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| - | ==Crystal structure of an immune receptor== | + | ==Crystal structure of F5 TCR -DR11-RQ13 peptide complex== |
| - | <StructureSection load='6cqn' size='340' side='right' caption='[[6cqn]], [[Resolution|resolution]] 2.50Å' scene=''> | + | <StructureSection load='6cqn' size='340' side='right'caption='[[6cqn]], [[Resolution|resolution]] 2.50Å' scene=''> |
| | == Structural highlights == | | == Structural highlights == |
| - | <table><tr><td colspan='2'>[[6cqn]] is a 5 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6CQN OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6CQN FirstGlance]. <br> | + | <table><tr><td colspan='2'>[[6cqn]] is a 5 chain structure with sequence from [https://en.wikipedia.org/wiki/HIV-1_M:B_HXB2R HIV-1 M:B_HXB2R] and [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6CQN OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6CQN FirstGlance]. <br> |
| - | </td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr> | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.5Å</td></tr> |
| - | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6cqn FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6cqn OCA], [http://pdbe.org/6cqn PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6cqn RCSB], [http://www.ebi.ac.uk/pdbsum/6cqn PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6cqn ProSAT]</span></td></tr> | + | <tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=NAG:N-ACETYL-D-GLUCOSAMINE'>NAG</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr> |
| | + | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=6cqn FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6cqn OCA], [https://pdbe.org/6cqn PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6cqn RCSB], [https://www.ebi.ac.uk/pdbsum/6cqn PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6cqn ProSAT]</span></td></tr> |
| | </table> | | </table> |
| | == Function == | | == Function == |
| - | [[http://www.uniprot.org/uniprot/DRA_HUMAN DRA_HUMAN]] Binds peptides derived from antigens that access the endocytic route of antigen presenting cells (APC) and presents them on the cell surface for recognition by the CD4 T-cells. The peptide binding cleft accommodates peptides of 10-30 residues. The peptides presented by MHC class II molecules are generated mostly by degradation of proteins that access the endocytic route, where they are processed by lysosomal proteases and other hydrolases. Exogenous antigens that have been endocytosed by the APC are thus readily available for presentation via MHC II molecules, and for this reason this antigen presentation pathway is usually referred to as exogenous. As membrane proteins on their way to degradation in lysosomes as part of their normal turn-over are also contained in the endosomal/lysosomal compartments, exogenous antigens must compete with those derived from endogenous components. Autophagy is also a source of endogenous peptides, autophagosomes constitutively fuse with MHC class II loading compartments. In addition to APCs, other cells of the gastrointestinal tract, such as epithelial cells, express MHC class II molecules and CD74 and act as APCs, which is an unusual trait of the GI tract. To produce a MHC class II molecule that presents an antigen, three MHC class II molecules (heterodimers of an alpha and a beta chain) associate with a CD74 trimer in the ER to form a heterononamer. Soon after the entry of this complex into the endosomal/lysosomal system where antigen processing occurs, CD74 undergoes a sequential degradation by various proteases, including CTSS and CTSL, leaving a small fragment termed CLIP (class-II-associated invariant chain peptide). The removal of CLIP is facilitated by HLA-DM via direct binding to the alpha-beta-CLIP complex so that CLIP is released. HLA-DM stabilizes MHC class II molecules until primary high affinity antigenic peptides are bound. The MHC II molecule bound to a peptide