1
|
Barth KM, Hiller DA, Strobel SA. The Impact of Second-Shell Nucleotides on Ligand Specificity in Cyclic Dinucleotide Riboswitches. Biochemistry 2024. [PMID: 38329042 DOI: 10.1021/acs.biochem.3c00586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Ligand specificity is an essential requirement for all riboswitches. Some variant riboswitches utilize a common structural motif, yet through subtle sequence differences, they are able to selectively respond to different small molecule ligands and regulate downstream gene expression. These variants discriminate between structurally and chemically similar ligands. Crystal structures provide insight into how specificity is achieved. However, ligand specificity cannot always be explained solely by nucleotides in direct contact with the ligand. The cyclic dinucleotide variant family contains two classes, cyclic-di-GMP and cyclic-AMP-GMP riboswitches, that were distinguished based on the identity of a single nucleotide in contact with the ligand. Here we report a variant riboswitch with a mutation at a second ligand-contacting position that is promiscuous for both cyclic-di-GMP and cyclic-AMP-GMP despite a predicted preference for cyclic-AMP-GMP. A high-throughput mutational analysis, SMARTT, was used to quantitatively assess thousands of sites in the first- and second-shells of ligand contact for impacts on ligand specificity and promiscuity. In addition to nucleotides in direct ligand contact, nucleotides more distal from the binding site, within the J1/2 linker and the terminator helix, were identified that impact ligand specificity. These findings provide an example of how nucleotides outside the ligand binding pocket influence the riboswitch specificity. Moreover, these distal nucleotides could be used to predict promiscuous sequences.
Collapse
Affiliation(s)
- Kathryn M Barth
- Institute of Biomolecular Design and Discovery, Yale University, West Haven, Connecticut 06516, United States
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510, United States
| | - David A Hiller
- Institute of Biomolecular Design and Discovery, Yale University, West Haven, Connecticut 06516, United States
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510, United States
| | - Scott A Strobel
- Institute of Biomolecular Design and Discovery, Yale University, West Haven, Connecticut 06516, United States
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510, United States
| |
Collapse
|
2
|
Boughter CT, Meier-Schellersheim M. Conserved biophysical compatibility among the highly variable germline-encoded regions shapes TCR-MHC interactions. eLife 2023; 12:e90681. [PMID: 37861280 PMCID: PMC10631762 DOI: 10.7554/elife.90681] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Accepted: 10/19/2023] [Indexed: 10/21/2023] Open
Abstract
T cells are critically important components of the adaptive immune system primarily responsible for identifying and responding to pathogenic challenges. This recognition of pathogens is driven by the interaction between membrane-bound T cell receptors (TCRs) and antigenic peptides presented on major histocompatibility complex (MHC) molecules. The formation of the TCR-peptide-MHC complex (TCR-pMHC) involves interactions among germline-encoded and hypervariable amino acids. Germline-encoded and hypervariable regions can form contacts critical for complex formation, but only interactions between germline-encoded contacts are likely to be shared across many of all the possible productive TCR-pMHC complexes. Despite this, experimental investigation of these interactions have focused on only a small fraction of the possible interaction space. To address this, we analyzed every possible germline-encoded TCR-MHC contact in humans, thereby generating the first comprehensive characterization of these largely antigen-independent interactions. Our computational analysis suggests that germline-encoded TCR-MHC interactions that are conserved at the sequence level are rare due to the high amino acid diversity of the TCR CDR1 and CDR2 loops, and that such conservation is unlikely to dominate the dynamic protein-protein binding interface. Instead, we propose that binding properties such as the docking orientation are defined by regions of biophysical compatibility between these loops and the MHC surface.
