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de Villartay JP, Pannier E, Sibiude J, Frange P, Tubiana R, Blanche S. Brief Report: T-Cell Receptor α Repertoire Diversity at Birth After in utero Exposure to HIV Integrase Strand-Transfer Inhibitors. J Acquir Immune Defic Syndr 2023; 92:260-262. [PMID: 36343360 DOI: 10.1097/qai.0000000000003130] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 10/24/2022] [Indexed: 11/09/2022]
Abstract
ABSTRACT Effectiveness of anti-HIV in the prevention of perinatal transmission has been established. Assessing the tolerance of drug exposure during pregnancy is of the utmost importance given the number of children exposed. HIV integrase and the recombinase-activating gene enzyme involved in the establishment of the T-lymphocyte repertoire show structural similarity. The inhibition of recombinase-activating (RAG) gene by anti-integrases is observed in vitro, in a variable way according to the molecules. Here, we show that in utero exposure to raltegravir did not alter the T-lymphocyte repertoire of 12 newborns. These reassuring data merit verification for other anti-integrases. ( ClinicalTrial.org NCT04024150).
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Affiliation(s)
- Jean Pierre de Villartay
- Imagine Institute, Laboratory "Genome Dynamics in the Immune System", INSERM UMR 11635, Paris, France.,Université Paris-Cité, Paris, France; and
| | - Emmanuelle Pannier
- Université Paris-Cité, Paris, France; and.,Assistance Publique-Hôpitaux de Paris (APHP), Paris and Colombes, France
| | - Jeanne Sibiude
- Université Paris-Cité, Paris, France; and.,Assistance Publique-Hôpitaux de Paris (APHP), Paris and Colombes, France
| | - Pierre Frange
- Université Paris-Cité, Paris, France; and.,Assistance Publique-Hôpitaux de Paris (APHP), Paris and Colombes, France
| | - Roland Tubiana
- Assistance Publique-Hôpitaux de Paris (APHP), Paris and Colombes, France
| | - Stéphane Blanche
- Université Paris-Cité, Paris, France; and.,Assistance Publique-Hôpitaux de Paris (APHP), Paris and Colombes, France
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2
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Structural insights into the evolution of the RAG recombinase. Nat Rev Immunol 2022; 22:353-370. [PMID: 34675378 DOI: 10.1038/s41577-021-00628-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/09/2021] [Indexed: 11/09/2022]
Abstract
Adaptive immunity in jawed vertebrates relies on the assembly of antigen receptor genes by the recombination activating gene 1 (RAG1)-RAG2 (collectively RAG) recombinase in a reaction known as V(D)J recombination. Extensive biochemical and structural evidence indicates that RAG and V(D)J recombination evolved from the components of a RAG-like (RAGL) transposable element through a process known as transposon molecular domestication. This Review describes recent advances in our understanding of the functional and structural transitions that occurred during RAG evolution. We use the structures of RAG and RAGL enzymes to trace the evolutionary adaptations that yielded a RAG recombinase with exquisitely regulated cleavage activity and a multilayered array of mechanisms to suppress transposition. We describe how changes in modes of DNA binding, alterations in the dynamics of protein-DNA complexes, single amino acid mutations and a modular design likely enabled RAG family enzymes to survive and spread in the genomes of eukaryotes. These advances highlight the insight that can be gained from viewing evolution of vertebrate immunity through the lens of comparative genome analyses coupled with structural biology and biochemistry.
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3
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Nilavar NM, Raghavan SC. HIV integrase inhibitors that inhibit strand transfer interact with RAG1 and hamper its activities. Int Immunopharmacol 2021; 95:107515. [PMID: 33735713 DOI: 10.1016/j.intimp.2021.107515] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/08/2021] [Accepted: 02/15/2021] [Indexed: 12/16/2022]
Abstract
Multiple steps of the retroviral infection process have been targeted over the years to develop therapeutic approaches, starting from the entry of the virus into the cell till the viral DNA integration to host genome. Inhibitors against the Human Immunodeficiency Virus (HIV) integrase is the newest among the therapies employed against HIV. Recombination activating gene 1 (RAG1) is an integral protein involved in the generation of diversity of antibodies and T-cell receptors and is one of the partners of the RAG complex. Studies have shown structural and functional similarities between the HIV integrase and RAG1. Recently, we and others have shown that some of the integrase inhibitors can interfere with RAG binding and cleavage, hindering its physiological functions. This mini review focuses on the HIV integrase, integrase inhibitors and their effect on RAG activities.
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Affiliation(s)
- Namrata M Nilavar
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India
| | - Sathees C Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore 560012, India.
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4
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Nilavar NM, Paranjape AM, Raghavan SC. Biochemical activity of RAGs is impeded by Dolutegravir, an HIV integrase inhibitor. Cell Death Discov 2020; 6:50. [PMID: 32566255 PMCID: PMC7293277 DOI: 10.1038/s41420-020-0281-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 03/26/2020] [Accepted: 04/22/2020] [Indexed: 02/03/2023] Open
Abstract
HIV is a retrovirus that infects CD4+ T lymphocytes in human beings and causes immunodeficiency. In the recent years, various therapies have been developed against HIV, including targeting the HIV specific protein, integrase, responsible for integration of HIV cDNA into host DNA. Although, integrase is specific to HIV, it has functional and structural similarity with RAG1, one of the partner proteins associated with V(D)J recombination, a process by which immune diversity is generated in humans. Currently, there are three HIV integrase inhibitors: Elvitegravir, Dolutegravir, and Raltegravir, in the market which have been approved by the FDA (USA). All three drugs are used in anti-retroviral therapy (ART). Previously, we showed that amongst the HIV inhibitors, Elvitegravir could significantly decrease B cell maturation in vivo and inhibit the physiological activities of RAGs in vitro, unlike Raltegravir. In the present study, we address the effect of second-generation integrase inhibitor, Dolutegravir on RAG activities. Binding and nicking studies showed that, Dolutegravir could decrease the binding efficiency of RAG1 domains and cleavage on DNA substrates, but not as considerably as Elvitegravir. Thus, we show that although the integrase inhibitors such as Elvitegravir show an affinity towards RAG1, the newer molecules may have lesser side-effects.
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Affiliation(s)
- Namrata M. Nilavar
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012 India
| | - Amita M. Paranjape
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012 India
| | - Sathees C. Raghavan
- Department of Biochemistry, Indian Institute of Science, Bangalore, 560012 India
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5
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Kesselring L, Miskey C, Zuliani C, Querques I, Kapitonov V, Laukó A, Fehér A, Palazzo A, Diem T, Lustig J, Sebe A, Wang Y, Dinnyés A, Izsvák Z, Barabas O, Ivics Z. A single amino acid switch converts the Sleeping Beauty transposase into an efficient unidirectional excisionase with utility in stem cell reprogramming. Nucleic Acids Res 2020; 48:316-331. [PMID: 31777924 PMCID: PMC6943129 DOI: 10.1093/nar/gkz1119] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 11/07/2019] [Accepted: 11/22/2019] [Indexed: 12/26/2022] Open
Abstract
The Sleeping Beauty (SB) transposon is an advanced tool for genetic engineering and a useful model to investigate cut-and-paste DNA transposition in vertebrate cells. Here, we identify novel SB transposase mutants that display efficient and canonical excision but practically unmeasurable genomic re-integration. Based on phylogenetic analyses, we establish compensating amino acid replacements that fully rescue the integration defect of these mutants, suggesting epistasis between these amino acid residues. We further show that the transposons excised by the exc+/int− transposase mutants form extrachromosomal circles that cannot undergo a further round of transposition, thereby representing dead-end products of the excision reaction. Finally, we demonstrate the utility of the exc+/int− transposase in cassette removal for the generation of reprogramming factor-free induced pluripotent stem cells. Lack of genomic integration and formation of transposon circles following excision is reminiscent of signal sequence removal during V(D)J recombination, and implies that cut-and-paste DNA transposition can be converted to a unidirectional process by a single amino acid change.
