1
|
Mayo-Muñoz D, Li H, Mestre MR, Pinilla-Redondo R. The role of noncoding RNAs in bacterial immunity. Trends Microbiol 2024:S0966-842X(24)00250-6. [PMID: 39396887 DOI: 10.1016/j.tim.2024.09.006] [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: 08/11/2024] [Revised: 09/18/2024] [Accepted: 09/18/2024] [Indexed: 10/15/2024]
Abstract
The evolutionary arms race between bacteria and phages has driven the development of diverse anti-phage defense mechanisms. Recent studies have identified noncoding RNAs (ncRNAs) as key players in bacteria-phage conflicts, including CRISPR-Cas, toxin-antitoxin (TA), and reverse transcriptase (RT)-based defenses; however, our understanding of their roles in immunity is still emerging. In this review, we explore the multifaceted roles of ncRNAs in bacterial immunity, offering insights into their contributions to defense and anti-defense mechanisms, their influence on immune regulatory networks, and potential biotechnological applications. Finally, we highlight key outstanding questions in the field to spark future research directions.
Collapse
Affiliation(s)
- David Mayo-Muñoz
- Department of Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Huijuan Li
- Section of Microbiology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark
| | - Mario Rodríguez Mestre
- Section of Microbiology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark
| | - Rafael Pinilla-Redondo
- Section of Microbiology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark.
| |
Collapse
|
2
|
Handa S, Biswas T, Chakraborty J, Ghosh G, Paul BG, Ghosh P. Structural Requirements for Reverse Transcription by a Diversity-generating Retroelement. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2023.10.23.563531. [PMID: 37961358 PMCID: PMC10634737 DOI: 10.1101/2023.10.23.563531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2023]
Abstract
Diversity-generating retroelements (DGRs) create massive protein sequence variation in ecologically diverse microbes. Variation occurs during reverse transcription of a protein-encoding RNA template coupled to misincorporation at adenosines. In the prototypical Bordetella bacteriophage DGR, the template must be surrounded by upstream and downstream RNA segments for cDNA synthesis by the reverse transcriptase bRT and associated protein Avd. The function of the surrounding RNA was unknown. Cryo-EM revealed that this RNA enveloped bRT and lay over barrel-shaped Avd, forming an intimate ribonucleoprotein (RNP). An abundance of essential interactions between RNA structural elements and bRT-Avd precisely positioned an RNA homoduplex for initiation of cDNA synthesis by cis -priming. Our results explain how the surrounding RNA primes cDNA synthesis, promotes processivity, terminates polymerization, and strictly limits mutagenesis to select proteins through mechanisms that are likely conserved in DGRs from distant taxa.
Collapse
|
3
|
Mohr G, Yao J, Park SK, Markham L, Lambowitz AM. Mechanisms used for cDNA synthesis and site-specific integration of RNA into DNA genomes by a reverse transcriptase-Cas1 fusion protein. SCIENCE ADVANCES 2024; 10:eadk8791. [PMID: 38608016 PMCID: PMC11014452 DOI: 10.1126/sciadv.adk8791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Accepted: 03/08/2024] [Indexed: 04/14/2024]
Abstract
Reverse transcriptase-Cas1 (RT-Cas1) fusion proteins found in some CRISPR systems enable spacer acquisition from both RNA and DNA, but the mechanism of RNA spacer acquisition has remained unclear. Here, we found that Marinomonas mediterranea RT-Cas1/Cas2 adds short 3'-DNA (dN) tails to RNA protospacers, enabling their direct integration into CRISPR arrays as 3'-dN-RNAs or 3'-dN-RNA/cDNA duplexes at rates comparable to similarly configured DNAs. Reverse transcription of RNA protospacers is initiated at 3' proximal sites by multiple mechanisms, including recently described de novo initiation, protein priming with any dNTP, and use of short exogenous or synthesized DNA oligomer primers, enabling synthesis of near full-length cDNAs of diverse RNAs without fixed sequence requirements. The integration of 3'-dN-RNAs or single-stranded DNAs (ssDNAs) is favored over duplexes at higher protospacer concentrations, potentially relevant to spacer acquisition from abundant pathogen RNAs or ssDNA fragments generated by phage defense nucleases. Our findings reveal mechanisms for site-specifically integrating RNA into DNA genomes with potential biotechnological applications.
Collapse
Affiliation(s)
- Georg Mohr
- Departments of Molecular Biosciences and Oncology, University of Texas at Austin, Austin, TX 78712, USA
| | - Jun Yao
- Departments of Molecular Biosciences and Oncology, University of Texas at Austin, Austin, TX 78712, USA
| | | | - Laura Markham
- Departments of Molecular Biosciences and Oncology, University of Texas at Austin, Austin, TX 78712, USA
| | | |
Collapse
|
4
|
Doré H, Eisenberg AR, Junkins EN, Leventhal GE, Ganesh A, Cordero OX, Paul BG, Valentine DL, O’Malley MA, Wilbanks EG. Targeted hypermutation of putative antigen sensors in multicellular bacteria. Proc Natl Acad Sci U S A 2024; 121:e2316469121. [PMID: 38354254 PMCID: PMC10907252 DOI: 10.1073/pnas.2316469121] [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: 09/29/2023] [Accepted: 01/10/2024] [Indexed: 02/16/2024] Open
Abstract
Diversity-generating retroelements (DGRs) are used by bacteria, archaea, and viruses as a targeted mutagenesis tool. Through error-prone reverse transcription, DGRs introduce random mutations at specific genomic loci, enabling rapid evolution of these targeted genes. However, the function and benefits of DGR-diversified proteins in cellular hosts remain elusive. We find that 82% of DGRs from one of the major monophyletic lineages of DGR reverse transcriptases are encoded by multicellular bacteria, which often have two or more DGR loci in their genomes. Using the multicellular purple sulfur bacterium Thiohalocapsa sp. PB-PSB1 as an example, we characterized nine distinct DGR loci capable of generating 10282 different combinations of target proteins. With environmental metagenomes from individual Thiohalocapsa aggregates, we show that most of PB-PSB1's DGR target genes are diversified across its biogeographic range, with spatial heterogeneity in the diversity of each locus. In Thiohalocapsa PB-PSB1 and other bacteria hosting this lineage of cellular DGRs, the diversified target genes are associated with NACHT-domain anti-phage defenses and putative ternary conflict systems previously shown to be enriched in multicellular bacteria. We propose that these DGR-diversified targets act as antigen sensors that confer a form of adaptive immunity to their multicellular consortia, though this remains to be experimentally tested. These findings could have implications for understanding the evolution of multicellularity, as the NACHT-domain anti-phage systems and ternary systems share both domain homology and conceptual similarities with the innate immune and programmed cell death pathways of plants and metazoans.
Collapse
Affiliation(s)
- H. Doré
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA93106
| | - A. R. Eisenberg
- Department of Chemical Engineering, University of California, Santa Barbara, CA93106
| | - E. N. Junkins
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA93106
| | - G. E. Leventhal
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA02139
| | - Anakha Ganesh
- Bay Paul Center, Marine Biological Laboratory, Woods Hole, MA02543
| | - O. X. Cordero
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA02139
| | - B. G. Paul
- Bay Paul Center, Marine Biological Laboratory, Woods Hole, MA02543
| | - D. L. Valentine
- Department of Earth Science, University of California, Santa Barbara, CA93106
- Marine Science Institute, University of California, Santa Barbara, CA93106
| | - M. A. O’Malley
- Department of Chemical Engineering, University of California, Santa Barbara, CA93106
- Department of Bioengineering, University of California, Santa Barbara, CA93106
| | - E. G. Wilbanks
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, CA93106
- Department of Bioengineering, University of California, Santa Barbara, CA93106
| |
Collapse
|
5
|
Rozwalak P, Barylski J, Wijesekara Y, Dutilh BE, Zielezinski A. Ultraconserved bacteriophage genome sequence identified in 1300-year-old human palaeofaeces. Nat Commun 2024; 15:495. [PMID: 38263397 PMCID: PMC10805732 DOI: 10.1038/s41467-023-44370-0] [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: 06/13/2023] [Accepted: 12/11/2023] [Indexed: 01/25/2024] Open
Abstract
Bacteriophages are widely recognised as rapidly evolving biological entities. However, knowledge about ancient bacteriophages is limited. Here, we analyse DNA sequence datasets previously generated from ancient palaeofaeces and human gut-content samples, and identify an ancient phage genome nearly identical to present-day Mushuvirus mushu, a virus that infects gut commensal bacteria. The DNA damage patterns of the genome are consistent with its ancient origin and, despite 1300 years of evolution, the ancient Mushuvirus genome shares 97.7% nucleotide identity with its modern counterpart, indicating a long-term relationship between the prophage and its host. In addition, we reconstruct and authenticate 297 other phage genomes from the last 5300 years, including those belonging to unknown families. Our findings demonstrate the feasibility of reconstructing ancient phage genome sequences, thus expanding the known virosphere and offering insights into phage-bacteria interactions spanning several millennia.
