Epitopes described in "Main chain hydrogen bond interactions in the binding of proline-rich gluten peptides to the celiac disease-associated HLA-DQ2 molecule."

Article Authors:Elin Bergseng; Jiang Xia; Chu-Young Kim; Chaitan Khosla; Ludvig M Sollid
Article Title:Main chain hydrogen bond interactions in the binding of proline-rich gluten peptides to the celiac disease-associated HLA-DQ2 molecule.
Reference Detail
Reference ID:1005395
Abstract:Binding of peptide epitopes to major histocompatibility complex proteins involves multiple hydrogen bond interactions between the peptide main chain and major histocompatibility complex residues. The crystal structure of HLA-DQ2 complexed with the alphaI-gliadin epitope (LQPFPQPELPY) revealed four hydrogen bonds between DQ2 and peptide main chain amides. This is remarkable, given that four of the nine core residues in this peptide are proline residues that cannot engage in amide hydrogen bonding. Preserving main chain hydrogen bond interactions despite the presence of multiple proline residues in gluten peptides is a key element for the HLA-DQ2 association of celiac disease. We have investigated the relative contribution of each main chain hydrogen bond interaction by preparing a series of N-methylated alphaI epitope analogues and measuring their binding affinity and off-rate constants to DQ2. Additionally, we measured the binding of alphaI-gliadin peptide analogues in which norvaline, which contains a backbone amide hydrogen bond donor, was substituted for each proline. Our results demonstrate that hydrogen bonds at P4 and P2 positions are most important for binding, whereas the hydrogen bonds at P9 and P6 make smaller contributions to the overall binding affinity. There is no evidence for a hydrogen bond between DQ2 and the P1 amide nitrogen in peptides without proline at this position. This is a unique feature of DQ2 and is likely a key parameter for preferential binding of proline-rich gluten peptides and development of celiac disease.
Reference Type:Literature
PubMed ID:15826953
Journal:J Biol Chem
Journal Volume:280
Article Pages:21791-6
Journal ISSN:1083-351X
Article Chemical List:Epitopes;HLA-DQ Antigens;HLA-DQ2 antigen;Peptides;Glutens;Gliadin;Proline;norvaline;Valine
Article MeSH List:Amino Acid Sequence; Binding, Competitive; Celiac Disease(metabolism); Dose-Response Relationship, Drug; Epitopes(chemistry); Gliadin(chemistry); Glutens(chemistry); HLA-DQ Antigens(chemistry); Humans; Hydrogen Bonding; Inhibitory Concentration 50; Kinetics; Models, Chemical; Molecular Sequence Data; Peptides(chemistry); Proline(chemistry); Protein Binding; Time Factors; Valine(analogs & derivatives; chemistry)
Curation Last Updated:2014-10-03 20:40:25