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Affiliation(s)
- Lisa Kesselring
- Transposition and Genome Engineering, Division of Medical Biotechnology, Paul Ehrlich Institute, Langen, Germany
| | - Csaba Miskey
- Transposition and Genome Engineering, Division of Medical Biotechnology, Paul Ehrlich Institute, Langen, Germany
| | - Cecilia Zuliani
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Irma Querques
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Vladimir Kapitonov
- Transposition and Genome Engineering, Division of Medical Biotechnology, Paul Ehrlich Institute, Langen, Germany
| | | | - Anita Fehér
- BioTalentum Ltd, Gödöllő, 2100 Gödöllő, Hungary
| | - Antonio Palazzo
- Department of Biology, University of Bari 'Aldo Moro', Italy
| | - Tanja Diem
- Transposition and Genome Engineering, Division of Medical Biotechnology, Paul Ehrlich Institute, Langen, Germany
| | - Janna Lustig
- Transposition and Genome Engineering, Division of Medical Biotechnology, Paul Ehrlich Institute, Langen, Germany
| | - Attila Sebe
- Transposition and Genome Engineering, Division of Medical Biotechnology, Paul Ehrlich Institute, Langen, Germany
| | - Yongming Wang
- Mobile DNA, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | | | - Zsuzsanna Izsvák
- Mobile DNA, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Orsolya Barabas
- Structural and Computational Biology Unit, European Molecular Biology Laboratory, Heidelberg 69117, Germany
| | - Zoltán Ivics
- Transposition and Genome Engineering, Division of Medical Biotechnology, Paul Ehrlich Institute, Langen, Germany
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6
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Lapp HE, Hunter RG. Early life exposures, neurodevelopmental disorders, and transposable elements. Neurobiol Stress 2019; 11:100174. [PMID: 31193573 PMCID: PMC6536887 DOI: 10.1016/j.ynstr.2019.100174] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 03/27/2019] [Accepted: 05/21/2019] [Indexed: 12/26/2022] Open
Abstract
Transposable elements make up a much larger portion of the genome than protein-coding genes, yet we know relatively little about their function in the human genome. However, we are beginning to more fully understand their role in brain development, neuroinflammation, and adaptation to environmental insults such as stress. For instance, glucocorticoid receptor activation regulates transposable elements in the brain following acute stress. Early life is a period of substantial brain development during which transposable elements play a role. Environmental exposures and experiences during early life that promote abnormal regulation of transposable elements may lead to a cascade of events that ultimately increase susceptibility to disorders later in life. Recent attention to transposable elements in psychiatric illness has begun to clarify associations indicative of dysregulation of different classes of transposable elements in stress-related and neurodevelopmental illness. Though individual susceptibility or resiliency to psychiatric illness has not been explained by traditional genetic studies, the wide inter-individual variability in transposable element composition in the human genome make TEs attractive candidates to elucidate this differential susceptibility. In this review, we discuss evidence that regulation of transposable elements in the brain are stage-specific, sensitive to environmental factors, and may be impacted by early life perturbations. We further present evidence of associations with stress-related and neurodevelopmental psychiatric illness from a developmental perspective.
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Affiliation(s)
- Hannah E Lapp
- University of Massachusetts Boston, 100 Morrissey Blvd Boston, MA, 02125, USA
| | - Richard G Hunter
- University of Massachusetts Boston, 100 Morrissey Blvd Boston, MA, 02125, USA
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7
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Abstract
Canonical DNA non-homologous end-joining (c-NHEJ) and homologous recombination (HR), the two major DNA double-strand break (DSB) repair pathways, have long been depicted as competitors, fighting a race to rejoin DSBs. In human cells, Ku, an upstream component of NHEJ, is highly abundant and has exquisite end-binding capacity. Emerging evidence has suggested that Ku is the first protein binding most, if not all, DSBs, and creates a block to resection. Although most c-NHEJ proceeds without resection, recent studies have provided strong evidence for a process of resection-dependent c-NHEJ, that repairs a subset of DSBs. HR also repairs a subset of two-ended DSBs in G2 phase and processes one-ended DSBs that arise following replication fork stalling or collapse to promote replication restart. HR also necessitates end-resection. This raises the question of how end-resection takes place despite Ku's avid end-binding capacity. Insight into this enigma has been gained from the analysis of DSBs generated by Spo11 or TOP2, which create protein-bridged DSBs. The progression of repair by HR or NHEJ requires removal of the end-blocking lesions. The MRE11-RAD50-NBS1 (MRN) complex, CtIP and EXO1 play critical roles in this process. Here, we review our current understanding of how resection arises at lesions blocked by covalently bound Spo11 or TOP2 or following Ku binding, which effectively creates a distinct resection-blocking lesion due to its avid end-binding activity and abundance. Our review reveals that Ku plays an active role in determining pathway choice and exposes similarities yet distinctions in the progression of resection that is suited to the optimal repair pathway choice.
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Affiliation(s)
- Atsushi Shibata
- Education and Research Support Center, Graduate School of Medicine, Gunma University, Maebashi, Japan
| | - Penny Jeggo
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton BN19 RQ, UK
| | - Markus Löbrich
- Radiation Biology and DNA Repair, Darmstadt University of Technology, 64287 Darmstadt, Germany.
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8
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Sniezewski L, Janik S, Laszkiewicz A, Majkowski M, Kisielow P, Cebrat M. The evolutionary conservation of the bidirectional activity of the NWC gene promoter in jawed vertebrates and the domestication of the RAG transposon. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2018; 81:105-115. [PMID: 29175053 DOI: 10.1016/j.dci.2017.11.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 11/21/2017] [Accepted: 11/21/2017] [Indexed: 06/07/2023]
Abstract
The RAG-1 and RAG-2 genes form a recombinase complex that is indispensable for V(D)J recombination, which generates the diversity of immunoglobulins and T-cell receptors. It is widely accepted that the presence of RAGs in the genomes of jawed vertebrates and other lineages is a result of the horizontal transfer of a mobile genetic element. While a substantial amount of evidence has been gathered that clarifies the nature of the RAG transposon, far less attention has been paid to the genomic site of its integration in various host organisms. In all genomes of the jawed vertebrates that have been studied to date, the RAG genes are located in close proximity to the NWC gene. We have previously shown that the promoter of the murine NWC genes exhibits a bidirectional activity, which may have facilitated the integration and survival of the RAG transposon in the host genome. In this study, we characterise the promoters of the NWC homologues that are present in the representatives of other jawed vertebrates (H. sapiens, X. tropicalis and D. rerio). We show that the features that are characteristic for promoters as the hosts of a successful transposon integration (in terms of the arrangement, bidirectional and constitutive activity and the involvement of the Zfp143 transcription factor in the promoter regulation) are evolutionarily conserved, which indicates that the presence of RAG genes in jawed vertebrates is a direct result of a successful transposon integration into the NWC locus.
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Affiliation(s)
- Lukasz Sniezewski
- Laboratory of Molecular and Cellular Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114 Wroclaw, Poland
| | - Sylwia Janik
- Laboratory of Molecular and Cellular Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114 Wroclaw, Poland
| | - Agnieszka Laszkiewicz
- Laboratory of Molecular and Cellular Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114 Wroclaw, Poland
| | - Michal Majkowski
- Laboratory of Molecular and Cellular Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114 Wroclaw, Poland
| | - Pawel Kisielow
- Laboratory of Molecular and Cellular Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114 Wroclaw, Poland; Laboratory of Tumor Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114 Wroclaw, Poland
| | - Malgorzata Cebrat
- Laboratory of Molecular and Cellular Immunology, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114 Wroclaw, Poland.
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9
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Khan FA, Ali SO. Physiological Roles of DNA Double-Strand Breaks. J Nucleic Acids 2017; 2017:6439169. [PMID: 29181194 PMCID: PMC5664317 DOI: 10.1155/2017/6439169] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2017] [Accepted: 09/24/2017] [Indexed: 12/20/2022] Open
Abstract
Genomic integrity is constantly threatened by sources of DNA damage, internal and external alike. Among the most cytotoxic lesions is the DNA double-strand break (DSB) which arises from the cleavage of both strands of the double helix. Cells boast a considerable set of defences to both prevent and repair these breaks and drugs which derail these processes represent an important category of anticancer therapeutics. And yet, bizarrely, cells deploy this very machinery for the intentional and calculated disruption of genomic integrity, harnessing potentially destructive DSBs in delicate genetic transactions. Under tight spatiotemporal regulation, DSBs serve as a tool for genetic modification, widely used across cellular biology to generate diverse functionalities, ranging from the fundamental upkeep of DNA replication, transcription, and the chromatin landscape to the diversification of immunity and the germline. Growing evidence points to a role of aberrant DSB physiology in human disease and an understanding of these processes may both inform the design of new therapeutic strategies and reduce off-target effects of existing drugs. Here, we review the wide-ranging roles of physiological DSBs and the emerging network of their multilateral regulation to consider how the cell is able to harness DNA breaks as a critical biochemical tool.
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Affiliation(s)
- Farhaan A. Khan
- School of Clinical Medicine, Addenbrooke's Hospital, University of Cambridge, Hills Road, Cambridge CB2 0SP, UK
| | - Syed O. Ali
- School of Clinical Medicine, Addenbrooke's Hospital, University of Cambridge, Hills Road, Cambridge CB2 0SP, UK
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10
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Carmona LM, Schatz DG. New insights into the evolutionary origins of the recombination-activating gene proteins and V(D)J recombination. FEBS J 2017; 284:1590-1605. [PMID: 27973733 PMCID: PMC5459667 DOI: 10.1111/febs.13990] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 11/10/2016] [Accepted: 12/08/2016] [Indexed: 12/26/2022]
Abstract
The adaptive immune system of jawed vertebrates relies on V(D)J recombination as one of the main processes to generate the diverse array of receptors necessary for the recognition of a wide range of pathogens. The DNA cleavage reaction necessary for the assembly of the antigen receptor genes from an array of potential gene segments is mediated by the recombination-activating gene proteins RAG1 and RAG2. The RAG proteins have been proposed to originate from a transposable element (TE) as they share mechanistic and structural similarities with several families of transposases and are themselves capable of mediating transposition. A number of RAG-like proteins and TEs with sequence similarity to RAG1 and RAG2 have been identified, but only recently has their function begun to be characterized, revealing mechanistic links to the vertebrate RAGs. Of particular significance is the discovery of ProtoRAG, a transposon superfamily found in the genome of the basal chordate amphioxus. ProtoRAG has many of the sequence and mechanistic features predicted for the ancestral RAG transposon and is likely to be an evolutionary relative of RAG1 and RAG2. In addition, early observations suggesting that RAG1 is able to mediate V(D)J recombination in the absence of RAG2 have been confirmed, implying independent evolutionary origins for the two RAG genes. Here, recent progress in identifying and characterizing RAG-like proteins and the TEs that encode them is summarized and a refined model for the evolution of V(D)J recombination and the RAG proteins is presented.