Collapse
Affiliation(s)
- Piotr Rozwalak
- Department of Computational Biology, Faculty of Biology, Adam Mickiewicz University, Poznan, 61-614, Poland
| | - Jakub Barylski
- Department of Molecular Virology, Faculty of Biology, Adam Mickiewicz University, Poznan, 61-614, Poland
| | - Yasas Wijesekara
- Institute of Bioinformatics, University Medicine Greifswald, Felix-Hausdorff-Str. 8, 17475, Greifswald, Germany
| | - Bas E Dutilh
- Institute of Biodiversity, Faculty of Biological Sciences, Cluster of Excellence Balance of the Microverse, Friedrich Schiller University Jena, 07743, Jena, Germany.
- Theoretical Biology and Bioinformatics, Science4Life, Utrecht University, Padualaan 8, 3584 CH, Utrecht, the Netherlands.
| | - Andrzej Zielezinski
- Department of Computational Biology, Faculty of Biology, Adam Mickiewicz University, Poznan, 61-614, Poland.
| |
Collapse
|
6
|
Lou YC, Chen L, Borges AL, West-Roberts J, Firek BA, Morowitz MJ, Banfield JF. Infant gut DNA bacteriophage strain persistence during the first 3 years of life. Cell Host Microbe 2024; 32:35-47.e6. [PMID: 38096814 PMCID: PMC11156429 DOI: 10.1016/j.chom.2023.11.015] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 10/27/2023] [Accepted: 11/16/2023] [Indexed: 01/13/2024]
Abstract
Bacteriophages are key components of gut microbiomes, yet the phage colonization process in the infant gut remains uncertain. Here, we establish a large phage sequence database and use strain-resolved analyses to investigate DNA phage succession in infants throughout the first 3 years of life. Analysis of 819 fecal metagenomes collected from 28 full-term and 24 preterm infants and their mothers revealed that early-life phageome richness increases over time and reaches adult-like complexity by age 3. Approximately 9% of early phage colonizers, which are mostly maternally transmitted and infect Bacteroides, persist for 3 years and are more prevalent in full-term than in preterm infants. Although rare, phages with stop codon reassignment are more likely to persist than non-recoded phages and generally display an increase in in-frame reassigned stop codons over 3 years. Overall, maternal seeding, stop codon reassignment, host CRISPR-Cas locus prevalence, and diverse phage populations contribute to stable viral colonization.
Collapse
Affiliation(s)
- Yue Clare Lou
- Department of Plant and Microbial Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - LinXing Chen
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Earth and Planetary Science, University of California, Berkeley, Berkeley, CA 94709, USA
| | - Adair L Borges
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Jacob West-Roberts
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Brian A Firek
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Michael J Morowitz
- Department of Surgery, University of Pittsburgh School of Medicine, Pittsburgh, PA 15213, USA
| | - Jillian F Banfield
- Innovative Genomics Institute, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA 94720, USA.
| |
Collapse
|
7
|
Baykov IK, Tikunov AY, Babkin IV, Fedorets VA, Zhirakovskaia EV, Tikunova NV. Tentaclins-A Novel Family of Phage Receptor-Binding Proteins That Can Be Hypermutated by DGR Systems. Int J Mol Sci 2023; 24:17324. [PMID: 38139153 PMCID: PMC10743442 DOI: 10.3390/ijms242417324] [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: 11/06/2023] [Revised: 11/29/2023] [Accepted: 12/05/2023] [Indexed: 12/24/2023] Open
Abstract
Diversity-generating retroelements (DGRs) are prokaryotic systems providing rapid modification and adaptation of target proteins. In phages, the main targets of DGRs are receptor-binding proteins that are usually parts of tail structures and the variability of such host-recognizing structures enables phage adaptation to changes on the bacterial host surface. Sometimes, more than one target gene containing a hypermutated variable repeat (VR) can be found in phage DGRs. The role of mutagenesis of two functionally different genes is unclear. In this study, several phage genomes that contain DGRs with two target genes were found in the gut virome of healthy volunteers. Bioinformatics analysis of these genes indicated that they encode proteins with different topology; however, both proteins contain the C-type lectin (C-lec) domain with a hypermutated beta-hairpin on its surface. One of the target proteins belongs to a new family of proteins with a specific topology: N-terminal C-lec domain followed by one or more immunoglobulin domains. Proteins from the new family were named tentaclins after TENTACLe + proteIN. The genes encoding such proteins were found in the genomes of prophages and phages from the gut metagenomes. We hypothesized that tentaclins are involved in binding either to bacterial receptors or intestinal/immune cells.
Collapse
Affiliation(s)
- Ivan K. Baykov
- Federal State Public Scientific Institution «Institute of Chemical Biology and Fundamental Medicine», Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia
| | | | | | | | | | - Nina V. Tikunova
- Federal State Public Scientific Institution «Institute of Chemical Biology and Fundamental Medicine», Siberian Branch of the Russian Academy of Sciences, 630090 Novosibirsk, Russia
| |
Collapse
|
8
|
Mohr G, Yao J, Park SK, Markham LM, Lambowitz AM. Mechanisms used for cDNA synthesis and site-specific integration of RNA into DNA genomes by a reverse transcriptase-Cas1 fusion protein. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.01.555893. [PMID: 37693417 PMCID: PMC10491204 DOI: 10.1101/2023.09.01.555893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2023]
Abstract
Reverse transcriptase-Cas1 (RT-Cas1) fusion proteins found in some CRISPR systems enable spacer acquisition from both RNA and DNA, but the mechanism of RNA spacer acquisition has remained unclear. Here, we found Marinomonas mediterranea RT-Cas1/Cas2 adds short 3'-DNA (dN) tails to RNA protospacers enabling their direct integration into CRISPR arrays as 3'-dN-RNA/cDNA duplexes or 3'-dN-RNAs at rates comparable to similarly configured DNAs. Reverse transcription of RNA protospacers occurs by multiple mechanisms, including recently described de novo initiation, protein priming with any dNTP, and use of short exogenous or synthesized DNA oligomer primers, enabling synthesis of cDNAs from diverse RNAs without fixed sequence requirements. The integration of 3'-dN-RNAs or single-stranded (ss) DNAs is favored over duplexes at higher protospacer concentrations, potentially relevant to spacer acquisition from abundant pathogen RNAs or ssDNA fragments generated by phage-defense nucleases. Our findings reveal novel mechanisms for site-specifically integrating RNA into DNA genomes with potential biotechnological applications.
Collapse
Affiliation(s)
- Georg Mohr
- Departments of Molecular Biosciences and Oncology University of Texas at Austin Austin TX, 78712
| | - Jun Yao
- Departments of Molecular Biosciences and Oncology University of Texas at Austin Austin TX, 78712
| | | | - Laura M. Markham
- Departments of Molecular Biosciences and Oncology University of Texas at Austin Austin TX, 78712
| | - Alan M. Lambowitz
- Departments of Molecular Biosciences and Oncology University of Texas at Austin Austin TX, 78712
| |
Collapse
|
9
|
Diversity-Generating Retroelements in Prokaryotic Immunity. Int J Mol Sci 2023; 24:ijms24065614. [PMID: 36982690 PMCID: PMC10053308 DOI: 10.3390/ijms24065614] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 03/10/2023] [Accepted: 03/12/2023] [Indexed: 03/17/2023] Open
Abstract
Adaptive immunity systems found in different organisms fall into two major types. Prokaryotes possess CRISPR-Cas systems that recognize former invaders using memorized (captured) pieces of their DNA as pathogen signatures. Mammals possess a vast repertoire of antibodies and T-cell receptor variants generated in advance. In this second type of adaptive immunity, a pathogen presentation to the immune system specifically activates the cells that express matching antibodies or receptors. These cells proliferate to fight the infection and form the immune memory. The principle of preemptive production of diverse defense proteins for future use can hypothetically take place in microbes too. We propose a hypothesis that prokaryotes employ diversity-generating retroelements to prepare defense proteins against yet-unknown invaders. In this study, we test this hypothesis with the methods of bioinformatics and identify several candidate defense systems based on diversity-generating retroelements.
