Abstract
MHC-E regulates NK cells by displaying MHC class Ia signal peptides (VL9) to NKG2A:CD94 receptors. MHC-E can also present sequence-diverse, lower-affinity, pathogen-derived peptides to T cell receptors (TCRs) on CD8+ T cells. To understand these affinity differences, human MHC-E (HLA-E)-VL9 versus pathogen-derived peptide structures are compared. Small-angle X-ray scatter (SAXS) measures biophysical parameters in solution, allowing comparison with crystal structures. For HLA-E-VL9, there is concordance between SAXS and crystal parameters. In contrast, HLA-E-bound pathogen-derived peptides produce larger SAXS dimensions that reduce to their crystallographic dimensions only when excess peptide is supplied. Further crystallographic analysis demonstrates three amino acids, exclusive to MHC-E, that not only position VL9 close to the α2 helix, but also allow non-VL9 peptide binding with re-configuration of a key TCR-interacting α2 region. Thus, non-VL9-bound peptides introduce an alternative peptide-binding motif and surface recognition landscape, providing a likely basis for VL9- and non-VL9-HLA-E immune discrimination.
Original language | English |
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Article number | 110959 |
Number of pages | 15 |
Journal | Cell Reports |
Volume | 39 |
Issue number | 11 |
DOIs | |
Publication status | Published - 14 Jun 2022 |
Bibliographical note
Acknowledgments:This work was supported by grants from the BMGF (OPP1133649), MRC (MR/M019837/1), NIAID (5UM1AI126619-05 and 1UM1AI164567-01), and the Hester Cordelia Parsons Fund, Oxford University. D.R. was supported by the Czech Science Foundation (21-27204M) and Charles University (PRIMUS/21/SCI/003). We are grateful to Diamond Light Source for beamtime (proposal MX19946) and the staff of beamlines I03 and I04 for data collection assistance. We also thank Prof. Tao Dong and Dr. Yanchun Peng for provision of HLA-A∗02:01 heavy-chain material.
Keywords
- MHC-E
- HLA-E
- small-angle X-ray scatter
- SAXS
- X-ray crystallography
- VL9
- MHC Ia
- NK cells
- NKG2A
- CD8 T cells
- T cell receptor