title: The solvent-inaccessible Cys67 residue of HLA-B27 contributes to T cell recognition of HLA-B27/peptide complexes.
abstract: Crystallographic studies have suggested that the cysteine at position 67 (Cys(67)) in the B pocket of the MHC molecule HLA-B*2705 is of importance for peptide binding, and biophysical studies have documented altered thermodynamic stability of the molecule when Cys(67) was mutated to serine (Ser(67)). In this study, we used HLA-B27.Cys(67) and HLA-B27.Ser(67) tetramers with defined T cell epitopes to determine the contribution of this polymorphic, solvent-inaccessible MHC residue to T cell recognition. We generated these HLA-B27 tetramers using immunodominant viral peptides with high binding affinity to HLA-B27 and cartilage-derived peptides with lower affinity. We demonstrate that the yield of refolding of HLA-B27.Ser(67) molecules was higher than for HLA-B27.Cys(67) molecules and strongly dependent on the affinity of the peptide. T cell recognition did not differ between HLA-B27.Cys(67) and HLA.B27.Ser(67) tetramers for the viral peptides that were investigated. However, an aggrecan peptide-specific T cell line derived from an HLA-B27 transgenic BALB/c mouse bound significantly stronger to the HLA-B27.Cys(67) tetramer than to the HLA-B27.Ser(67) tetramer. Modeling studies of the molecular structure suggest the loss of a SH ... pi hydrogen bond with the Cys-->Ser substitution in the HLA-B27 H chain which reduces the stability of the HLA-B27/peptide complex. These results demonstrate that a solvent-inaccessible residue in the B pocket of HLA-B27 can affect TCR binding in a peptide-dependent fashion.
authors.affiliation: Division of Gastroenterology, Infectiology and Rheumatology, Charité Berlin, Campus Benjamin Franklin, Free University Berlin, Germany. heiner.appel@charite.de
authors.forename: Heiner
authors.initials: H
authors.lastname: Appel
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Kuon
authors.forename: Maren
authors.initials: M
authors.lastname: Kuhne
authors.forename: Martin
authors.initials: M
authors.lastname: Hülsmeyer
authors.forename: Simon
authors.initials: S
authors.lastname: Kollnberger
authors.forename: Stefanie
authors.initials: S
authors.lastname: Kuhlmann
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Weiss
authors.forename: Martin
authors.initials: M
authors.lastname: Zeitz
authors.forename: Kai
authors.initials: K
authors.lastname: Wucherpfennig
authors.forename: Paul
authors.initials: P
authors.lastname: Bowness
authors.forename: Joachim
authors.initials: J
authors.lastname: Sieper
mesh_terms: D053674:Aggrecans; D019943:Amino Acid Substitution / Q000235:genetics / Q000276:immunology; D000818:Animals; D017951:Antigen Presentation / Q000235:genetics; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D003545:Cysteine / Q000737:chemistry* / Q000235:genetics; D018984:Epitopes, T-Lymphocyte / Q000276:immunology / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000008:administration & dosage / Q000276:immunology / Q000378:metabolism; D005434:Flow Cytometry; D015796:HLA-B27 Antigen / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D004854:Herpesvirus 4, Human / Q000276:immunology; D006801:Humans; D016056:Immunodominant Epitopes / Q000276:immunology / Q000378:metabolism; D037181:Lectins, C-Type; D051379:Mice; D008807:Mice, Inbred BALB C; D008822:Mice, Transgenic; D010446:Peptide Fragments / Q000008:administration & dosage / Q000276:immunology* / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D017510:Protein Folding; D011509:Proteoglycans / Q000008:administration & dosage / Q000276:immunology / Q000378:metabolism; D011971:Receptors, Immunologic / Q000235:genetics; D012694:Serine / Q000235:genetics; D012997:Solvents / Q000737:chemistry; D014162:Transfection
chemical_list: C508320:Acan protein, mouse; D053674:Aggrecans; D018984:Epitopes, T-Lymphocyte; D016326:Extracellular Matrix Proteins; D015796:HLA-B27 Antigen; D016056:Immunodominant Epitopes; C105298:LILRA2 protein, human; D037181:Lectins, C-Type; D010446:Peptide Fragments; D011509:Proteoglycans; D011971:Receptors, Immunologic; D012997:Solvents; D012694:Serine; D003545:Cysteine