Collapse
Affiliation(s)
- Christopher T Boughter
- Computational Biology Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of HealthBethesdaUnited States
| | - Martin Meier-Schellersheim
- Computational Biology Section, Laboratory of Immune System Biology, National Institute of Allergy and Infectious Diseases, National Institutes of HealthBethesdaUnited States
| |
Collapse
|
3
|
Huisman W, de Gier M, Hageman L, Shomuradova AS, Leboux DA, Amsen D, Falkenburg JF, Jedema I. Amino acids at position 5 in the peptide/MHC binding region of a public virus-specific TCR are completely inter-changeable without loss of function. Eur J Immunol 2022; 52:1819-1828. [PMID: 36189878 PMCID: PMC9828479 DOI: 10.1002/eji.202249975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 08/25/2022] [Accepted: 09/28/2022] [Indexed: 01/12/2023]
Abstract
Anti-viral T-cell responses are usually directed against a limited set of antigens, but often contain many T cells expressing different T-cell receptors (TCRs). Identical TCRs found within virus-specific T-cell populations in different individuals are known as public TCRs, but also TCRs highly-similar to these public TCRs, with only minor variations in amino acids on specific positions in the Complementary Determining Regions (CDRs), are frequently found. However, the degree of freedom at these positions was not clear. In this study, we used the HLA-A*02:01-restricted EBV-LMP2FLY -specific public TCR as model and modified the highly-variable position 5 of the CDR3β sequence with all 20 amino acids. Our results demonstrate that amino acids at this particular position in the CDR3β region of this TCR are completely inter-changeable, without loss of TCR function. We show that the inability to find certain variants in individuals is explained by their lower recombination probability rather than by steric hindrance.
Collapse
Affiliation(s)
- Wesley Huisman
- Department of HematologyLeiden University Medical CenterThe Netherlands,Department of HematopoiesisSanquin Research and Landsteiner Laboratory for Blood Cell ResearchAmsterdamThe Netherlands
| | - Melanie de Gier
- Department of HematologyLeiden University Medical CenterThe Netherlands
| | - Lois Hageman
- Department of HematologyLeiden University Medical CenterThe Netherlands
| | - Alina S. Shomuradova
- Laboratory for Transplantation ImmunologyNational Research Center for HematologyMoscowRussia
| | | | - Derk Amsen
- Department of HematopoiesisSanquin Research and Landsteiner Laboratory for Blood Cell ResearchAmsterdamThe Netherlands
| | | | - Inge Jedema
- Department of HematologyLeiden University Medical CenterThe Netherlands
| |
Collapse
|
4
|
Wu L, Xue Z, Jin S, Zhang J, Guo Y, Bai Y, Jin X, Wang C, Wang L, Liu Z, Wang JQ, Lu L, Liu W. huARdb: human Antigen Receptor database for interactive clonotype-transcriptome analysis at the single-cell level. Nucleic Acids Res 2021; 50:D1244-D1254. [PMID: 34606616 PMCID: PMC8728177 DOI: 10.1093/nar/gkab857] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/31/2021] [Accepted: 09/14/2021] [Indexed: 12/15/2022] Open
Abstract
T-cell receptors (TCRs) and B-cell receptors (BCRs) are critical in recognizing antigens and activating the adaptive immune response. Stochastic V(D)J recombination generates massive TCR/BCR repertoire diversity. Single-cell immune profiling with transcriptome analysis allows the high-throughput study of individual TCR/BCR clonotypes and functions under both normal and pathological settings. However, a comprehensive database linking these data is not yet readily available. Here, we present the human Antigen Receptor database (huARdb), a large-scale human single-cell immune profiling database that contains 444 794 high confidence T or B cells (hcT/B cells) with full-length TCR/BCR sequence and transcriptomes from 215 datasets. All datasets were processed in a uniform workflow, including sequence alignment, cell subtype prediction, unsupervised cell clustering, and clonotype definition. We also developed a multi-functional and user-friendly web interface that provides interactive visualization modules for biologists to analyze the transcriptome and TCR/BCR features at the single-cell level. HuARdb is freely available at https://huarc.net/database with functions for data querying, browsing, downloading, and depositing. In conclusion, huARdb is a comprehensive and multi-perspective atlas for human antigen receptors.