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Affiliation(s)
- Lina Marcela Carmona
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA
| | - David G Schatz
- Department of Immunobiology, Yale University School of Medicine, New Haven, CT, USA.,Howard Hughes Medical Institute, New Haven, CT, USA
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11
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Abstract
Despite often being classified as selfish or junk DNA, transposable elements (TEs) are a group of abundant genetic sequences that have a significant impact on mammalian development and genome regulation. In recent years, our understanding of how pre-existing TEs affect genome architecture, gene regulatory networks and protein function during mammalian embryogenesis has dramatically expanded. In addition, the mobilization of active TEs in selected cell types has been shown to generate genetic variation during development and in fully differentiated tissues. Importantly, the ongoing domestication and evolution of TEs appears to provide a rich source of regulatory elements, functional modules and genetic variation that fuels the evolution of mammalian developmental processes. Here, we review the functional impact that TEs exert on mammalian developmental processes and discuss how the somatic activity of TEs can influence gene regulatory networks.
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Affiliation(s)
- Jose L Garcia-Perez
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
- Department of Genomic Medicine, GENYO, Centre for Genomics & Oncology (Pfizer - University of Granada & Andalusian Regional Government), PTS Granada, Avda. de la Ilustración 114, Granada 18016, Spain
| | - Thomas J Widmann
- Department of Genomic Medicine, GENYO, Centre for Genomics & Oncology (Pfizer - University of Granada & Andalusian Regional Government), PTS Granada, Avda. de la Ilustración 114, Granada 18016, Spain
| | - Ian R Adams
- Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
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12
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Ohta Y, Flajnik MF. Coevolution of MHC genes (LMP/TAP/class Ia, NKT-class Ib, NKp30-B7H6): lessons from cold-blooded vertebrates. Immunol Rev 2016; 267:6-15. [PMID: 26284468 DOI: 10.1111/imr.12324] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Comparative immunology provides the long view of what is conserved across all vertebrate taxa versus what is specific to particular organisms or group of organisms. Regarding the major histocompatibility complex (MHC) and coevolution, three striking cases have been revealed in cold-blooded vertebrates: lineages of class Ia antigen-processing and -presenting genes, evolutionary conservation of NKT-class Ib recognition, and the ancient emergence of the natural cytotoxicity receptor NKp30 and its ligand B7H6. While coevolution of transporter associated with antigen processing (TAP) and class Ia has been documented in endothermic birds and two mammals, lineages of LMP7 are restricted to ectotherms. The unambiguous discovery of natural killer T (NKT) cells in Xenopus demonstrated that NKT cells are not restricted to mammals and are likely to have emerged at the same time in evolution as classical α/β and γ/δ T cells. NK cell receptors evolve at a rapid rate, and orthologues are nearly impossible to identify in different vertebrate classes. By contrast, we have detected NKp30 in all gnathostomes, except in species where it was lost. The recently discovered ligand of NKp30, B7H6, shows strong signs of coevolution with NKp30 throughout evolution, i.e. coincident loss or expansion of both genes in some species. NKp30 also offers an attractive IgSF candidate for the invasion of the RAG transposon, which is believed to have initiated T-cell receptor/immunoglobulin adaptive immunity. Besides reviewing these intriguing features of MHC evolution and coevolution, we offer suggestions for future studies and propose a model for the primordial or proto MHC.
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Affiliation(s)
- Yuko Ohta
- Department of Microbiology and Immunology, University of Maryland Baltimore School of Medicine, Baltimore, MD, USA
| | - Martin F Flajnik
- Department of Microbiology and Immunology, University of Maryland Baltimore School of Medicine, Baltimore, MD, USA
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13
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Abstract
Sleeping Beauty (SB) is a synthetic transposon that was constructed based on sequences of transpositionally inactive elements isolated from fish genomes. SB is a Tc1/mariner superfamily transposon following a cut-and-paste transpositional reaction, during which the element-encoded transposase interacts with its binding sites in the terminal inverted repeats of the transposon, promotes the assembly of a synaptic complex, catalyzes excision of the element out of its donor site, and integrates the excised transposon into a new location in target DNA. SB transposition is dependent on cellular host factors. Transcriptional control of transposase expression is regulated by the HMG2L1 transcription factor. Synaptic complex assembly is promoted by the HMGB1 protein and regulated by chromatin structure. SB transposition is highly dependent on the nonhomologous end joining (NHEJ) pathway of double-strand DNA break repair that generates a transposon footprint at the excision site. Through its association with the Miz-1 transcription factor, the SB transposase downregulates cyclin D1 expression that results in a slowdown of the cell-cycle in the G1 phase, where NHEJ is preferentially active. Transposon integration occurs at TA dinucleotides in the target DNA, which are duplicated at the flanks of the integrated transposon. SB shows a random genome-wide insertion profile in mammalian cells when launched from episomal vectors and "local hopping" when launched from chromosomal donor sites. Some of the excised transposons undergo a self-destructive autointegration reaction, which can partially explain why longer elements transpose less efficiently. SB became an important molecular tool for transgenesis, insertional mutagenesis, and gene therapy.
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14
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Abstract
V(D)J recombination, the mechanism responsible for generating antigen receptor diversity, has the potential to generate aberrant DNA rearrangements in developing lymphocytes. Indeed, the recombinase has been implicated in several different kinds of errors leading to oncogenic transformation. Here we review the basic aspects of V(D)J recombination, mechanisms underlying aberrant DNA rearrangements, and the types of aberrant events uncovered in recent genomewide analyses of lymphoid neoplasms.
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15
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Han YW, Sugiyama H, Harada Y. The application of fluorescence-conjugated pyrrole/imidazole polyamides in the characterization of protein–DNA complex formation. Biomater Sci 2016; 4:391-9. [DOI: 10.1039/c5bm00214a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Fluorescent conjugates of Py–Im polyamides are used as sequence-specific fluorescent probes and applied to the characterisation of protein–DNA complex dynamics.
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Affiliation(s)
- Yong-Woon Han
- Institute for Integrated Cell-Materials Science (WPI-iCeMS)
- Kyoto University
- Kyoto 606-8501
- Japan
| | - Hiroshi Sugiyama
- Institute for Integrated Cell-Materials Science (WPI-iCeMS)
- Kyoto University
- Kyoto 606-8501
- Japan
- Department of Chemistry
| | - Yoshie Harada
- Institute for Integrated Cell-Materials Science (WPI-iCeMS)
- Kyoto University
- Kyoto 606-8501
- Japan
- Graduate School of Biostudies
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16
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Engelman A, Cherepanov P. Retroviral Integrase Structure and DNA Recombination Mechanism. Microbiol Spectr 2015; 2:1-22. [PMID: 25705574 PMCID: PMC4334468 DOI: 10.1128/microbiolspec.mdna3-0024-2014] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Indexed: 12/13/2022] Open
Abstract
Due to the importance of human immunodeficiency virus type 1 (HIV-1) integrase as a drug target, the biochemistry and structural aspects of retroviral DNA integration have been the focus of intensive research during the past three decades. The retroviral integrase enzyme acts on the linear double-stranded viral DNA product of reverse transcription. Integrase cleaves specific phosphodiester bonds near the viral DNA ends during the 3' processing reaction. The enzyme then uses the resulting viral DNA 3'-OH groups during strand transfer to cut chromosomal target DNA, which simultaneously joins both viral DNA ends to target DNA 5'-phosphates. Both reactions proceed via direct transesterification of scissile phosphodiester bonds by attacking nucleophiles: a water molecule for 3' processing, and the viral DNA 3'-OH for strand transfer. X-ray crystal structures of prototype foamy virus integrase-DNA complexes revealed the architectures of the key nucleoprotein complexes that form sequentially during the integration process and explained the roles of active site metal ions in catalysis. X-ray crystallography furthermore elucidated the mechanism of action of HIV-1 integrase strand transfer inhibitors, which are currently used to treat AIDS patients, and provided valuable insights into the mechanisms of viral drug resistance.
