Probing HLA-B7 Conformational Shifts Induced by Peptide-Binding Groove Mutations and Bound Peptide with Anti-HLA Monoclonal Antibodies

Kelly D. Smith, Brian E. Mace, Alicia Valenzuela, Janet L. Vigna, Jane A. McCutcheon, James A. Barbosa, Eric Huczko, Victor H. Engelhard, Charles T. Lutz

Research output: Contribution to journalArticlepeer-review

Abstract

To determine the influence of peptide-binding groove residues and MHC-bound peptide on HLA-B7 conformation, we investigated the binding sites of nine locus- or allele-specific mAbs using a panel of 82 HLA-B7 variants. The functional mAb epitopes encircle the HLA-B7 peptide-binding groove. Three mAbs are affected by mutations at solvent-accessible peptide-binding groove mutations. Mutations in peptide-binding groove residues 45, 63, and 150 affect multiple nonoverlapping mAb epitopes, probably by interaction with other MHC residues or bound peptide. However, 18 of 24 peptide-binding groove mutations do not affect mAb binding, indicating that the conformation of solvent-accessible HLA-B7 structures is largely dissociated from changes in the peptide-binding groove. To test whether bound peptides alter HLA-B7 conformation, we loaded HLA-B7 heavy chains on acid-stripped cells with β2-microglobulin and 20 individual synthetic peptides. Two of eight mAbs are sensitive to HLA-B7-bound peptides. A likely interpretation of these data is that the conformational flexibility of HLA-B7 is due to peptide-induced conformational shifts in MHC side chains, rather than major shifts in the MHC main chain. These results suggest that HLA-B7 conformation is largely maintained in the context of different bound peptides and different peptide-binding grooves.

Original languageEnglish (US)
Pages (from-to)2470-2478
Number of pages9
JournalJournal of Immunology
Volume157
Issue number6
StatePublished - Sep 15 1996

ASJC Scopus subject areas

  • Immunology and Allergy
  • Immunology

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