51
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Vialetto E, Yu Y, Collins SP, Wandera KG, Barquist L, Beisel CL. A target expression threshold dictates invader defense and prevents autoimmunity by CRISPR-Cas13. Cell Host Microbe 2022; 30:1151-1162.e6. [PMID: 35690065 PMCID: PMC9590104 DOI: 10.1016/j.chom.2022.05.013] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 03/30/2022] [Accepted: 05/17/2022] [Indexed: 11/20/2022]
Abstract
CRISPR-Cas systems must enact robust immunity against foreign genetic material without inducing cytotoxic autoimmunity. For type VI systems that use Cas13 nucleases and recognize RNA targets, immune activation requires extensive CRISPR RNA (crRNA) guide-target complementarity and a target-flanking motif. Here, we report a third requirement shaping the immune response: the expression of the target transcript exceeding a threshold. We found that endogenous non-essential transcripts targeted by crRNAs rarely elicited autoimmunity. Instead, autoimmune induction required over-expressing the targeted transcripts above a threshold. A genome-wide screen confirmed target expression levels as a global determinant of cytotoxic autoimmunity and revealed that this threshold shifts with each guide-target pair. This threshold further ensured defense against a lytic bacteriophage yet allowed the tolerance of a targeted beneficial gene expressed from an invading plasmid. These findings establish target expression levels as an additional criterion for immune defense by RNA-targeting CRISPR-Cas systems, preventing autoimmunity and distinguishing pathogenic and benign invaders.
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Affiliation(s)
- Elena Vialetto
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080 Würzburg, Germany
| | - Yanying Yu
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080 Würzburg, Germany
| | - Scott P Collins
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA
| | - Katharina G Wandera
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080 Würzburg, Germany
| | - Lars Barquist
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080 Würzburg, Germany; Medical Faculty, University of Würzburg, 97080 Würzburg, Germany
| | - Chase L Beisel
- Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080 Würzburg, Germany; Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695, USA; Medical Faculty, University of Würzburg, 97080 Würzburg, Germany.
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52
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Abstract
Viruses are obligate intracellular parasites. Despite their dependence on host cells, viruses are evolutionarily autonomous, with their own genomes and evolutionary trajectories locked in arms races with the hosts. Here, we discuss a simple functional logic to explain virus macroevolution that appears to define the course of virus evolution. A small core of virus hallmark genes that are responsible for genome replication apparently descended from primordial replicators, whereas most virus genes, starting with those encoding capsid proteins, were subsequently acquired from hosts. The oldest of these acquisitions antedate the last universal cellular ancestor (LUCA). Host gene capture followed two major routes: convergent recruitment of genes with functions that directly benefit virus reproduction and exaptation when host proteins are repurposed for unique virus functions. These forms of host protein recruitment by viruses result in different levels of similarity between virus and host homologs, with the exapted ones often changing beyond easy recognition.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA.
| | - Valerian V Dolja
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA; Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, F-75015 Paris, France.
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53
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Zaayman M, Wheatley RM. Fitness costs of CRISPR-Cas systems in bacteria. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35849532 DOI: 10.1099/mic.0.001209] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
CRISPR-Cas systems provide bacteria with both specificity and adaptability in defence against invading genetic elements. From a theoretical perspective, CRISPR-Cas systems confer many benefits. However, they are observed at an unexpectedly low prevalence across the bacterial domain. While these defence systems can be gained horizontally, fitness costs may lead to selection against their carriage. Understanding the source of CRISPR-related fitness costs will help us to understand the evolutionary dynamics of CRISPR-Cas systems and their role in shaping bacterial genome evolution. Here, we review our current understanding of the potential fitness costs associated with CRISPR-Cas systems. In addition to potentially restricting the acquisition of genetic material that could confer fitness benefits, we explore five alternative biological factors that from a theoretical perspective may influence the fitness costs associated with CRISPR-Cas system carriage: (1) the repertoire of defence mechanisms a bacterium has available to it, (2) the potential for a metabolic burden, (3) larger-scale population and environmental factors, (4) the phenomenon of self-targeting spacers, and (5) alternative non-defence roles for CRISPR-Cas.
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54
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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] [MESH Headings] [Grants] [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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55
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Structural insights into the evolution of the RAG recombinase. Nat Rev Immunol 2022; 22:353-370. [PMID: 34675378 DOI: 10.1038/s41577-021-00628-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/09/2021] [Indexed: 11/09/2022]
Abstract
Adaptive immunity in jawed vertebrates relies on the assembly of antigen receptor genes by the recombination activating gene 1 (RAG1)-RAG2 (collectively RAG) recombinase in a reaction known as V(D)J recombination. Extensive biochemical and structural evidence indicates that RAG and V(D)J recombination evolved from the components of a RAG-like (RAGL) transposable element through a process known as transposon molecular domestication. This Review describes recent advances in our understanding of the functional and structural transitions that occurred during RAG evolution. We use the structures of RAG and RAGL enzymes to trace the evolutionary adaptations that yielded a RAG recombinase with exquisitely regulated cleavage activity and a multilayered array of mechanisms to suppress transposition. We describe how changes in modes of DNA binding, alterations in the dynamics of protein-DNA complexes, single amino acid mutations and a modular design likely enabled RAG family enzymes to survive and spread in the genomes of eukaryotes. These advances highlight the insight that can be gained from viewing evolution of vertebrate immunity through the lens of comparative genome analyses coupled with structural biology and biochemistry.
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56
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Rousset F, Depardieu F, Miele S, Dowding J, Laval AL, Lieberman E, Garry D, Rocha EPC, Bernheim A, Bikard D. Phages and their satellites encode hotspots of antiviral systems. Cell Host Microbe 2022; 30:740-753.e5. [PMID: 35316646 PMCID: PMC9122126 DOI: 10.1016/j.chom.2022.02.018] [Citation(s) in RCA: 112] [Impact Index Per Article: 56.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 01/27/2022] [Accepted: 02/23/2022] [Indexed: 11/18/2022]
Abstract
Bacteria carry diverse genetic systems to defend against viral infection, some of which are found within prophages where they inhibit competing viruses. Phage satellites pose additional pressures on phages by hijacking key viral elements to their own benefit. Here, we show that E. coli P2-like phages and their parasitic P4-like satellites carry hotspots of genetic variation containing reservoirs of anti-phage systems. We validate the activity of diverse systems and describe PARIS, an abortive infection system triggered by a phage-encoded anti-restriction protein. Antiviral hotspots participate in inter-viral competition and shape dynamics between the bacterial host, P2-like phages, and P4-like satellites. Notably, the anti-phage activity of satellites can benefit the helper phage during competition with virulent phages, turning a parasitic relationship into a mutualistic one. Anti-phage hotspots are present across distant species and constitute a substantial source of systems that participate in the competition between mobile genetic elements.
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Affiliation(s)
- François Rousset
- Institut Pasteur, Université de Paris, CNRS UMR 6047, Synthetic Biology, 75015 Paris, France.
| | - Florence Depardieu
- Institut Pasteur, Université de Paris, CNRS UMR 6047, Synthetic Biology, 75015 Paris, France
| | - Solange Miele
- Institut Pasteur, Université de Paris, CNRS UMR 6047, Synthetic Biology, 75015 Paris, France
| | - Julien Dowding
- Institut Pasteur, Université de Paris, CNRS UMR 6047, Synthetic Biology, 75015 Paris, France
| | - Anne-Laure Laval
- Institut Pasteur, Université de Paris, CNRS UMR 6047, Synthetic Biology, 75015 Paris, France
| | | | | | - Eduardo P C Rocha
- Institut Pasteur, Université de Paris, CNRS UMR 3525, Microbial Evolutionary Genomics, 75015 Paris, France
| | - Aude Bernheim
- Université de Paris, INSERM, IAME, 75006 Paris, France
| | - David Bikard
- Institut Pasteur, Université de Paris, CNRS UMR 6047, Synthetic Biology, 75015 Paris, France.
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57
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Bowers RM, Nayfach S, Schulz F, Jungbluth SP, Ruhl IA, Sheremet A, Lee J, Goudeau D, Eloe-Fadrosh EA, Stepanauskas R, Malmstrom RR, Kyrpides NC, Dunfield PF, Woyke T. Dissecting the dominant hot spring microbial populations based on community-wide sampling at single-cell genomic resolution. THE ISME JOURNAL 2022; 16:1337-1347. [PMID: 34969995 PMCID: PMC9039060 DOI: 10.1038/s41396-021-01178-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Revised: 11/29/2021] [Accepted: 12/10/2021] [Indexed: 02/07/2023]
Abstract
With advances in DNA sequencing and miniaturized molecular biology workflows, rapid and affordable sequencing of single-cell genomes has become a reality. Compared to 16S rRNA gene surveys and shotgun metagenomics, large-scale application of single-cell genomics to whole microbial communities provides an integrated snapshot of community composition and function, directly links mobile elements to their hosts, and enables analysis of population heterogeneity of the dominant community members. To that end, we sequenced nearly 500 single-cell genomes from a low diversity hot spring sediment sample from Dewar Creek, British Columbia, and compared this approach to 16S rRNA gene amplicon and shotgun metagenomics applied to the same sample. We found that the broad taxonomic profiles were similar across the three sequencing approaches, though several lineages were missing from the 16S rRNA gene amplicon dataset, likely the result of primer mismatches. At the functional level, we detected a large array of mobile genetic elements present in the single-cell genomes but absent from the corresponding same species metagenome-assembled genomes. Moreover, we performed a single-cell population genomic analysis of the three most abundant community members, revealing differences in population structure based on mutation and recombination profiles. While the average pairwise nucleotide identities were similar across the dominant species-level lineages, we observed differences in the extent of recombination between these dominant populations. Most intriguingly, the creek's Hydrogenobacter sp. population appeared to be so recombinogenic that it more closely resembled a sexual species than a clonally evolving microbe. Together, this work demonstrates that a randomized single-cell approach can be useful for the exploration of previously uncultivated microbes from community composition to population structure.
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Affiliation(s)
- Robert M. Bowers
- grid.451309.a0000 0004 0449 479XU.S. Department of Energy, Joint Genome Institute, Berkeley, CA USA
| | - Stephen Nayfach
- grid.451309.a0000 0004 0449 479XU.S. Department of Energy, Joint Genome Institute, Berkeley, CA USA
| | - Frederik Schulz
- grid.451309.a0000 0004 0449 479XU.S. Department of Energy, Joint Genome Institute, Berkeley, CA USA
| | - Sean P. Jungbluth
- grid.184769.50000 0001 2231 4551Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA USA
| | - Ilona A. Ruhl
- grid.22072.350000 0004 1936 7697Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4 Canada ,grid.419357.d0000 0001 2199 3636National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO USA
| | - Andriy Sheremet
- grid.22072.350000 0004 1936 7697Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4 Canada
| | - Janey Lee
- grid.451309.a0000 0004 0449 479XU.S. Department of Energy, Joint Genome Institute, Berkeley, CA USA
| | - Danielle Goudeau
- grid.451309.a0000 0004 0449 479XU.S. Department of Energy, Joint Genome Institute, Berkeley, CA USA
| | - Emiley A. Eloe-Fadrosh
- grid.451309.a0000 0004 0449 479XU.S. Department of Energy, Joint Genome Institute, Berkeley, CA USA
| | - Ramunas Stepanauskas
- grid.296275.d0000 0000 9516 4913Bigelow Laboratory for Ocean Sciences, 60 Bigelow Drive, East Boothbay, ME USA
| | - Rex R. Malmstrom
- grid.451309.a0000 0004 0449 479XU.S. Department of Energy, Joint Genome Institute, Berkeley, CA USA
| | - Nikos C. Kyrpides
- grid.451309.a0000 0004 0449 479XU.S. Department of Energy, Joint Genome Institute, Berkeley, CA USA
| | - Peter F. Dunfield
- grid.22072.350000 0004 1936 7697Department of Biological Sciences, University of Calgary, 2500 University Dr. NW, Calgary, AB T2N 1N4 Canada
| | - Tanja Woyke
- U.S. Department of Energy, Joint Genome Institute, Berkeley, CA, USA.
