1
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Lucato CM, Lupton CJ, Halls ML, Ellisdon AM. Amyloidogenicity at a Distance: How Distal Protein Regions Modulate Aggregation in Disease. J Mol Biol 2017; 429:1289-1304. [PMID: 28342736 DOI: 10.1016/j.jmb.2017.03.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 03/12/2017] [Accepted: 03/14/2017] [Indexed: 12/14/2022]
Abstract
The misfolding of proteins to form amyloid is a key pathological feature of several progressive, and currently incurable, diseases. A mechanistic understanding of the pathway from soluble, native protein to insoluble amyloid is crucial for therapeutic design, and recent efforts have helped to elucidate the key molecular events that trigger protein misfolding. Generally, either global or local structural perturbations occur early in amyloidogenesis to expose aggregation-prone regions of the protein that can then self-associate to form toxic oligomers. Surprisingly, these initiating structural changes are often caused or influenced by protein regions distal to the classically amyloidogenic sequences. Understanding the importance of these distal regions in the pathogenic process has highlighted many remaining knowledge gaps regarding the precise molecular events that occur in classic aggregation pathways. In this review, we discuss how these distal regions can influence aggregation in disease and the recent technical and conceptual advances that have allowed this insight.
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Affiliation(s)
- Christina M Lucato
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia; Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800, Australia
| | - Christopher J Lupton
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia; Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800, Australia
| | - Michelle L Halls
- Drug Discovery Biology Theme, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Andrew M Ellisdon
- Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia; Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800, Australia.
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2
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Kaneko I, Dementhon K, Xiang Q, Glass NL. Nonallelic interactions between het-c and a polymorphic locus, pin-c, are essential for nonself recognition and programmed cell death in Neurospora crassa. Genetics 2009; 172:1545-55. [PMID: 16554411 PMCID: PMC1456284 DOI: 10.1534/genetics.105.051490] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Nonself recognition in filamentous fungi is conferred by genetic differences at het (heterokaryon incompatibility) loci. When individuals that differ in het specificity undergo hyphal fusion, the heterokaryon undergoes a programmed cell death reaction or is highly unstable. In Neurospora crassa, three allelic specificities at the het-c locus are conferred by a highly polymorphic domain. This domain shows trans-species polymorphisms indicative of balancing selection, consistent with the role of het loci in nonself recognition. We determined that a locus closely linked to het-c, called pin-c (partner for incompatibility with het-c) was required for het-c nonself recognition and heterokaryon incompatibility (HI). The pin-c alleles in isolates that differ in het-c specificity were extremely polymorphic. Heterokaryon and transformation tests showed that nonself recognition was mediated by synergistic nonallelic interactions between het-c and pin-c, while allelic interactions at het-c increased the severity of the HI phenotype. The pin-c locus encodes a protein containing a HET domain; predicted proteins containing HET domains are frequent in filamentous ascomycete genomes. These data suggest that nonallelic interactions may be important in nonself recognition in filamentous fungi and that proteins containing a HET domain may be a key factor in these interactions.
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Affiliation(s)
- Isao Kaneko
- Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA
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3
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Hodkinson JP, Jahn TR, Radford SE, Ashcroft AE. HDX-ESI-MS reveals enhanced conformational dynamics of the amyloidogenic protein beta(2)-microglobulin upon release from the MHC-1. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2009; 20:278-86. [PMID: 18996721 PMCID: PMC2642988 DOI: 10.1016/j.jasms.2008.10.005] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 09/30/2008] [Accepted: 10/01/2008] [Indexed: 05/11/2023]
Abstract
The light chain of the major histocompatibility complex class 1 (MHC-1), the protein beta(2)-microglobulin (beta(2)m), has amyloidogenic properties that arise only upon its dissociation from the MHC-1. Here hydrogen/deuterium exchange electrospray ionization mass spectrometry (HDX-ESI-MS) has been used to compare the solution dynamics of beta(2)m in its MHC-1 bound state compared with those of beta(2)m as a free monomer. The capability of tandem mass spectrometry to dissociate the MHC-1 into its individual constituents in the gas phase following deuterium incorporation in solution has permitted the direct observation of the exchange properties of MHC-1 bound beta(2)m for the first time. The HDX-ESI-MS data show clearly that the H-->D exchange of MHC-1 bound beta(2)m follows EX2 kinetics and that about 20 protons remain protected from exchange after 17 days. Free from the MHC-1, monomeric beta(2)m exhibits significantly different HDX behavior, which encompasses both EX1 and EX2 kinetics. The EX2 kinetics indicate a tenfold increase in the rate of exchange compared with MHC-1 bound beta(2)m, with just 10 protons remaining protected from EX2 exchange and therefore exchanging only via the EX1 mechanism. The EX1 kinetics observed for unbound beta(2)m are consistent with unfolding of its exchange-protected core with a t(1/2) of 68 min (pH 7, 37 degrees C). Thus, upon dissociation from the stabilizing influence of the MHC-1, free beta(2)m becomes highly dynamic and undergoes unfolding transitions that result in an aggregation-competent protein.
