1
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Alonso JA, Smith AR, Baker BM. Tumor rejection properties of gp100 209-specific T cells correlate with T cell receptor binding affinity towards the wild type rather than anchor-modified antigen. Mol Immunol 2021; 135:365-372. [PMID: 33990005 DOI: 10.1016/j.molimm.2021.05.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 05/03/2021] [Accepted: 05/03/2021] [Indexed: 10/21/2022]
Abstract
Although there are exceptions and outliers, T cell functional responses generally correlate with the affinity of a TCR for a peptide/MHC complex. In one recently described outlier case, the most promising clinical candidate in a series of TCRs specific for the gp100209 melanoma antigen bound with the weakest solution affinity and produced the least amount of cytokine in vitro. Hypotheses for this outlier behavior included unusual cytokine expression patterns arising from an atypical TCR binding geometry. Studying this instance in more detail, we found here that outlier behavior is attributable not to unusual cytokine patterns or TCR binding, but the use of a position 2 anchor-modified peptide variant in in vitro experiments instead of the wild type antigen that is present in vivo. Although the anchor-modified variant has been widely used in basic and clinical immunology as a surrogate for the wild type peptide, prior work has shown that TCRs can clearly distinguish between the two. We show that when this differential recognition is accounted for, the functional properties of gp100209-specific TCRs track with their affinity towards the peptide/MHC complex. Beyond demonstrating the correlates with T cell function for a clinically relevant TCR, our results provide important considerations for selection of TCRs for immunotherapy and the use of modified peptides in immunology.
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Affiliation(s)
- Jesus A Alonso
- Department of Chemistry & Biochemistry and the Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN, USA
| | - Angela R Smith
- Department of Chemistry & Biochemistry and the Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN, USA
| | - Brian M Baker
- Department of Chemistry & Biochemistry and the Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN, USA.
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2
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Rangarajan S, He Y, Chen Y, Kerzic MC, Ma B, Gowthaman R, Pierce BG, Nussinov R, Mariuzza RA, Orban J. Peptide-MHC (pMHC) binding to a human antiviral T cell receptor induces long-range allosteric communication between pMHC- and CD3-binding sites. J Biol Chem 2018; 293:15991-16005. [PMID: 30135211 PMCID: PMC6187629 DOI: 10.1074/jbc.ra118.003832] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 08/21/2018] [Indexed: 12/17/2022] Open
Abstract
T cells generate adaptive immune responses mediated by the T cell receptor (TCR)-CD3 complex comprising an αβ TCR heterodimer noncovalently associated with three CD3 dimers. In early T cell activation, αβ TCR engagement by peptide-major histocompatibility complex (pMHC) is first communicated to the CD3 signaling apparatus of the TCR-CD3 complex, but the underlying mechanism is incompletely understood. It is possible that pMHC binding induces allosteric changes in TCR conformation or dynamics that are then relayed to CD3. Here, we carried out NMR analysis and molecular dynamics (MD) simulations of both the α and β chains of a human antiviral TCR (A6) that recognizes the Tax antigen from human T cell lymphotropic virus-1 bound to the MHC class I molecule HLA-A2. We observed pMHC-induced NMR signal perturbations in the TCR variable (V) domains that propagated to three distinct sites in the constant (C) domains: 1) the Cβ FG loop projecting from the Vβ/Cβ interface; 2) a cluster of Cβ residues near the Cβ αA helix, a region involved in interactions with CD3; and 3) the Cα AB loop at the membrane-proximal base of the TCR. A biological role for each of these allosteric sites is supported by previous mutational and functional studies of TCR signaling. Moreover, the pattern of long-range, ligand-induced changes in TCR A6 revealed by NMR was broadly similar to that predicted by the MD simulations. We propose that the unique structure of the TCR β chain enables allosteric communication between the TCR-binding sites for pMHC and CD3.
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MESH Headings
- Allosteric Regulation
- Animals
- Binding Sites
- Gene Products, tax/chemistry
- Gene Products, tax/metabolism
- HLA-A2 Antigen/chemistry
- HLA-A2 Antigen/metabolism
- Human T-lymphotropic virus 1/chemistry
- Humans
- Mice
- Molecular Dynamics Simulation
- Protein Binding
- Protein Conformation
- Receptor-CD3 Complex, Antigen, T-Cell/chemistry
- Receptor-CD3 Complex, Antigen, T-Cell/metabolism
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
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Affiliation(s)
- Sneha Rangarajan
- From the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850
- the Departments of Cell Biology and Molecular Genetics and
| | - Yanan He
- From the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850
- Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, and
| | - Yihong Chen
- From the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850
| | - Melissa C Kerzic
- From the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850
| | - Buyong Ma
- the Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland 21702
| | - Ragul Gowthaman
- From the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850
- the Departments of Cell Biology and Molecular Genetics and
| | - Brian G Pierce
- From the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850
- the Departments of Cell Biology and Molecular Genetics and
| | - Ruth Nussinov
- the Cancer and Inflammation Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland 21702
| | - Roy A Mariuzza
- From the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850,
- the Departments of Cell Biology and Molecular Genetics and
| | - John Orban
- From the W. M. Keck Laboratory for Structural Biology, University of Maryland Institute for Bioscience and Biotechnology Research, Rockville, Maryland 20850,
- Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, and
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3
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Brameshuber M, Kellner F, Rossboth BK, Ta H, Alge K, Sevcsik E, Göhring J, Axmann M, Baumgart F, Gascoigne NRJ, Davis SJ, Stockinger H, Schütz GJ, Huppa JB. Monomeric TCRs drive T cell antigen recognition. Nat Immunol 2018; 19:487-496. [PMID: 29662172 DOI: 10.1038/s41590-018-0092-4] [Citation(s) in RCA: 91] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 03/15/2018] [Indexed: 11/09/2022]
Abstract
T cell antigen recognition requires T cell antigen receptors (TCRs) engaging MHC-embedded antigenic peptides (pMHCs) within the contact region of a T cell with its conjugated antigen-presenting cell. Despite micromolar TCR:pMHC affinities, T cells respond to even a single antigenic pMHC, and higher-order TCRs have been postulated to maintain high antigen sensitivity and trigger signaling. We interrogated the stoichiometry of TCRs and their associated CD3 subunits on the surface of living T cells through single-molecule brightness and single-molecule coincidence analysis, photon-antibunching-based fluorescence correlation spectroscopy and Förster resonance energy transfer measurements. We found exclusively monomeric TCR-CD3 complexes driving the recognition of antigenic pMHCs, which underscores the exceptional capacity of single TCR-CD3 complexes to elicit robust intracellular signaling.