Collapse
Affiliation(s)
- Lize Wu
- Institute of Immunology and Department of Rheumatology at Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Liangzhu Laboratory, Zhejiang University Medical Center, 1369 West Wenyi Road, Hangzhou, Zhejiang 311121, China
| | - Ziwei Xue
- Zhejiang University-University of Edinburgh Institute (ZJU-UoE Institute), Zhejiang University School of Medicine, International Campus, Zhejiang University, Haining, Zhejiang 314400, China
| | - Siqian Jin
- Zhejiang University-University of Edinburgh Institute (ZJU-UoE Institute), Zhejiang University School of Medicine, International Campus, Zhejiang University, Haining, Zhejiang 314400, China
| | - Jinchun Zhang
- Zhejiang University-University of Edinburgh Institute (ZJU-UoE Institute), Zhejiang University School of Medicine, International Campus, Zhejiang University, Haining, Zhejiang 314400, China
| | - Yixin Guo
- Zhejiang University-University of Edinburgh Institute (ZJU-UoE Institute), Zhejiang University School of Medicine, International Campus, Zhejiang University, Haining, Zhejiang 314400, China
| | - Yadan Bai
- Zhejiang University-University of Edinburgh Institute (ZJU-UoE Institute), Zhejiang University School of Medicine, International Campus, Zhejiang University, Haining, Zhejiang 314400, China
| | - Xuexiao Jin
- Institute of Immunology and Department of Rheumatology at Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Chaochen Wang
- Zhejiang University-University of Edinburgh Institute (ZJU-UoE Institute), Zhejiang University School of Medicine, International Campus, Zhejiang University, Haining, Zhejiang 314400, China
| | - Lie Wang
- Department of Immunology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Zuozhu Liu
- Zhejiang University-University of Illinois at Urbana-Champaign Institute (ZJU-UIUC Institute), International Campus, Zhejiang University, Haining, Zhejiang 314400, China
| | - James Q Wang
- Zhejiang University-University of Edinburgh Institute (ZJU-UoE Institute), Zhejiang University School of Medicine, International Campus, Zhejiang University, Haining, Zhejiang 314400, China
| | - Linrong Lu
- Institute of Immunology and Department of Rheumatology at Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China.,Liangzhu Laboratory, Zhejiang University Medical Center, 1369 West Wenyi Road, Hangzhou, Zhejiang 311121, China.,Zhejiang University-University of Edinburgh Institute (ZJU-UoE Institute), Zhejiang University School of Medicine, International Campus, Zhejiang University, Haining, Zhejiang 314400, China.,Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Wanlu Liu
- Liangzhu Laboratory, Zhejiang University Medical Center, 1369 West Wenyi Road, Hangzhou, Zhejiang 311121, China.,Zhejiang University-University of Edinburgh Institute (ZJU-UoE Institute), Zhejiang University School of Medicine, International Campus, Zhejiang University, Haining, Zhejiang 314400, China.,Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China.,Department of Orthopedic Surgery of the Second Affiliated Hospital of Zhejiang University School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, China.,Alibaba-Zhejiang University Joint Research Center of Future Digital Healthcare, Zhejiang University, Hangzhou, Zhejiang 310058, China
| |
Collapse
|
5
|
Fischer DS, Wu Y, Schubert B, Theis FJ. Predicting antigen specificity of single T cells based on TCR CDR3 regions. Mol Syst Biol 2020; 16:e9416. [PMID: 32779888 PMCID: PMC7418512 DOI: 10.15252/msb.20199416] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 07/13/2020] [Accepted: 07/22/2020] [Indexed: 11/12/2022] Open
Abstract
It has recently become possible to simultaneously assay T-cell specificity with respect to large sets of antigens and the T-cell receptor sequence in high-throughput single-cell experiments. Leveraging this new type of data, we propose and benchmark a collection of deep learning architectures to model T-cell specificity in single cells. In agreement with previous results, we found that models that treat antigens as categorical outcome variables outperform those that model the TCR and antigen sequence jointly. Moreover, we show that variability in single-cell immune repertoire screens can be mitigated by modeling cell-specific covariates. Lastly, we demonstrate that the number of bound pMHC complexes can be predicted in a continuous fashion providing a gateway to disentangle cell-to-dextramer binding strength and receptor-to-pMHC affinity. We provide these models in the Python package TcellMatch to allow imputation of antigen specificities in single-cell RNA-seq studies on T cells without the need for MHC staining.
