Polymorphism at position nine of the MHC class I heavy chain affects the stability of association with beta 2-microglobulin and presentation of a viral peptide.
To identify residues that control the interactions between MHC-heavy chains and (beta 2m) sequence comparisons were made between murine class I MHC molecules with high (H-2Dd, H-2Kb) and low (H-2Ld, H-2Db) affinities for beta 2m. A single residue at position 9 was evaluated for its contribution to the stability of the complex. Mutagenesis of the glutamic acid at position 9 of H-2Ld to valine, as is found in H-2Dd and H-2Kb, resulted in both qualitative and quantitative effects on inter-chain interactions, intracellular transport, peptide binding, and peptide presentation. In in vitro translation and assembly studies, the E9V mutation resulted in a more stable association of beta 2m with the heavy chain after immunoprecipitation with the alpha 2 domain-specific Ab 30-5-7 in the presence of an H-2Ld-restricted peptide. E9V variant expressed in transfected L cells had similar surface expression compared with H-2Ld despite exhibiting a slower rate of maturation. However, cells expressing E9V were unable to present peptide Ag to a specific T cell hybridoma. H-2LdE9V in E-3 cells, which are defective in TAP-dependent peptide transport, was expressed at higher levels than H-2Ld and was stabilized more efficiently by the addition of exogenous human beta 2m. Thus, amino acid position 9 not only plays an important role in the interaction of the MHC-1 molecule with the beta 2m, it also qualitatively and quantitatively influences peptide binding and Ag presentation.
Ribaudo
R K
RK
Molecular Biology Section, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Margulies
D H
DH
D000595:Amino Acid Sequence; D000818:Animals; D017951:Antigen Presentation / Q000235:genetics; D001483:Base Sequence; D002460:Cell Line; D018076:DNA, Complementary; D018014:Gene Transfer Techniques; D015395:Histocompatibility Antigens Class I / Q000235:genetics* / Q000276:immunology; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011110:Polymorphism, Genetic; D011940:Receptor Aggregation; D016415:Sequence Alignment; D014764:Viral Proteins / Q000276:immunology*; D001613:beta 2-Microglobulin / Q000276:immunology*
D018076:DNA, Complementary; D015395:Histocompatibility Antigens Class I; D014764:Viral Proteins; D001613:beta 2-Microglobulin