is then transported to the cell membrane surface. In B-cells, the interaction between HLA-DM and MHC class II molecules is regulated by HLA-DO. Primary dendritic cells (DCs) also to express HLA-DO. Lysosomal miroenvironment has been implicated in the regulation of antigen loading into MHC II molecules, increased acidification produces increased proteolysis and efficient peptide loading. [[http://www.uniprot.org/uniprot/GAG_HV1H2 GAG_HV1H2]] Matrix protein p17 targets Gag and Gag-Pol polyproteins to the plasma membrane via a multipartite membrane binding signal, that includes its myristoylated N-terminus. Also mediates nuclear localization of the preintegration complex. Implicated in the release from host cell mediated by Vpu. Capsid protein p24 forms the conical core of the virus that encapsulates the genomic RNA-nucleocapsid complex. Nucleocapsid protein p7 encapsulates and protects viral dimeric unspliced (genomic) RNA. Binds these RNAs through its zinc fingers. p6-gag plays a role in budding of the assembled particle by interacting with the host class E VPS proteins TSG101 and PDCD6IP/AIP1 (By similarity). [[http://www.uniprot.org/uniprot/2B1B_HUMAN 2B1B_HUMAN]] Binds peptides derived from antigens that access the endocytic route of antigen presenting cells (APC) and presents them on the cell surface for recognition by the CD4 T-cells. The peptide binding cleft accommodates peptides of 10-30 residues. The peptides presented by MHC class II molecules are generated mostly by degradation of proteins that access the endocytic route, where they are processed by lysosomal proteases and other hydrolases. Exogenous antigens that have been endocytosed by the APC are thus readily available for presentation via MHC II molecules, and for this reason this antigen presentation pathway is usually referred to as exogenous. As membrane proteins on their way to degradation in lysosomes as part of their normal turn-over are also contained in the endosomal/lysosomal compartments, exogenous antigens must compete with those derived from endogenous components. Autophagy is also a source of endogenous peptides, autophagosomes constitutively fuse with MHC class II loading compartments. In addition to APCs, other cells of the gastrointestinal tract, such as epithelial cells, express MHC class II molecules and CD74 and act as APCs, which is an unusual trait of the GI tract. To produce a MHC class II molecule that presents an antigen, three MHC class II molecules (heterodimers of an alpha and a beta chain) associate with a CD74 trimer in the ER to form a heterononamer. Soon after the entry of this complex into the endosomal/lysosomal system where antigen processing occurs, CD74 undergoes a sequential degradation by various proteases, including CTSS and CTSL, leaving a small fragment termed CLIP (class-II-associated invariant chain peptide). The removal of CLIP is facilitated by HLA-DM via direct binding to the alpha-beta-CLIP complex so that CLIP is released. HLA-DM stabilizes MHC class II molecules until primary high affinity antigenic peptides are bound. The MHC II molecule bound to a peptide is then transported to the cell membrane surface. In B-cells, the interaction between HLA-DM and MHC class II molecules is regulated by HLA-DO. Primary dendritic cells (DCs) also to express HLA-DO. Lysosomal microenvironment has been implicated in the regulation of antigen loading into MHC II molecules, increased acidification produces increased proteolysis and efficient peptide loading. | + | [https://www.uniprot.org/uniprot/TVA24_HUMAN TVA24_HUMAN] V region of the variable domain of T cell receptor (TR) alpha chain that participates in the antigen recognition (PubMed:24600447). Alpha-beta T cell receptors are antigen specific receptors which are essential to the immune response and are present on the cell surface of T lymphocytes. Recognize peptide-major histocompatibility (MH) (pMH) complexes that are displayed by antigen presenting cells (APC), a