1R5I

Crystal structure of the MAM-MHC complex

Summary for 1R5I

• Entry DOI: 10.2210/pdb1r5i/pdb
• Descriptor: HLA class II histocompatibility antigen, DR alpha chain, HLA class II histocompatibility antigen, DRB1-1 beta chain, Hemagglutinin peptide, ... (6 entities in total)
• Functional Keywords: superantigen, mhc, mam, complex, immune system
• Biological source: Homo sapiens (human); More
• Cellular location: Cell membrane; Single-pass type I membrane protein: P01903 P04229; Virion membrane; Single-pass type I membrane protein (Potential): P11133
• Total number of polymer chains: 8
• Total formula weight: 141185.08

Authors

Zhao, Y.,Li, Z.,Drozd, S.J.,Guo, Y.,Mourad, W.,Li, H. (deposition date: 2003-10-10, release date: 2004-03-16, Last modification date: 2024-10-30)

Primary citation

Zhao, Y.,Li, Z.,Drozd, S.J.,Guo, Y.,Mourad, W.,Li, H.
Crystal structure of Mycoplasma arthritidis mitogen complexed with HLA-DR1 reveals a novel superantigen fold and a dimerized superantigen-MHC complex.
Structure, 12:277-288, 2004

PubMed Abstract: Mycoplasma arthritidis-derived mitogen (MAM) is a superantigen that can activate large fractions of T cells bearing particular TCR Vbeta elements. Here we report the crystal structure of MAM complexed with a major histocompatibility complex (MHC) antigen, HLA-DR1, loaded with haemagglutinin peptide 306-318 (HA). The structure reveals that MAM has a novel fold composed of two alpha-helical domains. This fold is entirely different from that of the pyrogenic superantigens, consisting of a beta-grasped motif and a beta barrel. In the complex, the N-terminal domain of MAM binds orthogonally to the MHC alpha1 domain and the bound HA peptide, and to a lesser extent to the MHC beta1 domain. Two MAM molecules form an asymmetric dimer and cross-link two MHC antigens to form a plausible, dimerized MAM-MHC complex. These data provide the first crystallographic evidence that superantigens can dimerize MHC molecules. Based on our structure, a model of the TCR2MAM2MHC2 complex is proposed.

PubMed: 14962388
DOI: 10.1016/S0969-2126(04)00020-6

Experimental method

X-RAY DIFFRACTION (2.6 Å)