Collapse
|
10
|
Parida PK, Behera BK, Dehury B, Rout AK, Sarkar DJ, Rai A, Das BK, Mohapatra T. Community structure and function of microbiomes in polluted stretches of river Yamuna in New Delhi, India, using shotgun metagenomics. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:71311-71325. [PMID: 35596862 DOI: 10.1007/s11356-022-20766-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2022] [Accepted: 05/08/2022] [Indexed: 06/15/2023]
Abstract
The large population residing in the northern region of India surrounding Delhi mostly depends on water of River Yamuna, a tributary of mighty Ganga for agriculture, drinking and various religious activities. However, continuous anthropogenic activities mostly due to pollution mediated by rapid urbanization and industrialization have profoundly affected river microflora and their function thus its health. In this study, potential of whole-genome metagenomics was exploited to unravel the novel consortia of microbiome and their functional potential in the polluted sediments of the river at Delhi. Analysis of high-quality metagenome data from Illumina NextSeq500 revealed substantial differences in composition of microbiota at different sites dominated by Proteobacteria, Bacteroidetes, Firmicutes, Actinobacteria and Chloroflexi phyla. The presence of highly dominant anaerobic bacteria like Dechloromonas aromatica (benzene reducing and denitrifying), Rhodopseudomonas palustris (organic matter reducing), Syntrophus aciditrophicus (fatty acid reducing) and Syntrophobacter fumaroxidans (sulphate reducing) in the polluted river Yamuna signifies the impact of unchecked pollution in declining health of the river ecosystem. A decline in abundance of phages was also noticed along the downstream river Yamuna. Mining of mycobiome reads uncovered plethora of fungal communities (i.e. Nakaseomyces, Aspergillus, Schizosaccharomyces and Lodderomyces) in the polluted stretches due to the availability of higher organic carbon and total nitrogen (%) could be decoded as promising bioindicators of river trophic status. Pathway analysis through KEGG revealed higher abundance of genes involved in energy metabolism (nitrogen and sulphur), methane metabolism, degradation of xenobiotics (Nitrotoluene, Benzoate and Atrazine), two-component system (atoB, cusA and silA) and membrane transport (ABC transporters). Catalase-peroxidase and 4-hydroxybenzoate 3-monooxygenase were the most enriched pollution degrading enzymes in the polluted study sites of river Yamuna. Overall, our results provide crucial insights into microbial dynamics and their function in response to high pollution and could be insightful to the ongoing remediation strategies to clean river Yamuna.
Collapse
Affiliation(s)
- Pranaya Kumar Parida
- Aquatic Environmental Biotechnology and Nanotechnology Division, ICAR-Central Inland Fisheries Research Institute, Kolkata, 700120, West Bengal, India
| | - Bijay Kumar Behera
- Aquatic Environmental Biotechnology and Nanotechnology Division, ICAR-Central Inland Fisheries Research Institute, Kolkata, 700120, West Bengal, India.
| | - Budheswar Dehury
- Aquatic Environmental Biotechnology and Nanotechnology Division, ICAR-Central Inland Fisheries Research Institute, Kolkata, 700120, West Bengal, India
| | - Ajaya Kumar Rout
- Aquatic Environmental Biotechnology and Nanotechnology Division, ICAR-Central Inland Fisheries Research Institute, Kolkata, 700120, West Bengal, India
| | - Dhruba Jyoti Sarkar
- Aquatic Environmental Biotechnology and Nanotechnology Division, ICAR-Central Inland Fisheries Research Institute, Kolkata, 700120, West Bengal, India
| | - Anil Rai
- Centre for Agricultural Bioinformatics, ICAR-Indian Agricultural Statistics Research Institute, Library Avenue, Pusa, New Delhi, 110012, India
| | - Basanta Kumar Das
- Aquatic Environmental Biotechnology and Nanotechnology Division, ICAR-Central Inland Fisheries Research Institute, Kolkata, 700120, West Bengal, India
| | | |
Collapse
|
11
|
Macadangdang BR, Makanani SK, Miller JF. Accelerated Evolution by Diversity-Generating Retroelements. Annu Rev Microbiol 2022; 76:389-411. [PMID: 35650669 DOI: 10.1146/annurev-micro-030322-040423] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Diversity-generating retroelements (DGRs) create vast amounts of targeted, functional diversity by facilitating the rapid evolution of ligand-binding protein domains. Thousands of DGRs have been identified in bacteria, archaea, and their respective viruses. They are broadly distributed throughout the microbial world, with enrichment observed in certain taxa and environments. The diversification machinery works through a novel mechanism termed mutagenic retrohoming, whereby nucleotide sequence information is copied from an invariant DNA template repeat (TR) into an RNA intermediate, selectively mutagenized at TR adenines during cDNA synthesis by a DGR-encoded reverse transcriptase, and transferred to a variable repeat (VR) region within a variable-protein gene (54). This unidirectional flow of information leaves TR-DNA sequences unmodified, allowing for repeated rounds of mutagenic retrohoming to optimize variable-protein function. DGR target genes are often modular and can encode one or more of a wide variety of discrete functional domains appended to a diversifiable ligand-binding motif. Bacterial variable proteins often localize to cell surfaces, although a subset appear to be cytoplasmic, while phage-encoded DGRs commonly diversify tail fiber-associated receptor-binding proteins. Here, we provide a comprehensive review of the mechanism and consequences of accelerated protein evolution by these unique and beneficial genetic elements. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Collapse
Affiliation(s)
- Benjamin R Macadangdang
- Division of Neonatology and Developmental Biology, Department of Pediatrics, David Geffen School of Medicine, University of California, Los Angeles, California, USA; .,California NanoSystems Institute, University of California, Los Angeles, California, USA
| | - Sara K Makanani
- California NanoSystems Institute, University of California, Los Angeles, California, USA.,Department of Ecology and Evolutionary Biology, University of California, Los Angeles, California, USA; .,Department of Microbiology, Immunology and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, California, USA;
| | - Jeff F Miller
- California NanoSystems Institute, University of California, Los Angeles, California, USA.,Department of Microbiology, Immunology and Molecular Genetics, David Geffen School of Medicine, University of California, Los Angeles, California, USA; .,Molecular Biology Institute, University of California, Los Angeles, California, USA
| |
Collapse
|
12
|
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.
Collapse
Affiliation(s)
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, United States
| |
Collapse
|
13
|
Paul BG, Eren AM. Eco-evolutionary significance of domesticated retroelements in microbial genomes. Mob DNA 2022; 13:6. [PMID: 35197094 PMCID: PMC8867640 DOI: 10.1186/s13100-022-00262-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/03/2022] [Indexed: 01/03/2023] Open
Abstract
Since the first discovery of reverse transcriptase in bacteria, and later in archaea, bacterial and archaeal retroelements have been defined by their common enzyme that coordinates diverse functions. Yet, evolutionary refinement has produced distinct retroelements across the tree of microbial life that are perhaps best described in terms of their programmed RNA-a compact sequence that preserves core information for a sophisticated mechanism. From this perspective, reverse transcriptase has been selected as the modular tool for carrying out nature's instructions in various RNA templates. Beneficial retroelements-those that can provide a fitness advantage to their host-evolved to their extant forms in a wide array of microorganisms and their viruses, spanning nearly all habitats. Within each specialized retroelement class, several universal features seem to be shared across diverse taxa, while specific functional and mechanistic insights are based on only a few model retroelement systems from clinical isolates. Currently, little is known about the diversity of cellular functions and ecological significance of retroelements across different biomes. With increasing availability of isolate, metagenome-assembled, and single-amplified genomes, the taxonomic and functional breadth of prokaryotic retroelements is coming into clearer view. This review explores the recently characterized classes of beneficial, yet accessory retroelements of bacteria and archaea. We describe how these specialized mechanisms exploit a form of fixed mobility, whereby the retroelements do not appear to proliferate selfishly throughout the genome. Moreover, we discuss computational approaches for systematic identification of retroelements from vast sequence repositories and highlight recent discoveries in terms of their apparent distribution and ecological significance in nature. Lastly, we present a new perspective on the eco-evolutionary significance of these genetic elements in marine bacteria and demonstrate approaches that enable the characterization of their environmental diversity through metagenomics.
Collapse
Affiliation(s)
- Blair G Paul
- Marine Biological Laboratory, Josephine Bay Paul Center, Woods Hole, MA, USA.
| | - A Murat Eren
- Marine Biological Laboratory, Josephine Bay Paul Center, Woods Hole, MA, USA.