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Affiliation(s)
- Alan Engelman
- Department of Cancer Immunology and AIDS, Dana-Farber Cancer Institute, 450 Brookline, Avenue, CLS-1010, Boston, MA 02215
| | - Peter Cherepanov
- Cancer Research UK London Research Institute, Clare Hall Laboratories, Blanche Lane, Potters Bar, EN6 3LD, United Kingdom
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Illegitimate V(D)J recombination-mediated deletions in Notch1 and Bcl11b are not sufficient for extensive clonal expansion and show minimal age or sex bias in frequency or junctional processing. Mutat Res 2014; 761:34-48. [PMID: 24530429 DOI: 10.1016/j.mrfmmm.2014.01.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Revised: 12/23/2013] [Accepted: 01/28/2014] [Indexed: 01/22/2023]
Abstract
Illegitimate V(D)J recombination at oncogenes and tumor suppressor genes is implicated in formation of several T cell malignancies. Notch1 and Bcl11b, genes involved in developing T cell specification, selection, proliferation, and survival, were previously shown to contain hotspots for deletional illegitimate V(D)J recombination associated with radiation-induced thymic lymphoma. Interestingly, these deletions were also observed in wild-type animals. In this study, we conducted frequency, clonality, and junctional processing analyses of Notch1 and Bcl11b deletions during mouse development and compared results to published analyses of authentic V(D)J rearrangements at the T cell receptor beta (TCRβ) locus and illegitimate V(D)J deletions observed at the human, nonimmune HPRT1 locus not involved in T cell malignancies. We detect deletions in Notch1 and Bcl11b in thymic and splenic T cell populations, consistent with cells bearing deletions in the circulating lymphocyte pool. Deletions in thymus can occur in utero, increase in frequency between fetal and postnatal stages, are detected at all ages examined between fetal and 7 months, exhibit only limited clonality (contrasting with previous results in radiation-sensitive mouse strains), and consistent with previous reports are more frequent in Bcl11b, partially explained by relatively high Recombination Signal Information Content (RIC) scores. Deletion junctions in Bcl11b exhibit greater germline nucleotide loss, while in Notch1 palindromic (P) nucleotides are more abundant, although average P nucleotide length is similar for both genes and consistent with results at the TCRβ locus. Non-templated (N) nucleotide insertions appear to increase between fetal and postnatal stages for Notch1, consistent with normal terminal deoxynucleotidyl transferase (TdT) activity; however, neonatal Bcl11b junctions contain elevated levels of N insertions. Finally, contrasting with results at the HPRT1 locus, we find no obvious age or gender bias in junctional processing, and inverted repeats at recessed coding ends (Pr nucleotides) correspond mostly to single-base additions consistent with normal TdT activity.
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18
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Han YW, Tsunaka Y, Yokota H, Matsumoto T, Kashiwazaki G, Morinaga H, Hashiya K, Bando T, Sugiyama H, Harada Y. Construction and characterization of Cy3- or Cy5-conjugated hairpin pyrrole–imidazole polyamides binding to DNA in the nucleosome. Biomater Sci 2014; 2:297-307. [DOI: 10.1039/c3bm60202h] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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19
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Little AJ, Corbett E, Ortega F, Schatz DG. Cooperative recruitment of HMGB1 during V(D)J recombination through interactions with RAG1 and DNA. Nucleic Acids Res 2013; 41:3289-301. [PMID: 23325855 PMCID: PMC3597659 DOI: 10.1093/nar/gks1461] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
During V(D)J recombination, recombination activating gene (RAG)1 and RAG2 bind and cleave recombination signal sequences (RSSs), aided by the ubiquitous DNA-binding/-bending proteins high-mobility group box protein (HMGB)1 or HMGB2. HMGB1/2 play a critical, although poorly understood, role in vitro in the assembly of functional RAG–RSS complexes, into which HMGB1/2 stably incorporate. The mechanism of HMGB1/2 recruitment is unknown, although an interaction with RAG1 has been suggested. Here, we report data demonstrating only a weak HMGB1–RAG1 interaction in the absence of DNA in several assays, including fluorescence anisotropy experiments using a novel Alexa488-labeled HMGB1 protein. Addition of DNA to RAG1 and HMGB1 in fluorescence anisotropy experiments, however, results in a substantial increase in complex formation, indicating a synergistic binding effect. Pulldown experiments confirmed these results, as HMGB1 was recruited to a RAG1–DNA complex in a RAG1 concentration-dependent manner and, interestingly, without strict RSS sequence specificity. Our finding that HMGB1 binds more tightly to a RAG1–DNA complex over RAG1 or DNA alone provides an explanation for the stable integration of this typically transient architectural protein in the V(D)J recombinase complex throughout recombination. These findings also have implications for the order of events during RAG–DNA complex assembly and for the stabilization of sequence-specific and non-specific RAG1–DNA interactions.
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Affiliation(s)
- Alicia J Little
- Department of Immunobiology, Yale University School of Medicine, 300 Cedar Street, New Haven, CT 06511, USA
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20
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Transposable elements and human cancer: a causal relationship? Biochim Biophys Acta Rev Cancer 2012; 1835:28-35. [PMID: 22982062 DOI: 10.1016/j.bbcan.2012.09.001] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 08/30/2012] [Accepted: 09/04/2012] [Indexed: 12/18/2022]
Abstract
Transposable elements are present in almost all genomes including that of humans. These mobile DNA sequences are capable of invading genomes and their impact on genome evolution is substantial as they contribute to the genetic diversity of organisms. The mobility of transposable elements can cause deleterious mutations, gene disruption and chromosome rearrangements that may lead to several pathologies including cancer. This mini-review aims to give a brief overview of the relationship that transposons and retrotransposons may have in the genetic cause of human cancer onset, or conversely creating protection against cancer. Finally, the cause of TE mobility may also be the cancer cell environment itself.
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21
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Abstract
Retroviral infections cause a variety of cancers in animals and a number of diverse diseases in humans such as leukemia and acquired immune deficiency syndrome. Productive and efficient proviral integration is critical for retroviral function and is the key step in establishing a stable and productive infection, as well as the mechanism by which host genes are activated in leukemogenesis. Host factors are widely anticipated to be involved in all stages of the retroviral life cycle, and the identification of integrase interacting factors has the potential to increase our understanding of mechanisms by which the incoming virus might appropriate cellular proteins to target and capture host DNA sequences. Identification of MoMLV integrase interacting host factors may be key to designing efficient and benign retroviral-based gene therapy vectors; key to understanding the basic mechanism of integration; and key in designing efficient integrase inhibitors. In this review, we discuss current progress in the field of MoMLV integrase interacting proteins and possible roles for these proteins in integration.
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22
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Rhodes M, Laffan S, Genell C, Gower J, Maier C, Fukushima T, Nichols G, Bassiri AE. Assessing a Theoretical Risk of Dolutegravir-Induced Developmental Immunotoxicity in Juvenile Rats. Toxicol Sci 2012; 130:70-81. [DOI: 10.1093/toxsci/kfs220] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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23
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Danilova N. The evolution of adaptive immunity. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 738:218-35. [PMID: 22399382 DOI: 10.1007/978-1-4614-1680-7_13] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The concept of adaptive immunity suggests de novo generation in each individual of extremely large repertoires of diversified receptors and selective expansion of receptors that match the antigen/pathogen. Accordingly, adaptive immune system is also called "anticipatory". It allows each individual to have a unique repertoire of immune receptors corresponding to its life history. The memory of an antigen gets encoded in the clonal composition of the organism's immune cells instead of being encoded in the genome. Consequently, the immune response to repeated encounter with the same antigen becomes stronger, a phenomenon called immunological memory. Elements of adaptive immunity are found at all taxonomical levels, whereas in vertebrates, adaptive mechanisms have become the cornerstone of the immune system. In jaw vertebrates, adaptive immune receptors of T and B lymphoid cells belong to immunoglobulin superfamily and are created by rearrangement of gene segments. In jawless vertebrates lamprey and hagfish, recombination of leucine-rich repeat modules is used to form variable lymphocyte receptors. Striking functional similarity of the cellular and humoral branches of these systems suggests similar driving forces underlying their development.
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Affiliation(s)
- Nadia Danilova
- Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, CA,USA.
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24
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Goethals O, Van Ginderen M, Vos A, Cummings MD, Van Der Borght K, Van Wesenbeeck L, Feyaerts M, Verheyen A, Smits V, Van Loock M, Hertogs K, Schols D, Clayton RF. Resistance to raltegravir highlights integrase mutations at codon 148 in conferring cross-resistance to a second-generation HIV-1 integrase inhibitor. Antiviral Res 2011; 91:167-76. [PMID: 21669228 DOI: 10.1016/j.antiviral.2011.05.011] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2011] [Revised: 05/25/2011] [Accepted: 05/26/2011] [Indexed: 01/26/2023]
Abstract
Raltegravir is the first integrase strand-transfer inhibitor (INSTI) approved for use in highly active antiretroviral therapy (HAART) for the management of HIV infection. Resistance to antiretrovirals can compromise the efficacy of HAART regimens. Therefore it is important to understand the emergence of resistance to RAL and cross-resistance to other INSTIs including potential second-generation INSTIs such as MK-2048. We have now studied the question of whether in vitro resistance selection (IVRS) with RAL initiated with viruses derived from clinical isolates would result in selection of resistance mutations consistent with those arising during treatment regimens with HAART containing RAL. Some correlation was observed between the primary mutations selected in vitro and during therapy, initiated with viruses with identical IN sequences. Additionally, phenotypic cross-resistance conferred by specific mutations to RAL and MK-2048 was quantified. N155H, a RAL-associated primary resistance mutation, was selected after IVRS with MK-2048, suggesting similar mechanisms of resistance to RAL and MK-2048. This was confirmed by phenotypic analysis of 766 clonal viruses harboring IN sequences isolated at the point of virological failure from 106 patients on HAART (including RAL), where mutation Q148H/K/R together with additional secondary mutations conferred reduced susceptibility to both RAL and MK-2048. A homology model of full length HIV-1 integrase complexed with viral DNA and RAL or MK-2048, based on an X-ray structure of the prototype foamy virus integrase-DNA complex, was used to explain resistance to RAL and cross-resistance to MK-2048. These findings will be important for the further discovery and profiling of next-generation INSTIs.
