Dimerization of soluble disulfide trap single-chain major histocompatibility complex class I molecules dependent on peptide binding affinity

• Published in: Antioxidants & redox signaling Vol. 15; no. 3; p. 635
• Main Authors: Kotsiou, Eleni, Brzostek, Joanna, Lenart, Izabela, Antoniou, Antony N, Dyson, Julian, Gould, Keith G
• Format: Journal Article
• Language: English
• Published: United States 01-08-2011
• Subjects: Animals; Antibody Specificity - immunology; ATP-Binding Cassette Transporters - metabolism; beta 2-Microglobulin - immunology; beta 2-Microglobulin - metabolism; CD8-Positive T-Lymphocytes - immunology; Cell Line; CHO Cells; Cricetinae; Cricetulus; Epitopes - chemistry; Epitopes - metabolism; HEK293 Cells; Histocompatibility Antigens Class I - chemistry; Histocompatibility Antigens Class I - metabolism; HLA-A2 Antigen - immunology; HLA-A2 Antigen - metabolism; Humans; Peptides - immunology; Peptides - metabolism; Protein Folding; Protein Multimerization
• ISSN: 1557-7716
• DOI: 10.1089/ars.2010.3691

Stable presentation of peptide epitope by major histocompatibility complex (MHC) class I molecules is a prerequisite for the efficient expansion of CD8(+) T cells. The construction of single-chain MHC class I molecules in which the peptide, β(2)-microglobulin, and MHC heavy chain are all joined together via flexible linkers increases peptide-MHC stability. We have expressed two T cell epitopes that may be useful in leukemia treatment as single-chain MHC class I molecules, aiming to develop a system for the expansion of antigen-specific CD8(+) T cells in vitro. Disulfide trap versions of these single-chain MHC molecules were also created to improve anchoring of the peptides in the MHC molecule. Unexpectedly, we observed that soluble disulfide trap single-chain molecules expressed in eukaryotic cells were prone to homodimerization, depending on the binding affinity of the peptide epitope. The dimers were remarkably stable and efficiently recognized by conformation-specific antibodies, suggesting that they consisted of largely correctly folded molecules. However, dimerization was not observed when the disulfide trap molecules were expressed as full-length, transmembrane-anchored molecules. Our results further emphasize the importance of peptide binding affinity for the efficient folding of MHC class I molecules.