2GUO

Human Class I MHC HLA-A2 in complex with the native nonameric Melan-A/MART-1(27-35) peptide


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.244 
  • R-Value Work: 0.187 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Structures of MART-1(26/27-35) Peptide/HLA-A2 Complexes Reveal a Remarkable Disconnect between Antigen Structural Homology and T Cell Recognition

Borbulevych, O.Y.Insaidoo, F.K.Baxter, T.K.Powell, D.J.Johnson, L.A.Restifo, N.P.Baker, B.M.

(2007) J.Mol.Biol. 372: 1123-1136

  • DOI: 10.1016/j.jmb.2007.07.025
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Small structural changes in peptides presented by major histocompatibility complex (MHC) molecules often result in large changes in immunogenicity, supporting the notion that T cell receptors are exquisitely sensitive to antigen structure. Yet there ...

    Small structural changes in peptides presented by major histocompatibility complex (MHC) molecules often result in large changes in immunogenicity, supporting the notion that T cell receptors are exquisitely sensitive to antigen structure. Yet there are striking examples of TCR recognition of structurally dissimilar ligands. The resulting unpredictability of how T cells will respond to different or modified antigens impacts both our understanding of the physical bases for TCR specificity as well as efforts to engineer peptides for immunomodulation. In cancer immunotherapy, epitopes and variants derived from the MART-1/Melan-A protein are widely used as clinical vaccines. Two overlapping epitopes spanning amino acid residues 26 through 35 are of particular interest: numerous clinical studies have been performed using variants of the MART-1 26-35 decamer, although only the 27-35 nonamer has been found on the surface of targeted melanoma cells. Here, we show that the 26-35 and 27-35 peptides adopt strikingly different conformations when bound to HLA-A2. Nevertheless, clonally distinct MART-1(26/27-35)-reactive T cells show broad cross-reactivity towards these ligands. Simultaneously, however, many of the cross-reactive T cells remain unable to recognize anchor-modified variants with very subtle structural differences. These dichotomous observations challenge our thinking about how structural information on unligated peptide/MHC complexes should be best used when addressing questions of TCR specificity. Our findings also indicate that caution is warranted in the design of immunotherapeutics based on the MART-1 26/27-35 epitopes, as neither cross-reactivity nor selectivity is predictable based on the analysis of the structures alone.


    Organizational Affiliation

    Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
HLA class I histocompatibility antigen, A-2 alpha chain
A, D
275Homo sapiensMutation(s): 0 
Gene Names: HLA-A (HLAA)
Find proteins for P01892 (Homo sapiens)
Go to Gene View: HLA-A
Go to UniProtKB:  P01892
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Beta-2-microglobulin
B, E
100Homo sapiensMutation(s): 0 
Gene Names: B2M
Find proteins for P61769 (Homo sapiens)
Go to Gene View: B2M
Go to UniProtKB:  P61769
Entity ID: 3
MoleculeChainsSequence LengthOrganismDetails
Peptide
C, F
9Homo sapiensMutation(s): 0 
Gene Names: MLANA (MART1)
Find proteins for Q16655 (Homo sapiens)
Go to Gene View: MLANA
Go to UniProtKB:  Q16655
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NA
Query on NA

Download SDF File 
Download CCD File 
E
SODIUM ION
Na
FKNQFGJONOIPTF-UHFFFAOYSA-N
 Ligand Interaction
GOL
Query on GOL

Download SDF File 
Download CCD File 
A, D, E
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.244 
  • R-Value Work: 0.187 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 83.957α = 90.00
b = 58.369β = 109.66
c = 89.425γ = 90.00
Software Package:
Software NamePurpose
Blu-Icedata collection
HKL-2000data scaling
MOLREPphasing
REFMACrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-06-12
    Type: Initial release
  • Version 1.1: 2008-05-01
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Advisory, Version format compliance