- Department of Medicine, University of Chicago, Chicago, IL, USA.
| |
Collapse
|
14
|
Broecker F. Editorial for the Special Issue: The Role of the Virome in Health and Disease. Microorganisms 2021; 10:microorganisms10010020. [PMID: 35056466 PMCID: PMC8778850 DOI: 10.3390/microorganisms10010020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 12/20/2021] [Indexed: 11/22/2022] Open
Affiliation(s)
- Felix Broecker
- Idorsia Pharmaceuticals Ltd., Hegenheimermattweg 91, CH-4123 Allschwil, Switzerland
| |
Collapse
|
15
|
Sharifi F, Ye Y. Identification and classification of reverse transcriptases in bacterial genomes and metagenomes. Nucleic Acids Res 2021; 50:e29. [PMID: 34904653 PMCID: PMC8934634 DOI: 10.1093/nar/gkab1207] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 11/17/2021] [Accepted: 11/22/2021] [Indexed: 02/07/2023] Open
Abstract
Reverse transcriptases (RTs) are found in different systems including group II introns, Diversity Generating Retroelements (DGRs), retrons, CRISPR-Cas systems, and Abortive Infection (Abi) systems in prokaryotes. Different classes of RTs can play different roles, such as template switching and mobility in group II introns, spacer acquisition in CRISPR-Cas systems, mutagenic retrohoming in DGRs, programmed cell suicide in Abi systems, and recently discovered phage defense in retrons. While some classes of RTs have been studied extensively, others remain to be characterized. There is a lack of computational tools for identifying and characterizing various classes of RTs. In this study, we built a tool (called myRT) for identification and classification of prokaryotic RTs. In addition, our tool provides information about the genomic neighborhood of each RT, providing potential functional clues. We applied our tool to predict RTs in all complete and draft bacterial genomes, and created a collection that can be used for exploration of putative RTs and their associated protein domains. Application of myRT to metagenomes showed that gut metagenomes encode proportionally more RTs related to DGRs, outnumbering retron-related RTs, as compared to the collection of reference genomes. MyRT is both available as a standalone software (https://github.com/mgtools/myRT) and also through a website (https://omics.informatics.indiana.edu/myRT/).
Collapse
Affiliation(s)
- Fatemeh Sharifi
- Luddy School of Informatics, Computing, and Engineering, Indiana University, Bloomington, IN 47408, USA
| | - Yuzhen Ye
- Luddy School of Informatics, Computing, and Engineering, Indiana University, Bloomington, IN 47408, USA
| |
Collapse
|
16
|
González-Delgado A, Mestre MR, Martínez-Abarca F, Toro N. Prokaryotic reverse transcriptases: from retroelements to specialized defense systems. FEMS Microbiol Rev 2021; 45:fuab025. [PMID: 33983378 PMCID: PMC8632793 DOI: 10.1093/femsre/fuab025] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 05/07/2021] [Indexed: 12/30/2022] Open
Abstract
Reverse transcriptases (RTs) catalyze the polymerization of DNA from an RNA template. These enzymes were first discovered in RNA tumor viruses in 1970, but it was not until 1989 that they were found in prokaryotes as a key component of retrons. Apart from RTs encoded by the 'selfish' mobile retroelements known as group II introns, prokaryotic RTs are extraordinarily diverse, but their function has remained elusive. However, recent studies have revealed that different lineages of prokaryotic RTs, including retrons, those associated with CRISPR-Cas systems, Abi-like RTs and other yet uncharacterized RTs, are key components of different lines of defense against phages and other mobile genetic elements. Prokaryotic RTs participate in various antiviral strategies, including abortive infection (Abi), in which the infected cell is induced to commit suicide to protect the host population, adaptive immunity, in which a memory of previous infection is used to build an efficient defense, and other as yet unidentified mechanisms. These prokaryotic enzymes are attracting considerable attention, both for use in cutting-edge technologies, such as genome editing, and as an emerging research topic. In this review, we discuss what is known about prokaryotic RTs, and the exciting evidence for their domestication from retroelements to create specialized defense systems.
Collapse
Affiliation(s)
- Alejandro González-Delgado
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Mario Rodríguez Mestre
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
- Department of Biochemistry, Universidad Autónoma de Madrid and Instituto de Investigaciones Biomédicas “Alberto Sols”, CSIC-UAM, Madrid, Spain
| | - Francisco Martínez-Abarca
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Nicolás Toro
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
| |
Collapse
|
17
|
Chevallereau A, Pons BJ, van Houte S, Westra ER. Interactions between bacterial and phage communities in natural environments. Nat Rev Microbiol 2021; 20:49-62. [PMID: 34373631 DOI: 10.1038/s41579-021-00602-y] [Citation(s) in RCA: 190] [Impact Index Per Article: 63.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 06/28/2021] [Indexed: 12/20/2022]
Abstract
We commonly acknowledge that bacterial viruses (phages) shape the composition and evolution of bacterial communities in nature and therefore have important roles in ecosystem functioning. This view stems from studies in the 1990s to the first decade of the twenty-first century that revealed high viral abundance, high viral diversity and virus-induced microbial death in aquatic ecosystems as well as an association between collapses in bacterial density and peaks in phage abundance. The recent surge in metagenomic analyses has provided deeper insight into the abundance, genomic diversity and spatio-temporal dynamics of phages in a wide variety of ecosystems, ranging from deep oceans to soil and the mammalian digestive tract. However, the causes and consequences of variations in phage community compositions remain poorly understood. In this Review, we explore current knowledge of the composition and evolution of phage communities, as well as their roles in controlling the population and evolutionary dynamics of bacterial communities. We discuss the need for greater ecological realism in laboratory studies to capture the complexity of microbial communities that thrive in natural environments.
Collapse
Affiliation(s)
- Anne Chevallereau
- Environment and Sustainability Institute, Biosciences, University of Exeter, Penryn, UK. .,Department of Infection, Immunity and Inflammation, Institut Cochin, INSERM U1016, CNRS UMR8104, Université de Paris, Paris, France.
| | - Benoît J Pons
- Environment and Sustainability Institute, Biosciences, University of Exeter, Penryn, UK
| | - Stineke van Houte
- Environment and Sustainability Institute, Biosciences, University of Exeter, Penryn, UK
| | - Edze R Westra
- Environment and Sustainability Institute, Biosciences, University of Exeter, Penryn, UK.
| |
Collapse
|
18
|
Townsend EM, Kelly L, Muscatt G, Box JD, Hargraves N, Lilley D, Jameson E. The Human Gut Phageome: Origins and Roles in the Human Gut Microbiome. Front Cell Infect Microbiol 2021; 11:643214. [PMID: 34150671 PMCID: PMC8213399 DOI: 10.3389/fcimb.2021.643214] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 05/19/2021] [Indexed: 12/14/2022] Open
Abstract
The investigation of the microbial populations of the human body, known as the microbiome, has led to a revolutionary field of science, and understanding of its impacts on human development and health. The majority of microbiome research to date has focussed on bacteria and other kingdoms of life, such as fungi. Trailing behind these is the interrogation of the gut viruses, specifically the phageome. Bacteriophages, viruses that infect bacterial hosts, are known to dictate the dynamics and diversity of bacterial populations in a number of ecosystems. However, the phageome of the human gut, while of apparent importance, remains an area of many unknowns. In this paper we discuss the role of bacteriophages within the human gut microbiome. We examine the methods used to study bacteriophage populations, how this evolved over time and what we now understand about the phageome. We review the phageome development in infancy, and factors that may influence phage populations in adult life. The role and action of the phageome is then discussed at both a biological-level, and in the broader context of human health and disease.
Collapse
Affiliation(s)
- Eleanor M Townsend
- School of Life Sciences, The University of Warwick, Coventry, United Kingdom
| | - Lucy Kelly
- School of Life Sciences, The University of Warwick, Coventry, United Kingdom
| | - George Muscatt
- School of Life Sciences, The University of Warwick, Coventry, United Kingdom
| | - Joshua D Box
- School of Life Sciences, The University of Warwick, Coventry, United Kingdom
| | - Nicole Hargraves
- School of Life Sciences, The University of Warwick, Coventry, United Kingdom
| | - Daniel Lilley
- Warwick Medical School, The University of Warwick, Coventry, United Kingdom
| | - Eleanor Jameson
- School of Life Sciences, The University of Warwick, Coventry, United Kingdom
| |
Collapse
|
19
|
Kaur G, Iyer LM, Burroughs AM, Aravind L. Bacterial death and TRADD-N domains help define novel apoptosis and immunity mechanisms shared by prokaryotes and metazoans. eLife 2021; 10:70394. [PMID: 34061031 PMCID: PMC8195603 DOI: 10.7554/elife.70394] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 05/23/2021] [Indexed: 12/12/2022] Open
Abstract
Several homologous domains are shared by eukaryotic immunity and programmed cell-death systems and poorly understood bacterial proteins. Recent studies show these to be components of a network of highly regulated systems connecting apoptotic processes to counter-invader immunity, in prokaryotes with a multicellular habit. However, the provenance of key adaptor domains, namely those of the Death-like and TRADD-N superfamilies, a quintessential feature of metazoan apoptotic systems, remained murky. Here, we use sensitive sequence analysis and comparative genomics methods to identify unambiguous bacterial homologs of the Death-like and TRADD-N superfamilies. We show the former to have arisen as part of a radiation of effector-associated α-helical adaptor domains that likely mediate homotypic interactions bringing together diverse effector and signaling domains in predicted bacterial apoptosis- and counter-invader systems. Similarly, we show that the TRADD-N domain defines a key, widespread signaling bridge that links effector deployment to invader-sensing in multicellular bacterial and metazoan counter-invader systems. TRADD-N domains are expanded in aggregating marine invertebrates and point to distinctive diversifying immune strategies probably directed both at RNA and retroviruses and cellular pathogens that might infect such communities. These TRADD-N and Death-like domains helped identify several new bacterial and metazoan counter-invader systems featuring underappreciated, common functional principles: the use of intracellular invader-sensing lectin-like (NPCBM and FGS), transcription elongation GreA/B-C, glycosyltransferase-4 family, inactive NTPase (serving as nucleic acid receptors), and invader-sensing GTPase switch domains. Finally, these findings point to the possibility of multicellular bacteria-stem metazoan symbiosis in the emergence of the immune/apoptotic systems of the latter.