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Affiliation(s)
- Olivia Goethals
- Tibotec Virco Virology BVBA, Turnhoutseweg 30, 2340 Beerse, Belgium
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25
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Abstract
The repair of DNA double strand breaks (dsb) is important for maintaining the physical and genetic integrity of the genome. Moreover, in humans it is associated with the prevention of diseases such as immune deficiencies and cancer. This review briefly explores the fundamental strategies for repairing dsb, examines how cells maximize the fidelity of dsb repair in the cell cycle and discusses the requirements for dsb repair in the context of chromatin.
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Affiliation(s)
- Kevin Hiom
- Biomedical Research Institute & Dundee Cancer Centre, Ninewells Hospital & Medical School, Dundee DD1 9SY, Scotland, UK.
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26
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Abstract
Nucleases cleave the phosphodiester bonds of nucleic acids and may be endo or exo, DNase or RNase, topoisomerases, recombinases, ribozymes, or RNA splicing enzymes. In this review, I survey nuclease activities with known structures and catalytic machinery and classify them by reaction mechanism and metal-ion dependence and by their biological function ranging from DNA replication, recombination, repair, RNA maturation, processing, interference, to defense, nutrient regeneration or cell death. Several general principles emerge from this analysis. There is little correlation between catalytic mechanism and biological function. A single catalytic mechanism can be adapted in a variety of reactions and biological pathways. Conversely, a single biological process can often be accomplished by multiple tertiary and quaternary folds and by more than one catalytic mechanism. Two-metal-ion-dependent nucleases comprise the largest number of different tertiary folds and mediate the most diverse set of biological functions. Metal-ion-dependent cleavage is exclusively associated with exonucleases producing mononucleotides and endonucleases that cleave double- or single-stranded substrates in helical and base-stacked conformations. All metal-ion-independent RNases generate 2',3'-cyclic phosphate products, and all metal-ion-independent DNases form phospho-protein intermediates. I also find several previously unnoted relationships between different nucleases and shared catalytic configurations.
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27
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Ramsden DA, Weed BD, Reddy YVR. V(D)J recombination: Born to be wild. Semin Cancer Biol 2010; 20:254-60. [PMID: 20600921 PMCID: PMC2942997 DOI: 10.1016/j.semcancer.2010.06.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 06/08/2010] [Accepted: 06/24/2010] [Indexed: 11/22/2022]
Abstract
Vertebrates employ V(D)J recombination to generate diversity for an adaptive immune response. Born of a transposon, V(D)J recombination could conceivably cause more trouble than its worth. However, of the two steps required for transposon mobility (excision and integration) this particular transposon's integration step appears mostly blocked in cells. The employment of a transposon as raw material to develop adaptive immunity was thus a less-risky choice than it might have been … but is it completely risk-free?
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Affiliation(s)
- Dale A Ramsden
- Lineberger Comprehensive Cancer Center, Department of Biochemistry and Biophysics and Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, United States.
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28
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Hickman AB, Chandler M, Dyda F. Integrating prokaryotes and eukaryotes: DNA transposases in light of structure. Crit Rev Biochem Mol Biol 2010; 45:50-69. [PMID: 20067338 DOI: 10.3109/10409230903505596] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
DNA rearrangements are important in genome function and evolution. Genetic material can be rearranged inadvertently during processes such as DNA repair, or can be moved in a controlled manner by enzymes specifically dedicated to the task. DNA transposases comprise one class of such enzymes. These move DNA segments known as transposons to new locations, without the need for sequence homology between transposon and target site. Several biochemically distinct pathways have evolved for DNA transposition, and genetic and biochemical studies have provided valuable insights into many of these. However, structural information on transposases - particularly with DNA substrates - has proven elusive in most cases. On the other hand, large-scale genome sequencing projects have led to an explosion in the number of annotated prokaryotic and eukaryotic mobile elements. Here, we briefly review biochemical and mechanistic aspects of DNA transposition, and propose that integrating sequence information with structural information using bioinformatics tools such as secondary structure prediction and protein threading can lead not only to an additional level of understanding but possibly also to testable hypotheses regarding transposition mechanisms. Detailed understanding of transposition pathways is a prerequisite for the long-term goal of exploiting DNA transposons as genetic tools and as a basis for genetic medical applications.
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Affiliation(s)
- Alison Burgess Hickman
- Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, NIH, Bethesda, MD 20892, USA.
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29
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Muñoz-López M, García-Pérez JL. DNA transposons: nature and applications in genomics. Curr Genomics 2010; 11:115-28. [PMID: 20885819 PMCID: PMC2874221 DOI: 10.2174/138920210790886871] [Citation(s) in RCA: 257] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2009] [Revised: 11/18/2009] [Accepted: 12/01/2009] [Indexed: 12/19/2022] Open
Abstract
Repeated DNA makes up a large fraction of a typical mammalian genome, and some repetitive elements are able to move within the genome (transposons and retrotransposons). DNA transposons move from one genomic location to another by a cut-and-paste mechanism. They are powerful forces of genetic change and have played a significant role in the evolution of many genomes. As genetic tools, DNA transposons can be used to introduce a piece of foreign DNA into a genome. Indeed, they have been used for transgenesis and insertional mutagenesis in different organisms, since these elements are not generally dependent on host factors to mediate their mobility. Thus, DNA transposons are useful tools to analyze the regulatory genome, study embryonic development, identify genes and pathways implicated in disease or pathogenesis of pathogens, and even contribute to gene therapy. In this review, we will describe the nature of these elements and discuss recent advances in this field of research, as well as our evolving knowledge of the DNA transposons most widely used in these studies.
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Affiliation(s)
- Martín Muñoz-López
- Andalusian Stem Cell Bank, Center for Biomedical Research, University of Granada, Avda. del Conocimiento s/n, Armilla, 18100, Granada, Spain
| | - José L. García-Pérez
- Andalusian Stem Cell Bank, Center for Biomedical Research, University of Granada, Avda. del Conocimiento s/n, Armilla, 18100, Granada, Spain
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30
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Kasahara M. Genome duplication and T cell immunity. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2010; 92:7-36. [PMID: 20800811 DOI: 10.1016/s1877-1173(10)92002-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The adaptive immune system (AIS) mediated by T cells and B cells arose ~450 million years ago in a common ancestor of jawed vertebrates. This system was so successful that, once established, it has been maintained in all classes of jawed vertebrates with only minor modifications. One event thought to have contributed to the emergence of this form of AIS is two rounds of whole-genome duplication. This event enabled jawed vertebrate ancestors to acquire many paralogous genes, known as ohnologs, with essential roles in T cell and B cell immunity. Ohnologs encode the key components of the antigen presentation machinery and signal transduction pathway for lymphocyte activation as well as numerous transcription factors important for lymphocyte development. Recently, it has been discovered that jawless vertebrates have developed an AIS employing antigen receptors unrelated to T/B cell receptors, but with marked overall similarities to the AIS of jawed vertebrates. Emerging evidence suggests that a common ancestor of all vertebrates was equipped with T-lymphoid and B-lymphoid lineages.
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Affiliation(s)
- Masanori Kasahara
- Department of Pathology, Hokkaido, University Graduate School of Medicine, Sapporo, Japan
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Paleo-immunology: evidence consistent with insertion of a primordial herpes virus-like element in the origins of acquired immunity. PLoS One 2009; 4:e5778. [PMID: 19492059 PMCID: PMC2686171 DOI: 10.1371/journal.pone.0005778] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2008] [Accepted: 04/22/2009] [Indexed: 11/29/2022] Open
Abstract
Background The RAG encoded proteins, RAG-1 and RAG-2 regulate site-specific recombination events in somatic immune B- and T-lymphocytes to generate the acquired immune repertoire. Catalytic activities of the RAG proteins are related to the recombinase functions of a pre-existing mobile DNA element in the DDE recombinase/RNAse H family, sometimes termed the “RAG transposon”. Methodology/Principal Findings Novel to this work is the suggestion that the DDE recombinase responsible for the origins of acquired immunity was encoded by a primordial herpes virus, rather than a “RAG transposon.” A subsequent “arms race” between immunity to herpes infection and the immune system obscured primary amino acid similarities between herpes and immune system proteins but preserved regulatory, structural and functional similarities between the respective recombinase proteins. In support of this hypothesis, evidence is reviewed from previous published data that a modern herpes virus protein family with properties of a viral recombinase is co-regulated with both RAG-1 and RAG-2 by closely linked cis-acting co-regulatory sequences. Structural and functional similarity is also reviewed between the putative herpes recombinase and both DDE site of the RAG-1 protein and another DDE/RNAse H family nuclease, the Argonaute protein component of RISC (RNA induced silencing complex). Conclusions/Significance A “co-regulatory” model of the origins of V(D)J recombination and the acquired immune system can account for the observed linked genomic structure of RAG-1 and RAG-2 in non-vertebrate organisms such as the sea urchin that lack an acquired immune system and V(D)J recombination. Initially the regulated expression of a viral recombinase in immune cells may have been positively selected by its ability to stimulate innate immunity to herpes virus infection rather than V(D)J recombination Unlike the “RAG-transposon” hypothesis, the proposed model can be readily tested by comparative functional analysis of herpes virus replication and V(D)J recombination.
