Binding of viral antigens to major histocompatibility complex class I H-2Db molecules is controlled by dominant negative elements at peptide non-anchor residues. Implications for peptide selection and presentation.
Binding of viral antigens to major histocompatibility complex (MHC) class I molecules is a critical step in the activation process of CD8(+) cytotoxic T lymphocytes. In this study, we investigated the impact of structural factors at non-anchor residues in peptide-MHC interaction using the model of lymphocytic choriomeningitis virus (LCMV) infection of its natural host, the mouse. Altering viral genes by making reassortants, recombinants, and using synthetic peptides, CD8(+) cytotoxic T lymphocytes were shown to recognize only three H-2Db-restricted epitopes, GP amino acids 33-41/43, GP 276-286, and NP 396-404. However, LCMV NP and GP proteins contain 31 other peptides bearing the H-2Db motif. These 34 LCMV peptides and 11 other known H2-Db-restricted peptides were synthesized and examined for MHC binding properties. Despite the presence of the H-2Db binding motif, the majority of LCMV peptides showed weak or no affinity for H-2Db. We observed that dominant negative structural elements located at non-anchor positions played a crucial role in peptide-MHC interaction. By comparative sequence analysis of strong versus non-binders and using molecular modeling, we delineated these negative elements and evaluated their impact on peptide-MHC interaction. Our findings were validated by showing that a single mutation of a favorable non-anchor residue in the sequence of known viral epitopes for a negative element resulted in dramatic reduction of antigen presentation properties, while conversely, substitution of one negative for a positive element in the sequence of a non-binder conferred to the peptide an ability to now bind to MHC molecules.
Hudrisier
D
D
Institut de Pharmacologie et de Biologie Structurale, CNRS, 205 route de Narbonne, 31400 Toulouse, France.
Mazarguil
H
H
Laval
F
F
Oldstone
M B
MB
Gairin
J E
JE
D000595:Amino Acid Sequence; D000818:Animals; D000956:Antigens, Viral / Q000276:immunology* / Q000378:metabolism; D003198:Computer Simulation; D003602:Cytotoxicity, Immunologic; D006183:H-2 Antigens / Q000276:immunology* / Q000378:metabolism; D064532:Histocompatibility Antigen H-2D; D008217:Lymphocytic choriomeningitis virus / Q000276:immunology*; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000276:immunology* / Q000378:metabolism; D011485:Protein Binding; D013329:Structure-Activity Relationship; D013602:T-Lymphocytes, Cytotoxic / Q000276:immunology*
D000956:Antigens, Viral; D006183:H-2 Antigens; D064532:Histocompatibility Antigen H-2D; D009842:Oligopeptides