3D25

Crystal structure of HA-1 minor histocompatibility antigen bound to human class I MHC HLA-A2


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.3 Å
  • R-Value Free: 0.204 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Secondary anchor polymorphism in the HA-1 minor histocompatibility antigen critically affects MHC stability and TCR recognition

Nicholls, S.Piper, K.P.Mohammed, F.Dafforn, T.R.Tenzer, S.Salim, M.Mahendra, P.Craddock, C.van Endert, P.Schild, H.Cobbold, M.Engelhard, V.H.Moss, P.A.Willcox, B.E.

(2009) Proc.Natl.Acad.Sci.USA 106: 3889-3894

  • DOI: 10.1073/pnas.0900411106

  • PubMed Abstract: 
  • T cell recognition of minor histocompatibility antigens (mHags) underlies allogeneic immune responses that mediate graft-versus-host disease and the graft-versus-leukemia effect following stem cell transplantation. Many mHags derive from single amino ...

    T cell recognition of minor histocompatibility antigens (mHags) underlies allogeneic immune responses that mediate graft-versus-host disease and the graft-versus-leukemia effect following stem cell transplantation. Many mHags derive from single amino acid polymorphisms in MHC-restricted epitopes, but our understanding of the molecular mechanisms governing mHag immunogenicity and recognition is incomplete. Here we examined antigenic presentation and T-cell recognition of HA-1, a prototypic autosomal mHag derived from single nucleotide dimorphism (HA-1(H) versus HA-1(R)) in the HMHA1 gene. The HA-1(H) peptide is restricted by HLA-A2 and is immunogenic in HA-1(R/R) into HA-1(H) transplants, while HA-1(R) has been suggested to be a "null allele" in terms of T cell reactivity. We found that proteasomal cleavage and TAP transport of the 2 peptides is similar and that both variants can bind to MHC. However, the His>Arg change substantially decreases the stability and affinity of HLA-A2 association, consistent with the reduced immunogenicity of the HA-1(R) variant. To understand these findings, we determined the structure of an HLA-A2-HA-1(H) complex to 1.3A resolution. Whereas His-3 is accommodated comfortably in the D pocket, incorporation of the lengthy Arg-3 is predicted to require local conformational changes. Moreover, a soluble TCR generated from HA-1(H)-specific T-cells bound HA-1(H) peptide with moderate affinity but failed to bind HA-1(R), indicating complete discrimination of HA-1 variants at the level of TCR/MHC interaction. Our results define the molecular mechanisms governing immunogenicity of HA-1, and highlight how single amino acid polymorphisms in mHags can critically affect both MHC association and TCR recognition.


    Organizational Affiliation

    Cancer Research UK Institute for Cancer Studies, Edgbaston, Birmingham B15 2TT, United Kingdom.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
HLA class I histocompatibility antigen, A-2 alpha chain
A
274Homo 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
98Homo 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
Nonameric peptide from HA-1
C
9Homo sapiensMutation(s): 0 
Gene Names: ARHGAP45 (HMHA1, KIAA0223)
Find proteins for Q92619 (Homo sapiens)
Go to Gene View: ARHGAP45
Go to UniProtKB:  Q92619
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.3 Å
  • R-Value Free: 0.204 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 53.170α = 90.00
b = 80.980β = 112.32
c = 56.260γ = 90.00
Software Package:
Software NamePurpose
SHELXrefinement
SCALAdata scaling
CNSphasing
SCALAdata processing
PDB_EXTRACTdata extraction
MOSFLMdata reduction
SHELXL-97refinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2009-02-10
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance