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Gapińska M, Zajko W, Skowronek K, Figiel M, Krawczyk P, Egorov A, Dziembowski A, Johansson MO, Nowotny M. Structure-functional characterization of Lactococcus AbiA phage defense system. Nucleic Acids Res 2024; 52:4723-4738. [PMID: 38587192 PMCID: PMC11077055 DOI: 10.1093/nar/gkae230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2023] [Revised: 02/01/2024] [Accepted: 03/20/2024] [Indexed: 04/09/2024] Open
Abstract
Bacterial reverse transcriptases (RTs) are a large and diverse enzyme family. AbiA, AbiK and Abi-P2 are abortive infection system (Abi) RTs that mediate defense against bacteriophages. What sets Abi RTs apart from other RT enzymes is their ability to synthesize long DNA products of random sequences in a template- and primer-independent manner. Structures of AbiK and Abi-P2 representatives have recently been determined, but there are no structural data available for AbiA. Here, we report the crystal structure of Lactococcus AbiA polymerase in complex with a single-stranded polymerization product. AbiA comprises three domains: an RT-like domain, a helical domain that is typical for Abi polymerases, and a higher eukaryotes and prokaryotes nucleotide-binding (HEPN) domain that is common for many antiviral proteins. AbiA forms a dimer that distinguishes it from AbiK and Abi-P2, which form trimers/hexamers. We show the DNA polymerase activity of AbiA in an in vitro assay and demonstrate that it requires the presence of the HEPN domain which is enzymatically inactive. We validate our biochemical and structural results in vivo through bacteriophage infection assays. Finally, our in vivo results suggest that AbiA-mediated phage defense may not rely on AbiA-mediated cell death.
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Affiliation(s)
- Marta Gapińska
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Weronika Zajko
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Krzysztof Skowronek
- Biophysics Core Facility, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Małgorzata Figiel
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Paweł S Krawczyk
- Laboratory of RNA Biology, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Artyom A Egorov
- Department of Experimental Medical Science, Lund University, 221 00 Lund, Sweden
| | - Andrzej Dziembowski
- Laboratory of RNA Biology, International Institute of Molecular and Cell Biology, Warsaw, Poland
| | - Marcus J O Johansson
- Department of Experimental Medical Science, Lund University, 221 00 Lund, Sweden
| | - Marcin Nowotny
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology, Warsaw, Poland
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2
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Arkhipova IR, Yushenova IA. To Be Mobile or Not: The Variety of Reverse Transcriptases and Their Recruitment by Host Genomes. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:1754-1762. [PMID: 38105196 DOI: 10.1134/s000629792311007x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 09/18/2023] [Accepted: 09/20/2023] [Indexed: 12/19/2023]
Abstract
Reverse transcriptases (RT), or RNA-dependent DNA polymerases, are unorthodox enzymes that originally added a new angle to the conventional view of the unidirectional flow of genetic information in the cell from DNA to RNA to protein. First discovered in vertebrate retroviruses, RTs were since re-discovered in most eukaryotes, bacteria, and archaea, spanning essentially all domains of life. For retroviruses, RTs provide the ability to copy the RNA genome into DNA for subsequent incorporation into the host genome, which is essential for their replication and survival. In cellular organisms, most RT sequences originate from retrotransposons, the type of self-replicating genetic elements that rely on reverse transcription to copy and paste their sequences into new genomic locations. Some retroelements, however, can undergo domestication, eventually becoming a valuable addition to the overall repertoire of cellular enzymes. They can be beneficial yet accessory, like the diversity-generating elements, or even essential, like the telomerase reverse transcriptases. Nowadays, ever-increasing numbers of domesticated RT-carrying genetic elements are being discovered. It may be argued that domesticated RTs and reverse transcription in general is more widespread in cellular organisms than previously thought, and that many important cellular functions, such as chromosome end maintenance, may evolve from an originally selfish process of converting RNA into DNA.
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Affiliation(s)
- Irina R Arkhipova
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA 02543, USA.
| | - Irina A Yushenova
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA 02543, USA.
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3
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Cui G, Hua D, Zhao X, Zhou J, Yang Y, Huang T, Wang X, Zhao Y, Zhang T, Liao J, Guan Z, Luo P, Chen Z, Qi X, Hong W. A New EBS2b-IBS2b Base Paring (A -8/T -8) Improved the Gene-Targeting Efficiency of Thermotargetron in Escherichia coli. Microbiol Spectr 2023; 11:e0315922. [PMID: 36809044 PMCID: PMC10100991 DOI: 10.1128/spectrum.03159-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 01/21/2023] [Indexed: 02/23/2023] Open
Abstract
Thermophilic group II intron is one type of retrotransposon composed of intron RNA and intron-encoded protein (IEP), which can be utilized in gene targeting by harnessing their novel ribozyme-based DNA integration mechanism termed "retrohoming." It is mediated by a ribonucleoprotein (RNP) complex that contains the excised intron lariat RNA and an IEP with reverse transcriptase (RT) activity. The RNP recognizes targeting sites by exon-binding sequences 2 (EBS2)/intron-binding sequences 2 (IBS2), EBS1/IBS1, and EBS3/IBS3 bases pairing. Previously, we developed the TeI3c/4c intron as a thermophilic gene targeting system-Thermotargetron (TMT). However, we found that the targeting efficiency of TMT varies significantly at different targeting sites, which leads to a relatively low success rate. To further improve the success rate and gene-targeting efficiency of TMT, we constructed a Random Gene-targeting Plasmids Pool (RGPP) to analyze the sequence recognition preference of TMT. A new base pairing, located at the -8 site between EBS2/IBS2 and EBS1/IBS1 (named EBS2b-IBS2b), increased the success rate (2.45- to 5.07-fold) and significantly improved gene-targeting efficiency of TMT. A computer algorithm (TMT 1.0), based on the newly discovered sequence recognition roles, was also developed to facilitate the design of TMT gene-targeting primers. The present work could essentially expand the practicalities of TMT in the genome engineering of heat-tolerance mesophilic and thermophilic bacteria. IMPORTANCE The randomized base pairing in the interval of IBS2 and IBS1 of Tel3c/4c intron (-8 and -7 sites) in Thermotargetron (TMT) results in a low success rate and gene-targeting efficiency in bacteria. In the present work, we constructed a randomized gene-targeting plasmids pool (RGPP) to study whether there is a base preference in target sequences. Among all the successful "retrohoming" targets, we found that a new EBS2b-IBS2b base paring (A-8/T-8) significantly increased TMT's gene-targeting efficiency, and the concept is also applicable to other gene targets in redesigned gene-targeting plasmids pool in E. coli. The improved TMT is a promising tool for the genetic engineering of bacteria and could promote metabolic engineering and synthetic biology research in valuable microbes that recalcitrance for genetic manipulation.