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58
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Khedkar S, Smyshlyaev G, Letunic I, Maistrenko OM, Coelho LP, Orakov A, Forslund SK, Hildebrand F, Luetge M, Schmidt TSB, Barabas O, Bork P. Landscape of mobile genetic elements and their antibiotic resistance cargo in prokaryotic genomes. Nucleic Acids Res 2022; 50:3155-3168. [PMID: 35323968 PMCID: PMC8989519 DOI: 10.1093/nar/gkac163] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 01/30/2022] [Accepted: 03/11/2022] [Indexed: 12/02/2022] Open
Abstract
Prokaryotic Mobile Genetic Elements (MGEs) such as transposons, integrons, phages and plasmids, play important roles in prokaryotic evolution and in the dispersal of cargo functions like antibiotic resistance. However, each of these MGE types is usually annotated and analysed individually, hampering a global understanding of phylogenetic and environmental patterns of MGE dispersal. We thus developed a computational framework that captures diverse MGE types, their cargos and MGE-mediated horizontal transfer events, using recombinases as ubiquitous MGE marker genes and pangenome information for MGE boundary estimation. Applied to ∼84k genomes with habitat annotation, we mapped 2.8 million MGE-specific recombinases to six operational MGE types, which together contain on average 13% of all the genes in a genome. Transposable elements (TEs) dominated across all taxa (∼1.7 million occurrences), outnumbering phages and phage-like elements (<0.4 million). We recorded numerous MGE-mediated horizontal transfer events across diverse phyla and habitats involving all MGE types, disentangled and quantified the extent of hitchhiking of TEs (17%) and integrons (63%) with other MGE categories, and established TEs as dominant carriers of antibiotic resistance genes. We integrated all these findings into a resource (proMGE.embl.de), which should facilitate future studies on the large mobile part of genomes and its horizontal dispersal.
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Affiliation(s)
- Supriya Khedkar
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Georgy Smyshlyaev
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany.,Department of Molecular Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Ivica Letunic
- Biobyte solutions GmbH, Bothestr 142, 69117 Heidelberg, Germany
| | - Oleksandr M Maistrenko
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Luis Pedro Coelho
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai 200433, China
| | - Askarbek Orakov
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Sofia K Forslund
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany.,Max Delbrück Centre for Molecular Medicine, Berlin, Germany.,Experimental and Clinical Research Center, Charité-Universitätsmedizin and Max-Delbrück Center, Berlin, Germany.,Charité - Universitätsmedizin Berlin, Berlin, Germany
| | - Falk Hildebrand
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Mechthild Luetge
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Thomas S B Schmidt
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany
| | - Orsolya Barabas
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany.,Department of Molecular Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Peer Bork
- European Molecular Biology Laboratory, Structural and Computational Biology Unit, 69117 Heidelberg, Germany.,Max Delbrück Centre for Molecular Medicine, Berlin, Germany.,Department of Bioinformatics, Biocenter, University of Würzburg, Würzburg, Germany.,Yonsei Frontier Lab (YFL), Yonsei University, Seoul 03722, South Korea
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59
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Zaworski J, Dagva O, Brandt J, Baum C, Ettwiller L, Fomenkov A, Raleigh EA. Reassembling a cannon in the DNA defense arsenal: Genetics of StySA, a BREX phage exclusion system in Salmonella lab strains. PLoS Genet 2022; 18:e1009943. [PMID: 35377874 PMCID: PMC9009780 DOI: 10.1371/journal.pgen.1009943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 04/14/2022] [Accepted: 03/01/2022] [Indexed: 11/18/2022] Open
Abstract
Understanding mechanisms that shape horizontal exchange in prokaryotes is a key problem in biology. A major limit on DNA entry is imposed by restriction-modification (RM) processes that depend on the pattern of DNA modification at host-specified sites. In classical RM, endonucleolytic DNA cleavage follows detection of unprotected sites on entering DNA. Recent investigation has uncovered BREX (BacteRiophage EXclusion) systems. These RM-like activities employ host protection by DNA modification, but immediate replication arrest occurs without evident of nuclease action on unmodified phage DNA. Here we show that the historical stySA RM locus of Salmonella enterica sv Typhimurium is a variant BREX system. A laboratory strain disabled for both the restriction and methylation activity of StySA nevertheless has wild type sequence in pglX, the modification gene homolog. Instead, flanking genes pglZ and brxC each carry multiple mutations (μ) in their C-terminal domains. We further investigate this system in situ, replacing the mutated pglZμ and brxCμ genes with the WT counterpart. PglZ-WT supports methylation in the presence of either BrxCμ or BrxC-WT but not in the presence of a deletion/insertion allele, ΔbrxC::cat. Restriction requires both BrxC-WT and PglZ-WT, implicating the BrxC C-terminus specifically in restriction activity. These results suggests that while BrxC, PglZ and PglX are principal components of the BREX modification activity, BrxL is required for restriction only. Furthermore, we show that a partial disruption of brxL disrupts transcription globally. Horizontal gene transfer is a major driver of evolution and adaptation in bacteria. Genes from outside may be beneficial or dangerous to the receiving cell. Benefits include new food sources such as sugars, or new homes by adhesion, or new resistances, as to antibiotics. Dangers are posed by bacteriophages--viruses that take over the cell machinery, multiply, and release progeny to kill sister cells. Host-dependent restriction-modification systems enable defense that distinguishes relatives from strangers: using a modification pattern (M) carried by DNA bases added by the host cell to prevent restriction (R). Sisters and cousin cells will have the same protective pattern on DNA, while DNA of foreign origin will have the wrong M pattern and be restricted (R, rejected). Typically, restriction involves nuclease digestion. Here we address the enigmatic StySA RM system, one of the earliest to be genetically characterized. It is a variant of the newly recognized defense mechanism, BREX. BREX systems also track DNA history via modification pattern, but restrict by a novel, uncharacterized mechanism. Like other BREX family systems, StySA-BREX modification requires multiple components. When StySA-BREX transcription is unbalanced, we find global disruption of gene transcription. The disruption pattern does not suggest SOS-inducing damage to DNA.
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Affiliation(s)
- Julie Zaworski
- Research Department, New England Biolabs, Ipswich, Massachusetts, United States of America
| | - Oyut Dagva
- Research Department, New England Biolabs, Ipswich, Massachusetts, United States of America
| | - Julius Brandt
- Research Department, New England Biolabs, Ipswich, Massachusetts, United States of America
| | - Chloé Baum
- Research Department, New England Biolabs, Ipswich, Massachusetts, United States of America
| | - Laurence Ettwiller
- Research Department, New England Biolabs, Ipswich, Massachusetts, United States of America
| | - Alexey Fomenkov
- Research Department, New England Biolabs, Ipswich, Massachusetts, United States of America
| | - Elisabeth A. Raleigh
- Research Department, New England Biolabs, Ipswich, Massachusetts, United States of America
- * E-mail:
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60
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Benler S, Koonin EV. Recruitment of Mobile Genetic Elements for Diverse Cellular Functions in Prokaryotes. Front Mol Biosci 2022; 9:821197. [PMID: 35402511 PMCID: PMC8987985 DOI: 10.3389/fmolb.2022.821197] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 02/08/2022] [Indexed: 12/15/2022] Open
Abstract
Prokaryotic genomes are replete with mobile genetic elements (MGE) that span a continuum of replication autonomy. On numerous occasions during microbial evolution, diverse MGE lose their autonomy altogether but, rather than being quickly purged from the host genome, assume a new function that benefits the host, rendering the immobilized MGE subject to purifying selection, and resulting in its vertical inheritance. This mini-review highlights the diversity of the repurposed (exapted) MGE as well as the plethora of cellular functions that they perform. The principal contribution of the exaptation of MGE and their components is to the prokaryotic functional systems involved in biological conflicts, and in particular, defense against viruses and other MGE. This evolutionary entanglement between MGE and defense systems appears to stem both from mechanistic similarities and from similar evolutionary predicaments whereby both MGEs and defense systems tend to incur fitness costs to the hosts and thereby evolve mechanisms for survival including horizontal mobility, causing host addiction, and exaptation for functions beneficial to the host. The examples discussed demonstrate that the identity of an MGE, overall mobility and relationship with the host cell (mutualistic, symbiotic, commensal, or parasitic) are all factors that affect exaptation.
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Affiliation(s)
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, United States
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61
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Roy SW. Optimality versus opportunity the recurrent evolution of similar sex determination mechanisms. J Hered 2022; 113:235-237. [PMID: 35325170 DOI: 10.1093/jhered/esac001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 03/19/2022] [Indexed: 11/15/2022] Open
Affiliation(s)
- Scott William Roy
- San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
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62
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Recombination resolves the cost of horizontal gene transfer in experimental populations of Helicobacter pylori. Proc Natl Acad Sci U S A 2022; 119:e2119010119. [PMID: 35298339 PMCID: PMC8944584 DOI: 10.1073/pnas.2119010119] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Horizontal gene transfer (HGT)—the transfer of DNA between lineages—is responsible for a large proportion of the genetic variation that contributes to evolution in microbial populations. While HGT can bring beneficial genetic innovation, the transfer of DNA from other species or strains can also have deleterious effects. In this study, we evolve populations of the bacteria Helicobacter pylori and use DNA sequencing to identify over 40,000 genetic variants transferred by HGT. We measure the cost of many of these and find that both strongly beneficial mutations and deleterious mutations are genetic variants transferred by natural transformation. Importantly, we also show how recombination that separates linked beneficial and deleterious mutations resolves the cost of HGT. Horizontal gene transfer (HGT) is important for microbial evolution, yet we know little about the fitness effects and dynamics of horizontally transferred genetic variants. In this study, we evolve laboratory populations of Helicobacter pylori, which take up DNA from their environment by natural transformation, and measure the fitness effects of thousands of transferred genetic variants. We find that natural transformation increases the rate of adaptation but comes at the cost of significant genetic load. We show that this cost is circumvented by recombination, which increases the efficiency of selection by decoupling deleterious and beneficial genetic variants. Our results show that adaptation with HGT, pervasive in natural microbial populations, is shaped by a combination of selection, recombination, and genetic drift not accounted for in existing models of evolution.
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63
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Ibarra-Chávez R, Brady A, Chen J, Penadés JR, Haag AF. Phage-inducible chromosomal islands promote genetic variability by blocking phage reproduction and protecting transductants from phage lysis. PLoS Genet 2022; 18:e1010146. [PMID: 35344558 PMCID: PMC8989297 DOI: 10.1371/journal.pgen.1010146] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 04/07/2022] [Accepted: 03/14/2022] [Indexed: 11/18/2022] Open
Abstract
Phage-inducible chromosomal islands (PICIs) are a widespread family of highly mobile genetic elements that disseminate virulence and toxin genes among bacterial populations. Since their life cycle involves induction by helper phages, they are important players in phage evolution and ecology. PICIs can interfere with the lifecycle of their helper phages at different stages resulting frequently in reduced phage production after infection of a PICI-containing strain. Since phage defense systems have been recently shown to be beneficial for the acquisition of exogenous DNA via horizontal gene transfer, we hypothesized that PICIs could provide a similar benefit to their hosts and tested the impact of PICIs in recipient strains on host cell viability, phage propagation and transfer of genetic material. Here we report an important role for PICIs in bacterial evolution by promoting the survival of phage-mediated transductants of chromosomal or plasmid DNA. The presence of PICIs generates favorable conditions for population diversification and the inheritance of genetic material being transferred, such as antibiotic resistance and virulence genes. Our results show that by interfering with phage reproduction, PICIs can protect the bacterial population from phage attack, increasing the overall survival of the bacterial population as well as the transduced cells. Moreover, our results also demonstrate that PICIs reduce the frequency of lysogenization after temperate phage infection, creating a more genetically diverse bacterial population with increased bet-hedging opportunities to adapt to new niches. In summary, our results identify a new role for the PICIs and highlight them as important drivers of bacterial evolution.
