title: Analysis of HLA-E peptide-binding specificity and contact residues in bound peptide required for recognition by CD94/NKG2.
abstract: The MHC class Ib molecule HLA-E is the primary ligand for CD94/NKG2A-inhibitory receptors expressed on NK cells, and there is also evidence for TCR-mediated recognition of this molecule. HLA-E preferentially assembles with a homologous set of peptides derived from the leader sequence of class Ia molecules, but its capacity to bind and present other peptides remains to be fully explored. The peptide-binding motif of HLA-E was investigated by folding HLA-E in vitro in the presence of peptide libraries derived from a nonameric leader peptide sequence randomized at individual anchor positions. A high degree of selectivity was observed at four of five total anchor positions, with preference for amino acids present in HLA-E-binding peptides from class Ia leader sequences. Selectivity was also observed at the nonanchor P5 position, with preference for positively charged amino acids, suggesting that electrostatic interactions involving the P5 side chain may facilitate assembly of HLA-E peptide complexes. The observed HLA-E peptide-binding motif was strikingly similar to that previously identified for the murine class Ib molecule, Qa-1. Experiments with HLA-E tetramers bearing peptides substituted at nonanchor positions demonstrated that P5 and P8 are primary contact residues for interaction with CD94/NKG2 receptors. A conservative replacement of Arg for Lys at P5 completely abrogated binding to CD94/NKG2. Despite conservation of peptide-binding specificity in HLA-E and Qa-1, cross-species tetramer-staining experiments demonstrated that the interaction surfaces on CD94/NKG2 and the class Ib ligands have diverged between primates and rodents.
authors.affiliation: Emory Vaccine Research Center, Emory University School of Medicine, Atlanta, GA 30322, USA.
authors.forename: Joseph D
authors.initials: JD
authors.lastname: Miller
authors.forename: Dominique A
authors.initials: DA
authors.lastname: Weber
authors.forename: Chris
authors.initials: C
authors.lastname: Ibegbu
authors.forename: Jan
authors.initials: J
authors.lastname: Pohl
authors.forename: John D
authors.initials: JD
authors.lastname: Altman
authors.forename: Peter E
authors.initials: PE
authors.lastname: Jensen
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics / Q000276:immunology; D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D001667:Binding, Competitive / Q000235:genetics / Q000276:immunology; D000939:Epitopes / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000276:immunology; D006680:HLA Antigens / Q000235:genetics / Q000378:metabolism*; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007118:Immunoassay; D007694:Killer Cells, Natural / Q000276:immunology / Q000378:metabolism*; D037181:Lectins, C-Type / Q000037:antagonists & inhibitors / Q000378:metabolism*; D008239:Lysine / Q000235:genetics / Q000378:metabolism; D008253:Macaca mulatta; D051379:Mice; D008810:Mice, Inbred C57BL; D055654:NK Cell Lectin-Like Receptor Subfamily C; D051920:NK Cell Lectin-Like Receptor Subfamily D; D009842:Oligopeptides / Q000138:chemical synthesis / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D019151:Peptide Library; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D017510:Protein Folding; D011971:Receptors, Immunologic / Q000037:antagonists & inhibitors / Q000378:metabolism*; D055607:Receptors, Natural Killer Cell; D011994:Recombinant Proteins / Q000138:chemical synthesis / Q000378:metabolism; D000097625:HLA-E Antigens
chemical_list: D015703:Antigens, CD; D000939:Epitopes; D006680:HLA Antigens; D015395:Histocompatibility Antigens Class I; D037181:Lectins, C-Type; D008239:Lysine; D055654:NK Cell Lectin-Like Receptor Subfamily C; D051920:NK Cell Lectin-Like Receptor Subfamily D; D009842:Oligopeptides; D019151:Peptide Library; D011971:Receptors, Immunologic; D055607:Receptors, Natural Killer Cell; D011994:Recombinant Proteins; D000097625:HLA-E Antigens; C527054:KLRC1 protein, human; C497869:KLRD1 protein, human; C527057:Klrc1 protein, mouse; C497870:Klrd1 protein, mouse