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Affiliation(s)
| | | | | | - Alison E. Ashcroft
- Address reprint requests to Dr. Alison E. Ashcroft, The University of Leeds, Astbury Centre for Structural Molecular Biology, Institute of Molecular and Cellular Biology, Leeds LS2 9JT, United Kingdom
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4
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Dementhon K, Iyer G, Glass NL. VIB-1 is required for expression of genes necessary for programmed cell death in Neurospora crassa. EUKARYOTIC CELL 2006; 5:2161-73. [PMID: 17012538 PMCID: PMC1694810 DOI: 10.1128/ec.00253-06] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Nonself recognition during somatic growth is an essential and ubiquitous phenomenon in both prokaryotic and eukaryotic species. In filamentous fungi, nonself recognition is also important during vegetative growth. Hyphal fusion between genetically dissimilar individuals results in rejection of heterokaryon formation and in programmed cell death of the fusion compartment. In filamentous fungi, such as Neurospora crassa, nonself recognition and heterokaryon incompatibility (HI) are regulated by genetic differences at het loci. In N. crassa, mutations at the vib-1 locus suppress nonself recognition and HI mediated by genetic differences at het-c/pin-c, mat, and un-24/het-6. vib-1 is a homolog of Saccharomyces cerevisiae NDT80, which is a transcriptional activator of genes during meiosis. For this study, we determined that vib-1 encodes a nuclear protein and showed that VIB-1 localization varies during asexual reproduction and during HI. vib-1 is required for the expression of genes involved in nonself recognition and HI, including pin-c, tol, and het-6; all of these genes encode proteins containing a HET domain. vib-1 is also required for the production of downstream effectors associated with HI, including the production of extracellular proteases upon carbon and nitrogen starvation. Our data support a model in which mechanisms associated with starvation and nonself recognition/HI are interconnected. VIB-1 is a major regulator of responses to nitrogen and carbon starvation and is essential for the expression of genes involved in nonself recognition and death in N. crassa.
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Affiliation(s)
- Karine Dementhon
- Department of Plant and Microbial Biology, The University of California, Berkeley, CA 94720-3102, USA
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5
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Gakamsky DM, Luescher IF, Pramanik A, Kopito RB, Lemonnier F, Vogel H, Rigler R, Pecht I. CD8 kinetically promotes ligand binding to the T-cell antigen receptor. Biophys J 2005; 89:2121-33. [PMID: 15980174 PMCID: PMC1366714 DOI: 10.1529/biophysj.105.061671] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The mechanism of CD8 cooperation with the TCR in antigen recognition was studied on live T cells. Fluorescence correlation measurements yielded evidence of the presence of two TCR and CD8 subpopulations with different lateral diffusion rate constants. Independently, evidence for two subpopulations was derived from the experimentally observed two distinct association phases of cognate peptide bound to class I MHC (pMHC) tetramers and the T cells. The fast phase rate constant ((1.7 +/- 0.2) x 10(5) M(-1) s(-1)) was independent of examined cell type or MHC-bound peptides' structure. Its value was much faster than that of the association of soluble pMHC and TCR ((7.0 +/- 0.3) x 10(3) M(-1) s(-1)), and close to that of the association of soluble pMHC with CD8 ((1-2) x 10(5) M(-1) s(-1)). The fast binding phase disappeared when CD8-pMHC interaction was blocked by a CD8-specific mAb. The latter rate constant was slowed down approximately 10-fold after cells treatment with methyl-beta-cyclodextrin. These results suggest that the most efficient pMHC-cell association route corresponds to a fast tetramer binding to a colocalized CD8-TCR subpopulation, which apparently resides within membrane rafts: the reaction starts by pMHC association with the CD8. This markedly faster step significantly increases the probability of pMHC-TCR encounters and thereby promotes pMHC association with CD8-proximal TCR. The slow binding phase is assigned to pMHC association with a noncolocalized CD8-TCR subpopulation. Taken together with results of cytotoxicity assays, our data suggest that the colocalized, raft-associated CD8-TCR subpopulation is the one capable of inducing T-cell activation.