Collapse
Affiliation(s)
- Gurmeet Kaur
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, United States
| | - Lakshminarayan M Iyer
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, United States
| | - A Maxwell Burroughs
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, United States
| | - L Aravind
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, United States
| |
Collapse
|
20
|
Roux S, Paul BG, Bagby SC, Nayfach S, Allen MA, Attwood G, Cavicchioli R, Chistoserdova L, Gruninger RJ, Hallam SJ, Hernandez ME, Hess M, Liu WT, McAllister TA, O'Malley MA, Peng X, Rich VI, Saleska SR, Eloe-Fadrosh EA. Ecology and molecular targets of hypermutation in the global microbiome. Nat Commun 2021; 12:3076. [PMID: 34031405 PMCID: PMC8144416 DOI: 10.1038/s41467-021-23402-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 04/27/2021] [Indexed: 02/04/2023] Open
Abstract
Changes in the sequence of an organism's genome, i.e., mutations, are the raw material of evolution. The frequency and location of mutations can be constrained by specific molecular mechanisms, such as diversity-generating retroelements (DGRs). DGRs have been characterized from cultivated bacteria and bacteriophages, and perform error-prone reverse transcription leading to mutations being introduced in specific target genes. DGR loci were also identified in several metagenomes, but the ecological roles and evolutionary drivers of these DGRs remain poorly understood. Here, we analyze a dataset of >30,000 DGRs from public metagenomes, establish six major lineages of DGRs including three primarily encoded by phages and seemingly used to diversify host attachment proteins, and demonstrate that DGRs are broadly active and responsible for >10% of all amino acid changes in some organisms. Overall, these results highlight the constraints under which DGRs evolve, and elucidate several distinct roles these elements play in natural communities.
Collapse
Affiliation(s)
- Simon Roux
- DOE Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| | - Blair G Paul
- Marine Biological Laboratory, Woods Hole, MA, USA
| | - Sarah C Bagby
- Department of Biology, Case Western Reserve University, Cleveland, OH, USA
| | - Stephen Nayfach
- DOE Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | | | - Graeme Attwood
- AgResearch Limited, Grasslands Research Centre, Palmerston North, New Zealand
| | | | | | - Robert J Gruninger
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, Alberta, Canada
| | - Steven J Hallam
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
- Graduate Program in Bioinformatics, University of British Columbia, Genome Sciences Centre, Vancouver, Canada
- Genome Science and Technology Program, University of British Columbia, Vancouver, Canada
- Life Sciences Institute, University of British Columbia, Vancouver, Canada
- ECOSCOPE Training Program, University of British Columbia, Vancouver, Canada
| | - Maria E Hernandez
- Instituto de Ecología A.C. Red de Manejo Biotechnológico de Recursos. Xalapa, Veracruz, México
| | | | - Wen-Tso Liu
- University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Tim A McAllister
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, Alberta, Canada
| | - Michelle A O'Malley
- Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA, USA
| | - Xuefeng Peng
- Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA, USA
| | | | | | - Emiley A Eloe-Fadrosh
- DOE Joint Genome Institute, Lawrence Berkeley National Laboratory, Berkeley, CA, USA.
| |
Collapse
|
21
|
Hedžet S, Rupnik M, Accetto T. Novel Siphoviridae Bacteriophages Infecting Bacteroides uniformis Contain Diversity Generating Retroelement. Microorganisms 2021; 9:microorganisms9050892. [PMID: 33919474 PMCID: PMC8143477 DOI: 10.3390/microorganisms9050892] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 04/19/2021] [Accepted: 04/19/2021] [Indexed: 11/25/2022] Open
Abstract
Intestinal phages are abundant and important components of gut microbiota, yet the isolated and characterized representatives that infect abundant gut bacteria are sparse. Here we describe the isolation of human intestinal phages infecting Bacteroidesuniformis. Bacteroides is one of the most common bacterial groups in the global human gut microbiota; however, to date not many Bacteroides specific phages are known. Phages isolated in this study belong to a novel viral genus, Bacuni, within the Siphoviridae family. Their genomes encode diversity-generating retroelements (DGR), which were shown in other bacteriophages to promote phage adaptation to rapidly changing environmental conditions and to broaden their host range. Three isolated phages showed 99.83% genome identity but one of them infected a distinct B. uniformis strain. The tropism of Bacuni phages appeared to be dependent on the interplay of DGR mediated sequence variations of gene encoding putative phage fimbrial tip proteins and mutations in host genes coding for outer-membrane proteins. We found prophages with up to 85% amino acid similarity over two-thirds of the Bacuni phage genome in the B. acidifaciens and Prevotella sp. genomes. Despite the abundance of Bacteroides within the human microbiome, we found Bacuni phages only in a limited subset of published gut metagenomes.
Collapse
Affiliation(s)
- Stina Hedžet
- Centre for Medical Microbiology, Department for Microbiological Research, National Laboratory for Health, Environment and Food (NLZOH), 2000 Maribor, Slovenia; (S.H.); (M.R.)
| | - Maja Rupnik
- Centre for Medical Microbiology, Department for Microbiological Research, National Laboratory for Health, Environment and Food (NLZOH), 2000 Maribor, Slovenia; (S.H.); (M.R.)
- Faculty of Medicine, University of Maribor, 2000 Maribor, Slovenia
| | - Tomaž Accetto
- Animal Science Department, Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia
- Correspondence:
| |
Collapse
|
22
|
Benler S, Yutin N, Antipov D, Rayko M, Shmakov S, Gussow AB, Pevzner P, Koonin EV. Thousands of previously unknown phages discovered in whole-community human gut metagenomes. MICROBIOME 2021; 9:78. [PMID: 33781338 PMCID: PMC8008677 DOI: 10.1186/s40168-021-01017-w] [Citation(s) in RCA: 90] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Accepted: 02/02/2021] [Indexed: 05/07/2023]
Abstract
BACKGROUND Double-stranded DNA bacteriophages (dsDNA phages) play pivotal roles in structuring human gut microbiomes; yet, the gut virome is far from being fully characterized, and additional groups of phages, including highly abundant ones, continue to be discovered by metagenome mining. A multilevel framework for taxonomic classification of viruses was recently adopted, facilitating the classification of phages into evolutionary informative taxonomic units based on hallmark genes. Together with advanced approaches for sequence assembly and powerful methods of sequence analysis, this revised framework offers the opportunity to discover and classify unknown phage taxa in the human gut. RESULTS A search of human gut metagenomes for circular contigs encoding phage hallmark genes resulted in the identification of 3738 apparently complete phage genomes that represent 451 putative genera. Several of these phage genera are only distantly related to previously identified phages and are likely to found new families. Two of the candidate families, "Flandersviridae" and "Quimbyviridae", include some of the most common and abundant members of the human gut virome that infect Bacteroides, Parabacteroides, and Prevotella. The third proposed family, "Gratiaviridae," consists of less abundant phages that are distantly related to the families Autographiviridae, Drexlerviridae, and Chaseviridae. Analysis of CRISPR spacers indicates that phages of all three putative families infect bacteria of the phylum Bacteroidetes. Comparative genomic analysis of the three candidate phage families revealed features without precedent in phage genomes. Some "Quimbyviridae" phages possess Diversity-Generating Retroelements (DGRs) that generate hypervariable target genes nested within defense-related genes, whereas the previously known targets of phage-encoded DGRs are structural genes. Several "Flandersviridae" phages encode enzymes of the isoprenoid pathway, a lipid biosynthesis pathway that so far has not been known to be manipulated by phages. The "Gratiaviridae" phages encode a HipA-family protein kinase and glycosyltransferase, suggesting these phages modify the host cell wall, preventing superinfection by other phages. Hundreds of phages in these three and other families are shown to encode catalases and iron-sequestering enzymes that can be predicted to enhance cellular tolerance to reactive oxygen species. CONCLUSIONS Analysis of phage genomes identified in whole-community human gut metagenomes resulted in the delineation of at least three new candidate families of Caudovirales and revealed diverse putative mechanisms underlying phage-host interactions in the human gut. Addition of these phylogenetically classified, diverse, and distinct phages to public databases will facilitate taxonomic decomposition and functional characterization of human gut viromes. Video abstract.
