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The specificity of TCR/pMHC interaction.
Markus G Rudolph1, Ian A Wilson
1The Scripps Research Institute, Department of Molecular Biology, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
Current Opinion in Immunology
|January 16, 2002
Summary
T-cell receptors (TCRs) interact with peptide-MHC complexes through variable interfaces, with subtle conformational changes explaining diverse signaling outcomes. Alloreactive TCRs show increased interactions with peptide-MHC compared to syngeneic counterparts.
Area of Science:
- Immunology
- Structural Biology
- Molecular Recognition
Background:
- The T-cell receptor (TCR) complex is crucial for adaptive immunity, recognizing peptide-MHC (pMHC) complexes.
- Understanding TCR-pMHC interactions is key to deciphering immune responses and developing therapies.
Purpose of the Study:
- To analyze the structural basis of TCR recognition of peptide-MHC class I and class II complexes.
- To investigate the mechanisms underlying TCR conformational changes in response to different peptide ligands.
- To compare structural features of alloreactive TCR-pMHC interactions with syngeneic counterparts.
Main Methods:
- X-ray crystallography of 11 TCR-pMHC complexes.
- Structural analysis of TCR-pMHC interfaces.
- Comparison of structures with varying peptide ligands and TCR types.
Main Results:
- TCRs adopt a generally diagonal orientation on pMHC, but conserved interactions dictating this are unclear.
- TCR-pMHC interactions are variable, involving water molecules at the interface.
- Subtle TCR conformational changes, particularly in complementarity-determining regions, accommodate different peptide agonists/antagonists.
- Alloreactive TCRs exhibit enhanced interactions with pMHC compared to syngeneic TCRs.
Conclusions:
- TCRs utilize subtle conformational adjustments, akin to induced-fit mechanisms, to recognize diverse peptide-MHC ligands.
- The observed structural variability and water molecule involvement highlight the complexity of TCR-pMHC recognition.
- Alloreactivity may stem from increased TCR beta-chain engagement with the pMHC complex.