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Affiliation(s)
| | - Florian Kellner
- Center for Pathophysiology, Infectiology and Immunology, Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna, Austria
| | | | - Haisen Ta
- Department of NanoBiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Kevin Alge
- Center for Pathophysiology, Infectiology and Immunology, Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna, Austria
| | - Eva Sevcsik
- Institute of Applied Physics, TU Wien, Vienna, Austria
| | - Janett Göhring
- Institute of Applied Physics, TU Wien, Vienna, Austria.,Center for Pathophysiology, Infectiology and Immunology, Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna, Austria
| | - Markus Axmann
- Center for Pathobiochemistry and Genetics, Institute of Medical Chemistry and Pathobiochemistry, Medical University of Vienna, Vienna, Austria
| | | | - Nicholas R J Gascoigne
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore
| | - Simon J Davis
- Radcliffe Department of Medicine and MRC Human Immunology Unit, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Hannes Stockinger
- Center for Pathophysiology, Infectiology and Immunology, Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna, Austria
| | | | - Johannes B Huppa
- Center for Pathophysiology, Infectiology and Immunology, Institute for Hygiene and Applied Immunology, Medical University of Vienna, Vienna, Austria.
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4
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Wang JH, Reinherz EL. Revisiting the putative TCR Cα dimerization model through structural analysis. Front Immunol 2013; 4:16. [PMID: 23386853 PMCID: PMC3558723 DOI: 10.3389/fimmu.2013.00016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 01/08/2013] [Indexed: 12/18/2022] Open
Abstract
Despite major advances in T cell receptor (TCR) biology and structure, how peptide-MHC complex (pMHC) ligands trigger αβ TCR activation remains unresolved. Two views exist. One model postulates that monomeric TCR-pMHC ligation events are sufficient while a second proposes that TCR-TCR dimerization in cis via Cα domain interaction plus pMHC binding is critical. We scrutinized 22 known TCR/pMHC complex crystal structures, and did not find any predicted molecular Cα-Cα contacts in these crystals that would allow for physiological TCR dimerization. Moreover, the presence of conserved glycan adducts on the outer face of the Cα domain preclude the hypothesized TCR dimerization through the Cα domain. Observed functional consequences of Cα mutations are likely indirect, with TCR microclusters at the immunological synapse driven by TCR transmembrane/cytoplasmic interactions via signaling molecules, scaffold proteins, and/or cytoskeletal elements.
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Affiliation(s)
- Jia-Huai Wang
- Laboratory of Immunobiology, Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical SchoolBoston, MA, USA
- Department of Pediatrics, Harvard Medical SchoolBoston, MA, USA
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical SchoolBoston, MA, USA
| | - Ellis L. Reinherz
- Laboratory of Immunobiology, Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical SchoolBoston, MA, USA
- Department of Medicine, Harvard Medical SchoolBoston, MA, USA
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5
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Abstract
The recognition of peptide/MHC antigens by T-cells has continued to challenge the imagination of immunologists, biochemists, and cell biologists alike. This is at least in part because T-cell recognition connects a diversity of issues and transcends many scientific disciplines. A fundamental unsolved issue is how T-cells manage to detect even a single molecule of an agonist pMHC complex, which is vastly outnumbered by endogenous pMHCs, many of which involve the same MHC molecule. They do so although TCRs are cross-reactive and typically low in affinity when measured in isolation. Importantly, T-cell antigen recognition takes place within the contact zone between a T-cell and the antigen-presenting cell, termed the immunological synapse. This bimembrane structure sets the stage for the antigen-binding events and all subsequent molecular recognition events. There is increasing evidence that the molecular dynamics of receptor-ligand interactions are not only dependent on the intrinsic properties of the binding partners but also become transformed by cell biological parameters such as the geometrical constraints within the immune synapse, mechanical forces, and local molecular crowding. To appreciate the complete picture, we think a multidisciplinary approach is imperative, which includes genetics, biochemistry, and structure determination and also biophysical analyses and the latest molecular imaging techniques. Here, we review earlier pioneering work and also recent developments in the fascinating and interdisciplinary science of T-cell antigen recognition. In many ways, this work may present a useful "roadmap" for work in other systems of cell-cell recognition, which underlie many fundamental biological phenomenons of interest.
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6
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Kuhns MS, Davis MM. TCR Signaling Emerges from the Sum of Many Parts. Front Immunol 2012; 3:159. [PMID: 22737151 PMCID: PMC3381686 DOI: 10.3389/fimmu.2012.00159] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Accepted: 05/27/2012] [Indexed: 11/30/2022] Open
Abstract
“How does T cell receptor signaling begin?” Answering this question requires an understanding of how the parts of the molecular machinery that mediates this process fit and work together. Ultimately this molecular architecture must (i) trigger the relay of information from the TCR-pMHC interface to the signaling substrates of the CD3 molecules and (ii) bring the kinases that modify these substrates in close proximity to interact, initiate, and sustain signaling. In this contribution we will discuss advances of the last decade that have increased our understanding of the complex machinery and interactions that underlie this type of signaling.