Collapse
Affiliation(s)
- Sean Benler
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, Maryland 20894 USA
| | - Natalya Yutin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, Maryland 20894 USA
| | - Dmitry Antipov
- Center for Algorithmic Biotechnology, Institute for Translational Biomedicine, St. Petersburg State University, St. Petersburg, 199004 Russia
| | - Mikhail Rayko
- Center for Algorithmic Biotechnology, Institute for Translational Biomedicine, St. Petersburg State University, St. Petersburg, 199004 Russia
| | - Sergey Shmakov
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, Maryland 20894 USA
| | - Ayal B. Gussow
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, Maryland 20894 USA
| | - Pavel Pevzner
- Center for Algorithmic Biotechnology, Institute for Translational Biomedicine, St. Petersburg State University, St. Petersburg, 199004 Russia
- Department of Computer Science and Engineering, University of California, San Diego, La Jolla, CA 92093 USA
| | - Eugene V. Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, Maryland 20894 USA
| |
Collapse
|
23
|
Balance between promiscuity and specificity in phage λ host range. ISME JOURNAL 2021; 15:2195-2205. [PMID: 33589767 DOI: 10.1038/s41396-021-00912-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 01/18/2021] [Accepted: 01/25/2021] [Indexed: 01/21/2023]
Abstract
As hosts acquire resistance to viruses, viruses must overcome that resistance to re-establish infectivity, or go extinct. Despite the significant hurdles associated with adapting to a resistant host, viruses are evolutionarily successful and maintain stable coevolutionary relationships with their hosts. To investigate the factors underlying how pathogens adapt to their hosts, we performed a deep mutational scan of the region of the λ tail fiber tip protein that mediates contact with the receptor on λ's host, Escherichia coli. Phages harboring amino acid substitutions were subjected to selection for infectivity on wild type E. coli, revealing a highly restrictive fitness landscape, in which most substitutions completely abrogate function. A subset of positions that are tolerant of mutation in this assay, but diverse over evolutionary time, are associated with host range expansion. Imposing selection for phage infectivity on three λ-resistant hosts, each harboring a different missense mutation in the λ receptor, reveals hundreds of adaptive variants in λ. We distinguish λ variants that confer promiscuity, a general ability to overcome host resistance, from those that drive host-specific infectivity. Both processes may be important in driving adaptation to a novel host.
Collapse
|
24
|
Handa S, Reyna A, Wiryaman T, Ghosh P. Determinants of adenine-mutagenesis in diversity-generating retroelements. Nucleic Acids Res 2021; 49:1033-1045. [PMID: 33367793 PMCID: PMC7826257 DOI: 10.1093/nar/gkaa1240] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 12/07/2020] [Accepted: 12/09/2020] [Indexed: 02/01/2023] Open
Abstract
Diversity-generating retroelements (DGRs) vary protein sequences to the greatest extent known in the natural world. These elements are encoded by constituents of the human microbiome and the microbial ‘dark matter’. Variation occurs through adenine-mutagenesis, in which genetic information in RNA is reverse transcribed faithfully to cDNA for all template bases but adenine. We investigated the determinants of adenine-mutagenesis in the prototypical Bordetella bacteriophage DGR through an in vitro system composed of the reverse transcriptase bRT, Avd protein, and a specific RNA. We found that the catalytic efficiency for correct incorporation during reverse transcription by the bRT-Avd complex was strikingly low for all template bases, with the lowest occurring for adenine. Misincorporation across a template adenine was only somewhat lower in efficiency than correct incorporation. We found that the C6, but not the N1 or C2, purine substituent was a key determinant of adenine-mutagenesis. bRT-Avd was insensitive to the C6 amine of adenine but recognized the C6 carbonyl of guanine. We also identified two bRT amino acids predicted to nonspecifically contact incoming dNTPs, R74 and I181, as promoters of adenine-mutagenesis. Our results suggest that the overall low catalytic efficiency of bRT-Avd is intimately tied to its ability to carry out adenine-mutagenesis.
Collapse
Affiliation(s)
- Sumit Handa
- Department of Chemistry & Biochemistry, 9500 Gilman Drive, La Jolla, CA, 92093-0375, USA
| | - Andres Reyna
- Department of Chemistry & Biochemistry, 9500 Gilman Drive, La Jolla, CA, 92093-0375, USA
| | - Timothy Wiryaman
- Department of Chemistry & Biochemistry, 9500 Gilman Drive, La Jolla, CA, 92093-0375, USA
| | - Partho Ghosh
- Department of Chemistry & Biochemistry, 9500 Gilman Drive, La Jolla, CA, 92093-0375, USA
| |
Collapse
|
25
|
Mestre MR, González-Delgado A, Gutiérrez-Rus LI, Martínez-Abarca F, Toro N. Systematic prediction of genes functionally associated with bacterial retrons and classification of the encoded tripartite systems. Nucleic Acids Res 2021; 48:12632-12647. [PMID: 33275130 PMCID: PMC7736814 DOI: 10.1093/nar/gkaa1149] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Revised: 11/05/2020] [Accepted: 11/10/2020] [Indexed: 02/06/2023] Open
Abstract
Bacterial retrons consist of a reverse transcriptase (RT) and a contiguous non-coding RNA (ncRNA) gene. One third of annotated retrons carry additional open reading frames (ORFs), the contribution and significance of which in retron biology remains to be determined. In this study we developed a computational pipeline for the systematic prediction of genes specifically associated with retron RTs based on a previously reported large dataset representative of the diversity of prokaryotic RTs. We found that retrons generally comprise a tripartite system composed of the ncRNA, the RT and an additional protein or RT-fused domain with diverse enzymatic functions. These retron systems are highly modular, and their components have coevolved to different extents. Based on the additional module, we classified retrons into 13 types, some of which include additional variants. Our findings provide a basis for future studies on the biological function of retrons and for expanding their biotechnological applications.
Collapse
Affiliation(s)
- Mario Rodríguez Mestre
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Alejandro González-Delgado
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Luis I Gutiérrez-Rus
- Departamento de Química Física. Facultad de Ciencias, Universidad de Granada, 18071 Granada, Spain
| | - Francisco Martínez-Abarca
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Nicolás Toro
- Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Profesor Albareda 1, 18008 Granada, Spain
| |
Collapse
|
26
|
Sozhamannan S, Hofmann ER. The State of the Art in Biodefense Related Bacterial Pathogen Detection Using Bacteriophages: How It Started and How It's Going. Viruses 2020; 12:v12121393. [PMID: 33291831 PMCID: PMC7762055 DOI: 10.3390/v12121393] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/23/2020] [Accepted: 12/01/2020] [Indexed: 02/07/2023] Open
Abstract
Accurate pathogen detection and diagnosis is paramount in clinical success of treating patients. There are two general paradigms in pathogen detection: molecular and immuno-based, and phage-based detection is a third emerging paradigm due to its sensitivity and selectivity. Molecular detection methods look for genetic material specific for a given pathogen in a sample usually by polymerase chain reaction (PCR). Immuno-methods look at the pathogen components (antigens) by antibodies raised against that pathogen specific antigens. There are different variations and products based on these two paradigms with advantages and disadvantages. The third paradigm at least for bacterial pathogen detection entails bacteriophages specific for a given bacterium. Sensitivity and specificity are the two key parameters in any pathogen detection system. By their very nature, bacteriophages afford the best sensitivity for bacterial detection. Bacteria and bacteriophages form the predator-prey pair in the evolutionary arms race and has coevolved over time to acquire the exquisite specificity of the pair, in some instances at the strain level. This specificity has been exploited for diagnostic purposes of various pathogens of concern in clinical and other settings. Many recent reviews focus on phage-based detection and sensor technologies. In this review, we focus on a very special group of pathogens that are of concern in biodefense because of their potential misuse in bioterrorism and their extremely virulent nature and as such fall under the Centers for Disease and Prevention (CDC) Category A pathogen list. We describe the currently available phage methods that are based on the usual modalities of detection from culture, to molecular and immuno- and fluorescent methods. We further highlight the gaps and the needs for more modern technologies and sensors drawing from technologies existing for detection and surveillance of other pathogens of clinical relevance.
Collapse
Affiliation(s)
- Shanmuga Sozhamannan
- National Security Science & Technology, Management Advisory Services, Logistics Management Institute, 7940 Jones Branch Drive, Tysons, VA 22102, USA;
- Defense Biological Product Assurance Office (DBPAO), Joint Program Executive Office (JPEO) for Chemical, Biological, Radiological and Nuclear Defense (CBRND) Joint Project Lead (JPL) CBRND Enabling Biotechnologies (EB), 110 Thomas Johnson Drive, Suite 250, Frederick, MD 21702, USA
| | - Edward R. Hofmann
- EXCET, Inc., 6225 Brandon Ave #360, Springfield, VA 22150, USA
- US Army Combat Capabilities Development Command, Chemical Biological Center, 8908 Guard St, E3831, Edgewood, MD 21010, USA
- Correspondence:
| |
Collapse
|
27
|
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: 184] [Impact Index Per Article: 46.0] [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.
