Structural Basis for Galectin-1-dependent Pre-B Cell Receptor (Pre-BCR) Activation.Elantak, L., Espeli, M., Boned, A., Bornet, O., Bonzi, J., Gauthier, L., Feracci, M., Roche, P., Guerlesquin, F., Schiff, C.
(2012) J.Biol.Chem. 287: 44703-44713
- PubMed: 23124203
- DOI: 10.1074/jbc.M112.395152
- PubMed Abstract:
During B cell differentiation in the bone marrow, the expression and activation of the pre-B cell receptor (pre-BCR) constitute crucial checkpoints for B cell development. Both constitutive and ligand-dependent pre-BCR activation modes have been desc ...
During B cell differentiation in the bone marrow, the expression and activation of the pre-B cell receptor (pre-BCR) constitute crucial checkpoints for B cell development. Both constitutive and ligand-dependent pre-BCR activation modes have been described. The pre-BCR constitutes an immunoglobulin heavy chain (Igμ) and a surrogate light chain composed of the invariant λ5 and VpreB proteins. We previously showed that galectin-1 (GAL1), produced by bone marrow stromal cells, is a pre-BCR ligand that induces receptor clustering, leading to efficient pre-BII cell proliferation and differentiation. GAL1 interacts with the pre-BCR via the unique region of λ5 (λ5-UR). Here, we investigated the solution structure of a minimal λ5-UR motif that interacts with GAL1. This motif adopts a stable helical conformation that docks onto a GAL1 hydrophobic surface adjacent to its carbohydrate binding site. We identified key hydrophobic residues from the λ5-UR as crucial for the interaction with GAL1 and for pre-BCR clustering. These residues involved in GAL1-induced pre-BCR activation are different from those essential for autonomous receptor activation. Overall, our results indicate that constitutive and ligand-induced pre-BCR activation could occur in a complementary manner.
Laboratoire d'Ingénierie des Systèmes Macromoléculaires, CNRS UMR7255, Aix-Marseille Université, 13402 Marseille cedex 20, France.