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Yin FF, Bailey S, Innis CA, Ciubotaru M, Kamtekar S, Steitz TA, Schatz DG. Structure of the RAG1 nonamer binding domain with DNA reveals a dimer that mediates DNA synapsis. Nat Struct Mol Biol 2009; 16:499-508. [PMID: 19396172 PMCID: PMC2715281 DOI: 10.1038/nsmb.1593] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Accepted: 03/20/2009] [Indexed: 12/23/2022]
Abstract
The products of recombination-activating genes RAG1 and RAG2 mediate the assembly of antigen receptor genes during lymphocyte development in a process known as V(D)J recombination. Lack of structural information for the RAG proteins has hindered mechanistic studies of this reaction. We report here the crystal structure of an essential DNA binding domain of the RAG1 catalytic core bound to its nonamer DNA recognition motif. The RAG1 nonamer binding domain (NBD) forms a tightly interwoven dimer that binds and synapses two nonamer elements, with each NBD making contact with both DNA molecules. Biochemical and biophysical experiments confirm that the two nonamers are in close proximity in the RAG1/2-DNA synaptic complex and demonstrate the functional importance of the protein-DNA contacts revealed in the structure. These findings reveal a previously unsuspected function for the NBD in DNA synapsis and have implications for the regulation of DNA binding and cleavage by RAG1 and RAG2.
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Affiliation(s)
- Fang Fang Yin
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
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Abstract
This chapter defines the agents that provide for the movement of genetic material which fuels the adaptive potential of life on our planet. The chapter has been structured to be broadly comprehensive, arbitrarily categorizing the mobilome into four classes: (1) transposons, (2) plasmids, (3) bacteriophage, and (4) self-splicing molecular parasites.Our increasing understanding of the mobilome is as dynamic as the mobilome itself. With continuing discovery, it is clear that nature has not confined these genomic agents of change to neat categories, but rather the classification categories overlap and intertwine. Massive sequencing efforts and their published analyses are continuing to refine our understanding of the extent of the mobilome. This chapter provides a framework to describe our current understanding of the mobilome and a foundation on which appreciation of its impact on genome evolution can be understood.
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Matthews AGW, Oettinger MA. Regulation of RAG transposition. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2009; 650:16-31. [PMID: 19731798 DOI: 10.1007/978-1-4419-0296-2_2] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
V(D)J recombination is initiated by the lymphoid specific proteins RAG1 and RAG2, which together constitute the V(D)J recombinase. However, the RAG 1/2 complex can also act as a transposase, inserting the broken DNA molecules generated during V(D)J recombination into an unrelated piece of DNA. This process, termed RAG transposition, can potentially cause insertional mutagenesis, chromosomal translocations and genomic instability. This review focuses on the mechanism and regulation of RAG transposition. We first provide a brief overview of the biochemistry of V(D)J recombination. We then discuss the discovery of RAG transposition and present an overview of the RAG transposition pathway. Using this pathway as a framework, we discuss the factors and forces that regulate RAG transposition.
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Affiliation(s)
- Adam G W Matthews
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA.
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35
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Abstract
The adaptive immune system of jawed vertebrates is based on a vast, anticipatory repertoire of specific antigen receptors, immunoglobulins (Ig) in B-lymphocytes and T-cell receptors (TCR) in T-lymphocytes. The Ig and TCRdiversity is generated by a process called V(D)J recombination, which is initiated by the RAG recombinase. Although RAG activity is very well conserved, the regulated accessibility of the antigen receptor genes to RAG has evolved with the species' organizational structure, which differs most significantly between fishes and tetrapods. V(D)J recombination was primarily characterized in developing lymphocytes of mice and human beings and is often described as an ordered, two-stage program. Studies in rabbit, chicken and shark show that this process does not have to be ordered, nor does it need to take place in two stages to generate a diverse repertoire and enable the expression of a single species of antigen receptor per cell, a restriction called allelic exclusion.
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36
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Sinkovics JG. "Up-dating the monograph." [corrected] Cytolytic immune lymphocytes in the armamentarium of the human host. Acta Microbiol Immunol Hung 2008; 55:371-82. [PMID: 19130745 DOI: 10.1556/amicr.55.2008.4.2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The author of the monograph "Cytolytic Immune Lymphocytes..." (published in 2008 by Schenk Buchverlag Campus Dialog, Budapest, Passau, Pécs) proposed several research projects and described certain clinical events that require further elaboration and documentation. In this article the author provides what is required and has since become available. The first subject matter in question concerns the fusogenic viruses. The ancient fusogenic viruses might have created the first eukaryotic cell(s) by uniting archaeabacterial and prokaryotic/protobacterial protospheroplasts. Extant fusogenic viruses either produce tumor cell syncytia and lyse them, thus practicing viral oncolysis. Or, create chimaeric fusion products, the so-called "natural hybridomas", of lymphoma cells exhibiting transmembrane budding of retrovirus particles or envelope proteins, and anti-viral specific antibody-producing plasma cells. The second topic concerns the horizontal-lateral mode of acquisition of those genes, which were "present in the waiting" in the amphioxus, sea urchin, and the agnathans, and met in the primitive gnatostomata sharks to encode in unison the entire adaptive immune system. The consensus of opinion is such that these genes derived from newly acquired transposons/retrotransposons. The author points out that the extant Epstein-Barr virus harbors genes displaying sequence homology with those genes from the sharks up to mammals that regulate the somatic hypermutation of specific antibody production. The author proposes that an ancient herpesvirus might have propagated the V(D)J and RAG genes from sea urchins to sharks. The third area is that of lymphocytes cytotoxic/cytolytic to virally infected or malignantly transformed host cells. This discovery led to the adoptive immune lymphocyte therapy of tumors. Installed in the adaptive immune system are regulatory T cells and myeloid-derived suppressor cells for he protection of "self". Tumor cells masquerading as "self" are protected by these cells from attacks launched by immune T cells. The author supports the replacement of IL-2 by IL-15, inasmuch as IL-2 stimulates not only immune T cells, but also regulatory T cells expressing the CD25 IL-2 receptor. The administration of low dose whole body radiotherapy prior to immune lymphocyte therapy increases the efficacy of immune lymphocyte therapy. The author observed this phenomenon in the mid-1960s. The explanation of this phenomenon revealed itself just recently. In pre-irradiated hosts the intestinal wall becomes permeable to the gut flora; the intestinal bacteria activate the entire innate immune system in the mesenteric lymph nodes and a rapid activation of the adaptive immune faculties follows.
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Affiliation(s)
- J G Sinkovics
- Department of Medical Microbiology/Immunology, St. Joseph's Hospital Cancer Institute Affiliated with the H. L. Moffitt Comprehensive Cancer Center, University of South Florida College of Medicine, Tampa, FL, USA.
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Resistance mutations in human immunodeficiency virus type 1 integrase selected with elvitegravir confer reduced susceptibility to a wide range of integrase inhibitors. J Virol 2008; 82:10366-74. [PMID: 18715920 DOI: 10.1128/jvi.00470-08] [Citation(s) in RCA: 138] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Integration of viral DNA into the host chromosome is an essential step in the life cycle of retroviruses and is facilitated by the viral integrase enzyme. The first generation of integrase inhibitors recently approved or currently in late-stage clinical trials shows great promise for the treatment of human immunodeficiency virus (HIV) infection, but virus is expected to develop resistance to these drugs. Therefore, we used a novel resistance selection protocol to follow the emergence of resistant HIV in the presence of the integrase inhibitor elvitegravir (GS-9137). We find the primary resistance-conferring mutations to be Q148R, E92Q, and T66I and demonstrate that they confer a reduction in susceptibility not only to elvitegravir but also to raltegravir (MK-0518) and other integrase inhibitors. The locations of the mutations are highlighted in the catalytic sites of integrase, and we correlate the mutations with expected drug-protein contacts. In addition, mutations that do not confer reduced susceptibility when present alone (H114Y, L74M, R20K, A128T, E138K, and S230R) are also discussed in relation to their position in the catalytic core domain and their proximity to known structural features of integrase. These data broaden the understanding of antiviral resistance against integrase inhibitors and may give insight facilitating the discovery of second-generation compounds.
