Protein Structure Quaternary Molecular Biology Crystallography Binding Sites Plants Medicinal biology Lectin Fabaceae Legume lectin Amino Acid Substitution chemistry biology.protein Carbohydrate Metabolism Protein quaternary structure Plant Lectins Dimerization Sequence Alignment Protein Binding |
| Zdroj: | Journal of Molecular Biology. 309:193-201 |
| ISSN: | 0022-2836 |
| Popis: | The legume lectins are widely used as a model system for studying protein-carbohydrate and protein-protein interactions. They exhibit a fascinating quaternary structure variation, which becomes important when they interact with multivalent glycoconjugates, for instance those on cell surfaces. Recently, it has become clear that certain lectins form weakly associated oligomers. This phenomenon may play a role in the regulation of receptor crosslinking and subsequent signal transduction. The crystal structure of DB58, a dimeric lectin from the legume Dolichos biflorus reveals a separate dimer of a previously unobserved type, in addition to a tetramer consisting of two such dimers. This tetramer resembles that formed by DBL, the seed lectin from the same plant. A single amino acid substitution in DB58 affects the conformation and flexibility of a loop in the canonical dimer interface. This disrupts the formation of a stable DBL-like tetramer in solution, but does not prohibit its formation in suitable conditions, which greatly increases the possibilities for the crosslinking of multivalent ligands. The non-canonical DB58 dimer has a buried symmetrical α helix, which can be present in the crystal in either of two antiparallel orientations. Two existing structures and datasets for lectins with similar quaternary structures were reconsidered. A central α helix could be observed in the soybean lectin, but not in the leucoagglutinating lectin from Phaseolus vulgaris. The relative position and orientation of the carbohydrate-binding sites in the DB58 dimer may affect its ability to crosslink mulitivalent ligands, compared to the other legume lectin dimers. |
| Databáze: | OpenAIRE |
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