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MESH Headings
- Antibodies, Monoclonal/chemistry
- Binding Sites
- Biophysical Phenomena
- Biophysics
- Biotinylation
- CD8 Antigens/chemistry
- CD8 Antigens/physiology
- Cell Line
- Cell Membrane/metabolism
- Chromatography, High Pressure Liquid
- Cloning, Molecular
- Diffusion
- Humans
- Kinetics
- Ligands
- Microscopy, Confocal
- Microscopy, Fluorescence
- Models, Chemical
- Models, Statistical
- Peptides/chemistry
- Probability
- Protein Binding
- Receptors, Antigen, T-Cell/chemistry
- Spectrometry, Fluorescence
- T-Lymphocytes/metabolism
- Time Factors
- beta-Cyclodextrins/chemistry
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Affiliation(s)
- Dmitry M Gakamsky
- Department of Immunology, and Department of Materials and Interfaces, Weizmann Institute of Science, 76100 Rehovot, Israel.
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6
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Zacharias M, Springer S. Conformational flexibility of the MHC class I alpha1-alpha2 domain in peptide bound and free states: a molecular dynamics simulation study. Biophys J 2005; 87:2203-14. [PMID: 15454423 PMCID: PMC1304646 DOI: 10.1529/biophysj.104.044743] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Major histocompatibility complex class I proteins play a key role in the recognition and presentation of peptide antigens to the host immune system. The structure of various major histocompatibility complex class I proteins has been determined experimentally in complex with several antigenic peptides. However, the structure in the unbound (empty) form is not known. To study the conformational dynamics of the empty major histocompatibility complex class I molecule comparative molecular dynamics simulations have been performed starting from the crystal structure of a peptide bound class I peptide-binding domain in the presence and absence of a peptide ligand. Simulations including the bound peptide stayed close to the experimental start structure at both simulation temperatures (300 and 355 K) during the entire simulation of 26 ns. Several independent simulations in the absence of peptide indicate that the empty domain may not adopt a single defined conformation but is conformationally significantly more heterogeneous in particular within the alpha-helices that flank the peptide binding cleft. The calculated conformational dynamics along the protein chain correlate well with available spectroscopic data and with the observed site-specific sensitivity of the empty class I protein to proteolytic digestion. During the simulations at 300 K the binding region for the peptide N-terminus stayed close to the conformation in the bound state, whereas the anchor region for the C-terminus showed significantly larger conformational fluctuations. This included a segment at the beginning of the second alpha-helix in the domain that is likely to be involved in the interaction with the chaperone protein tapasin during the peptide-loading process. The simulation studies further indicate that peptide binding at the C- and N-terminus may follow different mechanisms that involve different degrees of induced conformational changes in the peptide-binding domain. In particular binding of the peptide C-terminus may require conformational stabilization by chaperone proteins during peptide loading.
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Affiliation(s)
- Martin Zacharias
- International University Bremen, School of Engineering and Science, D-28759 Bremen, Germany.
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7
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Wright CA, Kozik P, Zacharias M, Springer S. Tapasin and other chaperones: models of the MHC class I loading complex. Biol Chem 2005; 385:763-78. [PMID: 15493870 DOI: 10.1515/bc.2004.100] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
MHC (major histocompatibility complex) class I molecules bind intracellular virus-derived peptides in the endoplasmic reticulum (ER) and present them at the cell surface to cytotoxic T lymphocytes. Peptide-free class I molecules at the cell surface, however, could lead to aberrant T cell killing. Therefore, cells ensure that class I molecules bind high-affinity ligand peptides in the ER, and restrict the export of empty class I molecules to the Golgi apparatus. For both of these safeguard mechanisms, the MHC class I loading complex (which consists of the peptide transporter TAP, the chaperones tapasin and calreticulin, and the protein disulfide isomerase ERp57) plays a central role. This article reviews the actions of accessory proteins in the biogenesis of class I molecules, specifically the functions of the loading complex in high-affinity peptide binding and localization of class I molecules, and the known connections between these two regulatory mechanisms. It introduces new models for the mode of action of tapasin, the role of the class I loading complex in peptide editing, and the intracellular localization of class I molecules.
