During the last funding interval as a merit award, this grant focused on the T cell receptor (TCR) complex composed of an ?? heterodimer and non-covalently associated CD3 signaling components. We continued crystallographic analysis with TCRs, providing the first structure of an ?? heterodimer in complex with a peptide/MHC (pMHC) class II ligand. In conjunction with a crystallographic structure of CD4 D1D2 binding to the same MHC class II molecule, a hydrophobic concavity formed by residues from membrane proximal ?2 and ?2 MHC class II domains was revealed. We excluded a direct TCRab-CD4 interaction, instead revealing how TCR?? and CD4 signaling is coordinated in a """"""""V-shape"""""""" around the antigenic peptide/pMHC class II complex. Solution structures of CD3?? and CD3?? ectodomain complexes were determined by NMR, uncovering for each dimer a unique side-to-side hydrophobic interface between their two Ig-like domains with parallel pairing of respective C-terminal ?-strands, and suggesting how rigidified CD3 elements participate in TCR-based signal transduction. To now characterize the structural basis for early signal transduction events via this TCR?? complex, four aims are proposed involving the CD3?? heterodimer and associated TCR ? chain. First, NMR-based methods will be used to determine the precise binding site on CD3?? of activating and non-activating anti-CD3? mAbs, given equivalent binding affinities. Second, CD3??-associated TCR? chain recognition function during thymic development and T cell activation accounting for V? repertoire bias will be assessed. Third, the structure and function of the transmembrane (TM) segments of CD3? and ? will be determined and their interaction with that of TCR ? ascertained. Fourth, electron paramagnetic resonance (EPR) methods will be exploited to define the orientation and disposition of TM elements and how pMHC or anti-CD3? mAbs affect TM depth, orientation and structural conformation. Distance measurements between the ? chain and CD3? and CD3? ectodomains will also be examined before and after pMHC or anti- CD3 mAb ligation. That orthological rather than vertical force via CD3 components activates T cells suggests a dynamic mechanosensor TCR model;pMHC pulls on the TCR from the opposing antigen-presenting cell surface such that the ?? heterodimer then presses on the CD3 ectodomains to initiate signaling.

Public Health Relevance

The TCR is responsible for mediating antigen-specific T cell stimulation. As such, insights from this proposal will be relevant for design of inhibitory and activating anti-TCR monoclonal antibodies and other molecules to treat human autoimmune and immunodeficiency states, respectively.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
2R01AI019807-26A1
Application #
7729724
Study Section
Cellular and Molecular Immunology - B Study Section (CMIB)
Program Officer
Leitner, Wolfgang W
Project Start
2009-09-09
Project End
2011-08-31
Budget Start
2009-09-09
Budget End
2010-08-31
Support Year
26
Fiscal Year
2009
Total Cost
$431,502
Indirect Cost
Name
Dana-Farber Cancer Institute
Department
Type
DUNS #
076580745
City
Boston
State
MA
Country
United States
Zip Code
02215
Mallis, Robert J; Arthanari, Haribabu; Lang, Matthew J et al. (2018) NMR-directed design of pre-TCR? and pMHC molecules implies a distinct geometry for pre-TCR relative to ??TCR recognition of pMHC. J Biol Chem 293:754-766
Mallis, Robert J; Reinherz, Ellis L; Wagner, Gerhard et al. (2016) Backbone resonance assignment of N15, N30 and D10 T cell receptor ? subunits. Biomol NMR Assign 10:35-9
Reinherz, Ellis L; Wang, Jia-huai (2015) Codification of bidentate pMHC interaction with TCR and its co-receptor. Trends Immunol 36:300-6
Mallis, Robert J; Bai, Ke; Arthanari, Haribabu et al. (2015) Pre-TCR ligand binding impacts thymocyte development before ??TCR expression. Proc Natl Acad Sci U S A 112:8373-8
Choi, Young I; Duke-Cohan, Jonathan S; Chen, Wei et al. (2014) Dynamic control of ?1 integrin adhesion by the plexinD1-sema3E axis. Proc Natl Acad Sci U S A 111:379-84
Choi, Young I; Duke-Cohan, Jonathan S; Tan, Jing et al. (2013) Plxnd1 expression in thymocytes regulates their intrathymic migration while that in thymic endothelium impacts medullary topology. Front Immunol 4:392
Touma, Maki; Keskin, Derin B; Shiroki, Fumiko et al. (2011) Impaired B cell development and function in the absence of IkappaBNS. J Immunol 187:3942-52
Kim, Sun Taek; Touma, Maki; Takeuchi, Koh et al. (2010) Distinctive CD3 heterodimeric ectodomain topologies maximize antigen-triggered activation of alpha beta T cell receptors. J Immunol 185:2951-9
Vernier, Gregory; Wang, Jie; Jennings, Laura D et al. (2009) Solubilization and characterization of the anthrax toxin pore in detergent micelles. Protein Sci 18:1882-95
Kim, Sun Taek; Takeuchi, Koh; Sun, Zhen-Yu J et al. (2009) The alphabeta T cell receptor is an anisotropic mechanosensor. J Biol Chem 284:31028-37

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