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Mayo-Muñoz D, Pinilla-Redondo R, Camara-Wilpert S, Birkholz N, Fineran PC. Inhibitors of bacterial immune systems: discovery, mechanisms and applications. Nat Rev Genet 2024; 25:237-254. [PMID: 38291236 DOI: 10.1038/s41576-023-00676-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/07/2023] [Indexed: 02/01/2024]
Abstract
To contend with the diversity and ubiquity of bacteriophages and other mobile genetic elements, bacteria have developed an arsenal of immune defence mechanisms. Bacterial defences include CRISPR-Cas, restriction-modification and a growing list of mechanistically diverse systems, which constitute the bacterial 'immune system'. As a response, bacteriophages and mobile genetic elements have evolved direct and indirect mechanisms to circumvent or block bacterial defence pathways and ensure successful infection. Recent advances in methodological and computational approaches, as well as the increasing availability of genome sequences, have boosted the discovery of direct inhibitors of bacterial defence systems. In this Review, we discuss methods for the discovery of direct inhibitors, their diverse mechanisms of action and perspectives on their emerging applications in biotechnology and beyond.
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Affiliation(s)
- David Mayo-Muñoz
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
- Genetics Otago, University of Otago, Dunedin, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Otago, Dunedin, New Zealand
| | - Rafael Pinilla-Redondo
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand.
- Section of Microbiology, University of Copenhagen, Copenhagen, Denmark.
| | | | - Nils Birkholz
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
- Genetics Otago, University of Otago, Dunedin, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Otago, Dunedin, New Zealand
- Bioprotection Aotearoa, University of Otago, Dunedin, New Zealand
| | - Peter C Fineran
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand.
- Genetics Otago, University of Otago, Dunedin, New Zealand.
- Maurice Wilkins Centre for Molecular Biodiscovery, University of Otago, Dunedin, New Zealand.
- Bioprotection Aotearoa, University of Otago, Dunedin, New Zealand.
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Pas C, Latka A, Fieseler L, Briers Y. Phage tailspike modularity and horizontal gene transfer reveals specificity towards E. coli O-antigen serogroups. Virol J 2023; 20:174. [PMID: 37550759 PMCID: PMC10408124 DOI: 10.1186/s12985-023-02138-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 07/23/2023] [Indexed: 08/09/2023] Open
Abstract
BACKGROUND The interaction between bacteriophages and their hosts is intricate and highly specific. Receptor-binding proteins (RBPs) of phages such as tail fibers and tailspikes initiate the infection process. These RBPs bind to diverse outer membrane structures, including the O-antigen, which is a serogroup-specific sugar-based component of the outer lipopolysaccharide layer of Gram-negative bacteria. Among the most virulent Escherichia coli strains is the Shiga toxin-producing E. coli (STEC) pathotype dominated by a subset of O-antigen serogroups. METHODS Extensive phylogenetic and structural analyses were used to identify and validate specificity correlations between phage RBP subtypes and STEC O-antigen serogroups, relying on the principle of horizontal gene transfer as main driver for RBP evolution. RESULTS We identified O-antigen specific RBP subtypes for seven out of nine most prevalent STEC serogroups (O26, O45, O103, O104, O111, O145 and O157) and seven additional E. coli serogroups (O2, O8, O16, O18, 4s/O22, O77 and O78). Eight phage genera (Gamaleya-, Justusliebig-, Kaguna-, Kayfuna-, Kutter-, Lederberg-, Nouzilly- and Uetakeviruses) emerged for their high proportion of serogroup-specific RBPs. Additionally, we reveal sequence motifs in the RBP region, potentially serving as recombination hotspots between lytic phages. CONCLUSION The results contribute to a better understanding of mosaicism of phage RBPs, but also demonstrate a method to identify and validate new RBP subtypes for current and future emerging serogroups.
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Affiliation(s)
- Célia Pas
- Department of Biotechnology, Ghent University, Valentin Vaerwyckweg 1, 9000, Ghent, Belgium
| | - Agnieszka Latka
- Department of Biotechnology, Ghent University, Valentin Vaerwyckweg 1, 9000, Ghent, Belgium
- Department of Pathogen Biology and Immunology, University of Wroclaw, Przybyszewskiego 63, 51-148, Wrocław, Poland
| | - Lars Fieseler
- Centre for Food Safety and Quality Management, ZHAW School of Life Sciences and Facility Management, Einsiedlerstrasse 31, 8820, Wädenswil, Switzerland
| | - Yves Briers
- Department of Biotechnology, Ghent University, Valentin Vaerwyckweg 1, 9000, Ghent, Belgium.
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Gao Z, Feng Y. Bacteriophage strategies for overcoming host antiviral immunity. Front Microbiol 2023; 14:1211793. [PMID: 37362940 PMCID: PMC10286901 DOI: 10.3389/fmicb.2023.1211793] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 05/17/2023] [Indexed: 06/28/2023] Open
Abstract
Phages and their bacterial hosts together constitute a vast and diverse ecosystem. Facing the infection of phages, prokaryotes have evolved a wide range of antiviral mechanisms, and phages in turn have adopted multiple tactics to circumvent or subvert these mechanisms to survive. An in-depth investigation into the interaction between phages and bacteria not only provides new insight into the ancient coevolutionary conflict between them but also produces precision biotechnological tools based on anti-phage systems. Moreover, a more complete understanding of their interaction is also critical for the phage-based antibacterial measures. Compared to the bacterial antiviral mechanisms, studies into counter-defense strategies adopted by phages have been a little slow, but have also achieved important advances in recent years. In this review, we highlight the numerous intracellular immune systems of bacteria as well as the countermeasures employed by phages, with an emphasis on the bacteriophage strategies in response to host antiviral immunity.
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Wilkinson M, Wilkinson OJ, Feyerherm C, Fletcher EE, Wigley DB, Dillingham MS. Structures of RecBCD in complex with phage-encoded inhibitor proteins reveal distinctive strategies for evasion of a bacterial immunity hub. eLife 2022; 11:e83409. [PMID: 36533901 PMCID: PMC9836394 DOI: 10.7554/elife.83409] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Accepted: 12/18/2022] [Indexed: 12/23/2022] Open
Abstract
Following infection of bacterial cells, bacteriophage modulate double-stranded DNA break repair pathways to protect themselves from host immunity systems and prioritise their own recombinases. Here, we present biochemical and structural analysis of two phage proteins, gp5.9 and Abc2, which target the DNA break resection complex RecBCD. These exemplify two contrasting mechanisms for control of DNA break repair in which the RecBCD complex is either inhibited or co-opted for the benefit of the invading phage. Gp5.9 completely inhibits RecBCD by preventing it from binding to DNA. The RecBCD-gp5.9 structure shows that gp5.9 acts by substrate mimicry, binding predominantly to the RecB arm domain and competing sterically for the DNA binding site. Gp5.9 adopts a parallel coiled-coil architecture that is unprecedented for a natural DNA mimic protein. In contrast, binding of Abc2 does not substantially affect the biochemical activities of isolated RecBCD. The RecBCD-Abc2 structure shows that Abc2 binds to the Chi-recognition domains of the RecC subunit in a position that might enable it to mediate the loading of phage recombinases onto its single-stranded DNA products.
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Affiliation(s)
- Martin Wilkinson
- Section of Structural Biology, Department of Infectious Disease, Faculty of Medicine, Imperial College LondonLondonUnited Kingdom
| | - Oliver J Wilkinson
- DNA:protein Interactions Unit, School of Biochemistry, University of BristolBristolUnited Kingdom
| | - Connie Feyerherm
- DNA:protein Interactions Unit, School of Biochemistry, University of BristolBristolUnited Kingdom
| | - Emma E Fletcher
- DNA:protein Interactions Unit, School of Biochemistry, University of BristolBristolUnited Kingdom
| | - Dale B Wigley
- Section of Structural Biology, Department of Infectious Disease, Faculty of Medicine, Imperial College LondonLondonUnited Kingdom
| | - Mark S Dillingham
- DNA:protein Interactions Unit, School of Biochemistry, University of BristolBristolUnited Kingdom
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Strobel HM, Stuart EC, Meyer JR. A Trait-Based Approach to Predicting Viral Host-Range Evolvability. Annu Rev Virol 2022; 9:139-156. [PMID: 36173699 DOI: 10.1146/annurev-virology-091919-092003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Predicting the evolution of virus host range has proven to be extremely difficult, in part because of the sheer diversity of viruses, each with unique biology and ecological interactions. We have not solved this problem, but to make the problem more tractable, we narrowed our focus to three traits intrinsic to all viruses that may play a role in host-range evolvability: mutation rate, recombination rate, and phenotypic heterogeneity. Although each trait should increase evolvability, they cannot do so unbounded because fitness trade-offs limit the ability of all three traits to maximize evolvability. By examining these constraints, we can begin to identify groups of viruses with suites of traits that make them especially concerning, as well as ecological and environmental conditions that might push evolution toward accelerating host-range expansion.
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Affiliation(s)
- Hannah M Strobel
- Division of Biological Sciences, University of California, San Diego, La Jolla, California, USA;
| | - Elizabeth C Stuart
- Division of Biological Sciences, University of California, San Diego, La Jolla, California, USA;
| | - Justin R Meyer
- Division of Biological Sciences, University of California, San Diego, La Jolla, California, USA;
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6
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Subramaniam S, Smith GR. RecBCD enzyme and Chi recombination hotspots as determinants of self vs. non-self: Myths and mechanisms. ADVANCES IN GENETICS 2022; 109:1-37. [PMID: 36334915 PMCID: PMC10047805 DOI: 10.1016/bs.adgen.2022.06.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Bacteria face a challenge when DNA enters their cells by transformation, mating, or phage infection. Should they treat this DNA as an invasive foreigner and destroy it, or consider it one of their own and potentially benefit from incorporating new genes or alleles to gain useful functions? It is frequently stated that the short nucleotide sequence Chi (5' GCTGGTGG 3'), a hotspot of homologous genetic recombination recognized by Escherichia coli's RecBCD helicase-nuclease, allows E. coli to distinguish its DNA (self) from any other DNA (non-self) and to destroy non-self DNA, and that Chi is "over-represented" in the E. coli genome. We show here that these latter statements (dogmas) are not supported by available evidence. We note Chi's wide-spread occurrence and activity in distantly related bacterial species and phages. We illustrate multiple, highly non-random features of the genomes of E. coli and coliphage P1 that account for Chi's high frequency and genomic position, leading us to propose that P1 selects for Chi's enhancement of recombination, whereas E. coli selects for the preferred codons in Chi. We discuss other, previously described mechanisms for self vs. non-self determination involving RecBCD and for RecBCD's destruction of DNA that cannot recombine, whether foreign or domestic, with or without Chi.
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Affiliation(s)
| | - Gerald R Smith
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, WA, United States.
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Isaev A, Andriianov A, Znobishcheva E, Zorin E, Morozova N, Severinov K. Editing of Phage Genomes—Recombineering-assisted SpCas9 Modification of Model Coliphages T7, T5, and T3. Mol Biol 2022. [DOI: 10.1134/s0026893322060073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Abstract
Bacteriophages—viruses that infect bacterial cells—are the most abundant biological entities on Earth. The use of phages in fundamental research and industry requires tools for precise manipulation of their genomes. Yet, compared to bacterial genome engineering, modification of phage genomes is challenging because of the lack of selective markers and thus requires laborious screenings of recombinant/mutated phage variants. The development of the CRISPR-Cas technologies allowed to solve this issue by the implementation of negative selection that eliminates the parental phage genomes. In this manuscript, we summarize current methods of phage genome engineering and their coupling with CRISPR-Cas technologies. We also provide examples of our successful application of these methods for introduction of specific insertions, deletions, and point mutations in the genomes of model Escherichia coli lytic phages T7, T5, and T3.
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de Sousa KCM, Gutiérrez R, Yahalomi D, Shalit T, Markus B, Nachum-Biala Y, Hawlena H, Marcos-Hadad E, Hazkani-Covo E, de Rezende Neves HH, Covo S, Harrus S. Genomic structural plasticity of rodent-associated Bartonella in nature. Mol Ecol 2022; 31:3784-3797. [PMID: 35620948 PMCID: PMC9540758 DOI: 10.1111/mec.16547] [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] [Received: 02/11/2022] [Revised: 05/12/2022] [Accepted: 05/20/2022] [Indexed: 11/28/2022]
Abstract
Rodent‐associated Bartonella species have shown a remarkable genetic diversity and pathogenic potential. To further explore the extent of the natural intraspecific genomic variation and its potential role as an evolutionary driver, we focused on a single genetically diverse Bartonella species, Bartonella krasnovii, which circulates among gerbils and their associated fleas. Twenty genomes from 16 different B. krasnovii genotypes were fully characterized through a genome sequencing assay (using short and long read sequencing), pulse field gel electrophoresis (PFGE), and PCR validation. Genomic analyses were performed in comparison to the B. krasnovii strain OE 1–1. While, single nucleotide polymorphism represented only a 0.3% of the genome variation, structural diversity was identified in these genomes, with an average of 51 ± 24 structural variation (SV) events per genome. Interestingly, a large proportion of the SVs (>40%) was associated with prophages. Further analyses revealed that most of the SVs, and prophage insertions were found at the chromosome replication termination site (ter), suggesting this site as a plastic zone of the B. krasnovii chromosome. Accordingly, six genomes were found to be unbalanced, and essential genes near the ter showed a shift between the leading and lagging strands, revealing the SV effect on these genomes. In summary, our findings demonstrate the extensive genomic diversity harbored by wild B. krasnovii strains and suggests that its diversification is initially promoted by structural changes, probably driven by phages. These events may constantly feed the system with novel genotypes that ultimately lead to inter‐ and intraspecies competition and adaptation.
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Affiliation(s)
| | - Ricardo Gutiérrez
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel.,National Reference Center for Bacteriology. Costa Rican Institute for Research and Teaching in Nutrition and Health (INCIENSA)
| | - Dayana Yahalomi
- The Mantoux Bioinformatics institute of the Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot, Israel
| | - Tali Shalit
- The Mantoux Bioinformatics institute of the Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot, Israel
| | - Barak Markus
- The Mantoux Bioinformatics institute of the Nancy and Stephen Grand Israel National Center for Personalized Medicine, Weizmann Institute of Science, Rehovot, Israel
| | - Yaarit Nachum-Biala
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Hadas Hawlena
- Mitrani Department of Desert Ecology, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Midreshet Ben-Gurion, Israel
| | - Evgeniya Marcos-Hadad
- Department of Plant Pathology and Microbiology, Robert H. Smith Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Einat Hazkani-Covo
- Department of Natural and Life Sciences, Open University of Israel, Raanana, Israel
| | | | - Shay Covo
- Department of Plant Pathology and Microbiology, Robert H. Smith Faculty of Agriculture, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Shimon Harrus
- Koret School of Veterinary Medicine, The Hebrew University of Jerusalem, Rehovot, Israel.,National Reference Center for Bacteriology. Costa Rican Institute for Research and Teaching in Nutrition and Health (INCIENSA)
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9
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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: 73] [Impact Index Per Article: 36.5] [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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Fitzgerald SF, Lupolova N, Shaaban S, Dallman TJ, Greig D, Allison L, Tongue SC, Evans J, Henry MK, McNeilly TN, Bono JL, Gally DL. Genome structural variation in Escherichia coli O157:H7. Microb Genom 2021; 7. [PMID: 34751643 PMCID: PMC8743559 DOI: 10.1099/mgen.0.000682] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The human zoonotic pathogen Escherichia coli O157:H7 is defined by its extensive prophage repertoire including those that encode Shiga toxin, the factor responsible for inducing life-threatening pathology in humans. As well as introducing genes that can contribute to the virulence of a strain, prophage can enable the generation of large-chromosomal rearrangements (LCRs) by homologous recombination. This work examines the types and frequencies of LCRs across the major lineages of the O157:H7 serotype. We demonstrate that LCRs are a major source of genomic variation across all lineages of E. coli O157:H7 and by using both optical mapping and Oxford Nanopore long-read sequencing prove that LCRs are generated in laboratory cultures started from a single colony and that these variants can be recovered from colonized cattle. LCRs are biased towards the terminus region of the genome and are bounded by specific prophages that share large regions of sequence homology associated with the recombinational activity. RNA transcriptional profiling and phenotyping of specific structural variants indicated that important virulence phenotypes such as Shiga-toxin production, type-3 secretion and motility can be affected by LCRs. In summary, E. coli O157:H7 has acquired multiple prophage regions over time that act to continually produce structural variants of the genome. These findings raise important questions about the significance of this prophage-mediated genome contingency to enhance adaptability between environments.