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Affiliation(s)
- Rodrigo Ibarra-Chávez
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- Department of Biology, Section of Microbiology, University of Copenhagen, Copenhagen, Denmark
| | - Aisling Brady
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, United Kingdom
| | - John Chen
- Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - José R. Penadés
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, United Kingdom
- Universidad CEU Cardenal Herrera, Moncada, Spain
| | - Andreas F. Haag
- Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- School of Medicine, University of St Andrews, North Haugh, St Andrews, United Kingdom
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64
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Zhou Y, Zhou W, Zhou J, Yan J, Xu D, Zheng X, Zong S, Jiang P, Tian S, Han J, Qu D. The Clustered Regularly Interspaced Short Palindromic Repeats-Associated System and Its Relationship With Mobile Genetic Elements in Klebsiella. Front Microbiol 2022; 12:790673. [PMID: 35185818 PMCID: PMC8847753 DOI: 10.3389/fmicb.2021.790673] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 12/21/2021] [Indexed: 12/27/2022] Open
Abstract
Microorganisms have developed many strategies in the process of long-term defense against external attacks, one of which is the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated proteins (Cas) bacterial immunological system. In this study, the whole genome of 300 strains of Klebsiella was collected, the CRISPR-Cas system in the strains was statistically analyzed, and the types and structures of CRISPR system in Klebsiella were explored, as well as the correlation between CRISPR and mobile genetic elements (MGEs). Through principal component analysis (PCA), we found that Cas gene, plasmids, integron, IS1, IS609, and enzymes of DNA metabolism were closely related to CRISPR-Cas. Compared the structural characteristics of plasmids, the DinG family helicases, Cas6, Csf2, and IS5 were observed near the CRISPR loci in plasmid, which is also confirmed by the results of PCA that they may be important factors affecting the plasmid with CRISPR.
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Affiliation(s)
- Yuqiao Zhou
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
| | - Wei Zhou
- Zhejiang Provincial Center for Animal Disease Prevention and Control, Hangzhou, China
| | - Jinzhi Zhou
- Zhejiang Provincial Center for Animal Disease Prevention and Control, Hangzhou, China
| | - Jinchang Yan
- Agricultural and Rural Bureau of Wangdian Town, Jiaxing, China
| | - Dingting Xu
- The Second Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China
| | - Xiner Zheng
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
| | - Shuaizhou Zong
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
| | - Ping Jiang
- The Eighth People's Hospital of Qingdao, Qingdao, China
| | - Shiyi Tian
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
| | - Jianzhong Han
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
| | - Daofeng Qu
- Food Safety Key Laboratory of Zhejiang Province, School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China
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65
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Vanchurin V, Wolf YI, Katsnelson MI, Koonin EV. Toward a theory of evolution as multilevel learning. Proc Natl Acad Sci U S A 2022; 119:e2120037119. [PMID: 35121666 PMCID: PMC8833143 DOI: 10.1073/pnas.2120037119] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 01/03/2022] [Indexed: 12/28/2022] Open
Abstract
We apply the theory of learning to physically renormalizable systems in an attempt to outline a theory of biological evolution, including the origin of life, as multilevel learning. We formulate seven fundamental principles of evolution that appear to be necessary and sufficient to render a universe observable and show that they entail the major features of biological evolution, including replication and natural selection. It is shown that these cornerstone phenomena of biology emerge from the fundamental features of learning dynamics such as the existence of a loss function, which is minimized during learning. We then sketch the theory of evolution using the mathematical framework of neural networks, which provides for detailed analysis of evolutionary phenomena. To demonstrate the potential of the proposed theoretical framework, we derive a generalized version of the Central Dogma of molecular biology by analyzing the flow of information during learning (back propagation) and predicting (forward propagation) the environment by evolving organisms. The more complex evolutionary phenomena, such as major transitions in evolution (in particular, the origin of life), have to be analyzed in the thermodynamic limit, which is described in detail in the paper by Vanchurin et al. [V. Vanchurin, Y. I. Wolf, E. V. Koonin, M. I. Katsnelson, Proc. Natl. Acad. Sci. U.S.A. 119, 10.1073/pnas.2120042119 (2022)].
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Affiliation(s)
- Vitaly Vanchurin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894;
- Duluth Institute for Advanced Study, Duluth, MN 55804
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894
| | - Mikhail I Katsnelson
- Institute for Molecules and Materials, Radboud University, Nijmegen 6525AJ, The Netherlands
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894;
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66
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Klompe SE, Jaber N, Beh LY, Mohabir JT, Bernheim A, Sternberg SH. Evolutionary and mechanistic diversity of Type I-F CRISPR-associated transposons. Mol Cell 2022; 82:616-628.e5. [PMID: 35051352 PMCID: PMC8849592 DOI: 10.1016/j.molcel.2021.12.021] [Citation(s) in RCA: 36] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 10/20/2021] [Accepted: 12/16/2021] [Indexed: 02/05/2023]
Abstract
Canonical CRISPR-Cas systems utilize RNA-guided nucleases for targeted cleavage of foreign nucleic acids, whereas some nuclease-deficient CRISPR-Cas complexes have been repurposed to direct the insertion of Tn7-like transposons. Here, we established a bioinformatic and experimental pipeline to comprehensively explore the diversity of Type I-F CRISPR-associated transposons. We report DNA integration for 20 systems and identify a highly active subset that exhibits complete orthogonality in transposon DNA mobilization. We reveal the modular nature of CRISPR-associated transposons by exploring the horizontal acquisition of targeting modules and by characterizing a system that encodes both a programmable, RNA-dependent pathway, and a fixed, RNA-independent pathway. Finally, we analyzed transposon-encoded cargo genes and found the striking presence of anti-phage defense systems, suggesting a role in transmitting innate immunity between bacteria. Collectively, this study substantially advances our biological understanding of CRISPR-associated transposon function and expands the suite of RNA-guided transposases for programmable, large-scale genome engineering.
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MESH Headings
- Bacterial Proteins/genetics
- Bacterial Proteins/metabolism
- CRISPR-Cas Systems
- Clustered Regularly Interspaced Short Palindromic Repeats
- DNA Transposable Elements/genetics
- DNA, Bacterial/genetics
- DNA, Bacterial/metabolism
- Escherichia coli/genetics
- Escherichia coli/immunology
- Escherichia coli/metabolism
- Evolution, Molecular
- Gene Editing
- Gene Expression Regulation, Bacterial
- Genetic Variation
- Immunity, Innate
- RNA, Bacterial/genetics
- RNA, Bacterial/metabolism
- RNA, Guide, CRISPR-Cas Systems/genetics
- RNA, Guide, CRISPR-Cas Systems/metabolism
- Transposases/genetics
- Transposases/metabolism
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Affiliation(s)
- Sanne E Klompe
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Nora Jaber
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Leslie Y Beh
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA
| | - Jason T Mohabir
- Department of Computer Science, Columbia University, New York, NY 10027, USA
| | - Aude Bernheim
- French National Institute of Health and Medical Research (INSERM), University of Paris, Paris, France
| | - Samuel H Sternberg
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA.
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67
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Wu F, Speth DR, Philosof A, Crémière A, Narayanan A, Barco RA, Connon SA, Amend JP, Antoshechkin IA, Orphan VJ. Unique mobile elements and scalable gene flow at the prokaryote-eukaryote boundary revealed by circularized Asgard archaea genomes. Nat Microbiol 2022; 7:200-212. [PMID: 35027677 PMCID: PMC8813620 DOI: 10.1038/s41564-021-01039-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 11/29/2021] [Indexed: 12/22/2022]
Abstract
Eukaryotic genomes are known to have garnered innovations from both archaeal and bacterial domains but the sequence of events that led to the complex gene repertoire of eukaryotes is largely unresolved. Here, through the enrichment of hydrothermal vent microorganisms, we recovered two circularized genomes of Heimdallarchaeum species that belong to an Asgard archaea clade phylogenetically closest to eukaryotes. These genomes reveal diverse mobile elements, including an integrative viral genome that bidirectionally replicates in a circular form and aloposons, transposons that encode the 5,000 amino acid-sized proteins Otus and Ephialtes. Heimdallaechaeal mobile elements have garnered various genes from bacteria and bacteriophages, likely playing a role in shuffling functions across domains. The number of archaea- and bacteria-related genes follow strikingly different scaling laws in Asgard archaea, exhibiting a genome size-dependent ratio and a functional division resembling the bacteria- and archaea-derived gene repertoire across eukaryotes. Bacterial gene import has thus likely been a continuous process unaltered by eukaryogenesis and scaled up through genome expansion. Our data further highlight the importance of viewing eukaryogenesis in a pan-Asgard context, which led to the proposal of a conceptual framework, that is, the Heimdall nucleation-decentralized innovation-hierarchical import model that accounts for the emergence of eukaryotic complexity.
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Affiliation(s)
- Fabai Wu
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA.
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
| | - Daan R Speth
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Alon Philosof
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
| | - Antoine Crémière
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
| | - Aditi Narayanan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Roman A Barco
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
| | - Stephanie A Connon
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA
| | - Jan P Amend
- Department of Earth Sciences, University of Southern California, Los Angeles, CA, USA
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, USA
| | - Igor A Antoshechkin
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Victoria J Orphan
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA.
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
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68
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Wallau GL. RNA virus EVEs in insect genomes. CURRENT OPINION IN INSECT SCIENCE 2022; 49:42-47. [PMID: 34839033 DOI: 10.1016/j.cois.2021.11.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 11/01/2021] [Accepted: 11/16/2021] [Indexed: 06/13/2023]
Abstract
Insects are infected by a diverse set of RNA viruses that are more broadly distinguished by their ability to infect single or multiple host species. During replication into the host cell, partial or complete double strand DNA derived from the viral genome may be integrated into their host genomes giving origin to endogenous viral elements (EVEs). EVEs from RNA viruses have been identified in a variety of insect genomes showing different evolutionary trajectories: from highly degraded viral genomic remains to partial and complete viral coding regions. Limited functional knowledge exists about RNA EVEs impact on hosts and circulating viruses, but exciting results are emerging showing a complex arms race interplay that influences the evolutionary trajectory of these interacting entities.
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Affiliation(s)
- Gabriel Luz Wallau
- Departamento de Entomologia e Núcleo de Bioinformática, Instituto Aggeu Magalhães (IAM), Fundação Oswaldo Cruz (FIOCRUZ), Recife, Pernambuco, CEP: 50.740-465, Brazil.