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Affiliation(s)
- Guzhen Cui
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
- Joint Laboratory of Helicobacter Pylori and Intestinal Microecology of Affiliated Hospital of Guizhou Medical University
| | - Dengxiong Hua
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
- Joint Laboratory of Helicobacter Pylori and Intestinal Microecology of Affiliated Hospital of Guizhou Medical University
| | - Xingxing Zhao
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
| | - Jia Zhou
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
| | - Ying Yang
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
| | - Tingyu Huang
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
| | - Xinxin Wang
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
- Joint Laboratory of Helicobacter Pylori and Intestinal Microecology of Affiliated Hospital of Guizhou Medical University
| | - Yan Zhao
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
| | - Ting Zhang
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
| | - Jian Liao
- School/Hospital of Stomatology, Guizhou Medical University, Guiyang, Guizhou, China
| | - Zhizhong Guan
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
| | - Peng Luo
- Collaborative Innovation Center for Prevention and Control of Endemic and Ethnic Regional Diseases Co-constructed by the Province and Ministry
| | - Zhenghong Chen
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
- Collaborative Innovation Center for Prevention and Control of Endemic and Ethnic Regional Diseases Co-constructed by the Province and Ministry
- Joint Laboratory of Helicobacter Pylori and Intestinal Microecology of Affiliated Hospital of Guizhou Medical University
| | - Xiaolan Qi
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
- Collaborative Innovation Center for Prevention and Control of Endemic and Ethnic Regional Diseases Co-constructed by the Province and Ministry
- Joint Laboratory of Helicobacter Pylori and Intestinal Microecology of Affiliated Hospital of Guizhou Medical University
| | - Wei Hong
- Key Laboratory of Endemic and Ethnic Diseases, Ministry of Education & Key Laboratory of Medical Molecular Biology of Guizhou Province & Key Laboratory of Microbiology and Parasitology of Education Department of Guizhou, Guizhou Medical University, Guiyang, Guizhou, China
- Collaborative Innovation Center for Prevention and Control of Endemic and Ethnic Regional Diseases Co-constructed by the Province and Ministry
- Joint Laboratory of Helicobacter Pylori and Intestinal Microecology of Affiliated Hospital of Guizhou Medical University
- School/Hospital of Stomatology, Guizhou Medical University, Guiyang, Guizhou, China
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4
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Moran JV, Wilson TE. Reverse transcriptase meets DNA, again: Possible roles for transposable elements in host DNA repair. Cell 2022; 185:3643-3645. [PMID: 36179663 DOI: 10.1016/j.cell.2022.09.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 09/05/2022] [Accepted: 09/06/2022] [Indexed: 01/26/2023]
Abstract
Retrotransposons are selfish genetic elements that encode an enzyme, reverse transcriptase (RT), which converts the element-encoded RNA into DNA prior to or during genomic integration. New studies provide compelling evidence that a bacterial group II intron-like RT has adapted enzymatic activities associated with RTs to function in host DNA repair.
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Affiliation(s)
- John V Moran
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA; Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Thomas E Wilson
- Department of Human Genetics, University of Michigan, Ann Arbor, MI 48109, USA; Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA.
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5
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Park SK, Mohr G, Yao J, Russell R, Lambowitz AM. Group II intron-like reverse transcriptases function in double-strand break repair. Cell 2022; 185:3671-3688.e23. [PMID: 36113466 PMCID: PMC9530004 DOI: 10.1016/j.cell.2022.08.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Revised: 06/16/2022] [Accepted: 08/14/2022] [Indexed: 01/26/2023]
Abstract
Bacteria encode reverse transcriptases (RTs) of unknown function that are closely related to group II intron-encoded RTs. We found that a Pseudomonas aeruginosa group II intron-like RT (G2L4 RT) with YIDD instead of YADD at its active site functions in DNA repair in its native host and when expressed in Escherichia coli. G2L4 RT has biochemical activities strikingly similar to those of human DNA repair polymerase θ and uses them for translesion DNA synthesis and double-strand break repair (DSBR) via microhomology-mediated end-joining (MMEJ). We also found that a group II intron RT can function similarly in DNA repair, with reciprocal active-site substitutions showing isoleucine favors MMEJ and alanine favors primer extension in both enzymes. These DNA repair functions utilize conserved structural features of non-LTR-retroelement RTs, including human LINE-1 and other eukaryotic non-LTR-retrotransposon RTs, suggesting such enzymes may have inherent ability to function in DSBR in a wide range of organisms.
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Affiliation(s)
- Seung Kuk Park
- Departments of Molecular Biosciences and Oncology, University of Texas at Austin, Austin, TX 78712, USA
| | - Georg Mohr
- Departments of Molecular Biosciences and Oncology, University of Texas at Austin, Austin, TX 78712, USA
| | - Jun Yao
- Departments of Molecular Biosciences and Oncology, University of Texas at Austin, Austin, TX 78712, USA
| | - Rick Russell
- Departments of Molecular Biosciences and Oncology, University of Texas at Austin, Austin, TX 78712, USA
| | - Alan M Lambowitz
- Departments of Molecular Biosciences and Oncology, University of Texas at Austin, Austin, TX 78712, USA.
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6
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Figiel M, Gapińska M, Czarnocki-Cieciura M, Zajko W, Sroka M, Skowronek K, Nowotny M. Mechanism of protein-primed template-independent DNA synthesis by Abi polymerases. Nucleic Acids Res 2022; 50:10026-10040. [PMID: 36107766 PMCID: PMC9508834 DOI: 10.1093/nar/gkac772] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Revised: 08/23/2022] [Accepted: 08/30/2022] [Indexed: 11/20/2022] Open
Abstract
Abortive infection (Abi) is a bacterial antiphage defense strategy involving suicide of the infected cell. Some Abi pathways involve polymerases that are related to reverse transcriptases. They are unique in the way they combine the ability to synthesize DNA in a template-independent manner with protein priming. Here, we report crystal and cryo-electron microscopy structures of two Abi polymerases: AbiK and Abi-P2. Both proteins adopt a bilobal structure with an RT-like domain that comprises palm and fingers subdomains and a unique helical domain. AbiK and Abi-P2 adopt a hexameric and trimeric configuration, respectively, which is unprecedented for reverse transcriptases. Biochemical experiments showed that the formation of these oligomers is required for the DNA polymerization activity. The structure of the AbiK–DNA covalent adduct visualized interactions between the 3′ end of DNA and the active site and covalent attachment of the 5′ end of DNA to a tyrosine residue used for protein priming. Our data reveal a structural basis of the mechanism of highly unusual template-independent protein-priming polymerases.
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Affiliation(s)
- Małgorzata Figiel
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology , Warsaw , Poland
| | - Marta Gapińska
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology , Warsaw , Poland
| | - Mariusz Czarnocki-Cieciura
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology , Warsaw , Poland
| | - Weronika Zajko
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology , Warsaw , Poland
| | - Małgorzata Sroka
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology , Warsaw , Poland
| | - Krzysztof Skowronek
- Biophysics and Bioanalytics Facility, International Institute of Molecular and Cell Biology , Warsaw , Poland
| | - Marcin Nowotny
- Laboratory of Protein Structure, International Institute of Molecular and Cell Biology , Warsaw , Poland
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7
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Mestre MR, Gao LA, Shah SA, López-Beltrán A, González-Delgado A, Martínez-Abarca F, Iranzo J, Redrejo-Rodríguez M, Zhang F, Toro N. UG/Abi: a highly diverse family of prokaryotic reverse transcriptases associated with defense functions. Nucleic Acids Res 2022; 50:6084-6101. [PMID: 35648479 PMCID: PMC9226505 DOI: 10.1093/nar/gkac467] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 04/11/2022] [Accepted: 05/17/2022] [Indexed: 11/20/2022] Open
Abstract
Reverse transcriptases (RTs) are enzymes capable of synthesizing DNA using RNA as a template. Within the last few years, a burst of research has led to the discovery of novel prokaryotic RTs with diverse antiviral properties, such as DRTs (Defense-associated RTs), which belong to the so-called group of unknown RTs (UG) and are closely related to the Abortive Infection system (Abi) RTs. In this work, we performed a systematic analysis of UG and Abi RTs, increasing the number of UG/Abi members up to 42 highly diverse groups, most of which are predicted to be functionally associated with other gene(s) or domain(s). Based on this information, we classified these systems into three major classes. In addition, we reveal that most of these groups are associated with defense functions and/or mobile genetic elements, and demonstrate the antiphage role of four novel groups. Besides, we highlight the presence of one of these systems in novel families of human gut viruses infecting members of the Bacteroidetes and Firmicutes phyla. This work lays the foundation for a comprehensive and unified understanding of these highly diverse RTs with enormous biotechnological potential.