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Affiliation(s)
- Stephen F Fitzgerald
- Division of Infection and Immunity, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Nadejda Lupolova
- Division of Infection and Immunity, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Sharif Shaaban
- Division of Infection and Immunity, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
| | - Timothy J Dallman
- Gastrointestinal Bacterial Reference Unit, 61 Colindale Avenue, Public Health England, NW9 5EQ London, UK
| | - David Greig
- Gastrointestinal Bacterial Reference Unit, 61 Colindale Avenue, Public Health England, NW9 5EQ London, UK
| | - Lesley Allison
- Scottish E. coli O157/VTEC Reference Laboratory, Department of Laboratory Medicine, Royal Infirmary of Edinburgh, 51 Little France Crescent, Edinburgh EH16 4SA, UK
| | - Sue C Tongue
- Epidemiology Research Unit (Inverness), Department of Veterinary and Animal Science, Northern Faculty, Scotland's Rural College (SRUC), Scotland, IV2 5NA, UK
| | - Judith Evans
- Epidemiology Research Unit (Inverness), Department of Veterinary and Animal Science, Northern Faculty, Scotland's Rural College (SRUC), Scotland, IV2 5NA, UK
| | - Madeleine K Henry
- Epidemiology Research Unit (Inverness), Department of Veterinary and Animal Science, Northern Faculty, Scotland's Rural College (SRUC), Scotland, IV2 5NA, UK
| | - Tom N McNeilly
- Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, EH26 OPZ, UK
| | - James L Bono
- United States Department of Agriculture, Agricultural Research Service, US Meat Animal Research Center, Clay Center, Nebraska, USA
| | - David L Gally
- Division of Infection and Immunity, The Roslin Institute and R(D)SVS, The University of Edinburgh, Easter Bush, Midlothian, EH25 9RG, UK
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Viral recombination systems limit CRISPR-Cas targeting through the generation of escape mutations. Cell Host Microbe 2021; 29:1482-1495.e12. [PMID: 34582782 DOI: 10.1016/j.chom.2021.09.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 06/24/2021] [Accepted: 09/02/2021] [Indexed: 12/26/2022]
Abstract
CRISPR-Cas systems provide immunity to bacteria by programing Cas nucleases with RNA guides that recognize and cleave infecting viral genomes. Bacteria and their viruses each encode recombination systems that could repair the cleaved viral DNA. However, it is unknown whether and how these systems can affect CRISPR immunity. Bacteriophage λ uses the Red system (gam-exo-bet) to promote recombination between related phages. Here, we show that λ Red also mediates evasion of CRISPR-Cas targeting. Gam inhibits the host E. coli RecBCD recombination system, allowing recombination and repair of the cleaved DNA by phage Exo-Beta, which promotes the generation of mutations within the CRISPR target sequence. Red recombination is strikingly more efficient than the host's RecBCD-RecA in the production of large numbers of phages that escape CRISPR targeting. These results reveal a role for Red-like systems in the protection of bacteriophages against sequence-specific nucleases, which may facilitate their spread across viral genomes.
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12
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Bacillus pumilus 15.1, a Strain Active against Ceratitis capitata, Contains a Novel Phage and a Phage-Related Particle with Bacteriocin Activity. Int J Mol Sci 2021; 22:ijms22158164. [PMID: 34360927 PMCID: PMC8347963 DOI: 10.3390/ijms22158164] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/19/2021] [Accepted: 07/26/2021] [Indexed: 11/16/2022] Open
Abstract
A 98.1 Kb genomic region from B. pumilus 15.1, a strain isolated as an entomopathogen toward C. capitata, the Mediterranean fruit fly, has been characterised in search of potential virulence factors. The 98.1 Kb region shows a high number of phage-related protein-coding ORFs. Two regions with different phylogenetic origins, one with 28.7 Kb in size, highly conserved in Bacillus strains, and one with 60.2 Kb in size, scarcely found in Bacillus genomes are differentiated. The content of each region is thoroughly characterised using comparative studies. This study demonstrates that these two regions are responsible for the production, after mitomycin induction, of a phage-like particle that packages DNA from the host bacterium and a novel phage for B. pumilus, respectively. Both the phage-like particles and the novel phage are observed and characterised by TEM, and some of their structural proteins are identified by protein fingerprinting. In addition, it is found that the phage-like particle shows bacteriocin activity toward other B. pumilus strains. The effect of the phage-like particles and the phage in the toxicity of the strain toward C. capitata is also evaluated.
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Gabashvili E, Kobakhidze S, Koulouris S, Robinson T, Kotetishvili M. Bi- and Multi-directional Gene Transfer in the Natural Populations of Polyvalent Bacteriophages, and Their Host Species Spectrum Representing Foodborne Versus Other Human and/or Animal Pathogens. FOOD AND ENVIRONMENTAL VIROLOGY 2021; 13:179-202. [PMID: 33484405 DOI: 10.1007/s12560-021-09460-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 01/06/2021] [Indexed: 06/12/2023]
Abstract
Unraveling the trends of phage-host versus phage-phage coevolution is critical for avoiding possible undesirable outcomes from the use of phage preparations intended for therapeutic, food safety or environmental safety purposes. We aimed to investigate a phenomenon of intergeneric recombination and its trajectories across the natural populations of phages predominantly linked to foodborne pathogens. The results from the recombination analyses, using a large array of the recombination detection algorithms imbedded in SplitsTree, RDP4, and Simplot software packages, provided strong evidence (fit: 100; P ≤ 0.014) for both bi- and multi-directional intergeneric recombination of the genetic loci involved collectively in phage morphogenesis, host specificity, virulence, replication, and persistence. Intergeneric recombination was determined to occur not only among conspecifics of the virulent versus temperate phages but also between the phages with these different lifestyles. The recombining polyvalent phages were suggested to interact with fairly large host species networks, including sometimes genetically very distinct species, such as e.g., Salmonella enterica and/or Escherichia coli versus Staphylococcus aureus or Yersinia pestis. Further studies are needed to understand whether phage-driven intergeneric recombination can lead to undesirable changes of intestinal and other microbiota in humans and animals.
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Affiliation(s)
- Ekaterine Gabashvili
- School of Natural Sciences and Medicine, Ilia State University, 1 Giorgi Tsereteli exit, 0162, Tbilisi, Georgia
- Division of Risk Assessment, Scientific-Research Center of Agriculture, 6 Marshal Gelovani ave., 0159, Tbilisi, Georgia
| | - Saba Kobakhidze
- Division of Risk Assessment, Scientific-Research Center of Agriculture, 6 Marshal Gelovani ave., 0159, Tbilisi, Georgia
| | - Stylianos Koulouris
- Engagement and Cooperation Unit, European Food Safety Authority, Via Carlo Magno 1A, 43126, Parma, Italy
| | - Tobin Robinson
- Scientific Committee, and Emerging Risks Unit, European Food Safety Authority, Via Carlo Magno 1A, 43126, Parma, Italy
| | - Mamuka Kotetishvili
- Division of Risk Assessment, Scientific-Research Center of Agriculture, 6 Marshal Gelovani ave., 0159, Tbilisi, Georgia.