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Affiliation(s)
- Cynthia Anne Wright
- Biochemistry and Cell Biology, International University Bremen, D-28759 Bremen, Germany
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8
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Gumperz JE. Antigen specificity of semi‐invariant CD1d‐restricted T cell receptors: The best of both worlds? Immunol Cell Biol 2004; 82:285-94. [PMID: 15186260 DOI: 10.1111/j.0818-9641.2004.01257.x] [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: 11/26/2022]
Abstract
T lymphocytes are characterized by the use of structurally diverse TCR. The discovery of subsets of canonical T cells that have structurally homogeneous TCR presents an enigma: What antigens do these T cells recognize, and how does their antigen specificity relate to their functions? One subset of canonical T cells is restricted by CD1d, a non-classical antigen presenting molecule that presents lipids and glycolipids. Canonical CD1d-restricted T cells have semi-invariant TCR consisting of an invariantly rearranged TCR alpha chain, paired with diversely rearranged TCR beta chains. Most respond strongly to the unusual glycolipid alpha-galactosylceramide (alpha-GalCer), and can also respond to cellular antigens presented by CD1d. Mounting evidence indicates that alpha-GalCer responsive T cells are heterogeneous in their reactivities to cellular antigens, suggesting that an individual semi-invariant TCR may be capable of recognizing more than one ligand. Recent crystal structures of CD1b molecules with three different bound lipids indicate that the antigenic features of lipids may be localized over a smaller area than those of peptides, and that the positioning of the polar head group can vary substantially. A model that explains how CD1d-restricted T cells could possess both conserved and heterogeneous antigen specificities, is that different lipid antigens may interact with distinct areas of a TCR due to differences in the positioning of the polar head group. Hence, canonical CD1d-restricted TCR could recognize conserved antigens via the invariant TCR alpha chain, and have diverse antigen specificities that are conferred by their individual TCR beta chains.
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Affiliation(s)
- Jenny E Gumperz
- Department of Medical Microbiology and Immunology, University of Wisconsin Medical School, 1300 University Avenue, Madison, WI 53706, USA.
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9
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Hill DM, Kasliwal T, Schwarz E, Hebert AM, Chen T, Gubina E, Zhang L, Kozlowski S. A dominant negative mutant beta 2-microglobulin blocks the extracellular folding of a major histocompatibility complex class I heavy chain. J Biol Chem 2003; 278:5630-8. [PMID: 12454016 DOI: 10.1074/jbc.m208381200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The major histocompatibility complex class I (MHC1) molecule plays a crucial role in cytotoxic lymphocyte function. beta 2-Microglobulin (beta 2m) has been demonstrated to be both a structural component of the MHC1 complex and a chaperone-like molecule for MHC1 folding. beta 2m binding to an isolated alpha 3 domain of MHC1 heavy chain at micromolar concentrations has been shown to accurately model the biochemistry and thermodynamics of beta 2m-driven MHC1 folding. These results suggested a model in which the chaperone-like role of beta 2m is dependent on initial binding to the alpha 3 domain interface of MHC1 with beta 2m. Such a model predicts that a mutant beta 2m molecule with an intact MHC1 alpha 3 domain interaction but a defective MHC1 alpha 1 alpha 2 domain interaction would block beta2m-driven folding of MHC1. In this study we generated such a beta 2m mutant and demonstrated that it blocks MHC1 folding by normal beta 2m at the expected micromolar concentrations. Our data support an initial interaction of beta 2m with the MHC1 alpha 3 domain in MHC1 folding. In addition, the dominant negative mutant beta 2m can block T-cell functional responses to antigenic peptide and MHC1.