Collapse
Affiliation(s)
- David S Fischer
- Institute of Computational BiologyHelmholtz Zentrum MünchenNeuherbergGermany
- TUM School of Life Sciences WeihenstephanTechnical University of MunichFreisingGermany
| | - Yihan Wu
- Institute of Computational BiologyHelmholtz Zentrum MünchenNeuherbergGermany
| | - Benjamin Schubert
- Institute of Computational BiologyHelmholtz Zentrum MünchenNeuherbergGermany
- Department of MathematicsTechnical University of MunichGarching bei MünchenGermany
| | - Fabian J Theis
- Institute of Computational BiologyHelmholtz Zentrum MünchenNeuherbergGermany
- TUM School of Life Sciences WeihenstephanTechnical University of MunichFreisingGermany
- Department of MathematicsTechnical University of MunichGarching bei MünchenGermany
| |
Collapse
|
6
|
MHC-II alleles shape the CDR3 repertoires of conventional and regulatory naïve CD4 + T cells. Proc Natl Acad Sci U S A 2020; 117:13659-13669. [PMID: 32482872 DOI: 10.1073/pnas.2003170117] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
T cell maturation and activation depend upon T cell receptor (TCR) interactions with a wide variety of antigenic peptides displayed in a given major histocompatibility complex (MHC) context. Complementarity-determining region 3 (CDR3) is the most variable part of the TCRα and -β chains, which govern interactions with peptide-MHC complexes. However, it remains unclear how the CDR3 landscape is shaped by individual MHC context during thymic selection of naïve T cells. We established two mouse strains carrying distinct allelic variants of H2-A and analyzed thymic and peripheral production and TCR repertoires of naïve conventional CD4+ T (Tconv) and naïve regulatory CD4+ T (Treg) cells. Compared with tuberculosis-resistant C57BL/6 (H2-Ab) mice, the tuberculosis-susceptible H2-Aj mice had fewer CD4+ T cells of both subsets in the thymus. In the periphery, this deficiency was only apparent for Tconv and was compensated for by peripheral reconstitution for Treg We show that H2-Aj favors selection of a narrower and more convergent repertoire with more hydrophobic and strongly interacting amino acid residues in the middle of CDR3α and CDR3β, suggesting more stringent selection against a narrower peptide-MHC-II context. H2-Aj and H2-Ab mice have prominent reciprocal differences in CDR3α and CDR3β features, probably reflecting distinct modes of TCR fitting to MHC-II variants. These data reveal the mechanics and extent of how MHC-II shapes the naïve CD4+ T cell CDR3 landscape, which essentially defines adaptive response to infections and self-antigens.
