3D39 image
Entry Detail
PDB ID:
3D39
Keywords:
Title:
The complex between TCR A6 and human Class I MHC HLA-A2 with the modified HTLV-1 TAX (Y5(4-fluoroPhenylalanine)) peptide
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2008-05-09
Release Date:
2009-06-16
Method Details:
Experimental Method:
Resolution:
2.81 Å
R-Value Free:
0.26
R-Value Work:
0.20
Space Group:
C 1 2 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:HLA class I histocompatibility antigen, A-2 alpha chain
Chain IDs:A
Chain Length:275
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Beta-2-microglobulin
Chain IDs:B
Chain Length:100
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Modified HTLV-1 TAX (Y5(4fluoro)F) peptide
Chain IDs:C
Chain Length:9
Number of Molecules:1
Biological Source:
Polymer Type:polypeptide(L)
Description:A6 TCR alpha chain
Chain IDs:D
Chain Length:200
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:A6 TCR beta chain
Chain IDs:E
Chain Length:245
Number of Molecules:1
Biological Source:Homo sapiens
Modified Residue
Compound ID Chain ID Parent Comp ID Details 2D Image
PFF C PHE 4-FLUORO-L-PHENYLALANINE
Ligand Molecules
Primary Citation
Fluorine substitutions in an antigenic peptide selectively modulate T-cell receptor binding in a minimally perturbing manner
Biochem.J. 423 353 361 (2009)
PMID: 19698083 DOI: 10.1042/BJ20090732

Abstact

TCR (T-cell receptor) recognition of antigenic peptides bound and presented by MHC (major histocompatibility complex) molecules forms the basis of the cellular immune response to pathogens and cancer. TCRs bind peptide-MHC complexes weakly and with fast kinetics, features which have hindered detailed biophysical studies of these interactions. Modified peptides resulting in enhanced TCR binding could help overcome these challenges. Furthermore, there is considerable interest in using modified peptides with enhanced TCR binding as the basis for clinical vaccines. In the present study, we examined how fluorine substitutions in an antigenic peptide can selectively impact TCR recognition. Using a structure-guided design approach, we found that fluorination of the Tax peptide [HTLV (human T-cell lymphotropic virus)-1 Tax(11-19)] enhanced binding by the Tax-specific TCR A6, yet weakened binding by the Tax-specific TCR B7. The changes in affinity were consistent with crystallographic structures and fluorine chemistry, and with the A6 TCR independent of other substitutions in the interface. Peptide fluorination thus provides a means to selectively modulate TCR binding affinity without significantly perturbing peptide composition or structure. Lastly, we probed the mechanism of fluorine's effect on TCR binding and we conclude that our results were most consistent with a 'polar hydrophobicity' mechanism, rather than a purely hydrophobic- or electrostatic-based mechanism. This finding should have an impact on other attempts to alter molecular recognition with fluorine.

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Primary Citation of related structures