Collapse
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.
| |
Collapse
|
28
|
Vallota-Eastman A, Arrington EC, Meeken S, Roux S, Dasari K, Rosen S, Miller JF, Valentine DL, Paul BG. Role of diversity-generating retroelements for regulatory pathway tuning in cyanobacteria. BMC Genomics 2020; 21:664. [PMID: 32977771 PMCID: PMC7517822 DOI: 10.1186/s12864-020-07052-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 09/03/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Cyanobacteria maintain extensive repertoires of regulatory genes that are vital for adaptation to environmental stress. Some cyanobacterial genomes have been noted to encode diversity-generating retroelements (DGRs), which promote protein hypervariation through localized retrohoming and codon rewriting in target genes. Past research has shown DGRs to mainly diversify proteins involved in cell-cell attachment or viral-host attachment within viral, bacterial, and archaeal lineages. However, these elements may be critical in driving variation for proteins involved in other core cellular processes. RESULTS Members of 31 cyanobacterial genera encode at least one DGR, and together, their retroelements form a monophyletic clade of closely-related reverse transcriptases. This class of retroelements diversifies target proteins with unique domain architectures: modular ligand-binding domains often paired with a second domain that is linked to signal response or regulation. Comparative analysis indicates recent intragenomic duplication of DGR targets as paralogs, but also apparent intergenomic exchange of DGR components. The prevalence of DGRs and the paralogs of their targets is disproportionately high among colonial and filamentous strains of cyanobacteria. CONCLUSION We find that colonial and filamentous cyanobacteria have recruited DGRs to optimize a ligand-binding module for apparent function in signal response or regulation. These represent a unique class of hypervariable proteins, which might offer cyanobacteria a form of plasticity to adapt to environmental stress. This analysis supports the hypothesis that DGR-driven mutation modulates signaling and regulatory networks in cyanobacteria, suggestive of a new framework for the utility of localized genetic hypervariation.
Collapse
Affiliation(s)
- Alec Vallota-Eastman
- Interdepartmental Graduate Program for Marine Science, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Eleanor C Arrington
- Interdepartmental Graduate Program for Marine Science, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Siobhan Meeken
- Josephine Bay Paul Center, Marine Biological Laboratory, 7 MBL St, Woods Hole, MA, 02543, USA
| | - Simon Roux
- DOE Joint Genome Institute, Berkeley, CA, 94720, USA
| | - Krishna Dasari
- Research Mentorship Program (RMP), University of California, Santa Barbara, CA, 93106, USA
| | - Sydney Rosen
- Research Mentorship Program (RMP), University of California, Santa Barbara, CA, 93106, USA
| | - Jeff F Miller
- Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA, 90095, USA
- California NanoSystems Institute, University of California, Los Angeles, CA, 90095, USA
| | - David L Valentine
- Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
- Department of Earth Science, University of California Santa Barbara, Santa Barbara, CA, 93106, USA
| | - Blair G Paul
- Josephine Bay Paul Center, Marine Biological Laboratory, 7 MBL St, Woods Hole, MA, 02543, USA.
| |
Collapse
|
29
|
Widespread transfer of mobile antibiotic resistance genes within individual gut microbiomes revealed through bacterial Hi-C. Nat Commun 2020; 11:4379. [PMID: 32873785 PMCID: PMC7463002 DOI: 10.1038/s41467-020-18164-7] [Citation(s) in RCA: 94] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Accepted: 08/06/2020] [Indexed: 01/13/2023] Open
Abstract
The gut microbiome harbors a ‘silent reservoir’ of antibiotic resistance (AR) genes that is thought to contribute to the emergence of multidrug-resistant pathogens through horizontal gene transfer (HGT). To counteract the spread of AR, it is paramount to know which organisms harbor mobile AR genes and which organisms engage in HGT. Despite methods that characterize the overall abundance of AR genes in the gut, technological limitations of short-read sequencing have precluded linking bacterial taxa to specific mobile genetic elements (MGEs) encoding AR genes. Here, we apply Hi-C, a high-throughput, culture-independent method, to surveil the bacterial carriage of MGEs. We compare two healthy individuals with seven neutropenic patients undergoing hematopoietic stem cell transplantation, who receive multiple courses of antibiotics, and are acutely vulnerable to the threat of multidrug-resistant infections. We find distinct networks of HGT across individuals, though AR and mobile genes are associated with more diverse taxa within the neutropenic patients than the healthy subjects. Our data further suggest that HGT occurs frequently over a several-week period in both cohorts. Whereas most efforts to understand the spread of AR genes have focused on pathogenic species, our findings shed light on the role of the human gut microbiome in this process. Linking antibiotic resistance (AR) in the gut microbiome with their bacterial hosts remains challenging. Here, the authors apply bacterial Hi-C to map mobile genetic elements in metagenomes, and illustrate that genes are present in more diverse taxa in neutropenic patients than healthy subjects.
Collapse
|
30
|
Morozova V, Fofanov M, Tikunova N, Babkin I, Morozov VV, Tikunov A. First crAss-Like Phage Genome Encoding the Diversity-Generating Retroelement (DGR). Viruses 2020; 12:v12050573. [PMID: 32456083 PMCID: PMC7290462 DOI: 10.3390/v12050573] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2020] [Revised: 05/15/2020] [Accepted: 05/19/2020] [Indexed: 12/20/2022] Open
Abstract
A new crAss-like genome encoding diversity-generating retroelement (DGR) was found in the fecal virome of a healthy volunteer. The genome of the phage referred to as the crAssphage LMMB, belonged to the candidate genus I of the AlphacrAssvirinae subfamily. The DGR-cassette of the crAssphage LMMB contained all the essential elements: the gene encoding reverse transcriptase (RT), the target gene (TG) encoding the tail-collar fiber protein, and variable and template repeats (VR and TR) with IMH (initiation of mutagenic homing) and IMH* sequences at the 3′-end of the VR and TR, respectively. Architecture of the DGR-cassette was TG-VR(IMH)-TR(IMH*)-RT and an accessory variable determinant (avd) was absent from the cassette. Analysis of 91 genomes and genome fragments from genus I of the AlphacrAssvirinae showed that 15 (16%) of the genomes had DGRs with the same architecture as the crAssphage LMMB, while 66 of the genomes contained incomplete DGR-cassettes or some elements of the DGR.
Collapse
|
31
|
Simon AJ, Ellington AD, Finkelstein IJ. Retrons and their applications in genome engineering. Nucleic Acids Res 2020; 47:11007-11019. [PMID: 31598685 PMCID: PMC6868368 DOI: 10.1093/nar/gkz865] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 09/19/2019] [Accepted: 10/02/2019] [Indexed: 11/14/2022] Open
Abstract
Precision genome editing technologies have transformed modern biology. These technologies have arisen from the redirection of natural biological machinery, such as bacteriophage lambda proteins for recombineering and CRISPR nucleases for eliciting site-specific double-strand breaks. Less well-known is a widely distributed class of bacterial retroelements, retrons, that employ specialized reverse transcriptases to produce noncoding intracellular DNAs. Retrons' natural function and mechanism of genetic transmission have remained enigmatic. However, recent studies have harnessed their ability to produce DNA in situ for genome editing and evolution. This review describes retron biology and function in both natural and synthetic contexts. We also highlight areas that require further study to advance retron-based precision genome editing platforms.
Collapse
Affiliation(s)
- Anna J Simon
- Center for Systems and Synthetic Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, USA
| | - Andrew D Ellington
- Center for Systems and Synthetic Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, USA
| | - Ilya J Finkelstein
- Center for Systems and Synthetic Biology and Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas 78712, USA
| |
Collapse
|
32
|
Gilbert RA, Townsend EM, Crew KS, Hitch TCA, Friedersdorff JCA, Creevey CJ, Pope PB, Ouwerkerk D, Jameson E. Rumen Virus Populations: Technological Advances Enhancing Current Understanding. Front Microbiol 2020; 11:450. [PMID: 32273870 PMCID: PMC7113391 DOI: 10.3389/fmicb.2020.00450] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Accepted: 03/02/2020] [Indexed: 01/07/2023] Open
Abstract
The rumen contains a multi-kingdom, commensal microbiome, including protozoa, bacteria, archaea, fungi and viruses, which enables ruminant herbivores to ferment and utilize plant feedstuffs that would be otherwise indigestible. Within the rumen, virus populations are diverse and highly abundant, often out-numbering the microbial populations that they both predate on and co-exist with. To date the research effort devoted to understanding rumen-associated viral populations has been considerably less than that given to the other microbial populations, yet their contribution to maintaining microbial population balance, intra-ruminal microbial lysis, fiber breakdown, nutrient cycling and genetic transfer may be highly significant. This review follows the technological advances which have contributed to our current understanding of rumen viruses and drawing on knowledge from other environmental and animal-associated microbiomes, describes the known and potential roles and impacts viruses have on rumen function and speculates on the future directions of rumen viral research.