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Affiliation(s)
- Mario Rodríguez Mestre
- Departamento de Bioquímica, Universidad Autónoma de Madrid (UAM) and Instituto de Investigaciones Biomédicas Alberto Sols (CSIC-UAM), Madrid, Spain
| | - Linyi Alex Gao
- Howard Hughes Medical Institute, Cambridge, MA, USA.,Broad Institute of MIT and Harvard, Massachusetts Institute of Technology, Cambridge, MA, USA.,McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA.,Society of Fellows, Harvard University, Cambridge, MA 02138, USA
| | - Shiraz A Shah
- Copenhagen Prospective Studies on Asthma in Childhood, Copenhagen University Hospital, Herlev-Gentofte, Ledreborg Allé 34, DK-2820 Gentofte, Denmark
| | - Adrián López-Beltrán
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid, Spain
| | - Alejandro González-Delgado
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Spain
| | - Francisco Martínez-Abarca
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Spain
| | - Jaime Iranzo
- Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM) - Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid, Spain.,Institute for Biocomputation and Physics of Complex Systems (BIFI), University of Zaragoza, Zaragoza, Spain
| | - Modesto Redrejo-Rodríguez
- Departamento de Bioquímica, Universidad Autónoma de Madrid (UAM) and Instituto de Investigaciones Biomédicas Alberto Sols (CSIC-UAM), Madrid, Spain
| | - Feng Zhang
- Howard Hughes Medical Institute, Cambridge, MA, USA.,Broad Institute of MIT and Harvard, Massachusetts Institute of Technology, Cambridge, MA, USA.,McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Nicolás Toro
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Spain
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8
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Paul BG, Eren AM. Eco-evolutionary significance of domesticated retroelements in microbial genomes. Mob DNA 2022; 13:6. [PMID: 35197094 PMCID: PMC8867640 DOI: 10.1186/s13100-022-00262-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/03/2022] [Indexed: 01/03/2023] Open
Abstract
Since the first discovery of reverse transcriptase in bacteria, and later in archaea, bacterial and archaeal retroelements have been defined by their common enzyme that coordinates diverse functions. Yet, evolutionary refinement has produced distinct retroelements across the tree of microbial life that are perhaps best described in terms of their programmed RNA—a compact sequence that preserves core information for a sophisticated mechanism. From this perspective, reverse transcriptase has been selected as the modular tool for carrying out nature’s instructions in various RNA templates. Beneficial retroelements—those that can provide a fitness advantage to their host—evolved to their extant forms in a wide array of microorganisms and their viruses, spanning nearly all habitats. Within each specialized retroelement class, several universal features seem to be shared across diverse taxa, while specific functional and mechanistic insights are based on only a few model retroelement systems from clinical isolates. Currently, little is known about the diversity of cellular functions and ecological significance of retroelements across different biomes. With increasing availability of isolate, metagenome-assembled, and single-amplified genomes, the taxonomic and functional breadth of prokaryotic retroelements is coming into clearer view. This review explores the recently characterized classes of beneficial, yet accessory retroelements of bacteria and archaea. We describe how these specialized mechanisms exploit a form of fixed mobility, whereby the retroelements do not appear to proliferate selfishly throughout the genome. Moreover, we discuss computational approaches for systematic identification of retroelements from vast sequence repositories and highlight recent discoveries in terms of their apparent distribution and ecological significance in nature. Lastly, we present a new perspective on the eco-evolutionary significance of these genetic elements in marine bacteria and demonstrate approaches that enable the characterization of their environmental diversity through metagenomics.
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Affiliation(s)
- Blair G Paul
- Marine Biological Laboratory, Josephine Bay Paul Center, Woods Hole, MA, USA.
| | - A Murat Eren
- Marine Biological Laboratory, Josephine Bay Paul Center, Woods Hole, MA, USA. .,Department of Medicine, University of Chicago, Chicago, IL, USA.
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9
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Sharifi F, Ye Y. Identification and classification of reverse transcriptases in bacterial genomes and metagenomes. Nucleic Acids Res 2021; 50:e29. [PMID: 34904653 PMCID: PMC8934634 DOI: 10.1093/nar/gkab1207] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 11/17/2021] [Accepted: 11/22/2021] [Indexed: 02/07/2023] Open
Abstract
Reverse transcriptases (RTs) are found in different systems including group II introns, Diversity Generating Retroelements (DGRs), retrons, CRISPR-Cas systems, and Abortive Infection (Abi) systems in prokaryotes. Different classes of RTs can play different roles, such as template switching and mobility in group II introns, spacer acquisition in CRISPR-Cas systems, mutagenic retrohoming in DGRs, programmed cell suicide in Abi systems, and recently discovered phage defense in retrons. While some classes of RTs have been studied extensively, others remain to be characterized. There is a lack of computational tools for identifying and characterizing various classes of RTs. In this study, we built a tool (called myRT) for identification and classification of prokaryotic RTs. In addition, our tool provides information about the genomic neighborhood of each RT, providing potential functional clues. We applied our tool to predict RTs in all complete and draft bacterial genomes, and created a collection that can be used for exploration of putative RTs and their associated protein domains. Application of myRT to metagenomes showed that gut metagenomes encode proportionally more RTs related to DGRs, outnumbering retron-related RTs, as compared to the collection of reference genomes. MyRT is both available as a standalone software (https://github.com/mgtools/myRT) and also through a website (https://omics.informatics.indiana.edu/myRT/).
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Affiliation(s)
- Fatemeh Sharifi
- Luddy School of Informatics, Computing, and Engineering, Indiana University, Bloomington, IN 47408, USA
| | - Yuzhen Ye
- Luddy School of Informatics, Computing, and Engineering, Indiana University, Bloomington, IN 47408, USA
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10
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González-Delgado A, Mestre MR, Martínez-Abarca F, Toro N. Prokaryotic reverse transcriptases: from retroelements to specialized defense systems. FEMS Microbiol Rev 2021; 45:fuab025. [PMID: 33983378 PMCID: PMC8632793 DOI: 10.1093/femsre/fuab025] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 05/07/2021] [Indexed: 12/30/2022] Open
Abstract
Reverse transcriptases (RTs) catalyze the polymerization of DNA from an RNA template. These enzymes were first discovered in RNA tumor viruses in 1970, but it was not until 1989 that they were found in prokaryotes as a key component of retrons. Apart from RTs encoded by the 'selfish' mobile retroelements known as group II introns, prokaryotic RTs are extraordinarily diverse, but their function has remained elusive. However, recent studies have revealed that different lineages of prokaryotic RTs, including retrons, those associated with CRISPR-Cas systems, Abi-like RTs and other yet uncharacterized RTs, are key components of different lines of defense against phages and other mobile genetic elements. Prokaryotic RTs participate in various antiviral strategies, including abortive infection (Abi), in which the infected cell is induced to commit suicide to protect the host population, adaptive immunity, in which a memory of previous infection is used to build an efficient defense, and other as yet unidentified mechanisms. These prokaryotic enzymes are attracting considerable attention, both for use in cutting-edge technologies, such as genome editing, and as an emerging research topic. In this review, we discuss what is known about prokaryotic RTs, and the exciting evidence for their domestication from retroelements to create specialized defense systems.
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Affiliation(s)
- Alejandro González-Delgado
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Mario Rodríguez Mestre
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
- Department of Biochemistry, Universidad Autónoma de Madrid and Instituto de Investigaciones Biomédicas “Alberto Sols”, CSIC-UAM, Madrid, Spain
| | - Francisco Martínez-Abarca
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Nicolás Toro
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
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11
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Endogenous reverse transcriptase and RNase H-mediated antiviral mechanism in embryonic stem cells. Cell Res 2021; 31:998-1010. [PMID: 34158624 PMCID: PMC8217788 DOI: 10.1038/s41422-021-00524-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 05/26/2021] [Indexed: 02/06/2023] Open
Abstract
Nucleic acid-based systems play important roles in antiviral defense, including CRISPR/Cas that adopts RNA-guided DNA cleavage to prevent DNA phage infection and RNA interference (RNAi) that employs RNA-guided RNA cleavage to defend against RNA virus infection. Here, we report a novel type of nucleic acid-based antiviral system that exists in mouse embryonic stem cells (mESCs), which suppresses RNA virus infection by DNA-mediated RNA cleavage. We found that the viral RNA of encephalomyocarditis virus can be reverse transcribed into complementary DNA (vcDNA) by the reverse transcriptase (RTase) encoded by endogenous retrovirus-like elements in mESCs. The vcDNA is negative-sense single-stranded and forms DNA/RNA hybrid with viral RNA. The viral RNA in the heteroduplex is subsequently destroyed by cellular RNase H1, leading to robust suppression of viral growth. Furthermore, either inhibition of the RTase activity or depletion of endogenous RNase H1 results in the promotion of virus proliferation. Altogether, our results provide intriguing insights into the antiviral mechanism of mESCs and the antiviral function of endogenized retroviruses and cellular RNase H. Such a natural nucleic acid-based antiviral mechanism in mESCs is referred to as ERASE (endogenous RTase/RNase H-mediated antiviral system), which is an addition to the previously known nucleic acid-based antiviral mechanisms including CRISPR/Cas in bacteria and RNAi in plants and invertebrates.
