Strategic mutations in the class I major histocompatibility complex HLA-A2 independently affect both peptide binding and T cell receptor recognition

J Biol Chem. 2004 Jul 9;279(28):29175-84. doi: 10.1074/jbc.M403372200. Epub 2004 May 6.

Abstract

Mutational studies of T cell receptor (TCR) contact residues on the surface of the human class I major histocompatibility complex (MHC) molecule HLA-A2 have identified a "functional hot spot" that comprises Arg(65) and Lys(66) and is involved in recognition by most peptide-specific HLA-A2-restricted TCRs. Although there is a significant amount of functional data on the effects of mutations at these positions, there is comparatively little biochemical information that could illuminate their mode of action. Here, we have used a combination of fluorescence anisotropy, functional assays, and Biacore binding experiments to examine the effects of mutations at these positions on the peptide-MHC interaction and TCR recognition. The results indicate that mutations at both position 65 and position 66 influence peptide binding by HLA-A2 to various extents. In particular, mutations at position 66 result in significantly increased peptide dissociation rates. However, these effects are independent of their effects on TCR recognition, and the Arg(65)-Lys(66) region thus represents a true "hot spot" for TCR recognition. We also made the observation that in vitro T cell reactivity does not scale with the half-life of the peptide-MHC complex, as is often assumed. Finally, position 66 is implicated in the "dual recognition" of both peptide and TCR, emphasizing the multiple roles of the class I MHC peptide-binding domain.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Arginine / metabolism
  • Epitopes, T-Lymphocyte
  • Genes, MHC Class I
  • HLA-A2 Antigen / genetics
  • HLA-A2 Antigen / metabolism*
  • Humans
  • Lysine / metabolism
  • Major Histocompatibility Complex*
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation*
  • Peptides / metabolism*
  • Protein Binding
  • Protein Conformation
  • Receptors, Antigen, T-Cell / genetics
  • Receptors, Antigen, T-Cell / metabolism*
  • T-Lymphocytes / cytology
  • T-Lymphocytes / metabolism
  • Thermodynamics

Substances

  • Epitopes, T-Lymphocyte
  • HLA-A2 Antigen
  • Peptides
  • Receptors, Antigen, T-Cell
  • Arginine
  • Lysine