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Affiliation(s)
- Michael S Kuhns
- Department of Immunobiology, The University of Arizona College of Medicine Tucson, AZ, USA
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7
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Sethi DK, Schubert DA, Anders AK, Heroux A, Bonsor DA, Thomas CP, Sundberg EJ, Pyrdol J, Wucherpfennig KW. A highly tilted binding mode by a self-reactive T cell receptor results in altered engagement of peptide and MHC. ACTA ACUST UNITED AC 2011; 208:91-102. [PMID: 21199956 PMCID: PMC3023130 DOI: 10.1084/jem.20100725] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A TCR derived from a patient with relapsing-remitting multiple sclerosis engages the self-peptide myelin basic protein in the context of HLA-DQ1 in a very unusual way. Self-reactive T cells that escape elimination in the thymus can cause autoimmune pathology, and it is therefore important to understand the structural mechanisms of self-antigen recognition. We report the crystal structure of a T cell receptor (TCR) from a patient with relapsing-remitting multiple sclerosis that engages its self-peptide–major histocompatibility complex (pMHC) ligand in an unusual manner. The TCR is bound in a highly tilted orientation that prevents interaction of the TCR-α chain with the MHC class II β chain helix. In this structure, only a single germline-encoded TCR loop engages the MHC protein, whereas in most other TCR-pMHC structures all four germline-encoded TCR loops bind to the MHC helices. The tilted binding mode also prevents peptide contacts by the short complementarity-determining region (CDR) 3β loop, and interactions that contribute to peptide side chain specificity are focused on the CDR3α loop. This structure is the first example in which only a single germline-encoded TCR loop contacts the MHC helices. Furthermore, the reduced interaction surface with the peptide may facilitate TCR cross-reactivity. The structural alterations in the trimolecular complex are distinct from previously characterized self-reactive TCRs, indicating that there are multiple unusual ways for self-reactive TCRs to bind their pMHC ligand.
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Affiliation(s)
- Dhruv K Sethi
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, Boston, MA 02115, USA
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8
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Pre-clustered TCR complexes. FEBS Lett 2010; 584:4832-7. [DOI: 10.1016/j.febslet.2010.09.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Revised: 08/21/2010] [Accepted: 09/01/2010] [Indexed: 11/22/2022]
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9
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Constitutively active Lck kinase in T cells drives antigen receptor signal transduction. Immunity 2010; 32:766-77. [PMID: 20541955 PMCID: PMC2996607 DOI: 10.1016/j.immuni.2010.05.011] [Citation(s) in RCA: 270] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 03/15/2010] [Accepted: 04/20/2010] [Indexed: 11/20/2022]
Abstract
T cell antigen receptor (TCR) and coreceptor ligation is thought to initiate signal transduction by inducing activation of the kinase Lck. Here we showed that catalytically active Lck was present in unstimulated naive T cells and thymocytes and was readily detectable in these cells in lymphoid organs. In naive T cells up to ∼40% of total Lck was constitutively activated, part of which was also phosphorylated on the C-terminal inhibitory site. Formation of activated Lck was independent of TCR and coreceptors but required Lck catalytic activity and its maintenance relied on monitoring by the HSP90-CDC37 chaperone complex to avoid degradation. The amount of activated Lck did not change after TCR and coreceptor engagement; however it determined the extent of TCR-ζ phosphorylation. Our findings suggest a dynamic regulation of Lck activity that can be promptly utilized to initiate T cell activation and have implications for signaling by other immune receptors.
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10
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Kuhns MS, Girvin AT, Klein LO, Chen R, Jensen KD, Newell EW, Huppa JB, Lillemeier BF, Huse M, Chien YH, Garcia KC, Davis MM. Evidence for a functional sidedness to the alphabetaTCR. Proc Natl Acad Sci U S A 2010; 107:5094-9. [PMID: 20202921 PMCID: PMC2841884 DOI: 10.1073/pnas.1000925107] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The T cell receptor (TCR) and associated CD3gammaepsilon, deltaepsilon, and zetazeta signaling dimers allow T cells to discriminate between different antigens and respond accordingly, but our knowledge of how these parts fit and work together is incomplete. In this study, we provide additional evidence that the CD3 heterodimers congregate on one side of the TCR in both the alphabeta and gammadeltaTCR-CD3 complexes. We also report that the other side of the alphabetaTCR mediates homotypic alphabetaTCR interactions and signaling. Specifically, an erythropoietin receptor-based dimerization assay was used to show that, upon complex assembly, the CD3epsilon chains of two CD3 heterodimers are arranged side-by-side in both the alphabeta and gammadeltaTCR-CD3 complexes. This system was also used to show that alphabetaTCRs can dimerize in the cell membrane and that mutating the unusual outer strands of the Calpha domain impairs this dimerization. Finally, we present data showing that, for CD4 T cells, the mutations that impair alphabetaTCR dimerization also alter ligand-induced calcium mobilization, TCR accumulation at the site of pMHC contact, and polarization toward the site of antigen contact. These data reveal a "functional-sidedness" to the alphabetaTCR constant region, with dimerization occurring on the side of the TCR opposite from where the CD3 heterodimers are located.