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69
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Rocha EPC, Bikard D. Microbial defenses against mobile genetic elements and viruses: Who defends whom from what? PLoS Biol 2022; 20:e3001514. [PMID: 35025885 PMCID: PMC8791490 DOI: 10.1371/journal.pbio.3001514] [Citation(s) in RCA: 75] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 01/26/2022] [Indexed: 12/27/2022] Open
Abstract
Prokaryotes have numerous mobile genetic elements (MGEs) that mediate horizontal gene transfer (HGT) between cells. These elements can be costly, even deadly, and cells use numerous defense systems to filter, control, or inactivate them. Recent studies have shown that prophages, conjugative elements, their parasites (phage satellites and mobilizable elements), and other poorly described MGEs encode defense systems homologous to those of bacteria. These constitute a significant fraction of the repertoire of cellular defense genes. As components of MGEs, these defense systems have presumably evolved to provide them, not the cell, adaptive functions. While the interests of the host and MGEs are aligned when they face a common threat such as an infection by a virulent phage, defensive functions carried by MGEs might also play more selfish roles to fend off other antagonistic MGEs or to ensure their maintenance in the cell. MGEs are eventually lost from the surviving host genomes by mutational processes and their defense systems can be co-opted when they provide an advantage to the cell. The abundance of defense systems in MGEs thus sheds new light on the role, effect, and fate of the so-called "cellular defense systems," whereby they are not only merely microbial defensive weapons in a 2-partner arms race, but also tools of intragenomic conflict between multiple genetic elements with divergent interests that shape cell fate and gene flow at the population level.
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Affiliation(s)
- Eduardo P. C. Rocha
- Institut Pasteur, Université de Paris, CNRS UMR3525, Microbial Evolutionary Genomics, Paris, France
| | - David Bikard
- Institut Pasteur, Université de Paris, Synthetic Biology, Department of Microbiology, Paris, France
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70
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Abstract
The principal biological function of bacterial and archaeal CRISPR systems is RNA-guided adaptive immunity against viruses and other mobile genetic elements (MGEs). These systems show remarkable evolutionary plasticity and functional versatility at multiple levels, including both the defense mechanisms that lead to direct, specific elimination of the target DNA or RNA and those that cause programmed cell death (PCD) or induction of dormancy. This flexibility is also evident in the recruitment of CRISPR systems for nondefense functions. Defective CRISPR systems or individual CRISPR components have been recruited by transposons for RNA-guided transposition, by plasmids for interplasmid competition, and by viruses for antidefense and interviral conflicts. Additionally, multiple highly derived CRISPR variants of yet unknown functions have been discovered. A major route of innovation in CRISPR evolution is the repurposing of diverged repeat variants encoded outside CRISPR arrays for various structural and regulatory functions. The evolutionary plasticity and functional versatility of CRISPR systems are striking manifestations of the ubiquitous interplay between defense and “normal” cellular functions. The CRISPR systems show remarkable functional versatility beyond their principal function as an adaptive immune mechanism. This Essay discusses how derived CRISPR systems have been recruited by transposons on multiple occasions and mediate RNA-guided transposition; derived CRISPR RNAs are frequently recruited for regulatory functions.
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Affiliation(s)
- Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, United States of America
- * E-mail:
| | - Kira S. Makarova
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland, United States of America
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71
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Haase AD. An introduction to PIWI-interacting RNAs (piRNAs) in the context of metazoan small RNA silencing pathways. RNA Biol 2022; 19:1094-1102. [PMID: 36217279 PMCID: PMC9559041 DOI: 10.1080/15476286.2022.2132359] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 09/23/2022] [Indexed: 11/05/2022] Open
Abstract
PIWI proteins and their associated PIWI-interacting RNAs (piRNAs) constitute a small RNA-based adaptive immune system that restricts the deleterious activity of mobile genetic elements to protect genome integrity. Self/nonself discrimination is at the very core of successful defence and relies on complementary base-pairing in RNA-guided immunity. How the millions of piRNA sequences faithfully discriminate between self and nonself and how they adapt to novel genomic invaders remain key outstanding questions in genome biology. This review aims to introduce principles of piRNA silencing in the context of metazoan small RNA pathways. A distinct feature of piRNAs is their origin from single-stranded instead of double-stranded RNA precursors, and piRNAs require a unique set of processing factors. Novel nucleases, helicases and RNA binding proteins have been identified in piRNA biology, and while we are starting to understand some mechanisms of piRNA biogenesis and function, this diverse and prolific class of small RNAs remains full of surprises.
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Affiliation(s)
- Astrid D. Haase
- National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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72
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Abstract
Gene drives are selfish genetic elements that are transmitted to progeny at super-Mendelian (>50%) frequencies. Recently developed CRISPR-Cas9-based gene-drive systems are highly efficient in laboratory settings, offering the potential to reduce the prevalence of vector-borne diseases, crop pests and non-native invasive species. However, concerns have been raised regarding the potential unintended impacts of gene-drive systems. This Review summarizes the phenomenal progress in this field, focusing on optimal design features for full-drive elements (drives with linked Cas9 and guide RNA components) that either suppress target mosquito populations or modify them to prevent pathogen transmission, allelic drives for updating genetic elements, mitigating strategies including trans-complementing split-drives and genetic neutralizing elements, and the adaptation of drive technology to other organisms. These scientific advances, combined with ethical and social considerations, will facilitate the transparent and responsible advancement of these technologies towards field implementation.
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Affiliation(s)
- Ethan Bier
- Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, USA.
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73
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Koonin EV, Dolja VV, Krupovic M, Kuhn JH. Viruses Defined by the Position of the Virosphere within the Replicator Space. Microbiol Mol Biol Rev 2021; 85:e0019320. [PMID: 34468181 PMCID: PMC8483706 DOI: 10.1128/mmbr.00193-20] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Originally, viruses were defined as miniscule infectious agents that passed through filters that retain even the smallest cells. Subsequently, viruses were considered obligate intracellular parasites whose reproduction depends on their cellular hosts for energy supply and molecular building blocks. However, these features are insufficient to unambiguously define viruses as they are broadly understood today. We outline possible approaches to define viruses and explore the boundaries of the virosphere within the virtual space of replicators and the relationships between viruses and other types of replicators. Regardless of how, exactly, viruses are defined, viruses clearly have evolved on many occasions from nonviral replicators, such as plasmids, by recruiting host proteins to become virion components. Conversely, other types of replicators have repeatedly evolved from viruses. Thus, the virosphere is a dynamic entity with extensive evolutionary traffic across its boundaries. We argue that the virosphere proper, here termed orthovirosphere, consists of a distinct variety of replicators that encode structural proteins encasing the replicators' genomes, thereby providing protection and facilitating transmission among hosts. Numerous and diverse replicators, such as virus-derived but capsidless RNA and DNA elements, or defective viruses occupy the zone surrounding the orthovirosphere in the virtual replicator space. We define this zone as the perivirosphere. Although intense debates on the nature of certain replicators that adorn the internal and external boundaries of the virosphere will likely continue, we present an operational definition of virus that recently has been accepted by the International Committee on 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
- Archaeal Virology Unit, Institut Pasteur, Paris, France
| | - 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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74
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Rybarski JR, Hu K, Hill AM, Wilke CO, Finkelstein IJ. Metagenomic discovery of CRISPR-associated transposons. Proc Natl Acad Sci U S A 2021; 118:e2112279118. [PMID: 34845024 PMCID: PMC8670466 DOI: 10.1073/pnas.2112279118] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 10/26/2021] [Indexed: 12/26/2022] Open
Abstract
CRISPR-associated Tn7 transposons (CASTs) co-opt cas genes for RNA-guided transposition. CASTs are exceedingly rare in genomic databases; recent surveys have reported Tn7-like transposons that co-opt Type I-F, I-B, and V-K CRISPR effectors. Here, we expand the diversity of reported CAST systems via a bioinformatic search of metagenomic databases. We discover architectures for all known CASTs, including arrangements of the Cascade effectors, target homing modalities, and minimal V-K systems. We also describe families of CASTs that have co-opted the Type I-C and Type IV CRISPR-Cas systems. Our search for non-Tn7 CASTs identifies putative candidates that include a nuclease dead Cas12. These systems shed light on how CRISPR systems have coevolved with transposases and expand the programmable gene-editing toolkit.
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Affiliation(s)
- James R Rybarski
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712
| | - Kuang Hu
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712
| | - Alexis M Hill
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712
| | - Claus O Wilke
- Department of Integrative Biology, The University of Texas at Austin, Austin, TX 78712;
| | - Ilya J Finkelstein
- Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712;
- Center for Systems and Synthetic Biology, The University of Texas at Austin, Austin, TX 78712
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75
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Ibarra-Chávez R, Hansen MF, Pinilla-Redondo R, Seed KD, Trivedi U. Phage satellites and their emerging applications in biotechnology. FEMS Microbiol Rev 2021; 45:fuab031. [PMID: 34104956 PMCID: PMC8632786 DOI: 10.1093/femsre/fuab031] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Accepted: 06/07/2021] [Indexed: 12/11/2022] Open
Abstract
The arms race between (bacterio)phages and their hosts is a recognised hot spot for genome evolution. Indeed, phages and their components have historically paved the way for many molecular biology techniques and biotech applications. Further exploration into their complex lifestyles has revealed that phages are often parasitised by distinct types of hyperparasitic mobile genetic elements. These so-called phage satellites exploit phages to ensure their own propagation and horizontal transfer into new bacterial hosts, and their prevalence and peculiar lifestyle has caught the attention of many researchers. Here, we review the parasite-host dynamics of the known phage satellites, their genomic organisation and their hijacking mechanisms. Finally, we discuss how these elements can be repurposed for diverse biotech applications, kindling a new catalogue of exciting tools for microbiology and synthetic biology.
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Affiliation(s)
- Rodrigo Ibarra-Chávez
- Section of Microbiology, Department of Biology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Mads Frederik Hansen
- Section of Microbiology, Department of Biology, University of Copenhagen, 2100 Copenhagen, Denmark
- Max Planck Institute for Terrestrial Microbiology, 35043 Marburg, Germany
| | - Rafael Pinilla-Redondo
- Section of Microbiology, Department of Biology, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Kimberley D Seed
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA
- Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
| | - Urvish Trivedi
- Section of Microbiology, Department of Biology, University of Copenhagen, 2100 Copenhagen, Denmark
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76
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To export, or not to export: how nuclear export factor variants resolve Piwi's dilemma. Biochem Soc Trans 2021; 49:2073-2079. [PMID: 34643228 DOI: 10.1042/bst20201171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 09/06/2021] [Accepted: 09/15/2021] [Indexed: 11/17/2022]
Abstract
Piwi-interacting RNAs (piRNAs) defend animal gonads by guiding PIWI-clade Argonaute proteins to silence transposons. The nuclear Piwi/piRNA complexes confer transcriptional repression of transposons, which is accompanied with heterochromatin formation at target loci. On the other hand, piRNA clusters, genomic loci that transcribe piRNA precursors composed of transposon fragments, are often recognized by piRNAs to define their heterochromatic identity. Therefore, Piwi/piRNA complexes must resolve this conundrum of silencing transposons while allowing the expression of piRNA precursors, at least in Drosophila germlines. This review is focused on recent advances how the piRNA pathway deals with this genetic conflict.
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77
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Viviani A, Ventimiglia M, Fambrini M, Vangelisti A, Mascagni F, Pugliesi C, Usai G. Impact of transposable elements on the evolution of complex living systems and their epigenetic control. Biosystems 2021; 210:104566. [PMID: 34718084 DOI: 10.1016/j.biosystems.2021.104566] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 10/21/2021] [Accepted: 10/21/2021] [Indexed: 10/20/2022]
Abstract
Transposable elements (TEs) contribute to genomic innovations, as well as genome instability, across a wide variety of species. Popular designations such as 'selfish DNA' and 'junk DNA,' common in the 1980s, may be either inaccurate or misleading, while a more enlightened view of the TE-host relationship covers a range from parasitism to mutualism. Both plant and animal hosts have evolved epigenetic mechanisms to reduce the impact of TEs, both by directly silencing them and by reducing their ability to transpose in the genome. However, TEs have also been co-opted by both plant and animal genomes to perform a variety of physiological functions, ranging from TE-derived proteins acting directly in normal biological functions to innovations in transcription factor activity and also influencing gene expression. Their presence, in fact, can affect a range of features at genome, phenotype, and population levels. The impact TEs have had on evolution is multifaceted, and many aspects still remain unexplored. In this review, the epigenetic control of TEs is contextualized according to the evolution of complex living systems.