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Affiliation(s)
- Dawn M Hill
- Division of Monoclonal Antibodies, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA
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10
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Sarkar S, Iyer G, Wu J, Glass N. Nonself recognition is mediated by HET-C heterocomplex formation during vegetative incompatibility. EMBO J 2002; 21:4841-50. [PMID: 12234924 PMCID: PMC126278 DOI: 10.1093/emboj/cdf479] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Nonself recognition during vegetative growth in filamentous fungi is mediated by heterokaryon incompatibility (het) loci. In Neurospora crassa, het-c is one of 11 het loci. Three allelic specificity groups, termed het-c(OR), het-c(PA) and het-c(GR), exist in natural populations. Heterokaryons or partial diploids that contain het-c alleles of alternative specificity show severe growth inhibition, repression of conidiation and hyphal compartmentation and death (HCD). Using epitope-tagged HET-C, we show that nonself recognition is mediated by the presence of a heterocomplex composed of polypeptides encoded by het-c alleles of alternative specificity. The HET-C heterocomplex localized to the plasma membrane (PM); PM-bound HET-C heterocomplexes occurred in all three het-c incompatible allelic interactions. Strains containing het-c constructs deleted for a predicted signal peptide sequence formed HET-C heterocomplexes in the cytoplasm and showed a growth arrest phenotype. Our finding is a step towards understanding nonself recognition mechanisms that operate during vegetative growth in filamentous fungi, and provides a model for investigating relationships between recognition mechanisms and cell death.
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Affiliation(s)
- Sovan Sarkar
- Plant and Microbial Biology Department, 111 Koshland Hall, University of California, Berkeley, CA 94720, USA and The Biotechnology Laboratory and the Botany Department, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada Present address: Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA Corresponding author e-mail: S.Sarkar and G.Iyer contributed equally to this work
| | - Gopal Iyer
- Plant and Microbial Biology Department, 111 Koshland Hall, University of California, Berkeley, CA 94720, USA and The Biotechnology Laboratory and the Botany Department, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada Present address: Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA Corresponding author e-mail: S.Sarkar and G.Iyer contributed equally to this work
| | - Jennifer Wu
- Plant and Microbial Biology Department, 111 Koshland Hall, University of California, Berkeley, CA 94720, USA and The Biotechnology Laboratory and the Botany Department, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada Present address: Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA Corresponding author e-mail: S.Sarkar and G.Iyer contributed equally to this work
| | - N.Louise Glass
- Plant and Microbial Biology Department, 111 Koshland Hall, University of California, Berkeley, CA 94720, USA and The Biotechnology Laboratory and the Botany Department, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada Present address: Clinical Research Division, Fred Hutchinson Cancer Research Center, Seattle, WA 98109, USA Corresponding author e-mail: S.Sarkar and G.Iyer contributed equally to this work
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11
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Boyton RJ, Zaccai N, Jones EY, Altmann DM. CD4 T cells selected by antigen under Th2 polarizing conditions favor an elongated TCR alpha chain complementarity-determining region 3. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2002; 168:1018-27. [PMID: 11801634 DOI: 10.4049/jimmunol.168.3.1018] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The affinity of the MHC/peptide/TCR interaction is thought to be one factor determining the differentiation of CD4+ T cells into Th1 or Th2 phenotypes. To study whether CD4+ cells generated under conditions favoring Th1 or Th2 responses select structurally different TCRs, Th1 and Th2 clones and lines were generated from nonobese diabetic and nonobese diabetic H2-E transgenic mice against the peptides proteolipoprotein 56-70, glutamic acid decarboxylase(65) 524-543, and heat shock protein-60 peptides 168-186 and 248-264. Th1/Th2 polarization allowed the generation of clones and lines with fixed peptide specificity and class II restriction but differing in Th1/Th2 phenotype in which the impact on TCR selection and structure could be studied. The Th2 clones tended to use longer TCR complementarity-determining region (CDR)3alpha loops than their Th1 counterparts. This trend was confirmed by analyzing TCRalpha transcripts from Th1 and Th2 polarized, bulk populations. Molecular modeling of Th1- and Th2-derived TCRs demonstrated that Th2 CDR3alpha comprised larger side chain residues than Th1 TCRs. The elongated, bulky Th2 CDR3alpha loops may be accommodated at the expense of less optimal interactions between the MHC class II/peptide and other CDR loops of the TCR. We propose that CD4+ T cells selected from the available repertoire under Th2 polarizing conditions tend to have elongated TCR CDR3alpha loops predicted to alter TCR binding, reducing contact at other interfaces and potentially leading to impeded TCR triggering.
