1. Direct recognition of an intact foreign protein by an αβ T cell receptor
- Author
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Catarina F. Almeida, Benjamin S. Gully, Claerwen M. Jones, Lukasz Kedzierski, Sachith D. Gunasinghe, Michael T. Rice, Richard Berry, Nicholas A. Gherardin, Trang T. Nguyen, Yee-Foong Mok, Josephine F. Reijneveld, D. Branch Moody, Ildiko Van Rhijn, Nicole L. La Gruta, Adam P. Uldrich, Jamie Rossjohn, and Dale I. Godfrey
- Subjects
Science - Abstract
Abstract αβ T cell receptors (αβTCRs) co-recognise antigens when bound to Major Histocompatibility Complex (MHC) or MHC class I-like molecules. Additionally, some αβTCRs can bind non-MHC molecules, but how much intact antigen reactivities are achieved remains unknown. Here, we identify an αβ T cell clone that directly recognises the intact foreign protein, R-phycoerythrin (PE), a multimeric (αβ)6γ protein complex. This direct αβTCR–PE interaction occurs in an MHC-independent manner, yet triggers T cell activation and bound PE with an affinity comparable to αβTCR–peptide–MHC interactions. The crystal structure reveals how six αβTCR molecules simultaneously engage the PE hexamer, mediated by the complementarity-determining regions (CDRs) of the αβTCR. Here, the αβTCR mainly binds to two α-helices of the globin fold in the PE α-subunit, which is analogous to the antigen-binding platform of the MHC molecule. Using retrogenic mice expressing this TCR, we show that it supports intrathymic T cell development, maturation, and exit into the periphery as mature CD4/CD8 double negative (DN) T cells with TCR-mediated functional capacity. Accordingly, we show how an αβTCR can recognise an intact foreign protein in an antibody-like manner.
- Published
- 2024
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