Toxoplasma gondii peptide ligands open the gate of the HLA class I binding groove
- University of Oklahoma Health Sciences Center, United States
- Technical University of Denmark, Denmark
- University at Buffalo School of Medicine, United States
- La Jolla Institute for Allergy and Immunology, United States
- University of Chicago, United States
- University of Oklahoma Health Science Center, United States
Abstract
HLA class I presentation of pathogen-derived peptide ligands is essential for CD8+ T-cell recognition of Toxoplasma gondii infected cells. Currently, little data exist pertaining to peptides that are presented after T. gondii infection. Herein we purify HLA-A*02:01 complexes from T. gondii infected cells and characterize the peptide ligands using LCMS. We identify 195 T. gondii encoded ligands originating from both secreted and cytoplasmic proteins. Surprisingly, T. gondii ligands are significantly longer than uninfected host ligands, and these longer pathogen-derived peptides maintain a canonical N-terminal binding core yet exhibit a C-terminal extension of 1-30 amino acids. Structural analysis demonstrates that binding of extended peptides opens the HLA class I F' pocket, allowing the C-terminal extension to protrude through one end of the binding groove. In summary, we demonstrate that unrealized structural flexibility makes MHC class I receptive to parasite-derived ligands that exhibit unique C-terminal peptide extensions.
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© 2016, McMurtrey et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Toxoplasma gondii peptide ligands open the gate of the HLA class I binding groove
eLife 5:e12556.
https://doi.org/10.7554/eLife.12556
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