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12
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Structural basis for template switching by a group II intron-encoded non-LTR-retroelement reverse transcriptase. J Biol Chem 2021; 297:100971. [PMID: 34280434 PMCID: PMC8363836 DOI: 10.1016/j.jbc.2021.100971] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Revised: 06/30/2021] [Accepted: 07/15/2021] [Indexed: 12/02/2022] Open
Abstract
Reverse transcriptases (RTs) can switch template strands during complementary DNA synthesis, enabling them to join discontinuous nucleic acid sequences. Template switching (TS) plays crucial roles in retroviral replication and recombination, is used for adapter addition in RNA-Seq, and may contribute to retroelement fitness by increasing evolutionary diversity and enabling continuous complementary DNA synthesis on damaged templates. Here, we determined an X-ray crystal structure of a TS complex of a group II intron RT bound simultaneously to an acceptor RNA and donor RNA template–DNA primer heteroduplex with a 1-nt 3′-DNA overhang. The structure showed that the 3′ end of the acceptor RNA binds in a pocket formed by an N-terminal extension present in non–long terminal repeat–retroelement RTs and the RT fingertips loop, with the 3′ nucleotide of the acceptor base paired to the 1-nt 3′-DNA overhang and its penultimate nucleotide base paired to the incoming dNTP at the RT active site. Analysis of structure-guided mutations identified amino acids that contribute to acceptor RNA binding and a phenylalanine residue near the RT active site that mediates nontemplated nucleotide addition. Mutation of the latter residue decreased multiple sequential template switches in RNA-Seq. Our results provide new insights into the mechanisms of TS and nontemplated nucleotide addition by RTs, suggest how these reactions could be improved for RNA-Seq, and reveal common structural features for TS by non–long terminal repeat–retroelement RTs and viral RNA–dependent RNA polymerases.
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13
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The Baltimore Classification of Viruses 50 Years Later: How Does It Stand in the Light of Virus Evolution? Microbiol Mol Biol Rev 2021; 85:e0005321. [PMID: 34259570 DOI: 10.1128/mmbr.00053-21] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Fifty years ago, David Baltimore published a brief conceptual paper delineating the classification of viruses by the routes of genome expression. The six "Baltimore classes" of viruses, with a subsequently added 7th class, became the conceptual framework for the development of virology during the next five decades. During this time, it became clear that the Baltimore classes, with relatively minor additions, indeed cover the diversity of virus genome expression schemes that also define the replication cycles. Here, we examine the status of the Baltimore classes 50 years after their advent and explore their links with the global ecology and biology of the respective viruses. We discuss an extension of the Baltimore scheme and why many logically admissible expression-replication schemes do not appear to be realized in nature. Recent phylogenomic analyses allow tracing the complex connections between the Baltimore classes and the monophyletic realms of viruses. The five classes of RNA viruses and reverse-transcribing viruses share an origin, whereas both the single-stranded DNA viruses and double-stranded DNA (dsDNA) viruses evolved on multiple independent occasions. Most of the Baltimore classes of viruses probably emerged during the earliest era of life evolution, at the stage of the primordial pool of diverse replicators, and before the advent of modern-like cells with large dsDNA genomes. The Baltimore classes remain an integral part of the conceptual foundation of biology, providing the essential structure for the logical space of information transfer processes, which is nontrivially connected with the routes of evolution of viruses and other replicators.
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14
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Gao L, Altae-Tran H, Böhning F, Makarova KS, Segel M, Schmid-Burgk JL, Koob J, Wolf YI, Koonin EV, Zhang F. Diverse enzymatic activities mediate antiviral immunity in prokaryotes. Science 2020; 369:1077-1084. [PMID: 32855333 DOI: 10.1126/science.aba0372] [Citation(s) in RCA: 226] [Impact Index Per Article: 56.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Accepted: 07/06/2020] [Indexed: 12/18/2022]
Abstract
Bacteria and archaea are frequently attacked by viruses and other mobile genetic elements and rely on dedicated antiviral defense systems, such as restriction endonucleases and CRISPR, to survive. The enormous diversity of viruses suggests that more types of defense systems exist than are currently known. By systematic defense gene prediction and heterologous reconstitution, here we discover 29 widespread antiviral gene cassettes, collectively present in 32% of all sequenced bacterial and archaeal genomes, that mediate protection against specific bacteriophages. These systems incorporate enzymatic activities not previously implicated in antiviral defense, including RNA editing and retron satellite DNA synthesis. In addition, we computationally predict a diverse set of other putative defense genes that remain to be characterized. These results highlight an immense array of molecular functions that microbes use against viruses.
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Affiliation(s)
- Linyi Gao
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA.,Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Han Altae-Tran
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA.,Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Francisca Böhning
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA.,Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Kira S Makarova
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Michael Segel
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA.,Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jonathan L Schmid-Burgk
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA.,Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jeremy Koob
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA.,Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Feng Zhang
- Howard Hughes Medical Institute, Cambridge, MA 02139, USA. .,Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.,Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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15
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Abstract
The last universal cellular ancestor (LUCA) is the most recent population of organisms from which all cellular life on Earth descends. The reconstruction of the genome and phenotype of the LUCA is a major challenge in evolutionary biology. Given that all life forms are associated with viruses and/or other mobile genetic elements, there is no doubt that the LUCA was a host to viruses. Here, by projecting back in time using the extant distribution of viruses across the two primary domains of life, bacteria and archaea, and tracing the evolutionary histories of some key virus genes, we attempt a reconstruction of the LUCA virome. Even a conservative version of this reconstruction suggests a remarkably complex virome that already included the main groups of extant viruses of bacteria and archaea. We further present evidence of extensive virus evolution antedating the LUCA. The presence of a highly complex virome implies the substantial genomic and pan-genomic complexity of the LUCA itself.
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16
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Koonin EV, Dolja VV, Krupovic M, Varsani A, Wolf YI, Yutin N, Zerbini FM, Kuhn JH. Global Organization and Proposed Megataxonomy of the Virus World. Microbiol Mol Biol Rev 2020; 84:e00061-19. [PMID: 32132243 PMCID: PMC7062200 DOI: 10.1128/mmbr.00061-19] [Citation(s) in RCA: 295] [Impact Index Per Article: 73.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Viruses and mobile genetic elements are molecular parasites or symbionts that coevolve with nearly all forms of cellular life. The route of virus replication and protein expression is determined by the viral genome type. Comparison of these routes led to the classification of viruses into seven "Baltimore classes" (BCs) that define the major features of virus reproduction. However, recent phylogenomic studies identified multiple evolutionary connections among viruses within each of the BCs as well as between different classes. Due to the modular organization of virus genomes, these relationships defy simple representation as lines of descent but rather form complex networks. Phylogenetic analyses of virus hallmark genes combined with analyses of gene-sharing networks show that replication modules of five BCs (three classes of RNA viruses and two classes of reverse-transcribing viruses) evolved from a common ancestor that encoded an RNA-directed RNA polymerase or a reverse transcriptase. Bona fide viruses evolved from this ancestor on multiple, independent occasions via the recruitment of distinct cellular proteins as capsid subunits and other structural components of virions. The single-stranded DNA (ssDNA) viruses are a polyphyletic class, with different groups evolving by recombination between rolling-circle-replicating plasmids, which contributed the replication protein, and positive-sense RNA viruses, which contributed the capsid protein. The double-stranded DNA (dsDNA) viruses are distributed among several large monophyletic groups and arose via the combination of distinct structural modules with equally diverse replication modules. Phylogenomic analyses reveal the finer structure of evolutionary connections among RNA viruses and reverse-transcribing viruses, ssDNA viruses, and large subsets of dsDNA viruses. Taken together, these analyses allow us to outline the global organization of the virus world. Here, we describe the key aspects of this organization and propose a comprehensive hierarchical taxonomy of viruses.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA
| | - Valerian V Dolja
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, Oregon, USA
| | - Mart Krupovic
- Institut Pasteur, Archaeal Virology Unit, Department of Microbiology, Paris, France
| | - Arvind Varsani
- The Biodesign Center for Fundamental and Applied Microbiomics, Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, Arizona, USA
- Structural Biology Research Unit, Department of Clinical Laboratory Sciences, University of Cape Town, Observatory, Cape Town, South Africa
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA
| | - Natalya Yutin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, USA
| | - F Murilo Zerbini
- Departamento de Fitopatologia/Bioagro, Universidade Federal de Viçosa, Viçosa, Minas Gerais, Brazil
| | - Jens H Kuhn
- Integrated Research Facility at Fort Detrick, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Frederick, Maryland, USA
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17
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Simon AJ, Ellington AD, Finkelstein IJ. Retrons and their applications in genome engineering. Nucleic Acids Res 2020; 47:11007-11019. [PMID: 31598685 PMCID: PMC6868368 DOI: 10.1093/nar/gkz865] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 09/19/2019] [Accepted: 10/02/2019] [Indexed: 11/14/2022] Open
Abstract
Precision genome editing technologies have transformed modern biology. These technologies have arisen from the redirection of natural biological machinery, such as bacteriophage lambda proteins for recombineering and CRISPR nucleases for eliciting site-specific double-strand breaks. Less well-known is a widely distributed class of bacterial retroelements, retrons, that employ specialized reverse transcriptases to produce noncoding intracellular DNAs. Retrons' natural function and mechanism of genetic transmission have remained enigmatic. However, recent studies have harnessed their ability to produce DNA in situ for genome editing and evolution. This review describes retron biology and function in both natural and synthetic contexts. We also highlight areas that require further study to advance retron-based precision genome editing platforms.
