Mutagenesis of beryllium-specific TCRs suggests an unusual binding topology for antigen recognition

J Immunol. 2011 Oct 1;187(7):3694-703. doi: 10.4049/jimmunol.1101872. Epub 2011 Aug 26.

Abstract

Unconventional Ags, such as metals, stimulate T cells in a very specific manner. To delineate the binding landscape for metal-specific T cell recognition, alanine screens were performed on a set of Be-specific TCRs derived from the lung of a chronic beryllium disease patient. These TCRs are HLA-DP2-restricted and express nearly identical TCR Vβ5.1 chains coupled with different TCR α-chains. Site-specific mutagenesis of all amino acids comprising the CDRs of the TCRA and TCRB genes showed a dominant role for Vβ5.1 residues in Be recognition, with little contribution from the TCR α-chain. Solvent-exposed residues along the α-helices of the HLA-DP2 α- and β-chains were also mutated to alanine. Two β-chain residues, located near the proposed Be binding site of HLA-DP2, played a dominant role in T cell recognition with no contribution from the HLA-DP2 α-chain. These findings suggest that Be-specific T cells recognize Ag using an unconventional binding topology, with the majority of interactions contributed by TCR Vβ5.1 residues and the HLA-DP2 β1-chain. Thus, unusual docking topologies are not exclusively used by autoreactive T cells, but also for the recognition of unconventional metal Ags, such as Be.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Beryllium / immunology*
  • Epitope Mapping
  • Epitopes, T-Lymphocyte / chemistry
  • Epitopes, T-Lymphocyte / genetics
  • Epitopes, T-Lymphocyte / immunology
  • Fluorescent Antibody Technique
  • HLA-DP beta-Chains / chemistry
  • HLA-DP beta-Chains / genetics
  • HLA-DP beta-Chains / immunology
  • Humans
  • Lymphocyte Activation / immunology*
  • Mice
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Protein Binding
  • Receptors, Antigen, T-Cell, alpha-beta / chemistry*
  • Receptors, Antigen, T-Cell, alpha-beta / genetics
  • Receptors, Antigen, T-Cell, alpha-beta / immunology*

Substances

  • Epitopes, T-Lymphocyte
  • HLA-DP beta-Chains
  • HLA-DPw2 antigen
  • Receptors, Antigen, T-Cell, alpha-beta
  • Beryllium