- Hygiene and Medical Ecology, G. Natadze Scientific-Research Institute of Sanitation, 78 D. Uznadze St., 0102, Tbilisi, Georgia.
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14
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Dragoš A, Priyadarshini B, Hasan Z, Strube ML, Kempen PJ, Maróti G, Kaspar C, Bose B, Burton BM, Bischofs IB, Kovács ÁT. Pervasive prophage recombination occurs during evolution of spore-forming Bacilli. ISME JOURNAL 2020; 15:1344-1358. [PMID: 33343000 DOI: 10.1038/s41396-020-00854-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Revised: 11/12/2020] [Accepted: 11/20/2020] [Indexed: 02/06/2023]
Abstract
Phages are the main source of within-species bacterial diversity and drivers of horizontal gene transfer, but we know little about the mechanisms that drive genetic diversity of these mobile genetic elements (MGEs). Recently, we showed that a sporulation selection regime promotes evolutionary changes within SPβ prophage of Bacillus subtilis, leading to direct antagonistic interactions within the population. Herein, we reveal that under a sporulation selection regime, SPβ recombines with low copy number phi3Ts phage DNA present within the B. subtilis population. Recombination results in a new prophage occupying a different integration site, as well as the spontaneous release of virulent phage hybrids. Analysis of Bacillus sp. strains suggests that SPβ and phi3T belong to a distinct cluster of unusually large phages inserted into sporulation-related genes that are equipped with a spore-related genetic arsenal. Comparison of Bacillus sp. genomes indicates that similar diversification of SPβ-like phages takes place in nature. Our work is a stepping stone toward empirical studies on phage evolution, and understanding the eco-evolutionary relationships between bacteria and their phages. By capturing the first steps of new phage evolution, we reveal striking relationship between survival strategy of bacteria and evolution of their phages.
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Affiliation(s)
- Anna Dragoš
- Bacterial Interactions and Evolution Group, Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800, Kongens Lyngby, Denmark.
| | - B Priyadarshini
- Bacterial Interactions and Evolution Group, Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Zahraa Hasan
- Bacterial Interactions and Evolution Group, Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Mikael Lenz Strube
- Bacterial Ecophysiology and Biotechnology Group, Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Paul J Kempen
- Department of Health Technology, Technical University of Denmark, 2800, Kongens Lyngby, Denmark
| | - Gergely Maróti
- Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, Szeged, H-6701, Hungary
| | - Charlotte Kaspar
- BioQuant Center of the University of Heidelberg, 69120, Heidelberg, Germany.,Max-Planck-Institute for Terrestrial Microbiology, 35043, Marburg, Germany
| | | | - Briana M Burton
- Department of Bacteriology, University of Wisconsin, Madison, WI, 53706, USA
| | - Ilka B Bischofs
- BioQuant Center of the University of Heidelberg, 69120, Heidelberg, Germany.,Max-Planck-Institute for Terrestrial Microbiology, 35043, Marburg, Germany
| | - Ákos T Kovács
- Bacterial Interactions and Evolution Group, Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800, Kongens Lyngby, Denmark.
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15
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Millman A, Bernheim A, Stokar-Avihail A, Fedorenko T, Voichek M, Leavitt A, Oppenheimer-Shaanan Y, Sorek R. Bacterial Retrons Function In Anti-Phage Defense. Cell 2020; 183:1551-1561.e12. [PMID: 33157039 DOI: 10.1016/j.cell.2020.09.065] [Citation(s) in RCA: 168] [Impact Index Per Article: 42.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 08/04/2020] [Accepted: 09/28/2020] [Indexed: 01/06/2023]
Abstract
Retrons are bacterial genetic elements comprised of a reverse transcriptase (RT) and a non-coding RNA (ncRNA). The RT uses the ncRNA as template, generating a chimeric RNA/DNA molecule in which the RNA and DNA components are covalently linked. Although retrons were discovered three decades ago, their function remained unknown. We report that retrons function as anti-phage defense systems. The defensive unit is composed of three components: the RT, the ncRNA, and an effector protein. We examined multiple retron systems and show that they confer defense against a broad range of phages via abortive infection. Focusing on retron Ec48, we show evidence that it "guards" RecBCD, a complex with central anti-phage functions in bacteria. Inhibition of RecBCD by phage proteins activates the retron, leading to abortive infection and cell death. Thus, the Ec48 retron forms a second line of defense that is triggered if the first lines of defense have collapsed.
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Affiliation(s)
- Adi Millman
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Aude Bernheim
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | | | - Taya Fedorenko
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Maya Voichek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Azita Leavitt
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | | | - Rotem Sorek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
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16
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Affiliation(s)
- Karen L. Maxwell
- Department of Biochemistry, University of Toronto, Toronto, Canada
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17
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Kuzmenko A, Oguienko A, Esyunina D, Yudin D, Petrova M, Kudinova A, Maslova O, Ninova M, Ryazansky S, Leach D, Aravin AA, Kulbachinskiy A. DNA targeting and interference by a bacterial Argonaute nuclease. Nature 2020; 587:632-637. [PMID: 32731256 DOI: 10.1038/s41586-020-2605-1] [Citation(s) in RCA: 93] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Accepted: 07/24/2020] [Indexed: 12/21/2022]
Abstract
Members of the conserved Argonaute protein family use small RNA guides to locate their mRNA targets and regulate gene expression and suppress mobile genetic elements in eukaryotes1,2. Argonautes are also present in many bacterial and archaeal species3-5. Unlike eukaryotic proteins, several prokaryotic Argonaute proteins use small DNA guides to cleave DNA, a process known as DNA interference6-10. However, the natural functions and targets of DNA interference are poorly understood, and the mechanisms of DNA guide generation and target discrimination remain unknown. Here we analyse the activity of a bacterial Argonaute nuclease from Clostridium butyricum (CbAgo) in vivo. We show that CbAgo targets multicopy genetic elements and suppresses the propagation of plasmids and infection by phages. CbAgo induces DNA interference between homologous sequences and triggers DNA degradation at double-strand breaks in the target DNA. The loading of CbAgo with locus-specific small DNA guides depends on both its intrinsic endonuclease activity and the cellular double-strand break repair machinery. A similar interaction was reported for the acquisition of new spacers during CRISPR adaptation, and prokaryotic genomes that encode Ago nucleases are enriched in CRISPR-Cas systems. These results identify molecular mechanisms that generate guides for DNA interference and suggest that the recognition of foreign nucleic acids by prokaryotic defence systems involves common principles.
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Affiliation(s)
- Anton Kuzmenko
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia. .,Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
| | - Anastasiya Oguienko
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Daria Esyunina
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Denis Yudin
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia.,Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Mayya Petrova
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Alina Kudinova
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Olga Maslova
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Maria Ninova
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Sergei Ryazansky
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - David Leach
- Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
| | - Alexei A Aravin
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia. .,Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.
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18
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Bernheim A, Bikard D, Touchon M, Rocha EPC. A matter of background: DNA repair pathways as a possible cause for the sparse distribution of CRISPR-Cas systems in bacteria. Philos Trans R Soc Lond B Biol Sci 2020; 374:20180088. [PMID: 30905287 PMCID: PMC6452273 DOI: 10.1098/rstb.2018.0088] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The absence of CRISPR-Cas systems in more than half of the sequenced bacterial genomes is intriguing, because their role in adaptive immunity and their frequent transfer between species should have made them almost ubiquitous, as is the case in Archaea. Here, we investigate the possibility that the success of CRISPR-Cas acquisition by horizontal gene transfer is affected by the interactions of these systems with the host genetic background and especially with components of double-strand break repair systems (DSB-RS). We first described the distribution of systems specialized in the repair of double-strand breaks in Bacteria: homologous recombination and non-homologous end joining. This allowed us to show that such systems are more often positively or negatively correlated with the frequency of CRISPR-Cas systems than random genes of similar frequency. The detailed analysis of these co-occurrence patterns shows that our method identifies previously known cases of mechanistic interactions between these systems. It also reveals other positive and negative patterns of co-occurrence between DSB-RS and CRISPR-Cas systems. Notably, it shows that the patterns of distribution of CRISPR-Cas systems in Proteobacteria are strongly dependent on the epistatic groups including RecBCD and AddAB. Our results suggest that the genetic background plays an important role in the success of adaptive immunity in different bacterial clades and provide insights to guide further experimental research on the interactions between CRISPR-Cas and DSB-RS. This article is part of a discussion meeting issue 'The ecology and evolution of prokaryotic CRISPR-Cas adaptive immune systems'.
