The central residues of a T cell receptor sequence motif are key determinants of autoantigen recognition in murine experimental autoimmune encephalomyelitis.
The autoreactive response in murine experimental autoimmune encephalomyelitis (EAE) is dominated by an oligoclonal expansion of V beta 8(+) CD4(+) T cells. These T cells recognize the immunodominant N-terminal nonapeptide of myelin basic protein (MBP1-9) associated with the MHC class II molecule, I-A(u). Amongst the autoreactive cells, T cells bearing TCR containing the CDR3 beta motif Asp-Ala-Gly-Gly-Gly-Tyr (DAGGGY) play a dominant role in the disease process. Here we have investigated the molecular basis for antigen recognition by a representative TCR (172.10) that contains the DAGGGY motif. The roles of the three glycines in this motif in the corresponding TCR-peptide-MHC interactions have been analyzed using a combination of site-directed mutagenesis and surface plasmon resonance. Our data show that mutation of either of the first two glycines (G97, G98) to alanine results in soluble, recombinant TCR that do not bind to recombinant antigen at detectable levels. Mutation of the third glycine (G99) of the 172.10 TCR results in a substantial decrease in affinity. The importance of the triple glycines for antigen recognition provides an explanation at the molecular level for the recruitment of T cells bearing the DAGGGY motif into the responding repertoire during EAE induction.
Huang
Jason C
JC
Center for Immunology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9093, USA.
Ober
Raimund J
RJ
Ward
E Sally
ES
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D001324:Autoantigens / Q000378:metabolism; D001665:Binding Sites; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D004681:Encephalomyelitis, Autoimmune, Experimental / Q000276:immunology*; D005998:Glycine / Q000737:chemistry; D016056:Immunodominant Epitopes / Q000378:metabolism; D066298:In Vitro Techniques; D051379:Mice; D016297:Mutagenesis, Site-Directed; D004676:Myelin Basic Protein; D009419:Nerve Tissue Proteins / Q000276:immunology; D010446:Peptide Fragments / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020349:Surface Plasmon Resonance; D013816:Thermodynamics; D014157:Transcription Factors / Q000276:immunology
D001324:Autoantigens; D016056:Immunodominant Epitopes; C499047:Mbp protein, mouse; D004676:Myelin Basic Protein; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D011948:Receptors, Antigen, T-Cell; D011994:Recombinant Proteins; D014157:Transcription Factors; D005998:Glycine