Summary
PDB 1JWU deposited: 2001-09-05 modified: 2009-02-24
Title Crystal Structure of the Complex of the MHC Class II Molecule HLA-DR1 (HA peptide 306-318) with the superantigen SEC3 Variant 3B2
Authors Andersen, P.S., Karjalainen, K., Mariuzza, R.A., Schlievert, P.M., Sundberg, E.J.
Method X-RAY DIFFRACTION
Structure factors resolution 2.3 rfactor 0.2 rfree 0.237
DPI 0.69 theoretical min: 0.27
Related PDB Entries 1JWM 1JWS
Citations

Due to a paucity of studies that synthesize structural, energetic, and functional analyses of a series of protein complexes representing distinct stages in an affinity maturation pathway, the biophysical basis for the molecular evolution of protein-protein interactions is poorly understood. Here, we combine crystal structures and binding-free energies of a series of variant superantigen (SAG)-major histocompatibility complex (MHC) class II complexes exhibiting increasingly higher affinity to reveal that this affinity maturation pathway is controlled largely by two biophysical factors: shape complementarity and buried hydrophobic surface. These factors, however, do not contribute equivalently to the affinity maturation of the interface, as the former dominates the early steps of the maturation process while the latter is responsible for improved binding in later steps. Functional assays reveal how affinity maturation of the SAG-MHC interface corresponds to T cell activation by SAGs.

Structure. 2003 Sep;11(9):1151-61.

Cross References
Database source Identifier Description
PubMed 12962633 STRUE6
Biomolecule Structure Assembly Serial Assembly Type Conformational State Chains Ligands Atoms
1JWU/1 1JWU 1 tetramer 0 4 0 4878