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Mitra R, Fain-Thornton J, Craig NL. piggyBac can bypass DNA synthesis during cut and paste transposition. EMBO J 2008; 27:1097-109. [PMID: 18354502 PMCID: PMC2323262 DOI: 10.1038/emboj.2008.41] [Citation(s) in RCA: 161] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2007] [Accepted: 02/07/2008] [Indexed: 12/20/2022] Open
Abstract
DNA synthesis is considered a defining feature in the movement of transposable elements. In determining the mechanism of piggyBac transposition, an insect transposon that is being increasingly used for genome manipulation in a variety of systems including mammalian cells, we have found that DNA synthesis can be avoided during piggyBac transposition, both at the donor site following transposon excision and at the insertion site following transposon integration. We demonstrate that piggyBac transposon excision occurs through the formation of transient hairpins on the transposon ends and that piggyBac target joining occurs by the direct attack of the 3'OH transposon ends on to the target DNA. This is the same strategy for target joining used by the members of DDE superfamily of transposases and retroviral integrases. Analysis of mutant piggyBac transposases in vitro and in vivo using a piggyBac transposition system we have established in Saccharomyces cerevisiae suggests that piggyBac transposase is a member of the DDE superfamily of recombinases, an unanticipated result because of the lack of sequence similarity between piggyBac and DDE family of recombinases.
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Affiliation(s)
- Rupak Mitra
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jennifer Fain-Thornton
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Nancy L Craig
- Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Abstract
Although alterations in the genomes of somatic cells cannot be passed on to future generations, they can have beneficial or detrimental effects on the host organism, depending on the context in which they occur. This review outlines the ways in which transposable elements have important consequences for somatic cell genomes.
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Affiliation(s)
- Lara S Collier
- The Department of Genetics, Cell Biology and Development, The Cancer Center, The University of Minnesota Twin Cities, Church St SE, Minneapolis, Minnesota 55455, USA.
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40
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Brandt VL, Roth DB. G.O.D.’s Holy Grail: Discovery of the RAG Proteins. THE JOURNAL OF IMMUNOLOGY 2007; 180:3-4. [DOI: 10.4049/jimmunol.180.1.3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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41
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Nishihara T, Nagawa F, Imai T, Sakano H. RAG-heptamer interaction in the synaptic complex is a crucial biochemical checkpoint for the 12/23 recombination rule. J Biol Chem 2007; 283:4877-85. [PMID: 18089566 DOI: 10.1074/jbc.m709890200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In V(D)J recombination, the RAG1 and RAG2 protein complex cleaves the recombination signal sequences (RSSs), generating a hairpin structure at the coding end. The cleavage occurs only between two RSSs with different spacer lengths of 12 and 23 bp. Here we report that in the synaptic complex, recombination-activating gene (RAG) proteins interact with the 7-mer and unstack the adjacent base in the coding region. We generated a RAG1 mutant that exhibits reduced RAG-7-mer interaction, unstacking of the coding base, and hairpin formation. Mutation of the 23-RSS at the first position of the 7-mer, which has been reported to impair the cleavage of the partner 12-RSS, demonstrated phenotypes similar to those of the RAG1 mutant; the RAG interaction and base unstacking in the partner 12-RSS are reduced. We propose that the RAG-7-mer interaction is a critical step for coding DNA distortion and hairpin formation in the context of the 12/23 rule.
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Affiliation(s)
- Tadashi Nishihara
- Department of Biophysics and Biochemistry, Graduate School of Science, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan
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Aihara H, Huang WM, Ellenberger T. An interlocked dimer of the protelomerase TelK distorts DNA structure for the formation of hairpin telomeres. Mol Cell 2007; 27:901-13. [PMID: 17889664 PMCID: PMC2041798 DOI: 10.1016/j.molcel.2007.07.026] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2007] [Revised: 06/11/2007] [Accepted: 07/25/2007] [Indexed: 12/27/2022]
Abstract
The termini of linear chromosomes are protected by specialized DNA structures known as telomeres that also facilitate the complete replication of DNA ends. The simplest type of telomere is a covalently closed DNA hairpin structure found in linear chromosomes of prokaryotes and viruses. Bidirectional replication of a chromosome with hairpin telomeres produces a catenated circular dimer that is subsequently resolved into unit-length chromosomes by a dedicated DNA cleavage-rejoining enzyme known as a hairpin telomere resolvase (protelomerase). Here we report a crystal structure of the protelomerase TelK from Klebsiella oxytoca phage varphiKO2, in complex with the palindromic target DNA. The structure shows the TelK dimer destabilizes base pairing interactions to promote the refolding of cleaved DNA ends into two hairpin ends. We propose that the hairpinning reaction is made effectively irreversible by a unique protein-induced distortion of the DNA substrate that prevents religation of the cleaved DNA substrate.
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Affiliation(s)
- Hideki Aihara
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave., Campus Box 8231, St. Louis, MO 63110
| | - Wai Mun Huang
- Department of Pathology, EEJ Medical Research Building, Room 5200B 15 N. Medical Dr. East, University of Utah Health Sciences Center, Salt Lake City, Utah 84112
| | - Tom Ellenberger
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, 660 S. Euclid Ave., Campus Box 8231, St. Louis, MO 63110
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43
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Mizuuchi M, Rice PA, Wardle SJ, Haniford DB, Mizuuchi K. Control of transposase activity within a transpososome by the configuration of the flanking DNA segment of the transposon. Proc Natl Acad Sci U S A 2007; 104:14622-7. [PMID: 17785414 PMCID: PMC1964541 DOI: 10.1073/pnas.0706556104] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Indexed: 11/18/2022] Open
Abstract
The multiple steps of DNA transposition take place within a large complex called the transpososome, in which a pair of transposon DNA ends are synapsed by a multimer of the transposase protein. The final step, a DNA strand transfer reaction that joins the transposon ends to the target DNA strands, entails no net change in the number of high-energy chemical bonds. Physiology demands that, despite remaining stably associated with the transpososome, the strand transfer products undergo neither the reverse reaction nor any further cleavage reactions. Accordingly, when the Mu or Tn10 strand transfer complex was produced in vitro through transposase-catalyzed reaction steps, reverse reactions were undetectable. In contrast, when the Mu or Tn10 strand transfer complexes were assembled from DNA already having the structure of the strand transfer product, we detected a reaction that resembled reversal of target DNA strand transfer. The stereoselectivity of phosphorothioate-containing substrates indicated that this reaction proceeds as the pseudoreversal of the normal target DNA strand transfer step. Comparison of the reactivity of closely related Mu substrate DNA structures indicated that the configuration of the flanking DNA outside of the transposon sequence plays a key role in preventing the transposon end cleavage reaction after the strand transfer step.
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Affiliation(s)
- Michiyo Mizuuchi
- *Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Phoebe A. Rice
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637; and
| | - Simon J. Wardle
- Department of Biochemistry, University of Western Ontario, London, ON, Canada N6A 5C1
| | - David B. Haniford
- Department of Biochemistry, University of Western Ontario, London, ON, Canada N6A 5C1
| | - Kiyoshi Mizuuchi
- *Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
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44
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Tan X, Mizuuchi M, Mizuuchi K. DNA transposition target immunity and the determinants of the MuB distribution patterns on DNA. Proc Natl Acad Sci U S A 2007; 104:13925-9. [PMID: 17709741 PMCID: PMC1950340 DOI: 10.1073/pnas.0706564104] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
MuB, an ATP-dependent DNA-binding protein, is critical for the selection of target sites on the host chromosome during the phage Mu transposition. We developed a multichannel fluidic system to study the MuB-DNA interaction dynamics at the single DNA molecule level by total internal reflection fluorescence microscopy. We analyzed the distribution of MuB along DNA during the assembly and disassembly of MuB polymers on immobilized DNA molecules. The results reveal the absence of a significant correlation of MuB polymer distribution between the assembly and disassembly phases. These observations argue against a model in which MuB polymers on DNA represent a mixture of higher and lower affinity forms, with higher affinity forms being the first to appear and the last to disappear. Instead, assembly and disassembly of MuB polymers involve independent stochastic events. Additionally, we demonstrate that MuB disassembles from the polymer ends at a higher rate than from internal regions of the polymer and MuA stimulates MuB disassembly both at the polymer ends and internally.