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Affiliation(s)
- Anna J Simon
- Center for Systems and Synthetic Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, USA
| | - Andrew D Ellington
- Center for Systems and Synthetic Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, USA
| | - Ilya J Finkelstein
- Center for Systems and Synthetic Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, USA
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18
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Kaur G, Burroughs AM, Iyer LM, Aravind L. Highly regulated, diversifying NTP-dependent biological conflict systems with implications for the emergence of multicellularity. eLife 2020; 9:52696. [PMID: 32101166 PMCID: PMC7159879 DOI: 10.7554/elife.52696] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Accepted: 02/25/2020] [Indexed: 12/12/2022] Open
Abstract
Social cellular aggregation or multicellular organization pose increased risk of transmission of infections through the system upon infection of a single cell. The generality of the evolutionary responses to this outside of Metazoa remains unclear. We report the discovery of several thematically unified, remarkable biological conflict systems preponderantly present in multicellular prokaryotes. These combine thresholding mechanisms utilizing NTPase chaperones (the MoxR-vWA couple), GTPases and proteolytic cascades with hypervariable effectors, which vary either by using a reverse transcriptase-dependent diversity-generating system or through a system of acquisition of diverse protein modules, typically in inactive form, from various cellular subsystems. Conciliant lines of evidence indicate their deployment against invasive entities, like viruses, to limit their spread in multicellular/social contexts via physical containment, dominant-negative interactions or apoptosis. These findings argue for both a similar operational 'grammar' and shared protein domains in the sensing and limiting of infections during the multiple emergences of multicellularity.
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Affiliation(s)
- Gurmeet Kaur
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, United States
| | - A Maxwell Burroughs
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, United States
| | - Lakshminarayan M Iyer
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, United States
| | - L Aravind
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, United States
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19
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Titov I, Kobalo N, Vorobyev D, Kulikov A. A Bioinformatic Method For Identifying Group II Introns In Organella Genomes. Front Genet 2019; 10:1135. [PMID: 31798632 PMCID: PMC6867995 DOI: 10.3389/fgene.2019.01135] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 10/18/2019] [Indexed: 01/11/2023] Open
Affiliation(s)
- Igor Titov
- The Laboratory of Molecular-Genetics Systems, the Federal Research Center Institute of Cytology and Genetics, Novosibirsk, Russia
| | - Nikolay Kobalo
- The Laboratory of Computational Problems of Geophysics, the Institute of Computational Mathematics and Mathematical Geophysics, Novosibirsk, Russia
| | - Denis Vorobyev
- INSERM U981, Gustave Roussy Cancer Center, Villejuif, France
| | - Alexander Kulikov
- The Laboratory of Computational Problems of Geophysics, the Institute of Computational Mathematics and Mathematical Geophysics, Novosibirsk, Russia
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20
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Mustafin RN, Khusnutdinova EK. The Role of Reverse Transcriptase in the Origin of Life. BIOCHEMISTRY (MOSCOW) 2019; 84:870-883. [DOI: 10.1134/s0006297919080030] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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21
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Toro N, Martínez-Abarca F, Mestre MR, González-Delgado A. Multiple origins of reverse transcriptases linked to CRISPR-Cas systems. RNA Biol 2019; 16:1486-1493. [PMID: 31276437 DOI: 10.1080/15476286.2019.1639310] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Prokaryotic genomes harbour a plethora of uncharacterized reverse transcriptases (RTs). RTs phylogenetically related to those encoded by group-II introns have been found associated with type III CRISPR-Cas systems, adjacent or fused at the C-terminus to Cas1. It is thought that these RTs may have a relevant function in the CRISPR immune response mediating spacer acquisition from RNA molecules. The origin and relationships of these RTs and the ways in which the various protein domains evolved remain matters of debate. We carried out a large survey of annotated RTs in databases (198,760 sequences) and constructed a large dataset of unique representative sequences (9,141). The combined phylogenetic reconstruction and identification of the RTs and their various protein domains in the vicinity of CRISPR adaptation and effector modules revealed three different origins for these RTs, consistent with their emergence on multiple occasions: a larger group that have evolved from group-II intron RTs, and two minor lineages that may have arisen more recently from Retron/retron-like sequences and Abi-P2 RTs, the latter associated with type I-C systems. We also identified a particular group of RTs associated with CRISPR-cas loci in clade 12, fused C-terminally to an archaeo-eukaryotic primase (AEP), a protein domain (AE-Prim_S_like) forming a particular family within the AEP proper clade. Together, these data provide new insight into the evolution of CRISPR-Cas/RT systems.
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Affiliation(s)
- Nicolás Toro
- Structure, Dynamics and Function of Rhizobacterial Genomes (Grupo de Ecología Genética de la Rizosfera), Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas , Granada , Spain
| | - Francisco Martínez-Abarca
- Structure, Dynamics and Function of Rhizobacterial Genomes (Grupo de Ecología Genética de la Rizosfera), Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas , Granada , Spain
| | - Mario Rodríguez Mestre
- Structure, Dynamics and Function of Rhizobacterial Genomes (Grupo de Ecología Genética de la Rizosfera), Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas , Granada , Spain
| | - Alejandro González-Delgado
- Structure, Dynamics and Function of Rhizobacterial Genomes (Grupo de Ecología Genética de la Rizosfera), Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas , Granada , Spain
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22
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Wu L, Gingery M, Abebe M, Arambula D, Czornyj E, Handa S, Khan H, Liu M, Pohlschroder M, Shaw KL, Du A, Guo H, Ghosh P, Miller JF, Zimmerly S. Diversity-generating retroelements: natural variation, classification and evolution inferred from a large-scale genomic survey. Nucleic Acids Res 2019; 46:11-24. [PMID: 29186518 PMCID: PMC5758913 DOI: 10.1093/nar/gkx1150] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Accepted: 11/04/2017] [Indexed: 01/12/2023] Open
Abstract
Diversity-generating retroelements (DGRs) are novel genetic elements that use reverse transcription to generate vast numbers of sequence variants in specific target genes. Here, we present a detailed comparative bioinformatic analysis that depicts the landscape of DGR sequences in nature as represented by data in GenBank. Over 350 unique DGRs are identified, which together form a curated reference set of putatively functional DGRs. We classify target genes, variable repeats and DGR cassette architectures, and identify two new accessory genes. The great variability of target genes implies roles of DGRs in many undiscovered biological processes. There is much evidence for horizontal transfers of DGRs, and we identify lineages of DGRs that appear to have specialized properties. Because GenBank contains data from only 10% of described species, the compilation may not be wholly representative of DGRs present in nature. Indeed, many DGR subtypes are present only once in the set and DGRs of the candidate phylum radiation bacteria, and Diapherotrites, Parvarchaeota, Aenigmarchaeota, Nanoarchaeota, Nanohaloarchaea archaea, are exceptionally diverse in sequence, with little information available about functions of their target genes. Nonetheless, this study provides a detailed framework for classifying and studying DGRs as they are uncovered and studied in the future.