prerequisite for efficient T cell adaptive immunity against pathogens (PubMed:25493333). Binding of alpha-beta TR to pMH complex initiates TR-CD3 clustering on the cell surface and intracellular activation of LCK that phosphorylates the ITAM motifs of CD3G, CD3D, CD3E and CD247 enabling the recruitment of ZAP70. In turn ZAP70 phosphorylates LAT, which recruits numerous signaling molecules to form the LAT signalosome. The LAT signalosome propagates signal branching to three major signaling pathways, the calcium, the mitogen-activated protein kinase (MAPK) kinase and the nuclear factor NF-kappa-B (NF-kB) pathways, leading to the mobilization of transcription factors that are critical for gene expression and essential for T cell growth and differentiation (PubMed:23524462). The T cell repertoire is generated in the thymus, by V-(D)-J rearrangement. This repertoire is then shaped by intrathymic selection events to generate a peripheral T cell pool of self-MH restricted, non-autoaggressive T cells. Post-thymic interaction of alpha-beta TR with the pMH complexes shapes TR structural and functional avidity (PubMed:15040585).<ref>PMID:15040585</ref> <ref>PMID:23524462</ref> <ref>PMID:24600447</ref> <ref>PMID:25493333</ref> |
| | + | <div style="background-color:#fffaf0;"> |
| | + | == Publication Abstract from PubMed == |
| | + | Rare individuals, termed HIV controllers, spontaneously control HIV infection by mounting efficient T cell responses against the virus. Protective CD4(+) T cell responses from HIV controllers involve high-affinity public T cell receptors (TCRs) recognizing an immunodominant capsid epitope (Gag293) presented by a remarkably broad array of human leukocyte antigen (HLA) class II molecules. Here, we determine the structures of a prototypical public TCR bound to HLA-DR1, HLA-DR11, and HLA-DR15 molecules presenting the Gag293 epitope. TCR recognition was driven by contacts with the Gag293 epitope, a feature that underpinned the extensive HLA cross-restriction. These high-affinity TCRs promoted mature immunological synapse formation and cytotoxic capacity in both CD4(+) and CD8(+) T cells. The public TCRs suppressed HIV replication in multiple genetic backgrounds ex vivo, emphasizing the functional advantage conferred by broad HLA class II cross-restriction. |
| | + | |
| | + | CD4(+) T cell-mediated HLA class II cross-restriction in HIV controllers.,Galperin M, Farenc C, Mukhopadhyay M, Jayasinghe D, Decroos A, Benati D, Tan LL, Ciacchi L, Reid HH, Rossjohn J, Chakrabarti LA, Gras S Sci Immunol. 2018 Jun 8;3(24). pii: 3/24/eaat0687. doi:, 10.1126/sciimmunol.aat0687. PMID:29884618<ref>PMID:29884618</ref> |
| | + | |
| | + | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> |
| | + | </div> |
| | + | <div class="pdbe-citations 6cqn" style="background-color:#fffaf0;"></div> |
| | + | |
| | + | ==See Also== |
| | + | *[[MHC 3D structures|MHC 3D structures]] |
| | + | *[[MHC II 3D structures|MHC II 3D structures]] |
| | + | *[[T-cell receptor 3D structures|T-cell receptor 3D structures]] |
| | + | == References == |
| | + | <references/> |
| | __TOC__ | | __TOC__ |
| | </StructureSection> | | </StructureSection> |
| - | [[Category: Farenc, C]] | + | [[Category: HIV-1 M:B_HXB2R]] |
| - | [[Category: Gras, S]] | + | [[Category: Homo sapiens]] |
| - | [[Category: Rossjohn, J]] | + | [[Category: Large Structures]] |
| - | [[Category: Immune receptor]] | + | [[Category: Farenc C]] |
| - | [[Category: Immune system]] | + | [[Category: Gras S]] |
| - | [[Category: Tcr]] | + | [[Category: Rossjohn J]] |
| Structural highlights
Function