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Affiliation(s)
- Aude Bernheim
- 1 Microbial Evolutionary Genomics, Institut Pasteur, CNRS, UMR3525, 25-28, rue Dr Roux, Paris, 75015, France.,2 Synthetic Biology Group, Institut Pasteur, 25-28 rue Dr Roux, Paris 75015, France.,3 AgroParisTech , Paris 75005 , France
| | - David Bikard
- 2 Synthetic Biology Group, Institut Pasteur, 25-28 rue Dr Roux, Paris 75015, France
| | - Marie Touchon
- 1 Microbial Evolutionary Genomics, Institut Pasteur, CNRS, UMR3525, 25-28, rue Dr Roux, Paris, 75015, France
| | - Eduardo P C Rocha
- 1 Microbial Evolutionary Genomics, Institut Pasteur, CNRS, UMR3525, 25-28, rue Dr Roux, Paris, 75015, France
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19
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Dion MB, Oechslin F, Moineau S. Phage diversity, genomics and phylogeny. Nat Rev Microbiol 2020; 18:125-138. [PMID: 32015529 DOI: 10.1038/s41579-019-0311-5] [Citation(s) in RCA: 381] [Impact Index Per Article: 95.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2019] [Indexed: 12/23/2022]
Abstract
Recent advances in viral metagenomics have enabled the rapid discovery of an unprecedented catalogue of phages in numerous environments, from the human gut to the deep ocean. Although these advances have expanded our understanding of phage genomic diversity, they also revealed that we have only scratched the surface in the discovery of novel viruses. Yet, despite the remarkable diversity of phages at the nucleotide sequence level, the structural proteins that form viral particles show strong similarities and conservation. Phages are uniquely interconnected from an evolutionary perspective and undergo multiple events of genetic exchange in response to the selective pressure of their hosts, which drives their diversity. In this Review, we explore phage diversity at the structural, genomic and community levels as well as the complex evolutionary relationships between phages, moulded by the mosaicity of their genomes.
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Affiliation(s)
- Moïra B Dion
- Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Québec City, Québec, Canada.,Groupe de recherche en écologie buccale, Faculté de médecine dentaire, Université Laval, Québec City, Québec, Canada
| | - Frank Oechslin
- Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Québec City, Québec, Canada.,Groupe de recherche en écologie buccale, Faculté de médecine dentaire, Université Laval, Québec City, Québec, Canada
| | - Sylvain Moineau
- Département de biochimie, de microbiologie et de bio-informatique, Faculté des sciences et de génie, Université Laval, Québec City, Québec, Canada. .,Groupe de recherche en écologie buccale, Faculté de médecine dentaire, Université Laval, Québec City, Québec, Canada. .,Félix d'Hérelle Reference Center for Bacterial Viruses, Université Laval, Québec City, Québec, Canada.
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20
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Wimmer F, Beisel CL. CRISPR-Cas Systems and the Paradox of Self-Targeting Spacers. Front Microbiol 2020; 10:3078. [PMID: 32038537 PMCID: PMC6990116 DOI: 10.3389/fmicb.2019.03078] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Accepted: 12/19/2019] [Indexed: 12/26/2022] Open
Abstract
CRISPR-Cas immune systems in bacteria and archaea record prior infections as spacers within each system’s CRISPR arrays. Spacers are normally derived from invasive genetic material and direct the immune system to complementary targets as part of future infections. However, not all spacers appear to be derived from foreign genetic material and instead can originate from the host genome. Their presence poses a paradox, as self-targeting spacers would be expected to induce an autoimmune response and cell death. In this review, we discuss the known frequency of self-targeting spacers in natural CRISPR-Cas systems, how these spacers can be incorporated into CRISPR arrays, and how the host can evade lethal attack. We also discuss how self-targeting spacers can become the basis for alternative functions performed by CRISPR-Cas systems that extend beyond adaptive immunity. Overall, the acquisition of genome-targeting spacers poses a substantial risk but can aid in the host’s evolution and potentially lead to or support new functionalities.
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Affiliation(s)
- Franziska Wimmer
- Helmholtz Institute for RNA-Based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany
| | - Chase L Beisel
- Helmholtz Institute for RNA-Based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), Würzburg, Germany.,Medical Faculty, University of Würzburg, Würzburg, Germany
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21
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Nussenzweig PM, McGinn J, Marraffini LA. Cas9 Cleavage of Viral Genomes Primes the Acquisition of New Immunological Memories. Cell Host Microbe 2019; 26:515-526.e6. [PMID: 31585845 PMCID: PMC7558852 DOI: 10.1016/j.chom.2019.09.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 09/04/2019] [Accepted: 09/09/2019] [Indexed: 02/06/2023]
Abstract
Type II CRISPR-Cas systems defend prokaryotes from bacteriophage infection through the acquisition of short viral DNA sequences known as spacers, which are transcribed into short RNA guides to specify the targets of the Cas9 nuclease. To counter the potentially devastating propagation of escaper phages with mutations in the target sequences, the host population acquires many different spacers. Whether and how pre-existing spacers in type II systems affect the acquisition of new ones is unknown. Here, we demonstrate that previously acquired spacers promote additional spacer acquisition from the vicinity of the target DNA site cleaved by Cas9. Therefore, CRISPR immune cells acquire additional spacers at the same time as they destroy the infecting virus. This anticipates the rise of escapers or related viruses that could escape targeting by the first spacer acquired. Our results thus reveal Cas9's role in the generation of immunological memories.
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Affiliation(s)
- Philip M Nussenzweig
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Ave., New York, NY 10065, USA
| | - Jon McGinn
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Ave., New York, NY 10065, USA
| | - Luciano A Marraffini
- Laboratory of Bacteriology, The Rockefeller University, 1230 York Ave., New York, NY 10065, USA; Howard Hughes Medical Institute, The Rockefeller University, 1230 York Ave., New York, NY 10065, USA.
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22
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Charubin K, Bennett RK, Fast AG, Papoutsakis ET. Engineering Clostridium organisms as microbial cell-factories: challenges & opportunities. Metab Eng 2018; 50:173-191. [DOI: 10.1016/j.ymben.2018.07.012] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 07/18/2018] [Accepted: 07/19/2018] [Indexed: 11/25/2022]
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23
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Abstract
Due to their dependence on cellular organisms for metabolism and replication, viruses are typically named and assigned to species according to their genome structure and the original host that they infect. But because viruses often infect multiple hosts and the numbers of distinct lineages within a host can be vast, their delineation into species is often dictated by arbitrary sequence thresholds, which are highly inconsistent across lineages. Here we apply an approach to determine the boundaries of viral species based on the detection of gene flow within populations, thereby defining viral species according to the biological species concept (BSC). Despite the potential for gene transfer between highly divergent genomes, viruses, like the cellular organisms they infect, assort into reproductively isolated groups and can be organized into biological species. This approach revealed that BSC-defined viral species are often congruent with the taxonomic partitioning based on shared gene contents and host tropism, and that bacteriophages can similarly be classified in biological species. These results open the possibility to use a single, universal definition of species that is applicable across cellular and acellular lifeforms.
