title: Mutagenesis of beryllium-specific TCRs suggests an unusual binding topology for antigen recognition.
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.
authors.affiliation: Department of Medicine, University of Colorado Denver, Aurora, CO 80045, USA.
authors.forename: Natalie A
authors.initials: NA
authors.lastname: Bowerman
authors.forename: Michael T
authors.initials: MT
authors.lastname: Falta
authors.forename: Douglas G
authors.initials: DG
authors.lastname: Mack
authors.forename: John W
authors.initials: JW
authors.lastname: Kappler
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Fontenot
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001608:Beryllium / Q000276:immunology*; D018604:Epitope Mapping; D018984:Epitopes, T-Lymphocyte / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D005455:Fluorescent Antibody Technique; D059868:HLA-DP beta-Chains / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000737:chemistry* / Q000235:genetics / Q000276:immunology*
chemical_list: D018984:Epitopes, T-Lymphocyte; D059868:HLA-DP beta-Chains; C083176:HLA-DPw2 antigen; D016693:Receptors, Antigen, T-Cell, alpha-beta; D001608:Beryllium