Collapse
|
7
|
Carter JA, Preall JB, Grigaityte K, Goldfless SJ, Jeffery E, Briggs AW, Vigneault F, Atwal GS. Single T Cell Sequencing Demonstrates the Functional Role of αβ TCR Pairing in Cell Lineage and Antigen Specificity. Front Immunol 2019; 10:1516. [PMID: 31417541 PMCID: PMC6684766 DOI: 10.3389/fimmu.2019.01516] [Citation(s) in RCA: 52] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Accepted: 06/18/2019] [Indexed: 12/13/2022] Open
Abstract
Although structural studies of individual T cell receptors (TCRs) have revealed important roles for both the α and β chain in directing MHC and antigen recognition, repertoire-level immunogenomic analyses have historically examined the β chain alone. To determine the amount of useful information about TCR repertoire function encoded within αβ pairings, we analyzed paired TCR sequences from nearly 100,000 unique CD4+ and CD8+ T cells captured using two different high-throughput, single-cell sequencing approaches. Our results demonstrate little overlap in the healthy CD4+ and CD8+ repertoires, with shared TCR sequences possessing significantly shorter CDR3 sequences corresponding to higher generation probabilities. We further utilized tools from information theory and machine learning to show that while α and β chains are only weakly associated with lineage, αβ pairings appear to synergistically drive TCR-MHC interactions. Vαβ gene pairings were found to be the TCR feature most informative of T cell lineage, supporting the existence of germline-encoded paired αβ TCR-MHC interaction motifs. Finally, annotating our TCR pairs using a database of sequences with known antigen specificities, we demonstrate that approximately a third of the T cells possess α and β chains that each recognize different known antigens, suggesting that αβ pairing is critical for the accurate inference of repertoire functionality. Together, these findings provide biological insight into the functional implications of αβ pairing and highlight the utility of single-cell sequencing in immunogenomics.
Collapse
Affiliation(s)
- Jason A. Carter
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY, United States
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States
| | | | - Kristina Grigaityte
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States
| | | | | | | | | | - Gurinder S. Atwal
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, United States
| |
Collapse
|
8
|
Tsuchiya Y, Namiuchi Y, Wako H, Tsurui H. A study of CDR3 loop dynamics reveals distinct mechanisms of peptide recognition by T-cell receptors exhibiting different levels of cross-reactivity. Immunology 2017; 153:466-478. [PMID: 28992359 DOI: 10.1111/imm.12849] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2017] [Revised: 10/04/2017] [Accepted: 10/05/2017] [Indexed: 01/09/2023] Open
Abstract
T-cell receptors (TCRs) can productively interact with many different peptides bound within the MHC binding groove. This property varies with the level of cross-reactivity of TCRs; some TCRs are particularly hyper cross-reactive while others exhibit greater specificity. To elucidate the mechanism behind these differences, we studied five TCRs in complex with the same class II MHC (1Ab )-peptide (3K), that are known to exhibit different levels of cross-reactivity. Although these complexes have similar binding affinities, the interface areas between the TCR and the peptide-MHC (pMHC) differ significantly. We investigated static and dynamic structural features of the TCR-pMHC complexes and of TCRs in a free state, as well as the relationship between binding affinity and interface area. It was found that the TCRs known to exhibit lower levels of cross-reactivity bound to pMHC using an induced-fitting mechanism, forming large and tight interfaces rich in specific hydrogen bonds. In contrast, TCRs known to exhibit high levels of cross-reactivity used a more rigid binding mechanism where non-specific π-interactions involving the bulky Trp residue in CDR3β dominated. As entropy loss upon binding in these highly degenerate and rigid TCRs is smaller than that in less degenerate TCRs, they can better tolerate changes in residues distal from the major contacts with MHC-bound peptide. Hence, our dynamics study revealed that differences in the peptide recognition mechanisms by TCRs appear to correlate with the levels of T-cell cross-reactivity.
Collapse
Affiliation(s)
- Yuko Tsuchiya
- Institute for Protein Research, Osaka University, Suita, Osaka, Japan
| | | | - Hiroshi Wako
- School of Social Sciences, Waseda University, Tokyo, Japan
| | - Hiromichi Tsurui
- Department of Pathology, Juntendo University School of Medicine, Tokyo, Japan
| |
Collapse
|
9
|
Singh NK, Riley TP, Baker SCB, Borrman T, Weng Z, Baker BM. Emerging Concepts in TCR Specificity: Rationalizing and (Maybe) Predicting Outcomes. THE JOURNAL OF IMMUNOLOGY 2017; 199:2203-2213. [PMID: 28923982 DOI: 10.4049/jimmunol.1700744] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 07/10/2017] [Indexed: 12/14/2022]
Abstract
T cell specificity emerges from a myriad of processes, ranging from the biological pathways that control T cell signaling to the structural and physical mechanisms that influence how TCRs bind peptides and MHC proteins. Of these processes, the binding specificity of the TCR is a key component. However, TCR specificity is enigmatic: TCRs are at once specific but also cross-reactive. Although long appreciated, this duality continues to puzzle immunologists and has implications for the development of TCR-based therapeutics. In this review, we discuss TCR specificity, emphasizing results that have emerged from structural and physical studies of TCR binding. We show how the TCR specificity/cross-reactivity duality can be rationalized from structural and biophysical principles. There is excellent agreement between predictions from these principles and classic predictions about the scope of TCR cross-reactivity. We demonstrate how these same principles can also explain amino acid preferences in immunogenic epitopes and highlight opportunities for structural considerations in predictive immunology.