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24
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Cornuault JK, Petit MA, Mariadassou M, Benevides L, Moncaut E, Langella P, Sokol H, De Paepe M. Phages infecting Faecalibacterium prausnitzii belong to novel viral genera that help to decipher intestinal viromes. MICROBIOME 2018; 6:65. [PMID: 29615108 PMCID: PMC5883640 DOI: 10.1186/s40168-018-0452-1] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 03/21/2018] [Indexed: 05/11/2023]
Abstract
BACKGROUND Viral metagenomic studies have suggested a role for bacteriophages in intestinal dysbiosis associated with several human diseases. However, interpretation of viral metagenomic studies is limited by the lack of knowledge of phages infecting major human gut commensal bacteria, such as Faecalibacterium prausnitzii, a bacterial symbiont repeatedly found depleted in inflammatory bowel disease (IBD) patients. In particular, no complete genomes of phages infecting F. prausnitzii are present in viral databases. METHODS We identified 18 prophages in 15 genomes of F. prausnitzii, used comparative genomics to define eight phage clades, and annotated the genome of the type phage of each clade. For two of the phages, we studied prophage induction in vitro and in vivo in mice. Finally, we aligned reads from already published viral metagenomic data onto the newly identified phages. RESULTS We show that each phage clade represents a novel viral genus and that a surprisingly large fraction of them (10 of the 18 phages) codes for a diversity-generating retroelement, which could contribute to their adaptation to the digestive tract environment. We obtained either experimental or in silico evidence of activity for at least one member of each genus. In addition, four of these phages are either significantly more prevalent or more abundant in stools of IBD patients than in those of healthy controls. CONCLUSION Since IBD patients generally have less F. prausnitzii in their microbiota than healthy controls, the higher prevalence or abundance of some of its phages may indicate that they are activated during disease. This in turn suggests that phages could trigger or aggravate F. prausnitzii depletion in patients. Our results show that prophage detection in sequenced strains of the microbiota can usefully complement viral metagenomic studies.
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Affiliation(s)
- Jeffrey K Cornuault
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Marie-Agnès Petit
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | | | - Leandro Benevides
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
- Department of General Biology, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Elisabeth Moncaut
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Philippe Langella
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Harry Sokol
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
- Sorbonne Universités, UPMC Univ. Paris 06, École normale supérieure, CNRS, INSERM, APHP Laboratoire des Biomolécules (LBM), 27 rue de Chaligny, 75012, Paris, France
- Department of Gastroenterology, Saint Antoine Hospital, Assistance Publique - Hopitaux de Paris, UPMC, Paris, France
| | - Marianne De Paepe
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France.
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25
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Brito PH, Chevreux B, Serra CR, Schyns G, Henriques AO, Pereira-Leal JB. Genetic Competence Drives Genome Diversity in Bacillus subtilis. Genome Biol Evol 2018; 10:108-124. [PMID: 29272410 PMCID: PMC5765554 DOI: 10.1093/gbe/evx270] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/19/2017] [Indexed: 12/18/2022] Open
Abstract
Prokaryote genomes are the result of a dynamic flux of genes, with increases achieved via horizontal gene transfer and reductions occurring through gene loss. The ecological and selective forces that drive this genomic flexibility vary across species. Bacillus subtilis is a naturally competent bacterium that occupies various environments, including plant-associated, soil, and marine niches, and the gut of both invertebrates and vertebrates. Here, we quantify the genomic diversity of B. subtilis and infer the genome dynamics that explain the high genetic and phenotypic diversity observed. Phylogenomic and comparative genomic analyses of 42 B. subtilis genomes uncover a remarkable genome diversity that translates into a core genome of 1,659 genes and an asymptotic pangenome growth rate of 57 new genes per new genome added. This diversity is due to a large proportion of low-frequency genes that are acquired from closely related species. We find no gene-loss bias among wild isolates, which explains why the cloud genome, 43% of the species pangenome, represents only a small proportion of each genome. We show that B. subtilis can acquire xenologous copies of core genes that propagate laterally among strains within a niche. While not excluding the contributions of other mechanisms, our results strongly suggest a process of gene acquisition that is largely driven by competence, where the long-term maintenance of acquired genes depends on local and global fitness effects. This competence-driven genomic diversity provides B. subtilis with its generalist character, enabling it to occupy a wide range of ecological niches and cycle through them.
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Affiliation(s)
- Patrícia H Brito
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
- Nova Medical School, Faculdade de Ciências Médicas, Universidade Nova de Lisboa, Portugal
| | - Bastien Chevreux
- DSM Nutritional Products, Ltd., 60 Westview street, Lexington MA, USA
| | - Cláudia R Serra
- Instituto de Tecnologia Química e Biológica, Oeiras, Portugal
| | - Ghislain Schyns
- DSM Nutritional Products, Ltd., 60 Westview street, Lexington MA, USA
| | | | - José B Pereira-Leal
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
- Ophiomics—Precision Medicine, Lisbon, Portugal
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26
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Oliveira PH, Touchon M, Cury J, Rocha EPC. The chromosomal organization of horizontal gene transfer in bacteria. Nat Commun 2017; 8:841. [PMID: 29018197 PMCID: PMC5635113 DOI: 10.1038/s41467-017-00808-w] [Citation(s) in RCA: 123] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 07/31/2017] [Indexed: 01/02/2023] Open
Abstract
Bacterial adaptation is accelerated by the acquisition of novel traits through horizontal gene transfer, but the integration of these genes affects genome organization. We found that transferred genes are concentrated in only ~1% of the chromosomal regions (hotspots) in 80 bacterial species. This concentration increases with genome size and with the rate of transfer. Hotspots diversify by rapid gene turnover; their chromosomal distribution depends on local contexts (neighboring core genes), and content in mobile genetic elements. Hotspots concentrate most changes in gene repertoires, reduce the trade-off between genome diversification and organization, and should be treasure troves of strain-specific adaptive genes. Most mobile genetic elements and antibiotic resistance genes are in hotspots, but many hotspots lack recognizable mobile genetic elements and exhibit frequent homologous recombination at flanking core genes. Overrepresentation of hotspots with fewer mobile genetic elements in naturally transformable bacteria suggests that homologous recombination and horizontal gene transfer are tightly linked in genome evolution. Horizontal gene transfer (HGT) is an important mechanism for genome evolution and adaptation in bacteria. Here, Oliveira and colleagues find HGT hotspots comprising ~ 1% of the chromosomal regions in 80 bacterial species.
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Affiliation(s)
- Pedro H Oliveira
- Microbial Evolutionary Genomics, Institut Pasteur, 25-28 rue du Docteur Roux, Paris, 75015, France. .,CNRS, UMR3525, 25-28 rue du Docteur Roux, Paris, 75015, France.
| | - Marie Touchon
- Microbial Evolutionary Genomics, Institut Pasteur, 25-28 rue du Docteur Roux, Paris, 75015, France. .,CNRS, UMR3525, 25-28 rue du Docteur Roux, Paris, 75015, France.
| | - Jean Cury
- Microbial Evolutionary Genomics, Institut Pasteur, 25-28 rue du Docteur Roux, Paris, 75015, France.,CNRS, UMR3525, 25-28 rue du Docteur Roux, Paris, 75015, France
| | - Eduardo P C Rocha
- Microbial Evolutionary Genomics, Institut Pasteur, 25-28 rue du Docteur Roux, Paris, 75015, France.,CNRS, UMR3525, 25-28 rue du Docteur Roux, Paris, 75015, France
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27
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CRISPR-Cas systems exploit viral DNA injection to establish and maintain adaptive immunity. Nature 2017; 544:101-104. [PMID: 28355179 PMCID: PMC5540373 DOI: 10.1038/nature21719] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 02/22/2017] [Indexed: 12/19/2022]
Abstract
CRISPR-Cas systems provide protection against viral1 and plasmid2 infection by capturing short DNA sequences from these invaders and integrating them into the CRISPR locus of the prokaryotic host1. These sequences, known as spacers, are transcribed into short RNA guides3–5 that specify the cleavage site of Cas nucleases in the genome of the invader6–8. When spacer sequences are acquired during viral infection is not known. To investigate this, we followed spacer acquisition in Staphylococcus aureus cells harboring a type II CRISPR-Cas9 system after infection with the staphylococcal bacteriophage ϕ12. We found that new spacers are acquired immediately following infection preferentially from the cos site, the viral free DNA end that is first injected into the cell. Analysis of spacer acquisition after infection with mutant phages demonstrated that most spacers are acquired during DNA injection, but not during other stages of the viral cycle that produce free DNA ends, such as DNA replication or packaging. Finally, we showed that spacers acquired from early-injected genomic regions, which direct Cas9 cleavage of the viral DNA immediately after infection, provide better immunity than spacers acquired from late-injected regions. Our results reveal that CRISPR-Cas systems exploit the phage life cycle to generate a pattern of spacer acquisition that ensures the success of the CRISPR immune response.