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MESH Headings
- Animals
- Antigen-Presenting Cells/cytology
- CD3 Complex/metabolism
- Calcium Signaling
- Cell Line
- Cell Membrane/metabolism
- Cell Polarity
- Humans
- Intracellular Space/metabolism
- Mice
- Models, Molecular
- Mutation/genetics
- Protein Multimerization
- Protein Structure, Secondary
- Protein Subunits/metabolism
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Receptors, Antigen, T-Cell, gamma-delta/metabolism
- T-Lymphocytes/cytology
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Affiliation(s)
- Michael S. Kuhns
- Department of Microbiology and Immunology
- Stanford University School of Medicine, Stanford, CA 94305
| | - Andrew T. Girvin
- Department of Microbiology and Immunology
- Graduate Program in Immunology
- Stanford University School of Medicine, Stanford, CA 94305
| | - Lawrence O. Klein
- Graduate Program in Biophysics
- Stanford University School of Medicine, Stanford, CA 94305
| | - Rebecca Chen
- CCIS/ITI Summer High School Research Program
- Stanford University School of Medicine, Stanford, CA 94305
| | - Kirk D.C. Jensen
- Department of Microbiology and Immunology
- Stanford University School of Medicine, Stanford, CA 94305
| | - Evan W. Newell
- Department of Microbiology and Immunology
- Stanford University School of Medicine, Stanford, CA 94305
| | - Johannes B. Huppa
- Department of Microbiology and Immunology
- Stanford University School of Medicine, Stanford, CA 94305
| | - Björn F. Lillemeier
- Department of Microbiology and Immunology
- Stanford University School of Medicine, Stanford, CA 94305
| | - Morgan Huse
- Department of Microbiology and Immunology
- Stanford University School of Medicine, Stanford, CA 94305
| | - Yueh-hsiu Chien
- Department of Microbiology and Immunology
- Stanford University School of Medicine, Stanford, CA 94305
| | - K. Christopher Garcia
- Department of Molecular and Cellular Physiology
- Department of Structural Biology, and
- The Howard Hughes Medical Institute, Chevy Chase, MD 20815; and
- Stanford University School of Medicine, Stanford, CA 94305
| | - Mark M. Davis
- Department of Microbiology and Immunology
- The Howard Hughes Medical Institute, Chevy Chase, MD 20815; and
- Stanford University School of Medicine, Stanford, CA 94305
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11
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Beddoe T, Chen Z, Clements CS, Ely LK, Bushell SR, Vivian JP, Kjer-Nielsen L, Pang SS, Dunstone MA, Liu YC, Macdonald WA, Perugini MA, Wilce MC, Burrows SR, Purcell AW, Tiganis T, Bottomley SP, McCluskey J, Rossjohn J. Antigen Ligation Triggers a Conformational Change within the Constant Domain of the αβ T Cell Receptor. Immunity 2009; 30:777-88. [DOI: 10.1016/j.immuni.2009.03.018] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Revised: 02/16/2009] [Accepted: 03/17/2009] [Indexed: 10/20/2022]
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12
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Acuto O, Di Bartolo V, Michel F. Tailoring T-cell receptor signals by proximal negative feedback mechanisms. Nat Rev Immunol 2009; 8:699-712. [PMID: 18728635 DOI: 10.1038/nri2397] [Citation(s) in RCA: 190] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The T-cell receptor (TCR) signalling machinery is central in determining the response of a T cell (establishing immunity or tolerance) following exposure to antigen. This process is made difficult by the narrow margin of self and non-self discrimination, and by the complexity of the genetic programmes that are induced for each outcome. Recent studies have identified novel negative feedback mechanisms that are rapidly induced by TCR engagement and that have key roles in the regulation of signal triggering and propagation. In vitro and in vivo data suggest that they are important in determining ligand discrimination by the TCR and in regulating signal output in response to antigen.
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Affiliation(s)
- Oreste Acuto
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK.
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13
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Choudhuri K, van der Merwe PA. Molecular mechanisms involved in T cell receptor triggering. Semin Immunol 2007; 19:255-61. [PMID: 17560121 DOI: 10.1016/j.smim.2007.04.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Accepted: 04/14/2007] [Indexed: 12/19/2022]
Abstract
Despite intensive investigation we still do not understand how the T cell antigen receptor (TCR) tranduces signals across the plasma membrane, a process referred to as TCR triggering. Three basic mechanisms have been proposed, involving aggregation, conformational change, or segregation of the TCR upon binding pMHC ligand. Given the low density of pMHC ligand it remains doubtful that TCR aggregation initiates triggering, although it is likely to enhance subsequent signalling. Structural studies to date have not provided definitive evidence for or against a conformational change mechanism, but they have ruled out certain types of conformational change. Size-induced segregation of the bound TCR from inhibitory membrane tyrosine phosphatases seems to be required, but is probably not the only mechanism. Current evidence suggests that TCR triggering is initiated by a combination of segregation and conformational change, with subsequent aggregation contributing to amplification of the signal.
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Affiliation(s)
- Kaushik Choudhuri
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, United Kingdom
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14
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Deng L, Langley RJ, Brown PH, Xu G, Teng L, Wang Q, Gonzales MI, Callender GG, Nishimura MI, Topalian SL, Mariuzza RA. Structural basis for the recognition of mutant self by a tumor-specific, MHC class II-restricted T cell receptor. Nat Immunol 2007; 8:398-408. [PMID: 17334368 DOI: 10.1038/ni1447] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2006] [Accepted: 02/05/2007] [Indexed: 12/23/2022]
Abstract
Structural studies of complexes of T cell receptor (TCR) and peptide-major histocompatibility complex (MHC) have focused on TCRs specific for foreign antigens or native self. An unexplored category of TCRs includes those specific for self determinants bearing alterations resulting from disease, notably cancer. We determined here the structure of a human melanoma-specific TCR (E8) bound to the MHC molecule HLA-DR1 and an epitope from mutant triosephosphate isomerase. The structure had features intermediate between 'anti-foreign' and autoimmune TCR-peptide-MHC class II complexes that may reflect the hybrid nature of altered self. E8 manifested very low affinity for mutant triosephosphate isomerase-HLA-DR1 despite the highly tumor-reactive properties of E8 cells. A second TCR (G4) had even lower affinity but underwent peptide-specific formation of dimers, suggesting this as a mechanism for enhancing low-affinity TCR-peptide-MHC interactions for T cell activation.