Collapse
Affiliation(s)
- Nishant K Singh
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556.,Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556; and
| | - Timothy P Riley
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556.,Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556; and
| | - Sarah Catherine B Baker
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556.,Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556; and
| | - Tyler Borrman
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Zhiping Weng
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, MA 01605
| | - Brian M Baker
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, IN 46556; .,Harper Cancer Research Institute, University of Notre Dame, Notre Dame, IN 46556; and
| |
Collapse
|
10
|
Yassai MB, Demos W, Gorski J. Structural and Mechanistic Implications of Rearrangement Frequencies within Human TCRBV Genes. THE JOURNAL OF IMMUNOLOGY 2017; 199:1142-1152. [PMID: 28659354 DOI: 10.4049/jimmunol.1601450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 05/22/2017] [Indexed: 11/19/2022]
Abstract
The T cell repertoire is a function of thymic V(D)J rearrangement and of peripheral selection. The mature repertoire embodies TCR sequences that are important for survival and can identify important structural aspects of the TCR. Analysis of the circulating TCRBV19 CD8 T cell repertoire showed that a majority of NDN-encoded CDR3 amino acid motifs start at CDR3 position four, well within the V region. Rearrangement at this position indicates that the DNA hairpin loop is not opened at the position adjacent to the recombination signal sequence, but rather is trimmed back three or more bases. In this article, we show that the rearrangement frequency distribution within the V region reveals selection on CDR3 position four. The selection is already established in single-positive CD8 thymocytes. Crystal structures reveal a possible basis for this selection due to the location of this residue in a bend that positions the remaining portion of CDR3 to interact with the peptide and MHC. Examination of other TCRBV families also shows selection for rearrangement within the V region of a number of genes and for CD8 and CD4 cells. The exact profile of rearrangement within the V region appears to be V gene specific. The frequent observation of side chains associated with turn motifs at CDR3 positions three and four fits with the structural need for a bend. The data are discussed in terms of the generation of a structural turn motif, the rearrangement mechanism, and selection of the repertoire on the peptide and MHC.