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Abstract
Since the first demonstration that CRISPR-Cas systems provide bacteria and archaea with adaptive immunity against phages and plasmids, numerous studies have yielded key insights into the molecular mechanisms governing how these systems attack and degrade foreign DNA. However, the molecular mechanisms underlying the adaptation stage, in which new immunological memory is formed, have until recently represented a major unresolved question. In this Progress article, we discuss recent discoveries that have shown both how foreign DNA is identified by the CRISPR-Cas adaptation machinery and the molecular basis for its integration into the chromosome to form an immunological memory. Furthermore, we describe the roles of each of the specific CRISPR-Cas components that are involved in memory formation, and consider current models for their evolutionary origin.
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Jobling MG. The chromosomal nature of LT-II enterotoxins solved: a lambdoid prophage encodes both LT-II and one of two novel pertussis-toxin-like toxin family members in type II enterotoxigenic Escherichia coli. Pathog Dis 2016; 74:ftw001. [PMID: 26755534 PMCID: PMC4957749 DOI: 10.1093/femspd/ftw001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/02/2016] [Indexed: 01/06/2023] Open
Abstract
Heat-labile enterotoxins (LT) of enterotoxigenic Escherichia coli (ETEC) are structurally and functionally related to cholera toxin (CT). LT-I toxins are plasmid-encoded and flanked by IS elements, while LT-II toxins of type II ETEC are chromosomally encoded with flanking genes that appear phage related. Here, I determined the complete genomic sequence of the locus for the LT-IIa type strain SA53, and show that the LT-IIa genes are encoded by a 51 239 bp lambdoid prophage integrated at the rac locus, the site of a defective prophage in E. coli K12 strains. Of 50 LT-IIa and LT-IIc, 46 prophages also encode one member of two novel two-gene ADP-ribosyltransferase toxin families that are both related to pertussis toxin, which I named eplBA or ealAB, respectively. The eplBA and ealAB genes are syntenic with the Shiga toxin loci in their lambdoid prophages of the enteric pathogen enterohemorrhagic E. coli. These novel AB5 toxins show pertussis-toxin-like activity on tissue culture cells, and like pertussis toxin bind to sialic acid containing glycoprotein ligands. Type II ETEC are the first mucosal pathogens known to simultaneously produce two ADP-ribosylating toxins predicted to act on and modulate activity of both stimulatory and inhibitory alpha subunits of host cell heterotrimeric G-proteins. Two novel pertussis-toxin-like toxins are also present in the genome of the prophage that also encodes the LT-II enterotoxin genes in type II enterotoxigenic Escherichi coli.
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Affiliation(s)
- Michael G Jobling
- Department of Immunology and Microbiology, University of Colorado School of Medicine, 12800 E 19th Ave, Aurora CO 80045, USA
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Abstract
Bacteria reproduce asexually and pass on a single genome copied from the parent, a reproductive mode that assures the clonal descent of progeny; however, a truly clonal bacterial species is extremely rare. The signal of clonality can be interrupted by gene uptake and exchange, initiating homologous recombination that results in the unique sequence of one clone being incorporated into another. Because recombination occurs sporadically and on local scales, these events are often difficult to recognize, even when considering large samples of completely sequenced genomes. Moreover, several processes can produce the appearance of clonality in populations that undergo frequent recombination. The rates and consequences of recombination have been studied in Escherichia coli for over 40 y, and, during this time, there have been several shifting views of its clonal status, population structure, and rates of gene exchange. We reexamine the studies and retrace the evolution of the methods that have assessed the extent of DNA flux, largely focusing on its impact on the E. coli genome.
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Henry M, Bobay LM, Chevallereau A, Saussereau E, Ceyssens PJ, Debarbieux L. The search for therapeutic bacteriophages uncovers one new subfamily and two new genera of Pseudomonas-infecting Myoviridae. PLoS One 2015; 10:e0117163. [PMID: 25629728 PMCID: PMC4309531 DOI: 10.1371/journal.pone.0117163] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 12/19/2014] [Indexed: 11/18/2022] Open
Abstract
In a previous study, six virulent bacteriophages PAK_P1, PAK_P2, PAK_P3, PAK_P4, PAK_P5 and CHA_P1 were evaluated for their in vivo efficacy in treating Pseudomonas aeruginosa infections using a mouse model of lung infection. Here, we show that their genomes are closely related to five other Pseudomonas phages and allow a subdivision into two clades, PAK_P1-like and KPP10-like viruses, based on differences in genome size, %GC and genomic contents, as well as number of tRNAs. These two clades are well delineated, with a mean of 86% and 92% of proteins considered homologous within individual clades, and 25% proteins considered homologous between the two clades. By ESI-MS/MS analysis we determined that their virions are composed of at least 25 different proteins and electron microscopy revealed a morphology identical to the hallmark Salmonella phage Felix O1. A search for additional bacteriophage homologs, using profiles of protein families defined from the analysis of the 11 genomes, identified 10 additional candidates infecting hosts from different species. By carrying out a phylogenetic analysis using these 21 genomes we were able to define a new subfamily of viruses, the Felixounavirinae within the Myoviridae family. The new Felixounavirinae subfamily includes three genera: Felixounalikevirus, PAK_P1likevirus and KPP10likevirus. Sequencing genomes of bacteriophages with therapeutic potential increases the quantity of genomic data on closely related bacteriophages, leading to establishment of new taxonomic clades and the development of strategies for analyzing viral genomes as presented in this article.
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Affiliation(s)
- Marine Henry
- Institut Pasteur, Molecular Biology of the Gene in Extremophiles Unit, Department of Microbiology, Paris, France
| | - Louis-Marie Bobay
- Institut Pasteur, Microbial Evolutionary Genomics Unit, Department of Genomes and Genetics, Paris, France
- CNRS, UMR3525, Paris, France
- Université Pierre et Marie Curie, Cellule Pasteur UPMC, Paris, France
| | - Anne Chevallereau
- Institut Pasteur, Molecular Biology of the Gene in Extremophiles Unit, Department of Microbiology, Paris, France
- Université Paris Diderot, Sorbonne Paris Cité, Cellule Pasteur, Paris, France
| | - Emilie Saussereau
- Institut Pasteur, Molecular Biology of the Gene in Extremophiles Unit, Department of Microbiology, Paris, France
- Université Pierre et Marie Curie, Cellule Pasteur UPMC, Paris, France
| | - Pieter-Jan Ceyssens
- Laboratory of Gene Technology, Division of Gene Technology, Katholieke Universiteit Leuven, Heverlee, B-3001, Belgium
- Unit of Bacterial Diseases, Scientific Institute of Public Health (WIV-ISP), Brussels, Belgium
| | - Laurent Debarbieux
- Institut Pasteur, Molecular Biology of the Gene in Extremophiles Unit, Department of Microbiology, Paris, France
- * E-mail:
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Cazares A, Mendoza-Hernández G, Guarneros G. Core and accessory genome architecture in a group of Pseudomonas aeruginosa Mu-like phages. BMC Genomics 2014; 15:1146. [PMID: 25527250 PMCID: PMC4378225 DOI: 10.1186/1471-2164-15-1146] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 12/11/2014] [Indexed: 12/27/2022] Open
Abstract
Background Bacteriophages that infect the opportunistic pathogen Pseudomonas aeruginosa have been classified into several groups. One of them, which includes temperate phage particles with icosahedral heads and long flexible tails, bears genomes whose architecture and replication mechanism, but not their nucleotide sequences, are like those of coliphage Mu. By comparing the genomic sequences of this group of P. aeruginosa phages one could draw conclusions about their ontogeny and evolution. Results Two newly isolated Mu-like phages of P. aeruginosa are described and their genomes sequenced and compared with those available in the public data banks. The genome sequences of the two phages are similar to each other and to those of a group of P. aeruginosa transposable phages. Comparing twelve of these genomes revealed a common genomic architecture in the group. Each phage genome had numerous genes with homologues in all the other genomes and a set of variable genes specific for each genome. The first group, which comprised most of the genes with assigned functions, was named “core genome”, and the second group, containing mostly short ORFs without assigned functions was called “accessory genome”. Like in other phage groups, variable genes are confined to specific regions in the genome. Conclusion Based on the known and inferred functions for some of the variable genes of the phages analyzed here, they appear to confer selective advantages for the phage survival under particular host conditions. We speculate that phages have developed a mechanism for horizontally acquiring genes to incorporate them at specific loci in the genome that help phage adaptation to the selective pressures imposed by the host. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-15-1146) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | - Gabriel Guarneros
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV IPN), Mexico City, Mexico.