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Affiliation(s)
- Lu Deng
- Center for Advanced Research in Biotechnology, WM Keck Laboratory for Structural Biology, University of Maryland Biotechnology Institute, Rockville, Maryland 20850, USA
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15
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Cebecauer M, Guillaume P, Mark S, Michielin O, Boucheron N, Bezard M, Meyer BH, Segura JM, Vogel H, Luescher IF. CD8+ cytotoxic T lymphocyte activation by soluble major histocompatibility complex-peptide dimers. J Biol Chem 2005; 280:23820-8. [PMID: 15805102 DOI: 10.1074/jbc.m500654200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
CD8+ cytotoxic T lymphocyte (CTL) can recognize and kill target cells that express only a few cognate major histocompatibility complex class I-peptide (pMHC) complexes. To better understand the molecular basis of this sensitive recognition process, we studied dimeric pMHC complexes containing linkers of different lengths. Although dimers containing short (10-30-A) linkers efficiently bound to and triggered intracellular calcium mobilization and phosphorylation in cloned CTL, dimers containing long linkers (> or = 80 A) did not. Based on this and on fluorescence resonance energy transfer experiments, we describe a dimeric binding mode in which two T cell receptors engage in an anti-parallel fashion two pMHC complexes facing each other with their constant domains. This binding mode allows integration of diverse low affinity interactions, which increases the overall binding and, hence, the sensitivity of antigen recognition. In proof of this, we demonstrated that pMHC dimers containing one agonist and one null ligand efficiently activate CTL, corroborating the importance of endogenous pMHC complexes in antigen recognition.
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Affiliation(s)
- Marek Cebecauer
- Ludwig Institute for Cancer Research, Lausanne Branch, University of Lausanne, 1066 Epalinges, Switzerland
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16
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Huang JC, Ober RJ, Ward ES. The central residues of a T cell receptor sequence motif are key determinants of autoantigen recognition in murine experimental autoimmune encephalomyelitis. Eur J Immunol 2005; 35:299-304. [PMID: 15593303 DOI: 10.1002/eji.200425501] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The autoreactive response in murine experimental autoimmune encephalomyelitis (EAE) is dominated by an oligoclonal expansion of V beta 8(+) CD4(+) T cells. These T cells recognize the immunodominant N-terminal nonapeptide of myelin basic protein (MBP1-9) associated with the MHC class II molecule, I-A(u). Amongst the autoreactive cells, T cells bearing TCR containing the CDR3 beta motif Asp-Ala-Gly-Gly-Gly-Tyr (DAGGGY) play a dominant role in the disease process. Here we have investigated the molecular basis for antigen recognition by a representative TCR (172.10) that contains the DAGGGY motif. The roles of the three glycines in this motif in the corresponding TCR-peptide-MHC interactions have been analyzed using a combination of site-directed mutagenesis and surface plasmon resonance. Our data show that mutation of either of the first two glycines (G97, G98) to alanine results in soluble, recombinant TCR that do not bind to recombinant antigen at detectable levels. Mutation of the third glycine (G99) of the 172.10 TCR results in a substantial decrease in affinity. The importance of the triple glycines for antigen recognition provides an explanation at the molecular level for the recruitment of T cells bearing the DAGGGY motif into the responding repertoire during EAE induction.
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Affiliation(s)
- Jason C Huang
- Center for Immunology, University of Texas Southwestern Medical Center, Dallas, TX 75390-9093, USA
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17
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Davis-Harrison RL, Armstrong KM, Baker BM. Two different T cell receptors use different thermodynamic strategies to recognize the same peptide/MHC ligand. J Mol Biol 2005; 346:533-50. [PMID: 15670602 DOI: 10.1016/j.jmb.2004.11.063] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2004] [Revised: 11/12/2004] [Accepted: 11/23/2004] [Indexed: 11/15/2022]
Abstract
A6 and B7 are two alphabeta T cell receptors (TCRs) that recognize the Tax peptide presented by the class I major histocompatibility molecule HLA-A2 (Tax/HLA-A2). Despite the fact that the two TCRs have different CDR loops and use different amino acid residues to contact their ligand, both receptors bind ligand with similar diagonal orientations. Here we show that they also bind with very similar binding affinities and kinetics (the DeltaDeltaG degrees for binding is approximately 0.3kcal/mol at 25 degrees C). The two receptors respond similarly to alterations in the MHC molecule, yet differ dramatically in their responses to ionic strength and temperature. The different responses to temperature indicate markedly different binding thermodynamics, which are not predictable from the surface area buried in the interfaces. A6 and B7 thus represent two TCRs that are both compatible with Tax/HLA-A2, although compatibility has been achieved through the use of different thermodynamic strategies. Finally, neither A6 nor B7 are predicted to undergo large conformational adaptations upon binding, distinguishing them from a number of other TCRs whose structure, thermodynamics, and kinetics have been characterized.
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Affiliation(s)
- Rebecca L Davis-Harrison
- Department of Chemistry and Biochemistry, 251 Nieuwland Science Hall, University of Notre Dame, Notre Dame, IN 46556, USA
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18
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Dam J, Guan R, Natarajan K, Dimasi N, Chlewicki LK, Kranz DM, Schuck P, Margulies DH, Mariuzza RA. Variable MHC class I engagement by Ly49 natural killer cell receptors demonstrated by the crystal structure of Ly49C bound to H-2Kb. Nat Immunol 2003; 4:1213-22. [PMID: 14595439 DOI: 10.1038/ni1006] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2003] [Accepted: 10/08/2003] [Indexed: 11/09/2022]
Abstract
The Ly49 family of natural killer (NK) receptors regulates NK cell function by sensing major histocompatibility complex (MHC) class I. Ly49 receptors show complex patterns of MHC class I cross-reactivity and, in certain cases, peptide selectivity. To investigate whether specificity differences result from topological differences in MHC class I engagement, we determined the structure of the peptide-selective receptor Ly49C in complex with H-2K(b). The Ly49C homodimer binds two MHC class I molecules in symmetrical way, a mode distinct from that of Ly49A, which binds MHC class I asymmetrically. Ly49C does not directly contact the MHC-bound peptide. In addition, MHC crosslinking by Ly49C was demonstrated in solution. We propose a dynamic model for Ly49-MHC class I interactions involving conformational changes in the receptor, whereby variations in Ly49 dimerization mediate different MHC-binding modes.
