PDB 2OJE deposited: 2007-01-12 modified: 2009-02-24
Title Mycoplasma arthritidis-derived mitogen complexed with class II MHC molecule HLA-DR1/HA complex in the presence of EDTA
Authors Eisele, L., Guo, Y., Li, H., Li, Z., Mourad, W., Zhao, Y.
Structure factors resolution 3.0 rfactor 0.211 rfree 0.261
DPI 1.37 theoretical min: 0.58

Dimerization of class II major histocompatibility complex (MHC) plays an important role in the MHC biological function. Mycoplasma arthritidis-derived mitogen (MAM) is a superantigen that can activate large fractions of T cells bearing specific T cell receptor Vbeta elements. Here we have used structural, sedimentation, and surface plasmon resonance detection approaches to investigate the molecular interactions between MAM and the class II MHC molecule HLA-DR1 in the context of a hemagglutinin peptide-(306-318) (HA). Our results revealed that zinc ion can efficiently induce the dimerization of the HLA-DR1/HA complex. Because the crystal structure of the MAM/HLA-DR1/hemagglutinin complex in the presence of EDTA is nearly identical to the structure of the complex crystallized in the presence of zinc ion, Zn(2+) is evidently not directly involved in the binding between MAM and HLA-DR1. Sedimentation and surface plasmon resonance studies further revealed that MAM binds the HLA-DR1/HA complex with high affinity in a 1:1 stoichiometry, in the absence of Zn(2+). However, in the presence of Zn(2+), a dimerized MAM/HLA-DR1/HA complex can arise through the Zn(2+)-induced DR1 dimer. In the presence of Zn(2+), cooperative binding of MAM to the DR1 dimer was also observed.

J.Biol.Chem. 2007 Mar; 282(9):5991-6000 doi:10.1074/jbc.M608482200

Cross References
Database source Identifier Description
PubMed 17166841 JBCHA3
Biomolecule Structure Assembly Serial Assembly Type Conformational State Chains Ligands Atoms
2OJE/1 2OJE 1 tetramer 0 4 2 4669
2OJE/2 2OJE 2 tetramer 0 4 2 4738
2OJE/3 2OJE 3 hexadecamer 0 16 8 18814