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MESH Headings
- Amino Acid Sequence
- Animals
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- Cell Line
- Chaperonin 60/immunology
- Clone Cells
- Complementarity Determining Regions/chemistry
- Complementarity Determining Regions/genetics
- Complementarity Determining Regions/metabolism
- Cytokines/biosynthesis
- Epitopes, T-Lymphocyte/immunology
- Genes, T-Cell Receptor alpha
- Glutamate Decarboxylase/immunology
- H-2 Antigens/metabolism
- Mice
- Mice, Inbred NOD
- Mice, Transgenic
- Molecular Sequence Data
- Myelin Proteolipid Protein/immunology
- Peptide Fragments/immunology
- Protein Structure, Tertiary/genetics
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/metabolism
- Th1 Cells/immunology
- Th1 Cells/metabolism
- Th2 Cells/immunology
- Th2 Cells/metabolism
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Affiliation(s)
- Rosemary J Boyton
- Transplantation Biology Group, Medical Research Council Clinical Sciences Centre, Department of Infectious Diseases, Imperial College School of Science, Technology, and Medicine, Hammersmith Hospital, London, United Kingdom
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12
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Hebert AM, Strohmaier J, Whitman MC, Chen T, Gubina E, Hill DM, Lewis MS, Kozlowski S. Kinetics and thermodynamics of beta 2-microglobulin binding to the alpha 3 domain of major histocompatibility complex class I heavy chain. Biochemistry 2001; 40:5233-42. [PMID: 11318646 DOI: 10.1021/bi002392s] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The major histocompatibility complex (MHC) class I molecule plays a crucial role in cytotoxic lymphocyte function. Functional class I MHC exists as a heterotrimer consisting of the MHC class I heavy chain, an antigenic peptide fragment, and beta2-microglobulin (beta2m). beta2m has been previously shown to play an important role in the folding of the MHC heavy chain without continued beta2m association with the MHC complex. Therefore, beta2m is both a structural component of the MHC complex and a chaperone-like molecule for MHC folding. In this study we provide data supporting a model in which the chaperone-like role of beta2m is dependent on initial binding to only one of the two beta2m interfaces with class 1 heavy chain. beta2-Microglobulin binding to an isolated alpha3 domain of the class I MHC heavy chain accurately models the biochemistry and thermodynamics of beta2m-driven refolding. Our results explain a 1000-fold discrepancy between beta2m binding and refolding of MHC1. The biochemical study of the individual domains of complex molecules is an important strategy for understanding their dynamic structure and multiple functions.
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Affiliation(s)
- A M Hebert
- Division of Monoclonal Ab, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA
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13
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Costello PJ, Winchester RJ, Curran SA, Peterson KS, Kane DJ, Bresnihan B, FitzGerald OM. Psoriatic arthritis joint fluids are characterized by CD8 and CD4 T cell clonal expansions appear antigen driven. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 166:2878-86. [PMID: 11160357 DOI: 10.4049/jimmunol.166.4.2878] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The CD8 alphabetaT cell receptor repertoire in joint fluid of individuals with active psoriatic arthritis contained an average of 32 major oligoclonal expansions in many variable genes of the TCR beta chain (BV) families, as shown by beta-chain CDR3 length analysis. Interestingly, a small number of oligoclonal expansions were shared between simultaneous samples of joint fluid and blood; however, most expansions found in joint fluid were not identifiable in blood emphasizing the immunologic specificity of the clonal events for the inflamed joint at a given point of time. The CD4 T cell joint fluid repertoire contained fewer and smaller oligoclonal expansions also largely restricted to the joint, suggesting that CD4 T cells participate perhaps by interacting cognitively to generate the CD8 clones. The inferred amino acid sequence of a single CD8 oligoclonal expansion revealed that they usually are composed of one or a few structurally related clones at the amino acid sequence level with beta-chains that encode identical or highly homologous CDR3 motifs. These were not shared among patients. Moreover, several clones that encoded the same amino acid sequence were found to be structurally distinct at the nucleotide level, strongly implying clonal selection and expansion is operating at the level of specific TCR-peptide interactions. The findings support a model of psoriatic arthritis inflammation involving extensive and selective Ag, likely autoantigen, driven intra-articular CD4, and CD8 T cell clonal expansions.
