Format

Send to

Choose Destination
Biochemistry. 2017 Aug 1;56(30):3945-3961. doi: 10.1021/acs.biochem.7b00385. Epub 2017 Jul 19.

The T-Cell Receptor Can Bind to the Peptide-Bound Major Histocompatibility Complex and Uncomplexed β2-Microglobulin through Distinct Binding Sites.

Author information

1
Department of Pharmacy, University of Copenhagen , 2100 Copenhagen, Denmark.
2
Swiss Institute of Bioinformatics , Bâtiment Génopode, UNIL Sorge, 1015 Lausanne, Switzerland.
3
Ludwig Branch for Cancer Research, University of Lausanne , 1015 Lausanne, Switzerland.
4
Department of Biochemistry and Molecular Biology, University of Southern Denmark , 5230 Odense M, Denmark.
5
Department of Physiology and Biophysics, Weill Cornell Medical College , 1300 York Avenue, New York, New York 10065, United States.

Abstract

T-Cell receptor (TCR)-mediated recognition of the peptide-bound major histocompatibility complex (pMHC) initiates an adaptive immune response against antigen-presenting target cells. The recognition events take place at the TCR-pMHC interface, and their effects on TCR conformation and dynamics are controversial. Here, we have measured the time-resolved hydrogen/deuterium exchange (HDX) of a soluble TCR in the presence and absence of its cognate pMHC by mass spectrometry to delineate the impact of pMHC binding on solution-phase structural dynamics in the TCR. Our results demonstrate that while TCR-pMHC complex formation significantly stabilizes distinct CDR loops of the TCR, it does not trigger structural changes in receptor segments remote from the binding interface. Intriguingly, our HDX measurements reveal that the TCR α-constant domain (C- and F-strand) directly interacts with the unbound MHC light chain, β2-microglobulin (β2m). Surface plasmon resonance measurements corroborated a binding event between TCR and β2m with a dissociation constant of 167 ± 20 μM. We propose a model structure for the TCR-β2m complex based on a refined protein-protein docking approach driven by HDX data and information from molecular dynamics simulations. Using a biological assay based on TCR gene-engineered primary human T cells, we did not observe a significant effect of β2m on T-cell cytotoxicity, suggesting an alternate role for β2m binding. Overall, we show that binding of β2m to the TCR occurs in vitro and, as such, not only should be considered in structure-function studies of the TCR-pMHC complex but also could play a hitherto unidentified role in T-cell function in vivo.

PMID:
28671821
DOI:
10.1021/acs.biochem.7b00385
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for American Chemical Society
Loading ...
Support Center