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Affiliation(s)
- Julie Dam
- Center for Advanced Research in Biotechnology, W.M. Keck Laboratory for Structural Biology, University of Maryland Biotechnology Institute, 9600 Gudelsky Drive, Rockville, Maryland 20850, USA
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19
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Abstract
Immunological synapses (ISs) are specialised signalling domains characterised by complex molecular clustering and segregation at the contact site between cells of the immune system. T lymphocytes form different ISs depending on their state of activation and on the antigen-presenting cells with which they interact. The structural features of the various ISs are better established than the functions they carry out. Recent advances point to the importance of taking into account diversity in both the structures and the functions of IS.
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Affiliation(s)
- Alain Trautmann
- Départment de Biologie Cellulaire, Institut COCHIN, Institut National de la santé et de la Recherche Médicale, Centre National de la Recherche Scientifique, 22, rue Méchain 75014, Paris, France
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20
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Holler PD, Kranz DM. Quantitative analysis of the contribution of TCR/pepMHC affinity and CD8 to T cell activation. Immunity 2003; 18:255-64. [PMID: 12594952 DOI: 10.1016/s1074-7613(03)00019-0] [Citation(s) in RCA: 285] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The relative roles of CD8, TCR:pepMHC affinity, and TCR:pepMHC dissociation rate in T cell activation have remained controversial. To determine the relationships among these factors, we used T cells transfected with normal and in vitro engineered alphabeta TCRs, in the presence or absence of CD8. The TCRs exhibited a wide range of affinities (K(D) values of 80 microM to 5 nM). T cells with the highest affinity TCRs were efficiently stimulated by peptide, with or without CD8. In contrast, CD8 was required for T cells that expressed TCRs with affinities typical of syngeneic reactions (K(D) values above approximately 3 microM). The results suggest that virtually all normal syngeneic interactions require CD8, which enhances peptide sensitivity by one million-fold or more.
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Affiliation(s)
- Phillip D Holler
- Department of Biochemistry, University of Illinois, Urbana, IL 61801, USA
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21
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Abstract
After a brief overview of the themes and variations that occur in the family of receptors containing immunoreceptor tyrosine-based activation motifs (ITAMs), and of recent structural data on the ligand-binding subunits of these receptors, we use these data to revisit how information on the state and quality of occupancy of the binding site of the T cell antigen receptor (TCR) is conveyed to the proximal components of the TCR transduction cassette.
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Affiliation(s)
- Bernard Malissen
- Centre d'Immunologie INSERM-CNRS de Marseille-Luminy, Marseille, France.
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22
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Abstract
Although our structural understanding of T cell recognition has rapidly evolved due to recent crystallographic results, the reality is that detailed answers to many of the most fundamental questions still remain elusive. In this issue, high-resolution insight into the phenomenon of TCR chain bias takes down another brick from the wall.
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Affiliation(s)
- Alexander J Bankovich
- Department of Microbiology and Immunology, Department of Structural Biology, Stanford University School of Medicine, Fairchild D319, 299 Campus Drive, Stanford, CA 94305, USA
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23
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Wetzel SA, McKeithan TW, Parker DC. Live-cell dynamics and the role of costimulation in immunological synapse formation. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:6092-101. [PMID: 12444111 DOI: 10.4049/jimmunol.169.11.6092] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Using transfected fibroblasts expressing both wild-type I-E(k) and green fluorescent protein-tagged I-E(k) with covalently attached antigenic peptide, we have monitored movement of specific MHC:peptide complexes during CD4(+) T cell-APC interactions by live-cell video microscopy. Ag recognition occurs within 30 s of T cell-APC contact, as shown by a sharp increase in cytoplasmic calcium ion concentration. Within 1 min, small MHC:peptide clusters form in the contact zone that coalesce into an immunological synapse over 3-20 min. When T cells conjugated to APC move across the APC surface, they appear to drag the synapse with them. This system was used to examine the role of costimulation in the formation of the immunological synapse. Blocking CD80/CD28 or ICAM-1/LFA-1 interactions alters synapse morphology and reduces the area and density of accumulated complexes. These reductions correlate with reduced T cell proliferation, while CD69 and CD25 expression and TCR down-modulation remain unaffected. Thus, costimulation is essential for normal mature immunological synapse formation.
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Affiliation(s)
- Scott A Wetzel
- Department of Molecular Microbiology and Immunology, Oregon Health Sciences University, Portland 97239, USA
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24
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Abstract
We have assembled references of 700 articles published in 2001 that describe work performed using commercially available optical biosensors. To illustrate the technology's diversity, the citation list is divided into reviews, methods and specific applications, as well as instrument type. We noted marked improvements in the utilization of biosensors and the presentation of kinetic data over previous years. These advances reflect a maturing of the technology, which has become a standard method for characterizing biomolecular interactions.
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Affiliation(s)
- Rebecca L Rich
- Center for Biomolecular Interaction Analysis, University of Utah, Salt Lake City, UT 84132, USA
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25
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Schott E, Bertho N, Ge Q, Maurice MM, Ploegh HL. Class I negative CD8 T cells reveal the confounding role of peptide-transfer onto CD8 T cells stimulated with soluble H2-Kb molecules. Proc Natl Acad Sci U S A 2002; 99:13735-40. [PMID: 12374858 PMCID: PMC129760 DOI: 10.1073/pnas.212515399] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2002] [Accepted: 08/26/2002] [Indexed: 11/18/2022] Open
Abstract
Crosslinking of the T cell receptor has been proposed to be a prerequisite for T cell activation. Although the evidence supports this notion for CD4 T cells, the situation for CD8 T cells is less clear. Soluble class I monomers have been used to determine activation requirements in vitro with contradictory results. The possibility of transfer of peptide from soluble class I molecules onto class I molecules present on the surface of CD8 T cells, with ensuing presentation to other CD8 T cells, has been widely ignored. We show that monomeric and tetrameric class I molecules as well as free peptide can stimulate naive CD8 T cells in vitro. We generate and characterize CD8 T cells that express the OT-I T cell receptor (for K(b)/SIINFEKL) yet lack K(b) and D(b) molecules, and show that their activation requirements differ from their class I positive counterparts when stimulated with soluble K(b) molecules. By eliminating the confounding effect of peptide transfer, we unmask the true activation requirements for naive CD8 T cells and show that multivalent engagement of T cell receptors, as well as costimulation, is required for optimal stimulation.