Collapse
Affiliation(s)
- Maryam B Yassai
- Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI 53226
| | - Wendy Demos
- Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI 53226
| | - Jack Gorski
- Blood Research Institute, BloodCenter of Wisconsin, Milwaukee, WI 53226
| |
Collapse
|
11
|
Lopes MD, Oliveira FM, Coelho IEV, Passos MJF, Alves CC, Taranto AG, Júnior MC, Santos LL, Fonseca CT, Villar JAFP, Lopes DO. Epitopes rationally selected through computational analyses induce T‐cell proliferation in mice and are recognized by serum from individuals infected with
Schistosoma mansoni. Biotechnol Prog 2017; 33:804-814. [DOI: 10.1002/btpr.2463] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 03/03/2017] [Indexed: 01/04/2023]
Affiliation(s)
- Marcelo D. Lopes
- Laboratório de Biologia Molecular, Universidade Federal de São João del‐Rei, Rua Sebastião Gonçalves CoelhoDivinópolis MG Brasil
| | - Flávio M. Oliveira
- Laboratório de Biologia Molecular, Universidade Federal de São João del‐Rei, Rua Sebastião Gonçalves CoelhoDivinópolis MG Brasil
| | - Ivan E. V. Coelho
- Laboratório de Química Farmacêutica, Universidade Federal de São João del‐ReiDivinópolis MGBrasil
| | - Maria J. F. Passos
- Laboratório de Síntese Orgânica e Nanoestruturas, Universidade Federal de São João del‐ReiDivinópolis MG Brasil
| | - Clarice C. Alves
- Grupo de Pesquisa em Biologia Parasitária e Imunologia, Centro de Pesquisas René Rachou, Fundação Oswaldo CruzBelo Horizonte MG30190‐002 Brasil
| | - Alex G. Taranto
- Laboratório de Química Farmacêutica, Universidade Federal de São João del‐ReiDivinópolis MGBrasil
| | - Moacyr C. Júnior
- Laboratório de Química Farmacêutica, Universidade Federal de São João del‐ReiDivinópolis MGBrasil
| | - Luciana L. Santos
- Laboratório de Biologia Molecular, Universidade Federal de São João del‐Rei, Rua Sebastião Gonçalves CoelhoDivinópolis MG Brasil
| | - Cristina T. Fonseca
- Grupo de Pesquisa em Biologia Parasitária e Imunologia, Centro de Pesquisas René Rachou, Fundação Oswaldo CruzBelo Horizonte MG30190‐002 Brasil
| | - José A. F. P. Villar
- Laboratório de Síntese Orgânica e Nanoestruturas, Universidade Federal de São João del‐ReiDivinópolis MG Brasil
| | - Débora O. Lopes
- Laboratório de Biologia Molecular, Universidade Federal de São João del‐Rei, Rua Sebastião Gonçalves CoelhoDivinópolis MG Brasil
| |
Collapse
|
12
|
Differential utilization of binding loop flexibility in T cell receptor ligand selection and cross-reactivity. Sci Rep 2016; 6:25070. [PMID: 27118724 PMCID: PMC4846865 DOI: 10.1038/srep25070] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Accepted: 04/11/2016] [Indexed: 12/27/2022] Open
Abstract
Complementarity determining region (CDR) loop flexibility has been suggested to play an important role in the selection and binding of ligands by T cell receptors (TCRs) of the cellular immune system. However, questions remain regarding the role of loop motion in TCR binding, and crystallographic structures have raised questions about the extent to which generalizations can be made. Here we studied the flexibility of two structurally well characterized αβ TCRs, A6 and DMF5. We found that the two receptors utilize loop motion very differently in ligand binding and cross-reactivity. While the loops of A6 move rapidly in an uncorrelated fashion, those of DMF5 are substantially less mobile. Accordingly, the mechanisms of binding and cross-reactivity are very different between the two TCRs: whereas A6 relies on conformational selection to select and bind different ligands, DMF5 uses a more rigid, permissive architecture with greater reliance on slower motions or induced-fit. In addition to binding site flexibility, we also explored whether ligand-binding resulted in common dynamical changes in A6 and DMF5 that could contribute to TCR triggering. Although binding-linked motional changes propagated throughout both receptors, no common features were observed, suggesting that changes in nanosecond-level TCR structural dynamics do not contribute to T cell signaling.
Collapse
|
13
|
How structural adaptability exists alongside HLA-A2 bias in the human αβ TCR repertoire. Proc Natl Acad Sci U S A 2016; 113:E1276-85. [PMID: 26884163 DOI: 10.1073/pnas.1522069113] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
How T-cell receptors (TCRs) can be intrinsically biased toward MHC proteins while simultaneously display the structural adaptability required to engage diverse ligands remains a controversial puzzle. We addressed this by examining αβ TCR sequences and structures for evidence of physicochemical compatibility with MHC proteins. We found that human TCRs are enriched in the capacity to engage a polymorphic, positively charged "hot-spot" region that is almost exclusive to the α1-helix of the common human class I MHC protein, HLA-A*0201 (HLA-A2). TCR binding necessitates hot-spot burial, yielding high energetic penalties that must be offset via complementary electrostatic interactions. Enrichment of negative charges in TCR binding loops, particularly the germ-line loops encoded by the TCR Vα and Vβ genes, provides this capacity and is correlated with restricted positioning of TCRs over HLA-A2. Notably, this enrichment is absent from antibody genes. The data suggest a built-in TCR compatibility with HLA-A2 that biases receptors toward, but does not compel, particular binding modes. Our findings provide an instructional example for how structurally pliant MHC biases can be encoded within TCRs.
