8VCY image
Entry Detail
PDB ID:
8VCY
Keywords:
Title:
Human TCR A2.13 in complex with DQ8-InsC8-15NPY
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2023-12-14
Release Date:
2024-08-07
Method Details:
Experimental Method:
Resolution:
2.60 Å
R-Value Free:
0.22
R-Value Work:
0.18
R-Value Observed:
0.18
Space Group:
P 21 21 21
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:MHC class II HLA-DQ-alpha chain
Mutations:I75C
Chain IDs:A
Chain Length:185
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:MHC class II HLA-DQ-beta-1
Chain IDs:B
Chain Length:192
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:Hybrid insulin peptide (HIP; InsC8-15-NPY68-74)
Chain IDs:C
Chain Length:15
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:T-CELL-RECEPTOR, TCR A2.13 alpha
Chain IDs:D
Chain Length:203
Number of Molecules:1
Biological Source:Homo sapiens
Polymer Type:polypeptide(L)
Description:T-CELL-RECEPTOR, TCR A2.13 beta
Chain IDs:E
Chain Length:239
Number of Molecules:1
Biological Source:Homo sapiens
Primary Citation
A structural basis of T cell cross-reactivity to native and spliced self-antigens presented by HLA-DQ8.
J.Biol.Chem. 300 107612 107612 (2024)
PMID: 39074636 DOI: 10.1016/j.jbc.2024.107612

Abstact

Type 1 diabetes (T1D) is a T cell-mediated autoimmune disease that has a strong HLA association, where a number of self-epitopes have been implicated in disease pathogenesis. Human pancreatic islet-infiltrating CD4+ T cell clones not only respond to proinsulin C-peptide (PI40-54; GQVELGGGPGAGSLQ) but also cross-react with a hybrid insulin peptide (HIP; PI40-47-IAPP74-80; GQVELGGG-NAVEVLK) presented by HLA-DQ8. How T cell receptors recognize self-peptide and cross-react to HIPs is unclear. We investigated the cross-reactivity of the CD4+ T cell clones reactive to native PI40-54 epitope and multiple HIPs fused at the same N-terminus (PI40-54) to the degradation products of two highly expressed pancreatic islet proteins, neuropeptide Y (NPY68-74) and amyloid polypeptide (IAPP23-29 and IAPP74-80). We observed that five out of the seven selected SKW3 T cell lines expressing TCRs isolated from CD4+ T cells of people with T1D responded to multiple HIPs. Despite shared TRAV26-1-TRBV5-1 gene usage in some T cells, these clones cross-reacted to varying degrees with the PI40-54 and HIP epitopes. Crystal structures of two TRAV26-1+-TRBV5-1+ T cell receptors (TCRs) in complex with PI40-54 and HIPs bound to HLA-DQ8 revealed that the two TCRs had distinct mechanisms responsible for their differential recognition of the PI40-54 and HIP epitopes. Alanine scanning mutagenesis of the PI40-54 and HIPs determined that the P2, P7, and P8 residues in these epitopes were key determinants of TCR specificity. Accordingly, we provide a molecular basis for cross-reactivity towards native insulin and HIP epitopes presented by HLA-DQ8.

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Primary Citation of related structures