Logo image
Critical Roles for Coiled-Coil Dimers of Butyrophilin 3A1 in the Sensing of Prenyl Pyrophosphates by Human V gamma 2V delta 2 T Cells
Journal article   Peer reviewed

Critical Roles for Coiled-Coil Dimers of Butyrophilin 3A1 in the Sensing of Prenyl Pyrophosphates by Human V gamma 2V delta 2 T Cells

Hong Wang, Mohanad H. Nada, Yoshimasa Tanaka, Shun Sakuraba and Craig T. Morita
The Journal of immunology (1950), Vol.203(3), pp.607-626
08/01/2019
DOI: 10.4049/jimmunol.1801252
PMCID: PMC6834341
PMID: 31227581

View Online

Abstract

V gamma 2V delta 2 T cells play important roles in human immunity to pathogens and tumors. Their TCRs respond to the sensing of isoprenoid metabolites, such as (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate and isopentenyl pyrophosphate, by butyrophilin (BTN) 3A1. BTN3A1 is an Ig superfamily protein with extracellular IgV/IgC domains and intracellular B30.2 domains that bind prenyl pyrophosphates. We have proposed that intracellular a helices form a coiled-coil dimer that functions as a spacer for the B30.2 domains. To test this, five pairs of anchor residues were mutated to glycine to destabilize the coiled-coil dimer. Despite maintaining surface expression, BTN3A1 mutagenesis either abrogated or decreased stimulation by (E)-4-hydroxy-3-methyl-but-2-enyl pyrophosphate. BTN3A2 and BTN3A3 proteins and orthologs in alpacas and dolphins are also predicted to have similar coiled-coil dimers. A second short coiled-coil region dimerizes the B30.2 domains. Molecular dynamics simulations predict that mutation of a conserved tryptophan residue in this region will destabilize the dimer, explaining the loss of stimulation by BTN3A1 proteins with this mutation. The juxtamembrane regions of other BTN/BTN-like proteins with B30.2 domains are similarly predicted to assume a helices, with many predicted to form coiled-coil dimers. An exon at the end of this region and the exon encoding the dimerization region for B30.2 domains are highly conserved. We propose that coiled-coil dimers function as rod-like helical molecular spacers to position B30.2 domains, as interaction sites for other proteins, and as dimerization regions to allow sensing by B30.2 domains. In these ways, the coiled-coil domains of BTN3A1 play critical roles for its function.
Immunology Life Sciences & Biomedicine Science & Technology

Details

Metrics

Logo image