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Fricker AD, Peters JE. Vulnerabilities on the lagging-strand template: opportunities for mobile elements. Annu Rev Genet 2014; 48:167-86. [PMID: 25195506 DOI: 10.1146/annurev-genet-120213-092046] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mobile genetic elements have the ability to move between positions in a genome. Some of these elements are capable of targeting one of the template strands during DNA replication. Examples found in bacteria include (a) Red recombination mediated by bacteriophage λ, (b) integration of group II mobile introns that reverse splice and reverse transcribe into DNA, (c) HUH endonuclease elements that move as single-stranded DNA, and (d) Tn7, a DNA cut-and-paste transposon that uses a target-site-selecting protein to target transposition into certain forms of DNA replication. In all of these examples, the lagging-strand template appears to be targeted using a variety of features specific to this strand. These features appear especially available in certain situations, such as when replication forks stall or collapse. In this review, we address the idea that features specific to the lagging-strand template represent vulnerabilities that are capitalized on by mobile genetic elements.
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Affiliation(s)
- Ashwana D Fricker
- Department of Microbiology, Cornell University, Ithaca, New York 14853;
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Oliveira PH, Touchon M, Rocha EPC. The interplay of restriction-modification systems with mobile genetic elements and their prokaryotic hosts. Nucleic Acids Res 2014; 42:10618-31. [PMID: 25120263 PMCID: PMC4176335 DOI: 10.1093/nar/gku734] [Citation(s) in RCA: 191] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 07/29/2014] [Accepted: 07/30/2014] [Indexed: 01/21/2023] Open
Abstract
The roles of restriction-modification (R-M) systems in providing immunity against horizontal gene transfer (HGT) and in stabilizing mobile genetic elements (MGEs) have been much debated. However, few studies have precisely addressed the distribution of these systems in light of HGT, its mechanisms and its vectors. We analyzed the distribution of R-M systems in 2261 prokaryote genomes and found their frequency to be strongly dependent on the presence of MGEs, CRISPR-Cas systems, integrons and natural transformation. Yet R-M systems are rare in plasmids, in prophages and nearly absent from other phages. Their abundance depends on genome size for small genomes where it relates with HGT but saturates at two occurrences per genome. Chromosomal R-M systems might evolve under cycles of purifying and relaxed selection, where sequence conservation depends on the biochemical activity and complexity of the system and total gene loss is frequent. Surprisingly, analysis of 43 pan-genomes suggests that solitary R-M genes rarely arise from the degradation of R-M systems. Solitary genes are transferred by large MGEs, whereas complete systems are more frequently transferred autonomously or in small MGEs. Our results suggest means of testing the roles for R-M systems and their associations with MGEs.
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Affiliation(s)
- Pedro H Oliveira
- Institut Pasteur, Microbial Evolutionary Genomics, Département Génomes et Génétique, Paris, France CNRS, UMR3525, Paris, France
| | - Marie Touchon
- Institut Pasteur, Microbial Evolutionary Genomics, Département Génomes et Génétique, Paris, France CNRS, UMR3525, Paris, France
| | - Eduardo P C Rocha
- Institut Pasteur, Microbial Evolutionary Genomics, Département Génomes et Génétique, Paris, France CNRS, UMR3525, Paris, France
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De Paepe M, Hutinet G, Son O, Amarir-Bouhram J, Schbath S, Petit MA. Temperate phages acquire DNA from defective prophages by relaxed homologous recombination: the role of Rad52-like recombinases. PLoS Genet 2014; 10:e1004181. [PMID: 24603854 PMCID: PMC3945230 DOI: 10.1371/journal.pgen.1004181] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 01/04/2014] [Indexed: 01/13/2023] Open
Abstract
Bacteriophages (or phages) dominate the biosphere both numerically and in terms of genetic diversity. In particular, genomic comparisons suggest a remarkable level of horizontal gene transfer among temperate phages, favoring a high evolution rate. Molecular mechanisms of this pervasive mosaicism are mostly unknown. One hypothesis is that phage encoded recombinases are key players in these horizontal transfers, thanks to their high efficiency and low fidelity. Here, we associate two complementary in vivo assays and a bioinformatics analysis to address the role of phage encoded recombinases in genomic mosaicism. The first assay allowed determining the genetic determinants of mosaic formation between lambdoid phages and Escherichia coli prophage remnants. In the second assay, recombination was monitored between sequences on phage λ, and allowed to compare the performance of three different Rad52-like recombinases on the same substrate. We also addressed the importance of homologous recombination in phage evolution by a genomic comparison of 84 E. coli virulent and temperate phages or prophages. We demonstrate that mosaics are mainly generated by homology-driven mechanisms that tolerate high substrate divergence. We show that phage encoded Rad52-like recombinases act independently of RecA, and that they are relatively more efficient when the exchanged fragments are divergent. We also show that accessory phage genes orf and rap contribute to mosaicism. A bioinformatics analysis strengthens our experimental results by showing that homologous recombination left traces in temperate phage genomes at the borders of recently exchanged fragments. We found no evidence of exchanges between virulent and temperate phages of E. coli. Altogether, our results demonstrate that Rad52-like recombinases promote gene shuffling among temperate phages, accelerating their evolution. This mechanism may prove to be more general, as other mobile genetic elements such as ICE encode Rad52-like functions, and play an important role in bacterial evolution itself.
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Affiliation(s)
- Marianne De Paepe
- INRA, UMR1319, Micalis, domaine de Vilvert, Jouy en Josas, France
- AgroParisTech, UMR1319, Micalis, domaine de Vilvert, Jouy en Josas, France
| | - Geoffrey Hutinet
- INRA, UMR1319, Micalis, domaine de Vilvert, Jouy en Josas, France
- AgroParisTech, UMR1319, Micalis, domaine de Vilvert, Jouy en Josas, France
| | - Olivier Son
- INRA, UMR1319, Micalis, domaine de Vilvert, Jouy en Josas, France
- AgroParisTech, UMR1319, Micalis, domaine de Vilvert, Jouy en Josas, France
| | - Jihane Amarir-Bouhram
- INRA, UMR1319, Micalis, domaine de Vilvert, Jouy en Josas, France
- AgroParisTech, UMR1319, Micalis, domaine de Vilvert, Jouy en Josas, France
| | - Sophie Schbath
- INRA, UR1077, MIG, domaine de Vilvert, Jouy en Josas, France
| | - Marie-Agnès Petit
- INRA, UMR1319, Micalis, domaine de Vilvert, Jouy en Josas, France
- AgroParisTech, UMR1319, Micalis, domaine de Vilvert, Jouy en Josas, France
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