TVA24_HUMAN V region of the variable domain of T cell receptor (TR) alpha chain that participates in the antigen recognition (PubMed:24600447). Alpha-beta T cell receptors are antigen specific receptors which are essential to the immune response and are present on the cell surface of T lymphocytes. Recognize peptide-major histocompatibility (MH) (pMH) complexes that are displayed by antigen presenting cells (APC), a prerequisite for efficient T cell adaptive immunity against pathogens (PubMed:25493333). Binding of alpha-beta TR to pMH complex initiates TR-CD3 clustering on the cell surface and intracellular activation of LCK that phosphorylates the ITAM motifs of CD3G, CD3D, CD3E and CD247 enabling the recruitment of ZAP70. In turn ZAP70 phosphorylates LAT, which recruits numerous signaling molecules to form the LAT signalosome. The LAT signalosome propagates signal branching to three major signaling pathways, the calcium, the mitogen-activated protein kinase (MAPK) kinase and the nuclear factor NF-kappa-B (NF-kB) pathways, leading to the mobilization of transcription factors that are critical for gene expression and essential for T cell growth and differentiation (PubMed:23524462). The T cell repertoire is generated in the thymus, by V-(D)-J rearrangement. This repertoire is then shaped by intrathymic selection events to generate a peripheral T cell pool of self-MH restricted, non-autoaggressive T cells. Post-thymic interaction of alpha-beta TR with the pMH complexes shapes TR structural and functional avidity (PubMed:15040585).[1] [2] [3] [4]
Publication Abstract from PubMed
Rare individuals, termed HIV controllers, spontaneously control HIV infection by mounting efficient T cell responses against the virus. Protective CD4(+) T cell responses from HIV controllers involve high-affinity public T cell receptors (TCRs) recognizing an immunodominant capsid epitope (Gag293) presented by a remarkably broad array of human leukocyte antigen (HLA) class II molecules. Here, we determine the structures of a prototypical public TCR bound to HLA-DR1, HLA-DR11, and HLA-DR15 molecules presenting the Gag293 epitope. TCR recognition was driven by contacts with the Gag293 epitope, a feature that underpinned the extensive HLA cross-restriction. These high-affinity TCRs promoted mature immunological synapse formation and cytotoxic capacity in both CD4(+) and CD8(+) T cells. The public TCRs suppressed HIV replication in multiple genetic backgrounds ex vivo, emphasizing the functional advantage conferred by broad HLA class II cross-restriction.
CD4(+) T cell-mediated HLA class II cross-restriction in HIV controllers.,Galperin M, Farenc C, Mukhopadhyay M, Jayasinghe D, Decroos A, Benati D, Tan LL, Ciacchi L, Reid HH, Rossjohn J, Chakrabarti LA, Gras S Sci Immunol. 2018 Jun 8;3(24). pii: 3/24/eaat0687. doi:, 10.1126/sciimmunol.aat0687. PMID:29884618[5]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
See Also
References
- ↑ Nikolich-Zugich J, Slifka MK, Messaoudi I. The many important facets of T-cell repertoire diversity. Nat Rev Immunol. 2004 Feb;4(2):123-32. doi: 10.1038/nri1292. PMID:15040585 doi:http://dx.doi.org/10.1038/nri1292
- ↑ Brownlie RJ, Zamoyska R. T cell receptor signalling networks: branched, diversified and bounded. Nat Rev Immunol. 2013 Apr;13(4):257-69. doi: 10.1038/nri3403. PMID:23524462 doi:http://dx.doi.org/10.1038/nri3403
- ↑ Lefranc MP. Immunoglobulin and T Cell Receptor Genes: IMGT((R)) and the Birth and Rise of Immunoinformatics. Front Immunol. 2014 Feb 5;5:22. doi: 10.3389/fimmu.2014.00022. eCollection 2014. PMID:24600447 doi:http://dx.doi.org/10.3389/fimmu.2014.00022
- ↑ Rossjohn J, Gras S, Miles JJ, Turner SJ, Godfrey DI, McCluskey J. T cell antigen receptor recognition of antigen-presenting molecules. Annu Rev Immunol. 2015;33:169-200. doi: 10.1146/annurev-immunol-032414-112334., Epub 2014 Dec 10. PMID:25493333 doi:http://dx.doi.org/10.1146/annurev-immunol-032414-112334
- ↑ Galperin M, Farenc C, Mukhopadhyay M, Jayasinghe D, Decroos A, Benati D, Tan LL, Ciacchi L, Reid HH, Rossjohn J, Chakrabarti LA, Gras S. CD4(+) T cell-mediated HLA class II cross-restriction in HIV controllers. Sci Immunol. 2018 Jun 8;3(24). pii: 3/24/eaat0687. doi:, 10.1126/sciimmunol.aat0687. PMID:29884618 doi:http://dx.doi.org/10.1126/sciimmunol.aat0687
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