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Affiliation(s)
- Ambra Viviani
- Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto, 80-56124, Pisa, Italy
| | - Maria Ventimiglia
- Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto, 80-56124, Pisa, Italy
| | - Marco Fambrini
- Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto, 80-56124, Pisa, Italy
| | - Alberto Vangelisti
- Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto, 80-56124, Pisa, Italy
| | - Flavia Mascagni
- Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto, 80-56124, Pisa, Italy
| | - Claudio Pugliesi
- Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto, 80-56124, Pisa, Italy.
| | - Gabriele Usai
- Department of Agriculture, Food and Environment (DAFE), University of Pisa, Via del Borghetto, 80-56124, Pisa, Italy
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78
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Ho EKH, Bellis ES, Calkins J, Adrion JR, Latta IV LC, Schaack S. Engines of change: Transposable element mutation rates are high and variable within Daphnia magna. PLoS Genet 2021; 17:e1009827. [PMID: 34723969 PMCID: PMC8594854 DOI: 10.1371/journal.pgen.1009827] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 11/16/2021] [Accepted: 09/16/2021] [Indexed: 12/22/2022] Open
Abstract
Transposable elements (TEs) represent a major portion of most eukaryotic genomes, yet little is known about their mutation rates or how their activity is shaped by other evolutionary forces. Here, we compare short- and long-term patterns of genome-wide mutation accumulation (MA) of TEs among 9 genotypes from three populations of Daphnia magna from across a latitudinal gradient. While the overall proportion of the genome comprised of TEs is highly similar among genotypes from Finland, Germany, and Israel, populations are distinguishable based on patterns of insertion site polymorphism. Our direct rate estimates indicate TE movement is highly variable (net rates ranging from -11.98 to 12.79 x 10-5 per copy per generation among genotypes), differing both among populations and TE families. Although gains outnumber losses when selection is minimized, both types of events appear to be highly deleterious based on their low frequency in control lines where propagation is not limited to random, single-progeny descent. With rate estimates 4 orders of magnitude higher than base substitutions, TEs clearly represent a highly mutagenic force in the genome. Quantifying patterns of intra- and interspecific variation in TE mobility with and without selection provides insight into a powerful mechanism generating genetic variation in the genome.
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Affiliation(s)
- Eddie K. H. Ho
- Department of Biology, Reed College, Portland, Oregon, United States of America
| | - Emily S. Bellis
- Department of Biology, Reed College, Portland, Oregon, United States of America
- Department of Computer Science, Arkansas State University, Jonesboro, Arkansas, United States of America
| | - Jaclyn Calkins
- Department of Biology, Reed College, Portland, Oregon, United States of America
- College of Human Medicine, Michigan State University, East Lansing, Michigan, United States of America
| | - Jeffrey R. Adrion
- Institute of Ecology and Evolution, University of Oregon, Eugene, Oregon, United States of America
| | - Leigh C. Latta IV
- Department of Biology, Reed College, Portland, Oregon, United States of America
- Lewis-Clark State College, Lewiston, Idaho, United States of America
| | - Sarah Schaack
- Department of Biology, Reed College, Portland, Oregon, United States of America
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79
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Flores Ramos S, Brugger SD, Escapa IF, Skeete CA, Cotton SL, Eslami SM, Gao W, Bomar L, Tran TH, Jones DS, Minot S, Roberts RJ, Johnston CD, Lemon KP. Genomic Stability and Genetic Defense Systems in Dolosigranulum pigrum, a Candidate Beneficial Bacterium from the Human Microbiome. mSystems 2021; 6:e0042521. [PMID: 34546072 PMCID: PMC8547433 DOI: 10.1128/msystems.00425-21] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Accepted: 08/27/2021] [Indexed: 01/05/2023] Open
Abstract
Dolosigranulum pigrum is positively associated with indicators of health in multiple epidemiological studies of human nasal microbiota. Knowledge of the basic biology of D. pigrum is a prerequisite for evaluating its potential for future therapeutic use; however, such data are very limited. To gain insight into D. pigrum's chromosomal structure, pangenome, and genomic stability, we compared the genomes of 28 D. pigrum strains that were collected across 20 years. Phylogenomic analysis showed closely related strains circulating over this period and closure of 19 genomes revealed highly conserved chromosomal synteny. Gene clusters involved in the mobilome and in defense against mobile genetic elements (MGEs) were enriched in the accessory genome versus the core genome. A systematic analysis for MGEs identified the first candidate D. pigrum prophage and insertion sequence. A systematic analysis for genetic elements that limit the spread of MGEs, including restriction modification (RM), CRISPR-Cas, and deity-named defense systems, revealed strain-level diversity in host defense systems that localized to specific genomic sites, including one RM system hot spot. Analysis of CRISPR spacers pointed to a wealth of MGEs against which D. pigrum defends itself. These results reveal a role for horizontal gene transfer and mobile genetic elements in strain diversification while highlighting that in D. pigrum this occurs within the context of a highly stable chromosomal organization protected by a variety of defense mechanisms. IMPORTANCE Dolosigranulum pigrum is a candidate beneficial bacterium with potential for future therapeutic use. This is based on its positive associations with characteristics of health in multiple studies of human nasal microbiota across the span of human life. For example, high levels of D. pigrum nasal colonization in adults predicts the absence of Staphylococcus aureus nasal colonization. Also, D. pigrum nasal colonization in young children is associated with healthy control groups in studies of middle ear infections. Our analysis of 28 genomes revealed a remarkable stability of D. pigrum strains colonizing people in the United States across a 20-year span. We subsequently identified factors that can influence this stability, including genomic stability, phage predators, the role of MGEs in strain-level variation, and defenses against MGEs. Finally, these D. pigrum strains also lacked predicted virulence factors. Overall, these findings add additional support to the potential for D. pigrum as a therapeutic bacterium.
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Affiliation(s)
| | - Silvio D. Brugger
- The Forsyth Institute (Microbiology), Cambridge, Massachusetts, USA
- Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Isabel Fernandez Escapa
- The Forsyth Institute (Microbiology), Cambridge, Massachusetts, USA
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
- Alkek Center for Metagenomics and Microbiome Research, Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | | | - Sean L. Cotton
- The Forsyth Institute (Microbiology), Cambridge, Massachusetts, USA
| | - Sara M. Eslami
- The Forsyth Institute (Microbiology), Cambridge, Massachusetts, USA
| | - Wei Gao
- The Forsyth Institute (Microbiology), Cambridge, Massachusetts, USA
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Lindsey Bomar
- The Forsyth Institute (Microbiology), Cambridge, Massachusetts, USA
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
| | - Tommy H. Tran
- Alkek Center for Metagenomics and Microbiome Research, Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
| | - Dakota S. Jones
- Vaccine and Infectious Diseases Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Samuel Minot
- Vaccine and Infectious Diseases Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | | | - Christopher D. Johnston
- The Forsyth Institute (Microbiology), Cambridge, Massachusetts, USA
- Department of Oral Medicine, Infection, and Immunity, Harvard School of Dental Medicine, Boston, Massachusetts, USA
- Vaccine and Infectious Diseases Division, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Katherine P. Lemon
- The Forsyth Institute (Microbiology), Cambridge, Massachusetts, USA
- Alkek Center for Metagenomics and Microbiome Research, Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, USA
- Division of Infectious Diseases, Boston Children’s Hospital, Harvard Medical School, Boston, Massachusetts, USA
- Section of Infectious Diseases, Texas Children’s Hospital, Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
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80
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Hussain FA, Dubert J, Elsherbini J, Murphy M, VanInsberghe D, Arevalo P, Kauffman K, Rodino-Janeiro BK, Gavin H, Gomez A, Lopatina A, Le Roux F, Polz MF. Rapid evolutionary turnover of mobile genetic elements drives bacterial resistance to phages. Science 2021; 374:488-492. [PMID: 34672730 DOI: 10.1126/science.abb1083] [Citation(s) in RCA: 79] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
[Figure: see text].
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Affiliation(s)
- Fatima Aysha Hussain
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Javier Dubert
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.,Department of Microbiology and Parasitology, University of Santiago de Compostela, Santiago de Compostela, Spain
| | - Joseph Elsherbini
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Mikayla Murphy
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - David VanInsberghe
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Philip Arevalo
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kathryn Kauffman
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Bruno Kotska Rodino-Janeiro
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.,Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Center for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Hannah Gavin
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Annika Gomez
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Anna Lopatina
- Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Center for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
| | - Frédérique Le Roux
- Ifremer, Unité Physiologie Fonctionnelle des Organismes Marins, CS 10070, F-29280 Plouzané, France.,Sorbonne Universités, UPMC Paris 06, CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, F-29688 Roscoff Cedex, France
| | - Martin F Polz
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA.,Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Center for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
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81
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Pinilla-Redondo R, Russel J, Mayo-Muñoz D, Shah SA, Garrett RA, Nesme J, Madsen JS, Fineran PC, Sørensen SJ. CRISPR-Cas systems are widespread accessory elements across bacterial and archaeal plasmids. Nucleic Acids Res 2021; 50:4315-4328. [PMID: 34606604 PMCID: PMC9071438 DOI: 10.1093/nar/gkab859] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Revised: 09/08/2021] [Accepted: 10/02/2021] [Indexed: 12/12/2022] Open
Abstract
Many prokaryotes encode CRISPR-Cas systems as immune protection against mobile genetic elements (MGEs), yet a number of MGEs also harbor CRISPR-Cas components. With a few exceptions, CRISPR-Cas loci encoded on MGEs are uncharted and a comprehensive analysis of their distribution, prevalence, diversity, and function is lacking. Here, we systematically investigated CRISPR-Cas loci across the largest curated collection of natural bacterial and archaeal plasmids. CRISPR-Cas loci are widely but heterogeneously distributed across plasmids and, in comparison to host chromosomes, their mean prevalence per Mbp is higher and their distribution is distinct. Furthermore, the spacer content of plasmid CRISPRs exhibits a strong targeting bias towards other plasmids, while chromosomal arrays are enriched with virus-targeting spacers. These contrasting targeting preferences highlight the genetic independence of plasmids and suggest a major role for mediating plasmid-plasmid conflicts. Altogether, CRISPR-Cas are frequent accessory components of many plasmids, which is an overlooked phenomenon that possibly facilitates their dissemination across microbiomes.