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Affiliation(s)
- Eckart Schott
- Department of Pathology, Harvard Medical School, Boston, MA 02115, USA
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26
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Fahmy TM, Bieler JG, Schneck JP. Probing T cell membrane organization using dimeric MHC-Ig complexes. J Immunol Methods 2002; 268:93-106. [PMID: 12213346 DOI: 10.1016/s0022-1759(02)00203-x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In this report, we review a novel method for probing the membrane organization of T cells using dimeric major histocompatibility complexes (MHC), MHC-Ig. MHC-Ig complexes are useful reagents for quantitative analysis of binding data since their valency is controlled. These complexes can be easily labeled and loaded with a variety of peptides. A binding assay using these dimers and quantitative analysis of the MHC-Ig dimer-T cell binding curves is described in detail. Using this approach, we show that the organization of TCR on activated T cells is different from TCR organization on nai;ve T cells. The implications of these findings are discussed with regards to current models of T cell recognition. This analysis offers insight into how T cell controls their biological range of responsiveness. Specifically, these findings reveal the biophysical basis of the ability of activated T cells to recognize low amounts of antigen independent of costimulation.
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Affiliation(s)
- Tarek M Fahmy
- Department of Pathology, Division of Immunopathology, Johns Hopkins School of Medicine, 664G Ross Bldg., 720 Rutland Avenue, Baltimore, MD 21205, USA
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27
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Wang Z, Turner R, Baker BM, Biddison WE. MHC allele-specific molecular features determine peptide/HLA-A2 conformations that are recognized by HLA-A2-restricted T cell receptors. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 169:3146-54. [PMID: 12218132 DOI: 10.4049/jimmunol.169.6.3146] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The structures of alphabeta TCRs bound to complexes of class I MHC molecules and peptide show that the TCRs make multiple contacts with the alpha1 and alpha2 helixes of the MHC. Previously we have shown that the A6 TCR in complex with the HLA-A2/Tax peptide has 15 contact sites on HLA-A2. Single amino acid mutagenesis of these contact sites demonstrated that mutation of only three amino acids clustered on the alpha1 helix (R65, K66, A69) disrupted recognition by the A6 TCR. In the present study we have asked whether TCRs that recognize four other peptides presented by HLA-A2 interact with the MHC in identical, similar, or different patterns as the A6 TCR. Mutants K66A and Q155A had the highest frequency of negative effects on lysis. A subset of peptide-specific CTL also selectively recognized mutants K66A or Q155A in the absence of exogenous cognate peptides, indicating that these mutations affected the presentation of endogenous peptide/HLA-A2 complexes. These findings suggest that most HLA-A2-restricted TCRs recognize surfaces on the HLA-A2/peptide complex that are dependent upon the side chains of K66 and Q155 in the central portion of the peptide binding groove. Crystallographic structures of several peptide/HLA-A2 structures have shown that the side chains of these critical amino acids that make contact with the A6 TCR also contact the bound peptide. Collectively, our results indicate that the generalized effects of changes at these critical amino acids are probably due to the fact that they can be directly contacted by TCRs as well as influence the binding and presentation of the bound peptides.
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Affiliation(s)
- Zichun Wang
- Molecular Immunology Section, Neuroimmunology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
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28
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Coombs D, Kalergis AM, Nathenson SG, Wofsy C, Goldstein B. Activated TCRs remain marked for internalization after dissociation from pMHC. Nat Immunol 2002; 3:926-31. [PMID: 12244312 DOI: 10.1038/ni838] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2002] [Accepted: 08/15/2002] [Indexed: 11/09/2022]
Abstract
To assess the roles of serial engagement and kinetic proofreading in T cell receptor (TCR) internalization, we have developed a mathematical model of this process. Our determination of TCR down-regulation for an array of TCR mutants, interpreted in the context of the model, has provided new information about peptide-induced TCR internalization. The amount of TCR down-regulation increases to a maximum value and then declines as a function of the half-life of the bond between the TCR and peptide-major histocompatibility complex (pMHC). The model shows that this behavior, which reflects competition between serial engagement and kinetic proofreading, arises only if it is postulated that activated TCRs remain marked for internalization after dissociation from pMHC. The model also predicts that because of kinetic proofreading, the range of TCR-pMHC-binding half-lives required for T cell activation depends on the concentrations and localization of intracellular signaling molecules. We show here that kinetic proofreading provides an explanation for the different requirements for activation observed in naïve and memory T cells.
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Affiliation(s)
- Daniel Coombs
- Theoretical Biology and Biophysics Group, Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA
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29
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Abstract
Adhesive interactions play important roles in coordinating T-cell migration and activation, specifically in the formation of the immunological synapse (IS), a specialized cell-cell junction. Recent demonstrations show several molecules implicated in T-cell signaling, including Vav, ADAP, and Rap-1, have major roles in integrin regulation and place adhesion molecules at center stage in addressing the question: what are the signals involved in the formation of the IS and full T-cell activation? This review focuses on the role of integrins as an essential system for both physical adhesion and signaling in T-cell activation. The role of integrins appears to be quite distinct from classical costimulation and has been largely overlooked due to the ubiquitous use of serum in lymphocyte functional assays. Each major signal transduction pathway has branches leading to the nucleus and others that feed back on cytoskeletal and membrane regulation at the IS.