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MESH Headings
- Amino Acid Sequence
- Arthritis, Psoriatic/genetics
- Arthritis, Psoriatic/immunology
- Arthritis, Psoriatic/metabolism
- Arthritis, Psoriatic/pathology
- Autoantigens/immunology
- Base Sequence
- CD4-Positive T-Lymphocytes/immunology
- CD4-Positive T-Lymphocytes/metabolism
- CD4-Positive T-Lymphocytes/pathology
- CD8-Positive T-Lymphocytes/immunology
- CD8-Positive T-Lymphocytes/metabolism
- CD8-Positive T-Lymphocytes/pathology
- Cell Division/genetics
- Cell Division/immunology
- Clone Cells
- Cloning, Molecular
- Humans
- Knee Joint/immunology
- Knee Joint/metabolism
- Knee Joint/pathology
- Molecular Sequence Data
- Receptors, Antigen, T-Cell, alpha-beta/biosynthesis
- Receptors, Antigen, T-Cell, alpha-beta/blood
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Reference Standards
- Reference Values
- Synovial Fluid/immunology
- Synovial Fluid/metabolism
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Affiliation(s)
- P J Costello
- Department of Rheumatology, Education and Research Centre, St. Vincent's University Hospital, Dublin, Ireland
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14
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De Oliveira DB, Harfouch-Hammoud E, Otto H, Papandreou NA, Stern LJ, Cohen H, Boehm BO, Bach J, Caillat-Zucman S, Walk T, Jung G, Eliopoulos E, Papadopoulos GK, van Endert PM. Structural analysis of two HLA-DR-presented autoantigenic epitopes: crucial role of peripheral but not central peptide residues for T-cell receptor recognition. Mol Immunol 2000; 37:813-25. [PMID: 11257303 DOI: 10.1016/s0161-5890(00)00109-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Specific and major histocompatibility complex (MHC)-restricted T-cell recognition of antigenic peptides is based on interactions of the T-cell receptor (TCR) with the MHC alpha helices and solvent exposed peptide residues termed TCR contacts. In the case of MHC class II-presented peptides, the latter are located in the positions p2/3, p5 and p7/8 between MHC anchor residues. For numerous epitopes, peptide substitution studies have identified the central residue p5 as primary TCR contact characterized by very low permissiveness for peptide substitution, while the more peripheral positions generally represent auxiliary TCR contacts. In structural studies of TCR/peptide/MHC complexes, this has been shown to be due to intimate contact between the TCR complementarity determining region (CDR) three loops and the central peptide residue. We asked whether this model also applied to two HLA-DR presented epitopes derived from an antigen targeted in type 1 diabetes. Large panels of epitope variants with mainly conservative single substitutions were tested for human leukocyte antigen (HLA) class II binding affinity and T cell stimulation. Both epitopes bind with high affinity to the presenting HLA-DR molecules. However, in striking contrast to the standard distribution of TCR contacts, recognition of the central p5 residue displayed high permissiveness even for non-conservative substitutions, while the more peripheral p2 and p8 TCR contacts showed very low permissiveness for substitution. This suggests that intimate TCR interaction with the central peptide residue is not always required for specific antigen recognition and can be compensated by interactions with positions normally acting as auxiliary contacts.
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Affiliation(s)
- D B De Oliveira
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
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15
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Wingren C, Crowley MP, Degano M, Chien Y, Wilson IA. Crystal structure of a gammadelta T cell receptor ligand T22: a truncated MHC-like fold. Science 2000; 287:310-4. [PMID: 10634787 DOI: 10.1126/science.287.5451.310] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Murine T10 and T22 are highly related nonclassical major histocompatibility complex (MHC) class Ib proteins that bind to certain gammadelta T cell receptors (TCRs) in the absence of other components. The crystal structure of T22b at 3.1 angstroms reveals similarities to MHC class I molecules, but one side of the normal peptide-binding groove is severely truncated, which allows direct access to the beta-sheet floor. Potential gammadelta TCR-binding sites can be inferred from functional mapping of T10 and T22 point mutants and allelic variants. Thus, T22 represents an unusual variant of the MHC-like fold and indicates that gammadelta and alphabeta TCRs interact differently with their respective MHC ligands.
