Specific Binding of a Solube Recombinant β-Chain T-Cell Antigen Receptor to Toxic Shock Syndrome Toxin-1, a Superantigen

Abstract

Toxic shock syndrome toxin-1 (TSST-1) is a bacterial superantigen that causes toxic shock in humans, probably by polyclonal activation of T-cells resulting from the cross linking of class II major histocompatability complex (MHC) molecules of antigen-presenting cells to the antigen receptors of T-cells (TCRs). The X-ray crystal structures of the complexes between superantigens and the human class II MHC molecule HLA-DR1 have revealed the molecular basis of the interaction between two proteins. However, structural studies of the TCR:superantigen complex have been hampered primarily by the lack of sufficient amounts of homogeneous TCR protein. Here we report the preparation of large amounts of a soluble β-chain TCR and its interaction with TSST-1. The β-chain TCR was expressed in E. coli as inclusion bodies. The inclusion body protein was refolded with an efficiency of 10-15% by a diabsis method in the presence of a reduced/oxidized glutathione redox buffer. The refolded β-chain TCR binds specifically to TSST-1 with a binding interaction strong enough to be detected by native gel shift assay and to make it possible to purify the complex by gel-filtration chromatography.