Download MendeleyCrystal structure of Mycoplasma arthritidis mitogen complexed with HLA-DR1 reveals a novel superantigen fold and a dimerized superantigen-MHC complex.
Zhao, Y., Li, Z., Drozd, S.J., Guo, Y., Mourad, W., Li, H.(2004) Structure 12: 277-288
- PubMed: 14962388
- DOI: https://doi.org/10.1016/j.str.2004.01.008
- Primary Citation of Related Structures:
1R5I - 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.
Organizational Affiliation:
Wadsworth Center, New York State Department of Health, Empire State Plaza, PO Box 509, Albany, NY 12201, USA.