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MESH Headings
- Alleles
- Amino Acid Substitution
- Animals
- Binding Sites
- Crystallography, X-Ray
- Glycosylation
- Histocompatibility Antigens Class I/chemistry
- Hydrogen Bonding
- Ligands
- Mice
- Models, Molecular
- Point Mutation
- Protein Conformation
- Protein Folding
- Protein Structure, Quaternary
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Proteins/chemistry
- Proteins/immunology
- Proteins/metabolism
- Receptors, Antigen, T-Cell, gamma-delta/immunology
- Receptors, Antigen, T-Cell, gamma-delta/metabolism
- Surface Properties
- beta 2-Microglobulin/chemistry
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Affiliation(s)
- C Wingren
- 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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16
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Garcia KC. Molecular interactions between extracellular components of the T-cell receptor signaling complex. Immunol Rev 1999; 172:73-85. [PMID: 10631938 DOI: 10.1111/j.1600-065x.1999.tb01357.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The structural and biochemical basis of antigen recognition by the T-cell receptor (TCR)-CD3 signaling complex has been illuminated greatly over the past few years. Structural biology has contributed enormously to this understanding through the determination of crystal structures of many of the individual components of this complex, and some of the complexes. A number of general principles can be derived for the structure of the alpha beta TCR and its interaction with peptide-major histocompatibility complex (pMHC) in class I systems, as well as interaction of the CD8 co-receptor with MHC. Large buried surface areas within the protein-protein interfaces, and varying degrees of shape complementarity appear critical for modulating the stability of the multicomponent, low-affinity macromolecular complexes consisting of TCR, pMHC, CD8 or CD4, and CD3 gamma, delta, epsilon and zeta. Significant structural alterations in TCR and pMHC, upon complex formation, hint at an as yet unclear role for conformational change in both recognition and activation. Subtle chemical alterations in key peptide residues which contact the TCR can have dramatic agonist or antagonist effects on receptor activation, which correlate only loosely with the TCR/pMHC complex affinity, implying an ability of the signaling complex to "sense" fine differences in the interface. The stoichiometry of an activated TCR signaling complex is still an unresolved issue, as is the structure and disposition of the CD3 components. However, functional experiments are bridging this gap and providing us with preliminary working models of the multimeric assemblies.
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Affiliation(s)
- K C Garcia
- Department of Microbiology and Immunology, Stanford University School of Medicine, CA 94305-5124, USA.
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17
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Fernández-Miguel G, Alarcón B, Iglesias A, Bluethmann H, Alvarez-Mon M, Sanz E, de la Hera A. Multivalent structure of an alphabetaT cell receptor. Proc Natl Acad Sci U S A 1999; 96:1547-52. [PMID: 9990061 PMCID: PMC15512 DOI: 10.1073/pnas.96.4.1547] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/1998] [Accepted: 12/10/1998] [Indexed: 11/18/2022] Open
Abstract
Whether there is one or multiple alphabetaT cell antigen receptor (TCR) recognition modules in a given TCR/CD3 complex is a long-standing controversy in immunology. We show that T cells from transgenic mice that coexpress comparable amounts of two distinct TCRbeta chains incorporate at least two alphabetaTCRs in a single TCR/CD3 complex. Evidence for bispecific alphabetaTCRs was obtained by immunoprecipitation and immunoblotting and confirmed on the surface of living cells both by fluorescence resonance energy transfer and comodulation assays by using antibodies specific for TCRbeta-variable regions. Such (alphabeta)2TCR/CD3 or higher-order complexes were evident in T cells studied either ex vivo or after expansion in vitro. T cell activation is thought by many, but not all, to require TCR cross-linking by its antigen/major histocompatibility complex ligand. The implications of a multivalent (alphabeta)2TCR/CD3 complex stoichiometry for the ordered docking of specific antigen/major histocompatibility complex, CD4, or CD8 coreceptors and additional TCRs are discussed.
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MESH Headings
- Animals
- Cell Line
- Crosses, Genetic
- Flow Cytometry
- Green Fluorescent Proteins
- Luminescent Proteins/biosynthesis
- Luminescent Proteins/genetics
- Macromolecular Substances
- Mice
- Mice, Transgenic
- Models, Molecular
- Receptor-CD3 Complex, Antigen, T-Cell/chemistry
- Receptor-CD3 Complex, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell, alpha-beta/biosynthesis
- Receptors, Antigen, T-Cell, alpha-beta/chemistry
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Recombinant Fusion Proteins/biosynthesis
- Spleen/immunology
- T-Lymphocytes/immunology
- Thymus Gland/immunology
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Affiliation(s)
- G Fernández-Miguel
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Department of Medicine, Alcalá University, Velázquez 144, Madrid, E-28006, Spain
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