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Affiliation(s)
- Li Wu
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Mari Gingery
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Michael Abebe
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Diego Arambula
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Elizabeth Czornyj
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Sumit Handa
- Department of Chemistry and Biochemistry, University of California, San Diego, CA 92093, USA
| | - Hamza Khan
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Minghsun Liu
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | | | - Kharissa L Shaw
- Department of Chemistry and Biochemistry, University of California, San Diego, CA 92093, USA
| | - Amy Du
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Huatao Guo
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA.,Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, MO 65212, USA
| | - Partho Ghosh
- Department of Chemistry and Biochemistry, University of California, San Diego, CA 92093, USA
| | - Jeff F Miller
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Steven Zimmerly
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
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23
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Abstract
The combination of modern biotechnologies such as DNA synthesis, λ red recombineering, CRISPR-based editing and next-generation high-throughput sequencing increasingly enables precise manipulation of genes and genomes. Beyond rational design, these technologies also enable the targeted, and potentially continuous, introduction of multiple mutations. While this might seem to be merely a return to natural selection, the ability to target evolution greatly reduces fitness burdens and focuses mutation and selection on those genes and traits that best contribute to a desired phenotype, ultimately throwing evolution into fast forward.
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24
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Morozov SY, Lezzhov AA, Lazareva EA, Erokhina TN, Solovyev AG. Potential Role of Accessory Domains in Polyproteins Encoded by Retrotransposons in Anti-viral Defense of Host Cells. Front Microbiol 2019; 9:3193. [PMID: 30687243 PMCID: PMC6338049 DOI: 10.3389/fmicb.2018.03193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 12/10/2018] [Indexed: 11/30/2022] Open
Affiliation(s)
- Sergey Y Morozov
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia.,Department of Virology, Biological Faculty, Moscow State University, Moscow, Russia
| | - Alexander A Lezzhov
- Faculty of Bioengineering and Bioinformatics, Moscow State University, Moscow, Russia
| | - Ekaterina A Lazareva
- Department of Virology, Biological Faculty, Moscow State University, Moscow, Russia
| | - Tatiana N Erokhina
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Science, Moscow, Russia
| | - Andrey G Solovyev
- A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow, Russia.,Department of Virology, Biological Faculty, Moscow State University, Moscow, Russia.,Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russia
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25
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Mohr G, Silas S, Stamos JL, Makarova KS, Markham LM, Yao J, Lucas-Elío P, Sanchez-Amat A, Fire AZ, Koonin EV, Lambowitz AM. A Reverse Transcriptase-Cas1 Fusion Protein Contains a Cas6 Domain Required for Both CRISPR RNA Biogenesis and RNA Spacer Acquisition. Mol Cell 2018; 72:700-714.e8. [PMID: 30344094 PMCID: PMC6242336 DOI: 10.1016/j.molcel.2018.09.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 08/10/2018] [Accepted: 09/12/2018] [Indexed: 01/30/2023]
Abstract
Prokaryotic CRISPR-Cas systems provide adaptive immunity by integrating portions of foreign nucleic acids (spacers) into genomic CRISPR arrays. Cas6 proteins then process CRISPR array transcripts into spacer-derived RNAs (CRISPR RNAs; crRNAs) that target Cas nucleases to matching invaders. We find that a Marinomonas mediterranea fusion protein combines three enzymatic domains (Cas6, reverse transcriptase [RT], and Cas1), which function in both crRNA biogenesis and spacer acquisition from RNA and DNA. We report a crystal structure of this divergent Cas6, identify amino acids required for Cas6 activity, show that the Cas6 domain is required for RT activity and RNA spacer acquisition, and demonstrate that CRISPR-repeat binding to Cas6 regulates RT activity. Co-evolution of putative interacting surfaces suggests a specific structural interaction between the Cas6 and RT domains, and phylogenetic analysis reveals repeated, stable association of free-standing Cas6s with CRISPR RTs in multiple microbial lineages, indicating that a functional interaction between these proteins preceded evolution of the fusion.
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Affiliation(s)
- Georg Mohr
- Institute for Cellular and Molecular Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Sukrit Silas
- Department of Pathology, Stanford University, Stanford, CA 94305, USA; Department of Chemical and Systems Biology, Stanford University, Stanford, CA 94305, USA
| | - Jennifer L Stamos
- Institute for Cellular and Molecular Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Kira S Makarova
- National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, MD 20894, USA
| | - Laura M Markham
- Institute for Cellular and Molecular Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Jun Yao
- Institute for Cellular and Molecular Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA
| | - Patricia Lucas-Elío
- Department of Genetics and Microbiology, Universidad de Murcia, Murcia 30100, Spain
| | - Antonio Sanchez-Amat
- Department of Genetics and Microbiology, Universidad de Murcia, Murcia 30100, Spain
| | - Andrew Z Fire
- Department of Pathology, Stanford University, Stanford, CA 94305, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, NIH, Bethesda, MD 20894, USA
| | - Alan M Lambowitz
- Institute for Cellular and Molecular Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, TX 78712, USA.
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26
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Poulter RTM, Ho J, Handley T, Taiaroa G, Butler MI. Comparison between complete genomes of an isolate of Pseudomonas syringae pv. actinidiae from Japan and a New Zealand isolate of the pandemic lineage. Sci Rep 2018; 8:10915. [PMID: 30026612 PMCID: PMC6053426 DOI: 10.1038/s41598-018-29261-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 07/09/2018] [Indexed: 11/21/2022] Open
Abstract
The modern pandemic of the bacterial kiwifruit pathogen Pseudomonas syringae pv actinidiae (Psa) is caused by a particular Psa lineage. To better understand the genetic basis of the virulence of this lineage, we compare the completely assembled genome of a pandemic New Zealand strain with that of the Psa type strain first isolated in Japan in 1983. Aligning the two genomes shows numerous translocations, constrained so as to retain the appropriate orientation of the Architecture Imparting Sequences (AIMs). There are several large horizontally acquired regions, some of which include Type I, Type II or Type III restriction systems. The activity of these systems is reflected in the methylation patterns of the two strains. The pandemic strain carries an Integrative Conjugative Element (ICE) located at a tRNA-Lys site. Two other complex elements are also present at tRNA-Lys sites in the genome. These elements are derived from ICE but have now acquired some alternative secretion function. There are numerous types of mobile element in the two genomes. Analysis of these elements reveals no evidence of recombination between the two Psa lineages.
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Affiliation(s)
| | - Joycelyn Ho
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Thomas Handley
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - George Taiaroa
- Department of Biochemistry, University of Otago, Dunedin, New Zealand
| | - Margi I Butler
- Department of Biochemistry, University of Otago, Dunedin, New Zealand.
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27
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Toro N, Martínez-Abarca F, González-Delgado A, Mestre MR. On the Origin and Evolutionary Relationships of the Reverse Transcriptases Associated With Type III CRISPR-Cas Systems. Front Microbiol 2018; 9:1317. [PMID: 29963037 PMCID: PMC6013744 DOI: 10.3389/fmicb.2018.01317] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 05/30/2018] [Indexed: 11/17/2022] Open
Abstract
Reverse transcriptases (RTs) closely related to those encoded by group II introns but lacking the intron RNA structure have been found associated with type III clustered regularly interspaced short palindromic repeats (CRISPR)-Cas systems, a prokaryotic immune system against invading viruses and foreign genetic elements. Two models have been proposed to explain the origin and evolutionary relationships of these RTs: (i) the “single point of origin” model, according to which these RTs originated from a single acquisition event in bacterial, with the various protein domains (RT, RT-Cas1, and Cas6-RT-Cas1 fusions) corresponding to single points in evolution; and (ii) the “various origins” model, according to which, independent acquisition events in different evolutionary episodes led to these fusions. We tested these alternative hypotheses, by analyzing and integrating published datasets of RT sequences associated with CRISPR-Cas systems and inferring phylogenetic trees by maximum likelihood (ML) methods. The RTs studied could be grouped into 13 clades, mostly in bacteria, in which they probably evolved. The various clades appear to form three independent lineages in bacteria and a recent lineage in archaea. Our data show that the Cas6 domain was acquired twice, independently, through RT-Cas1 fusion, in the bacterial lineages. Taken together, there more evidence to support the “various origins” hypothesis.
