title: HLA photoaffinity labeling reveals overlapping binding of homologous melanoma-associated gene peptides by HLA-A1, HLA-A29, and HLA-B44.
abstract: Melanoma-associated genes (MAGEs) encode tumor-specific antigens that can be recognized by CD8+ cytotoxic T lymphocytes. To investigate the interaction of the HLA-A1-restricted MAGE-1 peptide 161-169 (EADPT-GHSY) with HLA class I molecules, photoreactive derivatives were prepared by single amino acid substitution with N beta-[iodo-4-azidosalicyloyl]-L-2,3-diaminopropionic acid. These derivatives were tested for their ability to bind to, and to photoaffinity-label, HLA-A1 on C1R.A1 cells. Only the derivatives containing the photoreactive amino acid in position 1 or 7 fulfilled both criteria. Testing the former derivative on 14 lymphoid cell lines expressing over 44 different HLA class I molecules indicated that it efficiently photoaffinity-labeled not only HLA-A1, but possibility also HLA-A29 and HLA-B44. MAGE peptide binding by HLA-A29 and HLA-B44 was confirmed by photoaffinity labeling with photoreactive MAGE-3 peptide derivatives on C1R.A29 and C1R.B44 cells, respectively. The different photoaffinity labeling systems were used to access the ability of the homologous peptides derived from MAGE-1, -2, -3, -4a, -4b, -6, and -12 to bind to HLA-A1, HLA-A29, and HLA-B44. All but the MAGE-2 and MAGE-12 nonapeptides efficiently inhibited photoaffinity labeling of HLA-A1, which is in agreement with the known HLA-A1 peptide-binding motif (acidic residue in P3 and C-terminal tyrosine). In contrast, photoaffinity labeling of HLA-A29 was efficiently inhibited by these as well as by the MAGE-3 and MAGE-6 nonapeptides. Finally, the HLA-B44 photoaffinity labeling, unlike the HLA-A1 and HLA-A29 labeling, was inhibited more efficiently by the corresponding MAGE decapeptides, which is consistent with the reported HLA-B44 peptide-binding motif (glutamic acid in P2, and C-terminal tyrosine or phenylalanine). The overlapping binding of homologous MAGE peptides by HLA-A1, A29, and B44 is based on different binding principles and may have implications for immunotherapy of MAGE-positive tumors.
authors.affiliation: Ludwig Institute for Cancer Research, Lausanne Branch, University of Lausanne, Switzerland. iluesche@eliot.unil.ch
authors.forename: I F
authors.initials: IF
authors.lastname: Luescher
authors.forename: P
authors.initials: P
authors.lastname: Romero
authors.forename: D
authors.initials: D
authors.lastname: Kuznetsov
authors.forename: D
authors.initials: D
authors.lastname: Rimoldi
authors.forename: P
authors.initials: P
authors.lastname: Coulie
authors.forename: J C
authors.initials: JC
authors.lastname: Cerottini
authors.forename: C V
authors.initials: CV
authors.lastname: Jongeneel
mesh_terms: D000345:Affinity Labels; D000595:Amino Acid Sequence; D000951:Antigens, Neoplasm / Q000378:metabolism*; D002460:Cell Line; D015234:HLA-A Antigens / Q000378:metabolism*; D015788:HLA-A1 Antigen / Q000378:metabolism*; D015235:HLA-B Antigens / Q000378:metabolism*; D059948:HLA-B44 Antigen; D006801:Humans; D008545:Melanoma / Q000235:genetics*; D008969:Molecular Sequence Data; D011485:Protein Binding; D017386:Sequence Homology, Amino Acid
chemical_list: D000345:Affinity Labels; D000951:Antigens, Neoplasm; D015234:HLA-A Antigens; D015788:HLA-A1 Antigen; C035524:HLA-A29 antigen; D015235:HLA-B Antigens; D059948:HLA-B44 Antigen