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Affiliation(s)
- Rafael Pinilla-Redondo
- Section of Microbiology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark.,Department of Technological Educations, University College Copenhagen, Sigurdsgade 26, 2200 Copenhagen, Denmark
| | - Jakob Russel
- Section of Microbiology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark
| | - David Mayo-Muñoz
- Section of Microbiology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark.,Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Shiraz A Shah
- Copenhagen Prospective Studies on Asthma in Childhood (COPSAC), Herlev and Gentofte Hospital, University of Copenhagen, Ledreborg Alle 34, 2820 Gentofte, Denmark
| | - Roger A Garrett
- Danish Archaea Centre, Department of Biology, University of Copenhagen, University of Copenhagen, Ole Maaløes Vej 5, 2200 Copenhagen, Denmark
| | - Joseph Nesme
- Section of Microbiology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark
| | - Jonas S Madsen
- Section of Microbiology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark
| | - Peter C Fineran
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand.,Bio-Protection Research Centre, University of Otago, Dunedin, New Zealand
| | - Søren J Sørensen
- Section of Microbiology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark
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82
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Tang K, Wang W, Sun Y, Zhou Y, Wang P, Guo Y, Wang X. Prophage Tracer: precisely tracing prophages in prokaryotic genomes using overlapping split-read alignment. Nucleic Acids Res 2021; 49:e128. [PMID: 34551431 PMCID: PMC8682789 DOI: 10.1093/nar/gkab824] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Revised: 09/04/2021] [Accepted: 09/08/2021] [Indexed: 01/22/2023] Open
Abstract
The life cycle of temperate phages includes a lysogenic cycle stage when the phage integrates into the host genome and becomes a prophage. However, the identification of prophages that are highly divergent from known phages remains challenging. In this study, by taking advantage of the lysis-lysogeny switch of temperate phages, we designed Prophage Tracer, a tool for recognizing active prophages in prokaryotic genomes using short-read sequencing data, independent of phage gene similarity searching. Prophage Tracer uses the criterion of overlapping split-read alignment to recognize discriminative reads that contain bacterial (attB) and phage (attP) att sites representing prophage excision signals. Performance testing showed that Prophage Tracer could predict known prophages with precise boundaries, as well as novel prophages. Two novel prophages, dsDNA and ssDNA, encoding highly divergent major capsid proteins, were identified in coral-associated bacteria. Prophage Tracer is a reliable data mining tool for the identification of novel temperate phages and mobile genetic elements. The code for the Prophage Tracer is publicly available at https://github.com/WangLab-SCSIO/Prophage_Tracer.
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Affiliation(s)
- Kaihao Tang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China
| | - Weiquan Wang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yamin Sun
- Research Center for Functional Genomics and Biochip, 23 Hongda St., Tianjin 300457, China
| | - Yiqing Zhou
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Pengxia Wang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Yunxue Guo
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,University of Chinese Academy of Sciences, Beijing, China
| | - Xiaoxue Wang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, Innovation Academy of South China Sea Ecology and Environmental Engineering, South China Sea Institute of Oceanology, Chinese Academy of Sciences, No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), No. 1119, Haibin Road, Nansha District, Guangzhou 511458, China.,University of Chinese Academy of Sciences, Beijing, China
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83
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Dimitriu T, Szczelkun MD, Westra ER. Evolutionary Ecology and Interplay of Prokaryotic Innate and Adaptive Immune Systems. Curr Biol 2021; 30:R1189-R1202. [PMID: 33022264 DOI: 10.1016/j.cub.2020.08.028] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Like many organisms, bacteria and archaea have both innate and adaptive immune systems to defend against infection by viruses and other parasites. Innate immunity most commonly relies on the endonuclease-mediated cleavage of any incoming DNA that lacks a specific epigenetic modification, through a system known as restriction-modification. CRISPR-Cas-mediated adaptive immunity relies on the insertion of short DNA sequences from parasite genomes into CRISPR arrays on the host genome to provide sequence-specific protection. The discovery of each of these systems has revolutionised our ability to carry out genetic manipulations, and, as a consequence, the enzymes involved have been characterised in exquisite detail. In comparison, much less is known about the importance of these two arms of the defence for the ecology and evolution of prokaryotes and their parasites. Here, we review our current ecological and evolutionary understanding of these systems in isolation, and discuss the need to study how innate and adaptive immune responses are integrated when they coexist in the same cell.
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Affiliation(s)
- Tatiana Dimitriu
- Environment and Sustainability Institute, Biosciences, University of Exeter, Penryn TR10 9FE, UK.
| | - Mark D Szczelkun
- DNA-Protein Interactions Unit, School of Biochemistry, University of Bristol, Bristol BS8 1TD, UK.
| | - Edze R Westra
- Environment and Sustainability Institute, Biosciences, University of Exeter, Penryn TR10 9FE, UK.
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84
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Roy SW. CRISPR-Cas Toxin-Antitoxin Systems: Selfishness as a Constructive Evolutionary Force. Trends Microbiol 2021; 29:869-870. [PMID: 34376346 DOI: 10.1016/j.tim.2021.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 10/20/2022]
Abstract
A recent paper (Li et al.) reports a novel RNA-based Cas-dependent toxin-antitoxin system with the effect of 'addicting' cells to the cassette. Broadly-defined addiction systems could stabilize diverse genomic features, raising the question of the role of selfish elements and intragenomic conflict in the evolution of biological complexity.
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85
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Bier E, Nizet V. Driving to Safety: CRISPR-Based Genetic Approaches to Reducing Antibiotic Resistance. Trends Genet 2021; 37:745-757. [PMID: 33745750 DOI: 10.1016/j.tig.2021.02.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 02/23/2021] [Accepted: 02/23/2021] [Indexed: 02/07/2023]
Abstract
Bacterial resistance to antibiotics has reached critical levels, skyrocketing in hospitals and the environment and posing a major threat to global public health. The complex and challenging problem of reducing antibiotic resistance (AR) requires a network of both societal and science-based solutions to preserve the most lifesaving pharmaceutical intervention known to medicine. In addition to developing new classes of antibiotics, it is essential to safeguard the clinical efficacy of existing drugs. In this review, we examine the potential application of novel CRISPR-based genetic approaches to reducing AR in both environmental and clinical settings and prolonging the utility of vital antibiotics.
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Affiliation(s)
- Ethan Bier
- Tata Institute for Genetics and Society, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0349, USA; Section of Cell and Developmental Biology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0349, USA.
| | - Victor Nizet
- Tata Institute for Genetics and Society, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0349, USA; Collaborative to Halt Antibiotic-Resistant Microbes, Department of Pediatrics, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0687, USA; Skaggs School of Pharmacy & Pharmaceutical Sciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0687, USA
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86
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Yakovenko I, Agronin J, Smith LC, Oren M. Guardian of the Genome: An Alternative RAG/Transib Co-Evolution Hypothesis for the Origin of V(D)J Recombination. Front Immunol 2021; 12:709165. [PMID: 34394111 PMCID: PMC8355894 DOI: 10.3389/fimmu.2021.709165] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Accepted: 07/05/2021] [Indexed: 11/13/2022] Open
Abstract
The appearance of adaptive immunity in jawed vertebrates is termed the immunological 'Big Bang' because of the short evolutionary time over which it developed. Underlying it is the recombination activating gene (RAG)-based V(D)J recombination system, which initiates the sequence diversification of the immunoglobulins and lymphocyte antigen receptors. It was convincingly argued that the RAG1 and RAG2 genes originated from a single transposon. The current dogma postulates that the V(D)J recombination system was established by the split of a primordial vertebrate immune receptor gene into V and J segments by a RAG1/2 transposon, in parallel with the domestication of the same transposable element in a separate genomic locus as the RAG recombinase. Here, based on a new interpretation of previously published data, we propose an alternative evolutionary hypothesis suggesting that two different elements, a RAG1/2 transposase and a Transib transposon invader with RSS-like terminal inverted repeats, co-evolved to work together, resulting in a functional recombination process. This hypothesis offers an alternative understanding of the acquisition of recombinase function by RAGs and the origin of the V(D)J system.
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Affiliation(s)
- Iryna Yakovenko
- Department of Molecular Biology, Ariel University, Ariel, Israel
| | - Jacob Agronin
- Department of Biological Sciences, George Washington University, Washington, DC, United States
| | - L. Courtney Smith
- Department of Biological Sciences, George Washington University, Washington, DC, United States
| | - Matan Oren
- Department of Molecular Biology, Ariel University, Ariel, Israel
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87
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Improving mobilization of foreign DNA into Zymomonas mobilis ZM4 by removal of multiple restriction systems. Appl Environ Microbiol 2021; 87:e0080821. [PMID: 34288704 PMCID: PMC8432527 DOI: 10.1128/aem.00808-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Zymomonas mobilis has emerged as a promising candidate for production of high-value bioproducts from plant biomass. However, a major limitation in equipping Z. mobilis with novel pathways to achieve this goal is restriction of heterologous DNA. Here, we characterized the contribution of several defense systems of Z. mobilis strain ZM4 to impeding heterologous gene transfer from an Escherichia coli donor. Bioinformatic analysis revealed that Z. mobilis ZM4 encodes a previously described mrr-like type IV restriction modification (RM) system, a type I-F CRISPR system, a chromosomal type I RM system (hsdMSc), and a previously uncharacterized type I RM system, located on an endogenous plasmid (hsdRMSp). The DNA recognition motif of HsdRMSp was identified by comparing the methylated DNA sequence pattern of mutants lacking one or both of the hsdMSc and hsdRMSp systems to that of the parent strain. The conjugation efficiency of synthetic plasmids containing single or combinations of the HsdMSc and HsdRMSp recognition sites indicated that both systems are active and decrease uptake of foreign DNA. In contrast, deletions of mrr and cas3 led to no detectable improvement in conjugation efficiency for the exogenous DNA tested. Thus, the suite of markerless restriction-negative strains that we constructed and the knowledge of this new restriction system and its DNA recognition motif provide the necessary platform to flexibly engineer the next generation of Z. mobilis strains for synthesis of valuable products. IMPORTANCEZymomonas mobilis is equipped with a number of traits that make it a desirable platform organism for metabolic engineering to produce valuable bioproducts. Engineering strains equipped with synthetic pathways for biosynthesis of new molecules requires integration of foreign genes. In this study, we developed an all-purpose strain, devoid of known host restriction systems and free of any antibiotic resistance markers, which dramatically improves the uptake efficiency of heterologous DNA into Z. mobilis ZM4. We also confirmed the role of a previously known restriction system as well as identifying a previously unknown type I RM system on an endogenous plasmid. Elimination of the barriers to DNA uptake as shown here will allow facile genetic engineering of Z. mobilis.
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88
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Isaev AB, Musharova OS, Severinov KV. Microbial Arsenal of Antiviral Defenses. Part II. BIOCHEMISTRY (MOSCOW) 2021; 86:449-470. [PMID: 33941066 DOI: 10.1134/s0006297921040064] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Bacteriophages or phages are viruses that infect bacterial cells (for the scope of this review we will also consider viruses that infect Archaea). The constant threat of phage infection is a major force that shapes evolution of microbial genomes. To withstand infection, bacteria had evolved numerous strategies to avoid recognition by phages or to directly interfere with phage propagation inside the cell. Classical molecular biology and genetic engineering had been deeply intertwined with the study of phages and host defenses. Nowadays, owing to the rise of phage therapy, broad application of CRISPR-Cas technologies, and development of bioinformatics approaches that facilitate discovery of new systems, phage biology experiences a revival. This review describes variety of strategies employed by microbes to counter phage infection. In the first part defense associated with cell surface, roles of small molecules, and innate immunity systems relying on DNA modification were discussed. The second part focuses on adaptive immunity systems, abortive infection mechanisms, defenses associated with mobile genetic elements, and novel systems discovered in recent years through metagenomic mining.
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Affiliation(s)
- Artem B Isaev
- Skolkovo Institute of Science and Technology, Skolkovo, Moscow, 143028, Russia.
| | - Olga S Musharova
- Skolkovo Institute of Science and Technology, Skolkovo, Moscow, 143028, Russia. .,Institute of Molecular Genetics, Moscow, 119334, Russia
| | - Konstantin V Severinov
- Skolkovo Institute of Science and Technology, Skolkovo, Moscow, 143028, Russia. .,Waksman Institute of Microbiology, Piscataway, NJ 08854, USA
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89
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Kirchberger PC, Martinez ZA, Luker LJ, Ochman H. Defensive hypervariable regions confer superinfection exclusion in microviruses. Proc Natl Acad Sci U S A 2021; 118:e2102786118. [PMID: 34244443 PMCID: PMC8285946 DOI: 10.1073/pnas.2102786118] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Single-stranded DNA phages of the family Microviridae have fundamentally different evolutionary origins and dynamics than the more frequently studied double-stranded DNA phages. Despite their small size (around 5 kb), which imposes extreme constraints on genomic innovation, they have adapted to become prominent members of viromes in numerous ecosystems and hold a dominant position among viruses in the human gut. We show that multiple, divergent lineages in the family Microviridae have independently become capable of lysogenizing hosts and have convergently developed hypervariable regions in their DNA pilot protein, which is responsible for injecting the phage genome into the host. By creating microviruses with combinations of genomic segments from different phages and infecting Escherichia coli as a model system, we demonstrate that this hypervariable region confers the ability of temperate Microviridae to prevent DNA injection and infection by other microviruses. The DNA pilot protein is present in most microviruses, but has been recruited repeatedly into this additional role as microviruses altered their lifestyle by evolving the ability to integrate in bacterial genomes, which linked their survival to that of their hosts. Our results emphasize that competition between viruses is a considerable and often overlooked source of selective pressure, and by producing similar evolutionary outcomes in distinct lineages, it underlies the prevalence of hypervariable regions in the genomes of microviruses and perhaps beyond.
