1r5i

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spinqualitylabelsall models 1r5i, resolution 2.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of the MAM-MHC complex

Overview

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.

About this Structure

1R5I is a Protein complex structure of sequences from Homo sapiens and Mycoplasma arthritidis with PO4 as ligand. Full crystallographic information is available from OCA.

Reference

Crystal 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 SJ, Guo Y, Mourad W, Li H, Structure. 2004 Feb;12(2):277-88. PMID:14962388

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