Analysis of Qa-1bPeptide Binding Specificity and the Capacity of Cd94/Nkg2a to Discriminate between Qa-1-Peptide Complexes

• Type of Material: Article
• Authors: Jennifer R. Kraft, Emory University; Russell E. Vance, University of California at Berkeley; Jan Pohl, Emory University; Amy M. Martin, Emory University; David H. Raulet, University of California at Berkeley; Peter Edward Jensen, Emory University
• Language: English
• Date: 2000-09-05
• Publisher: Rockefeller University Press
• Publication Version: Final Published Version
• Copyright Statement: © 2000 The Rockefeller University Press
• License: Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International
• Final Published Version (URL): http://jem.rupress.org/content/192/5/613.full?sid=04ed5e44-8c30-4e41-9826-a995cdda7b1f
• Title of Journal or Parent Work: Journal of Experimental Medicine
• ISSN: 0022-1007
• Volume: 192
• Issue: 5
• Start Page: 613
• End Page: 624
• Grant/Funding Information: We are grateful for infrastructural support from National Institutes of Health National Center for Research Resources shared instrumentation grants RR-02878, RR12878, and RR13948, and for an equipment grant from the Wilson Foundation of Atlanta. This work was supported by National Institutes of Health grants R01-AI33614 to P.E. Jensen and R01-AI35021 to D.H. Raulet. R.E. Vance is a Howard Hughes Medical Institute Predoctoral Fellow.
• Keywords: CD94; Qa-1; major histocompatibility complex; NKG2A; natural killer cell
• Research Categories: Health Sciences, Pathology; Health Sciences, Medicine and Surgery

Abstract

The major histocompatibility complex class Ib protein, Qa-1b, serves as a ligand for murine CD94/NKG2A natural killer (NK) cell inhibitory receptors. The Qa-1b peptide-binding site is predominantly occupied by a single nonameric peptide, Qa-1 determinant modifier (Qdm), derived from the leader sequence of H-2D and L molecules. Five anchor residues were identified in this study by measuring the peptide-binding affinities of substituted Qdm peptides in experiments with purified recombinant Qa-1b. A candidate peptide-binding motif was determined by sequence analysis of peptides eluted from Qa-1 that had been folded in the presence of random peptide libraries or pools of Qdm derivatives randomized at specific anchor positions. The results indicate that Qa-1b can bind a diverse repertoire of peptides but that Qdm has an optimal primary structure for binding Qa-1b. Flow cytometry experiments with Qa-1b tetramers and NK target cell lysis assays demonstrated that CD94/NKG2A discriminates between Qa-1b complexes containing peptides with substitutions at nonanchor positions P4, P5, or P8. Our findings suggest that it may be difficult for viruses to generate decoy peptides that mimic Qdm and raise the possibility that competitive replacement of Qdm with other peptides may provide a novel mechanism for activation of NK cells.