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Affiliation(s)
- Nicolás Toro
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Francisco Martínez-Abarca
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Alejandro González-Delgado
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Mario Rodríguez Mestre
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
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28
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Arkhipova IR. Using bioinformatic and phylogenetic approaches to classify transposable elements and understand their complex evolutionary histories. Mob DNA 2017; 8:19. [PMID: 29225705 PMCID: PMC5718144 DOI: 10.1186/s13100-017-0103-2] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 11/28/2017] [Indexed: 12/11/2022] Open
Abstract
In recent years, much attention has been paid to comparative genomic studies of transposable elements (TEs) and the ensuing problems of their identification, classification, and annotation. Different approaches and diverse automated pipelines are being used to catalogue and categorize mobile genetic elements in the ever-increasing number of prokaryotic and eukaryotic genomes, with little or no connectivity between different domains of life. Here, an overview of the current picture of TE classification and evolutionary relationships is presented, updating the diversity of TE types uncovered in sequenced genomes. A tripartite TE classification scheme is proposed to account for their replicative, integrative, and structural components, and the need to expand in vitro and in vivo studies of their structural and biological properties is emphasized. Bioinformatic studies have now become front and center of novel TE discovery, and experimental pursuits of these discoveries hold great promise for both basic and applied science.
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Affiliation(s)
- Irina R Arkhipova
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA 02543 USA
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29
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Mahbub MM, Chowdhury SM, Christensen SM. Globular domain structure and function of restriction-like-endonuclease LINEs: similarities to eukaryotic splicing factor Prp8. Mob DNA 2017; 8:16. [PMID: 29151899 PMCID: PMC5678591 DOI: 10.1186/s13100-017-0097-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 10/17/2017] [Indexed: 12/16/2022] Open
Abstract
Background R2 elements are a clade of early branching Long Interspersed Elements (LINEs). LINEs are retrotransposable elements whose replication can have profound effects on the genomes in which they reside. No crystal or EM structures exist for the reverse transcriptase (RT) and linker regions of LINEs. Results Using limited proteolysis as a probe for globular domain structure, we show that the protein encoded by the Bombyx mori R2 element has two major globular domains: (1) a small globular domain consisting of the N-terminal zinc finger and Myb motifs, and (2) a large globular domain consisting of the RT, linker, and type II restriction-like endonuclease (RLE). Further digestion of the large globular domain occurred within the RT. Mapping these RT cleavages onto an updated model of the R2Bm RT indicated that the thumb of the RT was largely protected from proteolytic cleavage. The crystal structure of the large globular domain of Prp8, a eukaryotic splicing factor, was a major template used in building the R2Bm RT model, particularly the thumb region. The large fragment of Prp8 consists not only of a RT similar to R2Bm, but also an RLE and a linker connecting the two regions. The linker sequences adjacent to the RLE in LINEs and Prp8 share a set of two important α-helices and a (presumptive) knuckle/ββα structural motif that are closely associated with the thumb. The RLEs of LINEs and Prp8 share a unique catalytic core residue spacing as well as other key residues. Conclusions The protein encoded by RLE LINEs consists of two major globular domains. The larger of the two globular domain contains the RT, linker, and RLE and is similar to the large fragment of the spliceosomal protein Prp8. The similarities are suggestive of possible common ancestry. Electronic supplementary material The online version of this article (10.1186/s13100-017-0097-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- M Murshida Mahbub
- Department of Biology, University of Texas at Arlington, 501 S. Nedderman Drive, Room 337, Arlington, TX 76010 USA
| | - Saiful M Chowdhury
- Department of Chemistry and Biochemistry, University of Texas at Arlington, 700 Planetarium Place, Room 130, Arlington, TX 76010 USA
| | - Shawn M Christensen
- Department of Biology, University of Texas at Arlington, 501 S. Nedderman Drive, Room 337, Arlington, TX 76010 USA
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30
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Weinberg Z, Lünse CE, Corbino KA, Ames TD, Nelson JW, Roth A, Perkins KR, Sherlock ME, Breaker RR. Detection of 224 candidate structured RNAs by comparative analysis of specific subsets of intergenic regions. Nucleic Acids Res 2017; 45:10811-10823. [PMID: 28977401 PMCID: PMC5737381 DOI: 10.1093/nar/gkx699] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2017] [Accepted: 08/02/2017] [Indexed: 11/29/2022] Open
Abstract
The discovery of structured non-coding RNAs (ncRNAs) in bacteria can reveal new facets of biology and biochemistry. Comparative genomics analyses executed by powerful computer algorithms have successfully been used to uncover many novel bacterial ncRNA classes in recent years. However, this general search strategy favors the discovery of more common ncRNA classes, whereas progressively rarer classes are correspondingly more difficult to identify. In the current study, we confront this problem by devising several methods to select subsets of intergenic regions that can concentrate these rare RNA classes, thereby increasing the probability that comparative sequence analysis approaches will reveal their existence. By implementing these methods, we discovered 224 novel ncRNA classes, which include ROOL RNA, an RNA class averaging 581 nt and present in multiple phyla, several highly conserved and widespread ncRNA classes with properties that suggest sophisticated biochemical functions and a multitude of putative cis-regulatory RNA classes involved in a variety of biological processes. We expect that further research on these newly found RNA classes will reveal additional aspects of novel biology, and allow for greater insights into the biochemistry performed by ncRNAs.
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Affiliation(s)
- Zasha Weinberg
- HHMI, Yale University, Box 208103, New Haven, CT 06520-8103, USA
| | - Christina E Lünse
- Department of Molecular, Cellular and Developmental Biology, Yale University, Box 208103, New Haven, CT 06520-8103, USA
| | - Keith A Corbino
- HHMI, Yale University, Box 208103, New Haven, CT 06520-8103, USA
| | - Tyler D Ames
- Department of Molecular, Cellular and Developmental Biology, Yale University, Box 208103, New Haven, CT 06520-8103, USA
| | - James W Nelson
- Department of Molecular, Cellular and Developmental Biology, Yale University, Box 208103, New Haven, CT 06520-8103, USA
| | - Adam Roth
- HHMI, Yale University, Box 208103, New Haven, CT 06520-8103, USA
| | - Kevin R Perkins
- Department of Molecular, Cellular and Developmental Biology, Yale University, Box 208103, New Haven, CT 06520-8103, USA
| | - Madeline E Sherlock
- Department of Molecular Biophysics and Biochemistry, Yale University, Box 208103, New Haven, CT 06520-8103, USA
| | - Ronald R Breaker
- HHMI, Yale University, Box 208103, New Haven, CT 06520-8103, USA.,Department of Molecular, Cellular and Developmental Biology, Yale University, Box 208103, New Haven, CT 06520-8103, USA.,Department of Molecular Biophysics and Biochemistry, Yale University, Box 208103, New Haven, CT 06520-8103, USA
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31
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Xie X, Yang R. Multi-copy single-stranded DNA in Escherichia coli. MICROBIOLOGY-SGM 2017; 163:1735-1739. [PMID: 29087272 DOI: 10.1099/mic.0.000563] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Multi-copy single-stranded DNA (msDNA) is composed of covalently bound single-stranded DNA and RNA, and synthesized by retron-encoded reverse transcriptase. msDNA-synthesizing systems are thought to be a recent acquisition by Escherichia coli because, to date, only seven types of msDNA, which differ markedly in their primary nucleotide sequences, have been found in a small subset of E. coli strains. The wide use of E. coli in molecular research means that it is important to understand more about these stable, covalently bound, single-stranded DNA or RNA compounds. The present review provides insights into the molecular biosynthesis, distribution and function of E. coli msDNA to raise awareness about these special molecules.