Collapse
|
14
|
Indoctrinating T cells to attack pathogens through homeschooling. Trends Immunol 2015; 36:337-43. [PMID: 25979654 DOI: 10.1016/j.it.2015.04.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 04/15/2015] [Accepted: 04/15/2015] [Indexed: 12/14/2022]
Abstract
Adaptive immunity is predicated on the ability of the T cell repertoire to have pre-existing specificity for the universe of potential pathogens. Recent findings suggest that T cell receptor (TCR)-self-major histocompatibility protein (pMHC) interactions limit autoimmune responses while enhancing T cell response to foreign antigens. We review these findings here, placing them in context of the current understanding of how TCR-self-pMHC interactions regulate T cell activation thresholds, and suggest that TCR-self-pMHC interactions increase the efficiency of the T cell repertoire by giving a competitive advantage to peptide cross-reactive T cells. We propose that self-reactivity and peptide cross-reactivity are controlled by particular CDR3 sequence motifs, which would allow thymic selection to contribute to solving the feat of broad pathogen specificity by exporting T cells that are pre-screened by positive and negative selection for the ability to be 'moderately' peptide cross-reactive.
Collapse
|
15
|
Løset GÅ, Berntzen G, Frigstad T, Pollmann S, Gunnarsen KS, Sandlie I. Phage Display Engineered T Cell Receptors as Tools for the Study of Tumor Peptide-MHC Interactions. Front Oncol 2015; 4:378. [PMID: 25629004 PMCID: PMC4290511 DOI: 10.3389/fonc.2014.00378] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Accepted: 12/17/2014] [Indexed: 11/13/2022] Open
Abstract
Cancer immunotherapy has finally come of age, demonstrated by recent progress in strategies that engage the endogenous adaptive immune response in tumor killing. Occasionally, significant and durable tumor regression has been achieved. A giant leap forward was the demonstration that the pre-existing polyclonal T cell repertoire could be re-directed by use of cloned T cell receptors (TCRs), to obtain a defined tumor-specific pool of T cells. However, the procedure must be performed with caution to avoid deleterious cross-reactivity. Here, the use of engineered soluble TCRs may represent a safer, yet powerful, alternative. There is also a need for deeper understanding of the processes that underlie antigen presentation in disease and homeostasis, how tumor-specific peptides are generated, and how epitope spreading evolves during tumor development. Due to its plasticity, the pivotal interaction where a TCR engages a peptide/MHC (pMHC) also requires closer attention. For this purpose, phage display as a tool to evolve cloned TCRs represents an attractive avenue to generate suitable reagents allowing the study of defined pMHC presentation, TCR engagement, as well as for the discovery of novel therapeutic leads. Here, we highlight important aspects of the current status in this field.
Collapse
Affiliation(s)
- Geir Åge Løset
- Nextera AS , Oslo , Norway ; Centre for Immune Regulation, Oslo University Hospital, University of Oslo , Oslo , Norway ; Department of Biosciences, University of Oslo , Oslo , Norway
| | | | | | | | - Kristin S Gunnarsen
- Centre for Immune Regulation, Oslo University Hospital, University of Oslo , Oslo , Norway
| | - Inger Sandlie
- Centre for Immune Regulation, Oslo University Hospital, University of Oslo , Oslo , Norway ; Department of Biosciences, University of Oslo , Oslo , Norway
| |
Collapse
|