title: Two different, highly exposed, bulged structures for an unusually long peptide bound to rat MHC class I RT1-Aa.
abstract: The rat MHC class Ia molecule RT1-Aa has the unusual capacity to bind long peptides ending in arginine, such as MTF-E, a thirteen-residue, maternally transmitted minor histocompatibility antigen. The antigenic structure of MTF-E was unpredictable due to its extraordinary length and two arginines that could serve as potential anchor residues. The crystal structure of RT1-Aa-MTF-E at 2.55 A shows that both peptide termini are anchored, as in other class I molecules, but the central residues in two independent pMHC complexes adopt completely different bulged conformations based on local environment. The MTF-E epitope is fully exposed within the putative T cell receptor (TCR) footprint. The flexibility demonstrated by the MTF-E structures illustrates how different TCRs may be raised against chemically identical, but structurally dissimilar, pMHC complexes.
authors.affiliation: Department of Molecular Biology and, Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Speir
authors.forename: J
authors.initials: J
authors.lastname: Stevens
authors.forename: E
authors.initials: E
authors.lastname: Joly
authors.forename: G W
authors.initials: GW
authors.lastname: Butcher
authors.forename: I A
authors.initials: IA
authors.lastname: Wilson
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000276:immunology; D000818:Animals; D018360:Crystallography, X-Ray; D018984:Epitopes, T-Lymphocyte / Q000737:chemistry* / Q000276:immunology; D006649:Histocompatibility Antigens / Q000737:chemistry* / Q000276:immunology; D015395:Histocompatibility Antigens Class I / Q000737:chemistry* / Q000276:immunology; D015778:Minor Histocompatibility Antigens / Q000737:chemistry* / Q000276:immunology; D025261:Mitochondrial Proton-Translocating ATPases; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry* / Q000276:immunology; D017433:Protein Structure, Secondary; D051381:Rats
chemical_list: D018984:Epitopes, T-Lymphocyte; D006649:Histocompatibility Antigens; D015395:Histocompatibility Antigens Class I; D015778:Minor Histocompatibility Antigens; D010455:Peptides; C038353:histocompatibility antigens RT, rat; D000251:Adenosine Triphosphatases; D025261:Mitochondrial Proton-Translocating ATPases