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Affiliation(s)
- Xin Tan
- Laboratory of Molecular Biology, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Michiyo Mizuuchi
- Laboratory of Molecular Biology, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Kiyoshi Mizuuchi
- Laboratory of Molecular Biology, National Institute of Diabetes, Digestive, and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892
- *To whom correspondence should be addressed. E-mail:
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45
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Drejer-Teel AH, Fugmann SD, Schatz DG. The beyond 12/23 restriction is imposed at the nicking and pairing steps of DNA cleavage during V(D)J recombination. Mol Cell Biol 2007; 27:6288-99. [PMID: 17636023 PMCID: PMC2099602 DOI: 10.1128/mcb.00835-07] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The beyond 12/23 (B12/23) rule ensures inclusion of a Dbeta gene segment in the assembled T-cell receptor (TCR) beta variable region exon and is manifest by a failure of direct Vbeta-to-Jbeta gene segment joining. The restriction is enforced during the DNA cleavage step of V(D)J recombination by the recombination-activating gene 1 and 2 (RAG1/2) proteins and the recombination signal sequences (RSSs) flanking the TCRbeta gene segments. Nothing is known about the step(s) at which DNA cleavage is defective or how TCRbeta locus sequences contribute to these defects. To address this, we examined the steps of DNA cleavage by the RAG proteins using TCRbeta locus V, D, and J RSS oligonucleotide substrates. The results demonstrate that the B12/23 rule is enforced through slow nicking of Jbeta substrates and to some extent through poor synapsis of Vbeta and Jbeta substrates. Nicking is controlled largely by the coding flank and, unexpectedly, the RSS spacer, while synapsis is controlled primarily by the RSS nonamer. The results demonstrate that different Jbeta substrates are crippled at different steps of cleavage by distinct combinations of defects in the various DNA elements and strongly suggest that the DNA nicking step of V(D)J recombination can be rate limiting in vivo.
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Affiliation(s)
- Anna H Drejer-Teel
- Department of Genetics, Yale University School of Medicine, 330 Cedar St., New Haven, Connecticut 06510, USA
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46
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Sasnauskas G, Connolly BA, Halford SE, Siksnys V. Site-specific DNA transesterification catalyzed by a restriction enzyme. Proc Natl Acad Sci U S A 2007; 104:2115-20. [PMID: 17267608 PMCID: PMC1785359 DOI: 10.1073/pnas.0608689104] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Most restriction endonucleases use Mg2+ to hydrolyze phosphodiester bonds at specific DNA sites. We show here that BfiI, a metal-independent restriction enzyme from the phospholipase D superfamily, catalyzes both DNA hydrolysis and transesterification reactions at its recognition site. In the presence of alcohols such as ethanol or glycerol, it attaches the alcohol covalently to the 5' terminus of the cleaved DNA. Under certain conditions, the terminal 3'-OH of one DNA strand can attack the target phosphodiester bond in the other strand to create a DNA hairpin. Transesterification reactions on DNA with phosphorothioate linkages at the target bond proceed with retention of stereoconfiguration at the phosphorus, indicating, uniquely for a restriction enzyme, a two-step mechanism. We propose that BfiI first makes a covalent enzyme-DNA intermediate, and then it resolves it by a nucleophilic attack of water or an alcohol, to yield hydrolysis or transesterification products, respectively.
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Affiliation(s)
| | - Bernard A. Connolly
- Institute for Cell and Molecular Biosciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, United Kingdom; and
| | - Stephen E. Halford
- Department of Biochemistry, School of Medical Sciences, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
| | - Virginijus Siksnys
- *Institute of Biotechnology, Graiciuno 8, Vilnius, LT-02241, Lithuania
- To whom correspondence should be addressed. E-mail:
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47
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Posey JE, Pytlos MJ, Sinden RR, Roth DB. Target DNA structure plays a critical role in RAG transposition. PLoS Biol 2006; 4:e350. [PMID: 17105341 PMCID: PMC1618415 DOI: 10.1371/journal.pbio.0040350] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Accepted: 08/22/2006] [Indexed: 11/19/2022] Open
Abstract
Antigen receptor gene rearrangements are initiated by the RAG1/2 protein complex, which recognizes specific DNA sequences termed RSS (recombination signal sequences). The RAG recombinase can also catalyze transposition: integration of a DNA segment bounded by RSS into an unrelated DNA target. For reasons that remain poorly understood, such events occur readily in vitro, but are rarely detected in vivo. Previous work showed that non-B DNA structures, particularly hairpins, stimulate transposition. Here we show that the sequence of the four nucleotides at a hairpin tip modulates transposition efficiency over a surprisingly wide (>100-fold) range. Some hairpin targets stimulate extraordinarily efficient transposition (up to 15%); one serves as a potent and specific transposition inhibitor, blocking capture of targets and destabilizing preformed target capture complexes. These findings suggest novel regulatory possibilities and may provide insight into the activities of other transposases.
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Affiliation(s)
- Jennifer E Posey
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- Program in Molecular Pathogenesis, Skirball Institute of Biomolecular Medicine, and Department of Pathology, New York University School of Medicine, New York, New York, United States of America
| | - Malgorzata J Pytlos
- Laboratory of DNA Structure and Mutagenesis, Center for Genome Research, Institute of Biosciences and Technology, Texas A&M University System Health Sciences Center, Houston, Texas, United States of America
| | - Richard R Sinden
- Laboratory of DNA Structure and Mutagenesis, Center for Genome Research, Institute of Biosciences and Technology, Texas A&M University System Health Sciences Center, Houston, Texas, United States of America
| | - David B Roth
- Program in Molecular Pathogenesis, Skirball Institute of Biomolecular Medicine, and Department of Pathology, New York University School of Medicine, New York, New York, United States of America
- * To whom correspondence should be addressed. E-mail:
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48
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Lu CP, Sandoval H, Brandt VL, Rice PA, Roth DB. Amino acid residues in Rag1 crucial for DNA hairpin formation. Nat Struct Mol Biol 2006; 13:1010-5. [PMID: 17028591 DOI: 10.1038/nsmb1154] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2006] [Accepted: 09/14/2006] [Indexed: 11/10/2022]
Abstract
The Rag proteins carry out V(D)J recombination through a process mechanistically similar to cut-and-paste transposition. Specifically, Rag complexes form DNA hairpins through direct transesterification, using a catalytic Asp-Asp-Glu (DDE) triad in Rag1. How is sufficient DNA distortion introduced to allow hairpin formation? We hypothesized that, like certain transposases, the Rag proteins might use aromatic amino acid residues to stabilize a flipped-out base. Through in vivo and in vitro experiments and structural predictions, we identified residues in Rag1 crucial for hairpin formation. One of these, a conserved tryptophan (Trp893), probably participates in base-stacking interactions near the cleavage site, as do Trp298, Trp265 and Trp319 in the Tn5, Tn10 and Hermes transposases, respectively. Other residues surrounding the catalytic glutamate (YKEFRK) may share functional similarities with the YREK motif in IS4 family transposases.
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Affiliation(s)
- Catherine P Lu
- Program in Molecular Pathogenesis, Skirball Institute of Biomolecular Medicine, and Department of Pathology, New York University School of Medicine, New York, New York 10016, USA
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49
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Zheng X, Schwarz K. Making V(D)J rearrangement visible: quantification of recombination efficiency in real time at the single cell level. J Immunol Methods 2006; 315:133-43. [PMID: 16935293 DOI: 10.1016/j.jim.2006.07.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2006] [Revised: 07/10/2006] [Accepted: 07/20/2006] [Indexed: 11/27/2022]
Abstract
V(D)J recombination is of fundamental importance for the diversity of immunoglobulin and T cell receptor genes. An enhanced green fluorescent protein (EGFP) based assay was successfully developed to monitor V(D)J recombination efficiency. This assay makes V(D)J recombination visible at the single cell level in real time. Surprisingly, despite a high (60% to 90%) transfection efficiency, the EGFP based V(D)J recombination efficiency was found to be low ( approximately 1%) in 293 cells. The EGFP based V(D)J recombination efficiency correlated well with that achieved by the classical V(D)J recombination assay. The EGFP based V(D)J recombination efficiency depended on the relative RAG (recombination activating gene)-1 and RAG-2 but not Artemis expression vector concentrations used for co-transfection. A rise of RAG-1 dosage increased recombination efficiency. In contrast, a surplus of RAG-2 inhibited V(D)J recombination efficiency. The test differentiates RAG null mutants as seen in human severe combined immunodeficiency (SCID).
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Affiliation(s)
- Xiao Zheng
- Department of Transfusion Medicine, University Hospital Ulm, Institute for Clinical Transfusion Medicine and Immunogenetics, German Red Cross Blood Service Baden-Württemberg-Hessen, Institute Ulm, Helmholtzstrasse 10, D-89081 Ulm, Germany
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50
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Reddy YVR, Perkins EJ, Ramsden DA. Genomic instability due to V(D)J recombination-associated transposition. Genes Dev 2006; 20:1575-82. [PMID: 16778076 PMCID: PMC1482478 DOI: 10.1101/gad.1432706] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The first step in assembling immunoglobulin and T-cell receptors by V(D)J recombination has similarities to transposon excision. The excised transposon-like element then integrates into DNA targets at random in vitro, but whether this activity significantly threatens the genomic integrity of its host has been unclear. Here, we recover examples where the putative transposon associated with V(D)J recombination integrated into the genome of a pre-B-cell line. Transposition accounted for a surprisingly high proportion (one-third) of integrations, while most of the remaining events had parallels to other aberrant V(D)J recombination pathways linked to oncogenic translocation. In total, transposition occurred approximately once every 50,000 V(D)J recombinations. Transposition may thus contribute significantly to genomic instability.
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Affiliation(s)
- Yeturu V R Reddy
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA
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