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Affiliation(s)
- Paul C Kirchberger
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712
| | - Zachary A Martinez
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712
| | - Landry J Luker
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712
| | - Howard Ochman
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712
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90
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Barth ZK, Nguyen MH, Seed KD. A chimeric nuclease substitutes a phage CRISPR-Cas system to provide sequence-specific immunity against subviral parasites. eLife 2021; 10:68339. [PMID: 34232860 PMCID: PMC8263062 DOI: 10.7554/elife.68339] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 06/27/2021] [Indexed: 02/06/2023] Open
Abstract
Mobile genetic elements, elements that can move horizontally between genomes, have profound effects on their host's fitness. The phage-inducible chromosomal island-like element (PLE) is a mobile element that integrates into the chromosome of Vibrio cholerae and parasitizes the bacteriophage ICP1 to move between cells. This parasitism by PLE is such that it abolishes the production of ICP1 progeny and provides a defensive boon to the host cell population. In response to the severe parasitism imposed by PLE, ICP1 has acquired an adaptive CRISPR-Cas system that targets the PLE genome during infection. However, ICP1 isolates that naturally lack CRISPR-Cas are still able to overcome certain PLE variants, and the mechanism of this immunity against PLE has thus far remained unknown. Here, we show that ICP1 isolates that lack CRISPR-Cas encode an endonuclease in the same locus, and that the endonuclease provides ICP1 with immunity to a subset of PLEs. Further analysis shows that this endonuclease is of chimeric origin, incorporating a DNA-binding domain that is highly similar to some PLE replication origin-binding proteins. This similarity allows the endonuclease to bind and cleave PLE origins of replication. The endonuclease appears to exert considerable selective pressure on PLEs and may drive PLE replication module swapping and origin restructuring as mechanisms of escape. This work demonstrates that new genome defense systems can arise through domain shuffling and provides a greater understanding of the evolutionary forces driving genome modularity and temporal succession in mobile elements.
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Affiliation(s)
- Zachary K Barth
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, United States
| | - Maria Ht Nguyen
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, United States
| | - Kimberley D Seed
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, United States.,Chan Zuckerberg Biohub, San Francisco, United States
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91
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Padilha VA, Alkhnbashi OS, Tran VD, Shah SA, Carvalho ACPLF, Backofen R. Casboundary: automated definition of integral Cas cassettes. Bioinformatics 2021; 37:1352-1359. [PMID: 33226067 PMCID: PMC8208735 DOI: 10.1093/bioinformatics/btaa984] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 10/28/2020] [Accepted: 11/11/2020] [Indexed: 11/13/2022] Open
Abstract
MOTIVATION CRISPR-Cas are important systems found in most archaeal and many bacterial genomes, providing adaptive immunity against mobile genetic elements in prokaryotes. The CRISPR-Cas systems are encoded by a set of consecutive cas genes, here termed cassette. The identification of cassette boundaries is key for finding cassettes in CRISPR research field. This is often carried out by using Hidden Markov Models and manual annotation. In this article, we propose the first method able to automatically define the cassette boundaries. In addition, we present a Cas-type predictive model used by the method to assign each gene located in the region defined by a cassette's boundaries a Cas label from a set of pre-defined Cas types. Furthermore, the proposed method can detect potentially new cas genes and decompose a cassette into its modules. RESULTS We evaluate the predictive performance of our proposed method on data collected from the two most recent CRISPR classification studies. In our experiments, we obtain an average similarity of 0.86 between the predicted and expected cassettes. Besides, we achieve F-scores above 0.9 for the classification of cas genes of known types and 0.73 for the unknown ones. Finally, we conduct two additional study cases, where we investigate the occurrence of potentially new cas genes and the occurrence of module exchange between different genomes. AVAILABILITY AND IMPLEMENTATION https://github.com/BackofenLab/Casboundary. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
- Victor A Padilha
- Institute of Mathematics and Computer Sciences, University of São Paulo, São Carlos, SP 13566-590, Brazil
| | - Omer S Alkhnbashi
- Bioinformatics Group, Department of Computer Science, University of Freiburg, 79110 Freiburg, Germany
| | - Van Dinh Tran
- Bioinformatics Group, Department of Computer Science, University of Freiburg, 79110 Freiburg, Germany
| | - Shiraz A Shah
- COPSAC, Copenhagen University Hospitals Herlev and Gentofte, DK-2820 Gentofte, Denmark
| | - André C P L F Carvalho
- Institute of Mathematics and Computer Sciences, University of São Paulo, São Carlos, SP 13566-590, Brazil
| | - Rolf Backofen
- Bioinformatics Group, Department of Computer Science, University of Freiburg, 79110 Freiburg, Germany.,Signalling Research Centres BIOSS and CIBSS, University of Freiburg, 79104 Freiburg, Germany
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92
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The Origin(s) of Cell(s): Pre-Darwinian Evolution from FUCAs to LUCA : To Carl Woese (1928-2012), for his Conceptual Breakthrough of Cellular Evolution. J Mol Evol 2021; 89:427-447. [PMID: 34173011 DOI: 10.1007/s00239-021-10014-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Accepted: 05/29/2021] [Indexed: 10/21/2022]
Abstract
The coming of the Last Universal Cellular Ancestor (LUCA) was the singular watershed event in the making of the biotic world. If the coming of LUCA marked the crossing of the "Darwinian Threshold", then pre-LUCA evolution must have been Pre-Darwinian and at least partly non-Darwinian. But how did Pre-Darwinian evolution before LUCA actually operate? I broaden our understanding of the central mechanism of biological evolution (i.e., variation-selection-inheritance) and then extend this broadened understanding to its natural starting point: the origin(s) of the First Universal Cellular Ancestors (FUCAs) before LUCA. My hypothesis centers upon vesicles' making-and-remaking as variation and competition as selection. More specifically, I argue that vesicles' acquisition and merger, via breaking-and-repacking, proto-endocytosis, proto-endosymbiosis, and other similar processes had been a central force of both variation and selection in the pre-Darwinian epoch. These new perspectives shed important new light upon the origin of FUCAs and their subsequent evolution into LUCA.
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93
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Zeng H, Xu H, Liu G, Wei Y, Zhang J, Shi H. Physiological and metagenomic strategies uncover the rhizosphere bacterial microbiome succession underlying three common environmental stresses in cassava. JOURNAL OF HAZARDOUS MATERIALS 2021; 411:125143. [PMID: 33858103 DOI: 10.1016/j.jhazmat.2021.125143] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 12/28/2020] [Accepted: 01/12/2021] [Indexed: 06/12/2023]
Abstract
The most common environmental pollutants such as cadmium (Cd), glyphosate and tetracycline have led to profoundly adverse impacts on plant productivity. However, how tropical crops such as cassava sense these pollutants via roots and how rhizosphere microbiome interacts with the host and pollutants remain largely unknown. In this study, we found these stresses significantly inhibited plant growth and triggered cell damage in a dosage-dependent manner, and the toxic effect on redox homeostasis was correlated with antioxidant metabolism. Using metagenomics technique, we found the rhizosphere microbiomes dynamically altered as the dose of these stresses increased. We also identified stressor-associated metagenome-assembled genomes and microbial metabolic pathways as well as mobile genetic elements in the rhizosphere microbiomes. Next, a co-occurrence network of both physiological and microbiome features was constructed to explore how these pollutants derived oxidative damage through the microbiome succession. Notably, phyllosphere transplantation of Agrobacterium tumefaciens or Pseudomonas stutzeri can significantly alleviate the negative effects of stresses on cassava growth and redox homeostasis. Collectively, this study demonstrated the dynamics of rhizosphere bacterial microbiome of cassava under three common environmental stresses, and A. tumefaciens and P. stutzeri could be developed as potential beneficial bacteria to alleviate Cd, glyphosate and tetracycline-triggered damage to cassava.
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Affiliation(s)
- Hongqiu Zeng
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Tropical Crops, Hainan University, Haikou, Hainan 570228, China
| | - Haoran Xu
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Tropical Crops, Hainan University, Haikou, Hainan 570228, China
| | - Guoyin Liu
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Tropical Crops, Hainan University, Haikou, Hainan 570228, China
| | - Yunxie Wei
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Tropical Crops, Hainan University, Haikou, Hainan 570228, China
| | - Jiachao Zhang
- College of Food Science and Engineering, Hainan University, Haikou, Hainan 570228, China.
| | - Haitao Shi
- Hainan Key Laboratory for Sustainable Utilization of Tropical Bioresources, College of Tropical Crops, Hainan University, Haikou, Hainan 570228, China.
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94
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Netter Z, Boyd CM, Silvas TV, Seed KD. A phage satellite tunes inducing phage gene expression using a domesticated endonuclease to balance inhibition and virion hijacking. Nucleic Acids Res 2021; 49:4386-4401. [PMID: 33823541 PMCID: PMC8096241 DOI: 10.1093/nar/gkab207] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2020] [Revised: 02/25/2021] [Accepted: 03/16/2021] [Indexed: 12/20/2022] Open
Abstract
Bacteria persist under constant threat of predation by bacterial viruses (phages). Bacteria-phage conflicts result in evolutionary arms races often driven by mobile genetic elements (MGEs). One such MGE, a phage satellite in Vibrio cholerae called PLE, provides specific and robust defense against a pervasive lytic phage, ICP1. The interplay between PLE and ICP1 has revealed strategies for molecular parasitism allowing PLE to hijack ICP1 processes in order to mobilize. Here, we describe the mechanism of PLE-mediated transcriptional manipulation of ICP1 structural gene transcription. PLE encodes a novel DNA binding protein, CapR, that represses ICP1’s capsid morphogenesis operon. Although CapR is sufficient for the degree of capsid repression achieved by PLE, its activity does not hinder the ICP1 lifecycle. We explore the consequences of repression of this operon, demonstrating that more stringent repression achieved through CRISPRi restricts both ICP1 and PLE. We also discover that PLE transduces in modified ICP1-like particles. Examination of CapR homologs led to the identification of a suite of ICP1-encoded homing endonucleases, providing a putative origin for the satellite-encoded repressor. This work unveils a facet of the delicate balance of satellite-mediated inhibition aimed at blocking phage production while successfully mobilizing in a phage-derived particle.
