Point mutations in the β chain CDR3 can alter the T cell receptor recognition pattern on an MHC class I\peptide complex over a broad interface area

• Published in: Molecular immunology 1998-07, Vol.35 (10), p.593-607
• Main Authors: Goyarts, Earl C., Vegh, Zsuzsa, Kalergis, Alexis M., Hörig, Heidi, Papadopoulos, Nicolas J., Young, Aideen C.M., Thomson, Cole T., Chang, Hsiu-Ching, Joyce, Sebastian, Nathenson, Stanley G.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Amino Acid Substitution; Animals; Antigen Presentation; Antigen recognition; Antigens, Viral - chemistry; Antigens, Viral - genetics; Antigens, Viral - immunology; H-2 Antigens - chemistry; H-2 Antigens - genetics; H-2 Antigens - immunology; Hybridomas - immunology; Interleukin-2 - metabolism; Lymphocyte Activation; Macromolecular Substances; Mice; Mice, Inbred C57BL; Models, Molecular; Molecular Sequence Data; Mutagenesis, Site-Directed; Nucleocapsid - chemistry; Nucleocapsid - genetics; Nucleocapsid - immunology; Nucleocapsid Proteins; Peptide Fragments - chemistry; Peptide Fragments - genetics; Peptide Fragments - immunology; Point Mutation; Protein Conformation; Receptors, Antigen, T-Cell, alpha-beta - chemistry; Receptors, Antigen, T-Cell, alpha-beta - genetics; Receptors, Antigen, T-Cell, alpha-beta - immunology; Site directed mutagenesis; Structure-Activity Relationship; T cell receptor; T-Lymphocytes, Cytotoxic - immunology; T-Lymphocytes, Cytotoxic - metabolism; TCR\MHC-peptideinteraction; Transfection; Vesicular stomatitis Indiana virus - genetics; Vesicular stomatitis Indiana virus - immunology
• ISSN: 0161-5890; 1872-9142
• DOI: 10.1016/S0161-5890(98)00056-X

To study how the T cell receptor interacts with its cognate ligand, the MHC\peptide complex, we used site directed mutagenesis to generate single point mutants that alter amino acids in the CDR3β loop of a H-2Kb restricted TCR (N30.7) specific for an immunodominant peptide N52–N59 (VSV8) derived from the vesicular stomatitis virus nucleocapsid. The effect of each mutation on antigen recognition was analyzed using wild type H-2Kb and VSV8 peptide, as well as H-2Kb and VSV8 variants carrying single replacements at residues known to be exposed to the TCR. These analyses revealed that point mutations at some positions in the CDR3β loop abrogated recognition entirely, while mutations at other CDR3β positions caused an altered pattern of antigen recognition over a broad area on the MHC\peptide surface. This area included the N-terminus of the peptide, as well as residues of the MHC α1 and α2 helices flanking this region. Assuming that the N30 TCR docks on the MHC\peptide with an orientation similar to that recently observed in two different TCR-MHC\peptide crystal structures, our findings would suggest that single amino acid alterations within CDR3β can affect the interaction of the TCR with an MHC surface region distal from the predicted CDR3β-Kb\VSV8 interface. Such unique recognition capabilities are generated with minimal alterations in the CDR3 loops of the TCR. These observations suggest the hypothesis that extensive changes in the recognition pattern due to small perturbations in the CDR3 structure appears to be a structural strategy for generating a highly diversified TCR repertoire with specificity for a wide variety of antigens.