TY - JOUR
T1 - Molecular architecture of the alphabeta T cell receptor-CD3 complex
AU - Birnbaum, Michael E
AU - Berry, Richard
AU - Hsiao, Yu-Shan Stephanie
AU - Chen, Zhenjun
AU - Shingu-Vazquez, Miguel A
AU - Yu, Xiaoling
AU - Waghray, Deepa
AU - Fischer, Suzanne
AU - McCluskey, James
AU - Rossjohn, Jamie
AU - Walz, Thomas
AU - Garcia, K Christopher
PY - 2014
Y1 - 2014
N2 - alphabeta T-cell receptor (TCR) activation plays a crucial role for T-cell function. However, the TCR itself does not possess signaling domains. Instead, the TCR is noncovalently coupled to a conserved multisubunit signaling apparatus, the CD3 complex, that comprises the CD3epsilongamma, CD3epsilondelta, and CD3zetazeta dimers. How antigen ligation by the TCR triggers CD3 activation and what structural role the CD3 extracellular domains (ECDs) play in the assembled TCR-CD3 complex remain unclear. Here, we use two complementary structural approaches to gain insight into the overall organization of the TCR-CD3 complex. Small-angle X-ray scattering of the soluble TCR-CD3epsilondelta complex reveals the CD3epsilondelta ECDs to sit underneath the TCR alpha-chain. The observed arrangement is consistent with EM images of the entire TCR-CD3 integral membrane complex, in which the CD3epsilondelta and CD3epsilongamma subunits were situated underneath the TCR alpha-chain and TCR beta-chain, respectively. Interestingly, the TCR-CD3 transmembrane complex bound to peptide-MHC is a dimer in which two TCRs project outward from a central core composed of the CD3 ECDs and the TCR and CD3 transmembrane domains. This arrangement suggests a potential ligand-dependent dimerization mechanism for TCR signaling. Collectively, our data advance our understanding of the molecular organization of the TCR-CD3 complex, and provides a conceptual framework for the TCR activation mechanism.
AB - alphabeta T-cell receptor (TCR) activation plays a crucial role for T-cell function. However, the TCR itself does not possess signaling domains. Instead, the TCR is noncovalently coupled to a conserved multisubunit signaling apparatus, the CD3 complex, that comprises the CD3epsilongamma, CD3epsilondelta, and CD3zetazeta dimers. How antigen ligation by the TCR triggers CD3 activation and what structural role the CD3 extracellular domains (ECDs) play in the assembled TCR-CD3 complex remain unclear. Here, we use two complementary structural approaches to gain insight into the overall organization of the TCR-CD3 complex. Small-angle X-ray scattering of the soluble TCR-CD3epsilondelta complex reveals the CD3epsilondelta ECDs to sit underneath the TCR alpha-chain. The observed arrangement is consistent with EM images of the entire TCR-CD3 integral membrane complex, in which the CD3epsilondelta and CD3epsilongamma subunits were situated underneath the TCR alpha-chain and TCR beta-chain, respectively. Interestingly, the TCR-CD3 transmembrane complex bound to peptide-MHC is a dimer in which two TCRs project outward from a central core composed of the CD3 ECDs and the TCR and CD3 transmembrane domains. This arrangement suggests a potential ligand-dependent dimerization mechanism for TCR signaling. Collectively, our data advance our understanding of the molecular organization of the TCR-CD3 complex, and provides a conceptual framework for the TCR activation mechanism.
UR - http://www.pnas.org/content/111/49/17576.full.pdf+html
U2 - 10.1073/pnas.1420936111
DO - 10.1073/pnas.1420936111
M3 - Article
VL - 111
SP - 17576
EP - 17581
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 49
ER -