Abstract
Human Vγ9/Vδ2 T-cells detect tumour cells and microbial infections by recognising small phosphorylated prenyl metabolites termed phosphoantigens (P-Ag). The type-1 transmembrane protein Butyrophilin 3A1 (BTN3A1) is critical to the P-Ag-mediated activation of Vγ9/Vδ2 T-cells, however, the molecular mechanisms involved in BTN3A1-mediated metabolite sensing are unclear, including how P-Ag are discriminated from non-antigenic small molecules. Here, we utilised NMR and X-ray crystallography to probe P-Ag sensing by BTN3A1. Whereas the BTN3A1 Immunoglobulin Variable domain failed to bind P-Ag, the intracellular B30.2 domain bound a range of negatively-charged small molecules, including P-Ag, in a positively-charged surface pocket. However, NMR chemical shift perturbations indicated BTN3A1 discriminated P-Ag from non-antigenic small molecules by their ability to induce a specific conformational change in the B30.2 domain that propagated from the P-Ag binding site to distal parts of the domain. These results suggest BTN3A1 selectively detects P-Ag intracellularly via a conformational antigenic sensor in its B30.2 domain, and have implications for rational design of antigens for Vγ9/Vδ2 -based T-cell immunotherapies.
Original language | English |
---|---|
Pages (from-to) | 2631-2643 |
Number of pages | 13 |
Journal | ACS chemical biology |
Volume | 12 |
Issue number | 10 |
Early online date | 1 Sept 2017 |
DOIs | |
Publication status | Published - 14 Sept 2017 |
Keywords
- Antigens
- Antigens, CD/genetics
- Butyrophilins/genetics
- Cloning, Molecular
- Coculture Techniques
- Gene Expression Regulation/physiology
- HEK293 Cells
- Humans
- Magnetic Resonance Spectroscopy
- Models, Chemical
- Mutation
- Phosphoproteins
- Protein Conformation
- Protein Domains
- Receptors, Antigen, T-Cell, gamma-delta/genetics
- T-Lymphocytes/metabolism