Download MendeleyStructural plasticity in I-A g7 links autoreactivity to hybrid insulin peptides in type I diabetes.
Erausquin, E., Serra, P., Parras, D., Santamaria, P., Lopez-Sagaseta, J.(2022) Front Immunol 13: 924311-924311
- PubMed: 35967292
- DOI: https://doi.org/10.3389/fimmu.2022.924311
- Primary Citation of Related Structures:
7QHP, 7Z50 - PubMed Abstract:
We recently provided evidence for promiscuous recognition of several different hybrid insulin peptides (HIPs) by the highly diabetogenic, I-A g7 -restricted 4.1-T cell receptor (TCR). To understand the structural determinants of this phenomenon, we solved the structure of an agonistic HIP/I-A g7 complex, both in isolation as well as bound to the 4.1-TCR. We find that HIP promiscuity of the 4.1-TCR is dictated, on the one hand, by an amino acid sequence pattern that ensures I-A g7 binding and, on the other hand, by the presence of three acidic residues at positions P5, P7 and P8 that favor an optimal engagement by the 4.1-TCR's complementary determining regions. Surprisingly, comparison of the TCR-bound and unbound HIP/I-A g7 structures reveals that 4.1-TCR binding triggers several novel and unique structural motions in both the I-A g7 molecule and the peptide that are essential for docking. This observation indicates that the type 1 diabetes-associated I-A g7 molecule is structurally malleable and that this plasticity allows the recognition of multiple peptides by individual TCRs that would otherwise be unable to do so.
Organizational Affiliation:
Unit of Protein Crystallography and Structural Immunology, Navarrabiomed, Navarra, Spain.
