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*
Cancer Research Campaign Institute for Cancer Studies and
Department of Rheumatology, The Medical School, University of Birmingham, Edgbaston, Birmingham, United Kingdom
TCR usage has been studied in a panel of Th cell clones specific
for the same peptide epitope (P N S Q D R G R P R R S D),
derived from the human papillomavirus type 1 (HPV1) E4 protein, and
restricted through HLA-DQ8. After identifying the V, D, and J genes
used by the TCRs and sequencing across the V(D)J junctions, five
different
-chain sequences and five different ß-chain sequences,
comprising six independent clones, were identified. A structural model
of our E4 peptide/HLA-DQ8 complex predicted that the guanidinyl side
chain on the arginine residue at position 6 of the peptide could exist
in different orientations. An intramolecular interaction between this
arginine and the glutamine residue at position four appeared to control
this orientation. Interacting HPV1 E4-specific TCRs would therefore
have to recognize the complex in different conformations, and molecular
modeling of the TCRs suggested that this could be achieved by changing
the dimensions of the central pocket formed where the CDR3 loops of the
TCR
- and ß-chains converge. It is known that interactions between
bound peptide and amino acid residues lining the peptide-binding cleft
of HLA molecules are important for determining the conformation and
orientation of the peptide/MHC complex. The suggestion here that
intramolecular interactions between amino acids of close proximity on
the bound peptide are also important adds a further level of complexity
to the mechanism by which TCRs interact with Ag.
This article has been cited by other articles:
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H. Toh, N. Kamikawaji, T. Tana, S. Muta, T. Sasazuki, and S. Kuhara Magnitude of structural changes of the T-cell receptor binding regions determine the strength of T-cell antagonism: molecular dynamics simulations of HLA-DR4 (DRB1*0405) complexed with analogue peptide Protein Eng. Des. Sel., June 1, 2000; 13(6): 423 - 429. [Abstract] [Full Text] [PDF] |
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