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Affiliation(s)
- Xianxing Xie
- State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing 100071, PR China
| | - Ruifu Yang
- State Key Laboratory of Pathogen and Biosecurity, Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing 100071, PR China
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32
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Koonin EV, Makarova KS. Mobile Genetic Elements and Evolution of CRISPR-Cas Systems: All the Way There and Back. Genome Biol Evol 2017; 9:2812-2825. [PMID: 28985291 PMCID: PMC5737515 DOI: 10.1093/gbe/evx192] [Citation(s) in RCA: 88] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/16/2017] [Indexed: 12/13/2022] Open
Abstract
The Clustered Regularly Interspaced Palindromic Repeats (CRISPR)-CRISPR-associated proteins (Cas) systems of bacterial and archaeal adaptive immunity show multifaceted evolutionary relationships with at least five classes of mobile genetic elements (MGE). First, the adaptation module of CRISPR-Cas that is responsible for the formation of the immune memory apparently evolved from a Casposon, a self-synthesizing transposon that employs the Cas1 protein as the integrase and might have brought additional cas genes to the emerging immunity loci. Second, a large subset of type III CRISPR-Cas systems recruited a reverse transcriptase from a Group II intron, providing for spacer acquisition from RNA. Third, effector nucleases of Class 2 CRISPR-Cas systems that are responsible for the recognition and cleavage of the target DNA were derived from transposon-encoded TnpB nucleases, most likely, on several independent occasions. Fourth, accessory nucleases in some variants of types I and III toxin and type VI effectors RNases appear to be ultimately derived from toxin nucleases of microbial toxin-antitoxin modules. Fifth, the opposite direction of evolution is manifested in the recruitment of CRISPR-Cas systems by a distinct family of Tn7-like transposons that probably exploit the capacity of CRISPR-Cas to recognize unique DNA sites to facilitate transposition as well as by bacteriophages that employ them to cope with host defense. Additionally, individual Cas proteins, such as the Cas4 nuclease, were recruited by bacteriophages and transposons. The two-sided evolutionary connection between CRISPR-Cas and MGE fits the "guns for hire" paradigm whereby homologous enzymatic machineries, in particular nucleases, are shuttled between MGE and defense systems and are used alternately as means of offense or defense.
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Affiliation(s)
- Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland
| | - Kira S. Makarova
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland
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33
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Novikova O, Belfort M. Mobile Group II Introns as Ancestral Eukaryotic Elements. Trends Genet 2017; 33:773-783. [PMID: 28818345 DOI: 10.1016/j.tig.2017.07.009] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 07/06/2017] [Accepted: 07/24/2017] [Indexed: 01/09/2023]
Abstract
The duality of group II introns, capable of carrying out both self-splicing and retromobility reactions, is hypothesized to have played a profound role in the evolution of eukaryotes. These introns likely provided the framework for the emergence of eukaryotic retroelements, spliceosomal introns and other key components of the spliceosome. Group II introns are found in all three domains of life and are therefore considered to be exceptionally successful mobile genetic elements. Initially identified in organellar genomes, group II introns are found in bacteria, chloroplasts, and mitochondria of plants and fungi, but not in nuclear genomes. Although there is no doubt that prokaryotic and organellar group II introns are evolutionary related, there are remarkable differences in survival strategies between them. Furthermore, an evolutionary relationship of group II introns to eukaryotic retroelements, including telomeres, and spliceosomes is unmistakable.
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Affiliation(s)
- Olga Novikova
- Department of Biological Sciences and RNA Institute, University at Albany, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Marlene Belfort
- Department of Biological Sciences and RNA Institute, University at Albany, 1400 Washington Avenue, Albany, NY 12222, USA; Department of Biomedical Sciences, School of Public Health, University at Albany, 1400 Washington Avenue, Albany, NY 12222, USA.
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34
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Retroelement-guided protein diversification abounds in vast lineages of Bacteria and Archaea. Nat Microbiol 2017; 2:17045. [PMID: 28368387 PMCID: PMC5436926 DOI: 10.1038/nmicrobiol.2017.45] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 03/03/2017] [Indexed: 11/08/2022]
Abstract
Major radiations of enigmatic bacteria and archaea with large inventories of uncharacterized proteins are a striking feature of the Tree of Life1,2,3,4,5. The processes that led to functional diversity in these lineages, which may contribute to a host-dependent lifestyle, are poorly understood. Here we show that diversity-generating retroelements (DGRs), which guide site-specific protein hypervariability6,7,8, are prominent features of genomically-reduced organisms from the bacterial candidate phyla radiation (CPR) and yet uncultivated phyla belonging to the DPANN archaeal superphylum. From reconstructed genomes we defined monophyletic bacterial and archaeal DGR lineages that expand known DGR range by 120% and reveal a history of horizontal retroelement transfer. Retroelement-guided diversification is further shown to be active in current CPR and DPANN populations, with an assortment of protein targets potentially involved in attachment, defense, and regulation. Based on observations of DGR abundance, function, and evolutionary history, we find that targeted protein diversification is a pronounced trait of CPR and DPANN phyla compared to other bacterial and archaeal phyla. This diversification mechanism may provide CPR and DPANN organisms a versatile tool that could be used for adaptation to a dynamic, host-dependent, existence.
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35
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Schwendener S, Cotting K, Perreten V. Novel methicillin resistance gene mecD in clinical Macrococcus caseolyticus strains from bovine and canine sources. Sci Rep 2017; 7:43797. [PMID: 28272476 PMCID: PMC5341023 DOI: 10.1038/srep43797] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 01/30/2017] [Indexed: 11/30/2022] Open
Abstract
Methicillin-resistant Macrococcus caseolyticus strains from bovine and canine origins were found to carry a novel mecD gene conferring resistance to all classes of β-lactams including anti-MRSA cephalosporins. Association of β-lactam resistance with mecD was demonstrated by gene expression in S. aureus and deletion of the mecD-containing island in M. caseolyticus. The mecD gene was located either on an 18,134-bp M. caseolyticus resistance island (McRImecD-1) or a 16,188-bp McRImecD-2. Both islands were integrated at the 3′ end of the rpsI gene, carried the mecD operon (mecD-mecR1m-mecIm), and genes for an integrase of the tyrosine recombinase family and a putative virulence-associated protein (virE). Apart from the mecD operon, that shared 66% overall nucleotide identity with the mecB operon, McRImecD islands were unrelated to any mecB-carrying elements or staphylococcal cassette chromosome mec. Only McRImecD-1 that is delimitated at both ends by direct repeats was capable of circular excision. The recombined excision pattern suggests site-specific activity of the integrase and allowed identification of a putative core attachment site. Detection of rpsI-associated integrases in Bacillus and S. aureus reveals a potential for broad-host range dissemination of the novel methicillin resistance gene mecD.
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Affiliation(s)
- Sybille Schwendener
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Kerstin Cotting
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
| | - Vincent Perreten
- Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
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36
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McNeil BA, Semper C, Zimmerly S. Group II introns: versatile ribozymes and retroelements. WILEY INTERDISCIPLINARY REVIEWS-RNA 2016; 7:341-55. [PMID: 26876278 DOI: 10.1002/wrna.1339] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 12/10/2015] [Accepted: 12/22/2015] [Indexed: 01/10/2023]
Abstract
Group II introns are catalytic RNAs (ribozymes) and retroelements found in the genomes of bacteria, archaebacteria, and organelles of some eukaryotes. The prototypical retroelement form consists of a structurally conserved RNA and a multidomain reverse transcriptase protein, which interact with each other to mediate splicing and mobility reactions. A wealth of biochemical, cross-linking, and X-ray crystal structure studies have helped to reveal how the two components cooperate to carry out the splicing and mobility reactions. In addition to the standard retroelement form, group II introns have evolved into derivative forms by either losing specific splicing or mobility characteristics, or becoming functionally specialized. Of particular interest are the eukaryotic derivatives-the spliceosome, spliceosomal introns, and non-LTR retroelements-which together make up approximately half of the human genome. On a practical level, the properties of group II introns have been exploited to develop group II intron-based biotechnological tools. WIREs RNA 2016, 7:341-355. doi: 10.1002/wrna.1339 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Bonnie A McNeil
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Cameron Semper
- Department of Biological Sciences, University of Calgary, Calgary, Canada
| | - Steven Zimmerly
- Department of Biological Sciences, University of Calgary, Calgary, Canada
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