Structural highlights
FunctionPublication Abstract from PubMedHLA-DQ8, a genetic risk factor in type I diabetes (T1D), presents hybrid insulin peptides (HIPs) to autoreactive CD4+ T cells. The abundance of spliced peptides binding to HLA-DQ8 and how they are subsequently recognised by the autoreactive T cell repertoire is unknown. Here we report, the HIP (GQVELGGGNAVEVLK), derived from splicing of insulin and islet amyloid polypeptides, generates a preferred peptide-binding motif for HLA-DQ8. HLA-DQ8-HIP tetramer(+) T cells from the peripheral blood of a T1D patient are characterised by repeated TRBV5 usage, which matches the TCR bias of CD4+ T cells reactive to the HIP peptide isolated from the pancreatic islets of a patient with T1D. The crystal structure of three TRBV5+ TCR-HLA-DQ8-HIP complexes shows that the TRBV5-encoded TCR beta-chain forms a common landing pad on the HLA-DQ8 molecule. The N- and C-termini of the HIP is recognised predominantly by the TCR alpha-chain and TCR beta-chain, respectively, in all three TCR ternary complexes. Accordingly, TRBV5 + TCR recognition of HIP peptides might occur via a 'polarised' mechanism, whereby each chain within the alphabetaTCR heterodimer recognises distinct origins of the spliced peptide presented by HLA-DQ8. T cell receptor recognition of hybrid insulin peptides bound to HLA-DQ8.,Tran MT, Faridi P, Lim JJ, Ting YT, Onwukwe G, Bhattacharjee P, Jones CM, Tresoldi E, Cameron FJ, La Gruta NL, Purcell AW, Mannering SI, Rossjohn J, Reid HH Nat Commun. 2021 Aug 25;12(1):5110. doi: 10.1038/s41467-021-25404-x. PMID:34433824[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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