期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 114, 期 35, 页码 E7311-E7320出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1707547114
关键词
human V gamma 9V delta 2 T cells; butyrophilin 3A1; phosphoantigen; conformational change
资金
- NIH [R01 AI115471]
Human V gamma 9V delta 2 T cells respond to microbial infections as well as certain types of tumors. The key initiators of V gamma 9V delta 2 activation are small, pyrophosphate-containing molecules called phosphoantigens (pAgs) that are present in infected cells or accumulate intracellularly in certain tumor cells. Recent studies demonstrate that initiation of the V gamma 9V delta 2 T cell response begins with sensing of pAg via the intracellular domain of the butyrophilin 3A1 (BTN3A1) molecule. However, it is unknown how downstream events can ultimately lead to T cell activation. Here, using NMR spectrometry and molecular dynamics (MD) simulations, we characterize a global conformational change in the B30.2 intracellular domain of BTN3A1 induced by pAg binding. We also reveal by crystallography two distinct dimer interfaces in the BTN3A1 full-length intracellular domain, which are stable in MD simulations. These interfaces lie in close proximity to the pAg-binding pocket and contain clusters of residues that experience major changes of chemical environment upon pAg binding. This suggests that pAg binding disrupts a preexisting conformation of the BTN3A1 intracellular domain. Using a combination of biochemical, structural, and cellular approaches we demonstrate that the extracellular domains of BTN3A1 adopt a V-shaped conformation at rest, and that locking them in this resting conformation without perturbing their membrane reorganization properties diminishes pAg-induced T cell activation. Based on these results, we propose a model in which a conformational change in BTN3A1 is a key event of pAg sensing that ultimately leads to T cell activation.
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