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Affiliation(s)
- Zoe Netter
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Caroline M Boyd
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Tania V Silvas
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Kimberley D Seed
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA.,Chan Zuckerberg Biohub, San Francisco, CA 94158, USA
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95
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Li M, Gong L, Cheng F, Yu H, Zhao D, Wang R, Wang T, Zhang S, Zhou J, Shmakov SA, Koonin EV, Xiang H. Toxin-antitoxin RNA pairs safeguard CRISPR-Cas systems. Science 2021; 372:372/6541/eabe5601. [PMID: 33926924 DOI: 10.1126/science.abe5601] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 12/29/2020] [Accepted: 03/10/2021] [Indexed: 12/18/2022]
Abstract
CRISPR-Cas systems provide RNA-guided adaptive immunity in prokaryotes. We report that the multisubunit CRISPR effector Cascade transcriptionally regulates a toxin-antitoxin RNA pair, CreTA. CreT (Cascade-repressed toxin) is a bacteriostatic RNA that sequesters the rare arginine tRNAUCU (transfer RNA with anticodon UCU). CreA is a CRISPR RNA-resembling antitoxin RNA, which requires Cas6 for maturation. The partial complementarity between CreA and the creT promoter directs Cascade to repress toxin transcription. Thus, CreA becomes antitoxic only in the presence of Cascade. In CreTA-deleted cells, cascade genes become susceptible to disruption by transposable elements. We uncover several CreTA analogs associated with diverse archaeal and bacterial CRISPR-cas loci. Thus, toxin-antitoxin RNA pairs can safeguard CRISPR immunity by making cells addicted to CRISPR-Cas, which highlights the multifunctionality of Cas proteins and the intricate mechanisms of CRISPR-Cas regulation.
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Affiliation(s)
- Ming Li
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China. .,CAS Key Laboratory of Microbial Physiological and Metabolic Engineering, Chinese Academy of Sciences, Beijing, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Luyao Gong
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Feiyue Cheng
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Haiying Yu
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Dahe Zhao
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Rui Wang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Tian Wang
- College of Life Sciences, Sichuan Normal University, Chengdu, China
| | - Shengjie Zhang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing, China
| | - Jian Zhou
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Sergey A Shmakov
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA
| | - Hua Xiang
- State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China. .,College of Life Science, University of Chinese Academy of Sciences, Beijing, China.,Center for Ocean Mega-Science, Chinese Academy of Sciences, Qingdao, China
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96
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Isaev AB, Musharova OS, Severinov KV. Microbial Arsenal of Antiviral Defenses - Part I. BIOCHEMISTRY (MOSCOW) 2021; 86:319-337. [PMID: 33838632 DOI: 10.1134/s0006297921030081] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Bacteriophages or phages are viruses that infect bacterial cells (for the scope of this review we will also consider viruses that infect Archaea). Constant threat of phage infection is a major force that shapes evolution of the microbial genomes. To withstand infection, bacteria had evolved numerous strategies to avoid recognition by phages or to directly interfere with phage propagation inside the cell. Classical molecular biology and genetic engineering have been deeply intertwined with the study of phages and host defenses. Nowadays, owing to the rise of phage therapy, broad application of CRISPR-Cas technologies, and development of bioinformatics approaches that facilitate discovery of new systems, phage biology experiences a revival. This review describes variety of strategies employed by microbes to counter phage infection, with a focus on novel systems discovered in recent years. First chapter covers defense associated with cell surface, role of small molecules, and innate immunity systems relying on DNA modification.
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Affiliation(s)
- Artem B Isaev
- Skolkovo Institute of Science and Technology, Moscow, 143028, Russia.
| | - Olga S Musharova
- Skolkovo Institute of Science and Technology, Moscow, 143028, Russia. .,Institute of Molecular Genetics, Moscow, 119334, Russia
| | - Konstantin V Severinov
- Skolkovo Institute of Science and Technology, Moscow, 143028, Russia. .,Waksman Institute of Microbiology, Piscataway, NJ 08854, USA
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97
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Smyshlyaev G, Bateman A, Barabas O. Sequence analysis of tyrosine recombinases allows annotation of mobile genetic elements in prokaryotic genomes. Mol Syst Biol 2021; 17:e9880. [PMID: 34018328 PMCID: PMC8138268 DOI: 10.15252/msb.20209880] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 04/18/2021] [Accepted: 04/20/2021] [Indexed: 11/16/2022] Open
Abstract
Mobile genetic elements (MGEs) sequester and mobilize antibiotic resistance genes across bacterial genomes. Efficient and reliable identification of such elements is necessary to follow resistance spreading. However, automated tools for MGE identification are missing. Tyrosine recombinase (YR) proteins drive MGE mobilization and could provide markers for MGE detection, but they constitute a diverse family also involved in housekeeping functions. Here, we conducted a comprehensive survey of YRs from bacterial, archaeal, and phage genomes and developed a sequence-based classification system that dissects the characteristics of MGE-borne YRs. We revealed that MGE-related YRs evolved from non-mobile YRs by acquisition of a regulatory arm-binding domain that is essential for their mobility function. Based on these results, we further identified numerous unknown MGEs. This work provides a resource for comparative analysis and functional annotation of YRs and aids the development of computational tools for MGE annotation. Additionally, we reveal how YRs adapted to drive gene transfer across species and provide a tool to better characterize antibiotic resistance dissemination.
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Affiliation(s)
- Georgy Smyshlyaev
- European Molecular Biology LaboratoryEuropean Bioinformatics Institute (EMBL‐EBI)HinxtonUK
- European Molecular Biology Laboratory (EMBL)Structural and Computational Biology UnitHeidelbergGermany
- Department of Molecular BiologyUniversity of GenevaGenevaSwitzerland
| | - Alex Bateman
- European Molecular Biology LaboratoryEuropean Bioinformatics Institute (EMBL‐EBI)HinxtonUK
| | - Orsolya Barabas
- European Molecular Biology Laboratory (EMBL)Structural and Computational Biology UnitHeidelbergGermany
- Department of Molecular BiologyUniversity of GenevaGenevaSwitzerland
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98
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Identification and distribution of novel badnaviral sequences integrated in the genome of cacao (Theobroma cacao). Sci Rep 2021; 11:8270. [PMID: 33859254 PMCID: PMC8050207 DOI: 10.1038/s41598-021-87690-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 03/22/2021] [Indexed: 12/03/2022] Open
Abstract
Theobroma cacao is one of the most economically important tropical trees, being the source of chocolate. As part of an ongoing study to understand the diversity of the badnavirus complex, responsible for the cacao swollen shoot virus disease in West Africa, evidence was found recently of virus-like sequences in asymptomatic cacao plants. The present study exploited the wealth of genomic resources in this crop, and combined bioinformatic, molecular, and genetic approaches to report for the first time the presence of integrated badnaviral sequences in most of the cacao genetic groups. These sequences, which we propose to name eTcBV for endogenous T. cacao bacilliform virus, varied in type with each predominating in a specific genetic group. A diagnostic multiplex PCR method was developed to identify the homozygous or hemizygous condition of one specific insert, which was inherited as a single Mendelian trait. These data suggest that these integration events occurred before or during the species diversification in Central and South America, and prior to its cultivation in other regions. Such evidence of integrated sequences is relevant to the management of cacao quarantine facilities and may also aid novel methods to reduce the impact of such viruses in this crop.
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99
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Tetracycline Resistance Mediated by tet(M) Has Variable Integrative Conjugative Element Composition in Mycoplasma hominis Strains Isolated in the United Kingdom from 2005 to 2015. Antimicrob Agents Chemother 2021; 65:AAC.02513-20. [PMID: 33468475 DOI: 10.1128/aac.02513-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 01/05/2021] [Indexed: 11/20/2022] Open
Abstract
A minimal genome and absent bacterial cell wall render Mycoplasma hominis inherently resistant to most antimicrobials except lincosamides, tetracyclines, and fluoroquinolones. Often dismissed as a commensal (except where linked to preterm birth), it causes septic arthritis in immunodeficient patients and is increasingly associated with transplant failure (particularly lung) accompanying immunosuppression. We examined antimicrobial susceptibility (AST) on strains archived from 2005 to 2015 submitted to the Public Health England reference laboratory and determined the underlying mechanism of resistance by whole-genome sequencing (WGS). Archived M. hominis strains included 32/115 from invasive infection (sepsis, cerebrospinal [CSF], peritoneal, and pleural fluid) over the 10-year period (6.4% of all samples submitted from 2010 to 2015 were positive). No clindamycin resistance was detected, while two strains were resistant to moxifloxacin and levofloxacin (resistance mutations S83L or E87G in gyrA and S81I or E84V in parC). One of these strains and 11 additional strains were tetracycline resistant, mediated by tet(M) carried within an integrative conjugative element (ICE) consistently integrated at the somatic rumA gene; however, the ICEs varied widely in 5 to 19 associated accessory genes. WGS analysis showed that tet(M)-carrying strains were not clonal, refuting previous speculation that the ICE was broken and immobile. We found tet(M)-positive and -negative strains (including the multiresistant 2015 strain) to be equally susceptible to tigecycline and josamycin; however, the British National Formulary does not include guidance for these. Continued M. hominis investigation and AST surveillance (especially immunocompromised patients) is warranted, and the limited number of therapeutics needs to be expanded in the United Kingdom.
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Waldern JM, Smith D, Piazza CL, Bailey EJ, Schiraldi NJ, Nemati R, Fabris D, Belfort M, Novikova O. Methylation of rRNA as a host defense against rampant group II intron retrotransposition. Mob DNA 2021; 12:9. [PMID: 33678171 PMCID: PMC7938551 DOI: 10.1186/s13100-021-00237-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 02/22/2021] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Group II introns are mobile retroelements, capable of invading new sites in DNA. They are self-splicing ribozymes that complex with an intron-encoded protein to form a ribonucleoprotein that targets DNA after splicing. These molecules can invade DNA site-specifically, through a process known as retrohoming, or can invade ectopic sites through retrotransposition. Retrotransposition, in particular, can be strongly influenced by both environmental and cellular factors. RESULTS To investigate host factors that influence retrotransposition, we performed random insertional mutagenesis using the ISS1 transposon to generate a library of over 1000 mutants in Lactococcus lactis, the native host of the Ll.LtrB group II intron. By screening this library, we identified 92 mutants with increased retrotransposition frequencies (RTP-ups). We found that mutations in amino acid transport and metabolism tended to have increased retrotransposition frequencies. We further explored a subset of these RTP-up mutants, the most striking of which is a mutant in the ribosomal RNA methyltransferase rlmH, which exhibited a reproducible 20-fold increase in retrotransposition frequency. In vitro and in vivo experiments revealed that ribosomes in the rlmH mutant were defective in the m3Ψ modification and exhibited reduced binding to the intron RNA. CONCLUSIONS Taken together, our results reinforce the importance of the native host organism in regulating group II intron retrotransposition. In particular, the evidence from the rlmH mutant suggests a role for ribosome modification in limiting rampant retrotransposition.
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Affiliation(s)
- Justin M. Waldern
- Department of Biological Sciences and RNA Institute, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
- Current address: Department of Biology, University of North Carolina, 270 Bell Tower Drive, Chapel Hill, NC 27599 USA
| | - Dorie Smith
- Department of Biological Sciences and RNA Institute, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
| | - Carol Lyn Piazza
- Department of Biological Sciences and RNA Institute, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
| | - E. Jake Bailey
- Department of Biological Sciences and RNA Institute, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
| | - Nicholas J. Schiraldi
- Academic and Research Computing Center, Information Technology Services, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
| | - Reza Nemati
- Department of Chemistry, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
- Current address: Biogen, 125 Broadway, Cambridge, MA 02142 USA
| | - Dan Fabris
- Department of Biological Sciences and RNA Institute, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
- Department of Chemistry, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
- Current address: Department of Chemistry, University of Connecticut, 55 N. Eagleville Road, Storrs, CT 06268 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
| | - Olga Novikova
- Department of Biological Sciences and RNA Institute, University at Albany, 1400 Washington Avenue, Albany, NY 12222 USA
- Current address: Biology Department, SUNY Buffalo State College, 1300 Elmwood Avenue, Buffalo, NY 14222 USA
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