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Affiliation(s)
- Tasha N Sims
- Molecular Pathogenesis Program, Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY 10016, USA
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30
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Rudolph MG, Luz JG, Wilson IA. Structural and thermodynamic correlates of T cell signaling. ANNUAL REVIEW OF BIOPHYSICS AND BIOMOLECULAR STRUCTURE 2002; 31:121-49. [PMID: 11988465 DOI: 10.1146/annurev.biophys.31.082901.134423] [Citation(s) in RCA: 95] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The first crystal structures of intact T cell receptors (TCRs) bound to class I peptide-MHC (pMHCs) antigens were determined in 1996. Since then, further structures of class I TCR/pMHC complexes have explored the degree of structural variability in the TCR-pMHC system and the structural basis for positive and negative selection. The recent determination of class II and allogeneic class I TCR/pMHC structures, as well as those of accessory molecules (e.g., CD3), has pushed our knowledge of TCR/pMHC interactions into new realms, shedding light on clinical pathologies, such as graft rejection and graft-versus-host disease. Furthermore, the determination of coreceptor structures lays the foundation for a more comprehensive structural description of the supramolecular TCR signaling events and those assemblies that arise in the immunological synapse. While these telling photodocumentaries of the TCR/pMHC interaction are composed mainly from static crystal structures, a full description of the biological snapshots in T cell signaling requires additional analytical methods that record the dynamics of the process. To this end, surface plasmon resonance (SPR), isothermal titration calorimetry (ITC), and ultracentrifugation (UC) have furnished both affinities and kinetics of the TCR/pMHC association. In the past year, structural, biochemical, and molecular biological data describing TCR/pMHC interactions have sublimely coalesced into a burgeoning well of understanding that promises to deliver further insights into T cell recognition. The coming years will, through a more intimate union of structural and kinetic data, allow many pressing questions to be addressed, such as how TCR/pMHC ligation is affected by coreceptor binding and what is the mechanism of TCR signaling in both early and late stages of T cell engagement with antigen-presenting cells.
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Affiliation(s)
- Markus G Rudolph
- Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA.
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31
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Abstract
T cells are tightly controlled cellular machines that monitor changes in epitope presentation. Although T-cell function is regulated by means of numerous interactions with other cell types and soluble factors, the T-cell receptor (TCR) is the only structure on the T-cell surface that defines its antigen-recognition potential. Consequently, the transfer of T-cell receptors into recipient cells can be used as a strategy for the passive transfer of T-cell immunity. In this review, I discuss the pros and cons of TCR gene transfer as a strategy to induce defined virus- and tumour-specific T-cell immunity.
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Affiliation(s)
- Ton N M Schumacher
- Division of Immunology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.
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32
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Werlen G, Palmer E. The T-cell receptor signalosome: a dynamic structure with expanding complexity. Curr Opin Immunol 2002; 14:299-305. [PMID: 11973126 DOI: 10.1016/s0952-7915(02)00339-4] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Signal transduction in T cells is a dynamic process involving a large number of membrane and cytosolic proteins. The TCR macromolecular complex (signalosome) is initiated by receptor occupancy and becomes more elaborate over time. This review describes how 'vertical' displacement mechanisms and lateral coalescence of lipid-raft-associated scaffold proteins combine to form distinct signalosomes, which control signal specificity.
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Affiliation(s)
- Guy Werlen
- Laboratory of Transplantation Immunology and Nephrology, Department of Research, University Hospital-Basel, Hebelstrasse 20, CH-4031, Basel, Switzerland.
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33
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Abstract
Crystal structures of 11 complexes of TCRs with peptide/MHC (pMHC), that represent 6 independent TCRs, constitute the current structural database for deriving general insights into how alphabeta TCRs recognise peptide-bound MHC class I or class II. The TCRs adopt a roughly diagonal orientation on top of the pMHCs, but the identification of a set of conserved interactions that dictate this orientation is not apparent. Furthermore, the specific interaction of each TCR with its cognate pMHC partner is quite variable and also involves bound water molecules at the TCR/pMHC interface. In two of the systems, the structural basis for binding of altered peptide ligands has illustrated that the only significant conformational changes occur in the TCR/pMHC interface, but their small magnitude is inconsistent with the enormous variation in signalling outcomes. The TCRs adjust to different agonist, partial agonist and antagonist peptides by subtle conformational changes in their complementarity-determining regions, as previously observed in induced-fit mechanisms of antibody/antigen recognition. Alloreactive-complex structures determined or modelled so far indicate increased interactions of the TCR beta-chain with the pMHC compared with their syngeneic counterparts.
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MESH Headings
- Animals
- Antigen Presentation/immunology
- Humans
- Ligands
- Major Histocompatibility Complex/immunology
- Peptides/chemistry
- Peptides/immunology
- Protein Binding
- Protein Conformation
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Receptors, Antigen, T-Cell, gamma-delta/chemistry
- Receptors, Antigen, T-Cell, gamma-delta/immunology
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Affiliation(s)
- Markus G Rudolph
- The Scripps Research Institute, Department of Molecular Biology, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
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34
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Krummel MF, Davis MM. Dynamics of the immunological synapse: finding, establishing and solidifying a connection. Curr Opin Immunol 2002; 14:66-74. [PMID: 11790534 DOI: 10.1016/s0952-7915(01)00299-0] [Citation(s) in RCA: 158] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
A coordinated series of molecular interactions leads to the establishment of an immunological synapse. Migrating lymphocytes scan antigen-processing cells and are made to stop upon recognition of their specific ligand. Microclusters of TCRs/CD4 form over a large contact site, then TCRs coalesce. Coalescence occurs in response to signals generated in the first encounters and in response to costimulatory signaling. The cytoskeleton rearranges and concentric rings of coreceptors and integrins surround the TCRs. This unexpected level of complexity of co-clustering and exclusion in the interface has generated much interest in the functional consequences of signaling and/or immune effector function.
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Affiliation(s)
- Matthew F Krummel
- Department of Pathology, University of California at San Francisco, San Francisco, CA 94143-0511, USA.
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35
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Maeurer M, Höhn H, Castelli C, Salter RD, Necker A, Reichert T, Knuth A, Jäger E. Antigen recognition by T cells: a strong sense of structure. Trends Immunol 2001; 22:599-601. [PMID: 11698218 DOI: 10.1016/s1471-4906(01)02061-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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36
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Affiliation(s)
- P A van der Merwe
- Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, United Kingdom.
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