Collapse
Affiliation(s)
- Rosalind A. Gilbert
- Department of Agriculture and Fisheries, Brisbane, QLD, Australia
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St Lucia, QLD, Australia
| | - Eleanor M. Townsend
- Warwick Integrative Synthetic Biology Centre, School of Life Sciences, University of Warwick, Coventry, United Kingdom
| | - Kathleen S. Crew
- Department of Agriculture and Fisheries, Brisbane, QLD, Australia
| | - Thomas C. A. Hitch
- Functional Microbiome Research Group, Institute of Medical Microbiology, RWTH University Hospital, Aachen, Germany
| | - Jessica C. A. Friedersdorff
- Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, United Kingdom
| | - Christopher J. Creevey
- Institute for Global Food Security, School of Biological Sciences, Queen’s University Belfast, Belfast, United Kingdom
| | - Phillip B. Pope
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
- Faculty of Biosciences, Norwegian University of Life Sciences, Ås, Norway
| | - Diane Ouwerkerk
- Department of Agriculture and Fisheries, Brisbane, QLD, Australia
- Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St Lucia, QLD, Australia
| | - Eleanor Jameson
- Warwick Integrative Synthetic Biology Centre, School of Life Sciences, University of Warwick, Coventry, United Kingdom
| |
Collapse
|
33
|
Kaur G, Burroughs AM, Iyer LM, Aravind L. Highly regulated, diversifying NTP-dependent biological conflict systems with implications for the emergence of multicellularity. eLife 2020; 9:e52696. [PMID: 32101166 PMCID: PMC7159879 DOI: 10.7554/elife.52696] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Accepted: 02/25/2020] [Indexed: 12/12/2022] Open
Abstract
Social cellular aggregation or multicellular organization pose increased risk of transmission of infections through the system upon infection of a single cell. The generality of the evolutionary responses to this outside of Metazoa remains unclear. We report the discovery of several thematically unified, remarkable biological conflict systems preponderantly present in multicellular prokaryotes. These combine thresholding mechanisms utilizing NTPase chaperones (the MoxR-vWA couple), GTPases and proteolytic cascades with hypervariable effectors, which vary either by using a reverse transcriptase-dependent diversity-generating system or through a system of acquisition of diverse protein modules, typically in inactive form, from various cellular subsystems. Conciliant lines of evidence indicate their deployment against invasive entities, like viruses, to limit their spread in multicellular/social contexts via physical containment, dominant-negative interactions or apoptosis. These findings argue for both a similar operational 'grammar' and shared protein domains in the sensing and limiting of infections during the multiple emergences of multicellularity.
Collapse
Affiliation(s)
- Gurmeet Kaur
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, National Institutes of HealthBethesdaUnited States
| | - A Maxwell Burroughs
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, National Institutes of HealthBethesdaUnited States
| | - Lakshminarayan M Iyer
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, National Institutes of HealthBethesdaUnited States
| | - L Aravind
- Computational Biology Branch, National Center for Biotechnology Information, National Library of Medicine, National Institutes of HealthBethesdaUnited States
| |
Collapse
|
34
|
Grigonyte AM, Harrison C, MacDonald PR, Montero-Blay A, Tridgett M, Duncan J, Sagona AP, Constantinidou C, Jaramillo A, Millard A. Comparison of CRISPR and Marker-Based Methods for the Engineering of Phage T7. Viruses 2020; 12:E193. [PMID: 32050613 PMCID: PMC7077284 DOI: 10.3390/v12020193] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Revised: 02/06/2020] [Accepted: 02/06/2020] [Indexed: 12/29/2022] Open
Abstract
With the recent rise in interest in using lytic bacteriophages as therapeutic agents, there is an urgent requirement to understand their fundamental biology to enable the engineering of their genomes. Current methods of phage engineering rely on homologous recombination, followed by a system of selection to identify recombinant phages. For bacteriophage T7, the host genes cmk or trxA have been used as a selection mechanism along with both type I and II CRISPR systems to select against wild-type phage and enrich for the desired mutant. Here, we systematically compare all three systems; we show that the use of marker-based selection is the most efficient method and we use this to generate multiple T7 tail fibre mutants. Furthermore, we found the type II CRISPR-Cas system is easier to use and generally more efficient than a type I system in the engineering of phage T7. These results provide a foundation for the future, more efficient engineering of bacteriophage T7.
Collapse
Affiliation(s)
- Aurelija M. Grigonyte
- Warwick Integrative Synthetic Biology Centre (WISB) and School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK; (A.M.G.); (M.T.); (J.D.); (A.P.S.)
| | - Christian Harrison
- Department Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK;
| | - Paul R. MacDonald
- MOAC DTC, Senate House, University of Warwick, Coventry CV4 7AL, UK;
| | - Ariadna Montero-Blay
- EMBL/CRG Systems Biology Research Unit, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr Aiguader 88, 08003 Barcelona, Spain;
| | - Matthew Tridgett
- Warwick Integrative Synthetic Biology Centre (WISB) and School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK; (A.M.G.); (M.T.); (J.D.); (A.P.S.)
| | - John Duncan
- Warwick Integrative Synthetic Biology Centre (WISB) and School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK; (A.M.G.); (M.T.); (J.D.); (A.P.S.)
| | - Antonia P. Sagona
- Warwick Integrative Synthetic Biology Centre (WISB) and School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK; (A.M.G.); (M.T.); (J.D.); (A.P.S.)
| | | | - Alfonso Jaramillo
- Warwick Integrative Synthetic Biology Centre (WISB) and School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK; (A.M.G.); (M.T.); (J.D.); (A.P.S.)
- Institute of Systems and Synthetic Biology (ISSB), CNRS, CEA, Université Paris-Saclay, 91025 Evry, France
- Institute for Integrative Systems Biology (I2SysBio), University of Valencia-CSIC, 46980 Paterna, Spain
| | - Andrew Millard
- Department Genetics and Genome Biology, University of Leicester, University Road, Leicester LE1 7RH, UK;
| |
Collapse
|
35
|
Safari F, Sharifi M, Farajnia S, Akbari B, Karimi Baba Ahmadi M, Negahdaripour M, Ghasemi Y. The interaction of phages and bacteria: the co-evolutionary arms race. Crit Rev Biotechnol 2019; 40:119-137. [PMID: 31793351 DOI: 10.1080/07388551.2019.1674774] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Since the dawn of life, bacteria and phages are locked in a constant battle and both are perpetually changing their tactics to overcome each other. Bacteria use various strategies to overcome the invading phages, including adsorption inhibition, restriction-modification (R/E) systems, CRISPR-Cas (clustered regularly interspaced short palindromic repeats-CRISPR-associated proteins) systems, abortive infection (Abi), etc. To counteract, phages employ intelligent tactics for the nullification of bacterial defense systems, such as accessing host receptors, evading R/E systems, and anti-CRISPR proteins. Intense knowledge about the details of these defense pathways is the basis for their broad utilities in various fields of research from microbiology to biotechnology. Hence, in this review, we discuss some strategies used by bacteria to inhibit phage infections as well as phage tactics to circumvent bacterial defense systems. In addition, the application of these strategies will be described as a lesson learned from bacteria and phage combats. The ecological factors that affect the evolution of bacterial immune systems is the other issue represented in this review.
Collapse
Affiliation(s)
- Fatemeh Safari
- Diagnostic Laboratory Sciences and Technology Research Center, School of Paramedical Sciences, Shiraz University of Medical Sciences, Shiraz, Iran.,Department of Medical Biotechnology, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mehrdad Sharifi
- Department of Emergency Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Safar Farajnia
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Bahman Akbari
- Department of Medical Biotechnology, School of Medical Sciences, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | | | - Manica Negahdaripour
- Pharmaceutical Sciences Research Center, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Younes Ghasemi
- Pharmaceutical Sciences Research Center, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran.,Department of Pharmaceutical Biotechnology, School of Pharmacy, Shiraz University of Medical Sciences, Shiraz, Iran
| |
Collapse
|
36
|
Ge H, Hu M, Zhao G, Du Y, Xu N, Chen X, Jiao X. The "fighting wisdom and bravery" of tailed phage and host in the process of adsorption. Microbiol Res 2019; 230:126344. [PMID: 31561173 DOI: 10.1016/j.micres.2019.126344] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 08/30/2019] [Accepted: 09/18/2019] [Indexed: 01/07/2023]
Abstract
In the process of bacteriophage and bacteria struggle, adsorption is the key factor to determine who is the winner. In this paper, the molecular mechanism of tailed bacteriophage recognition and adsorption to host and the strategy of "fighting wisdom and courage" between them are reviewed.
Collapse
Affiliation(s)
- Haojie Ge
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China
| | - Maozhi Hu
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China.
| | - Ge Zhao
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China
| | - Yi Du
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China
| | - Nannan Xu
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China
| | - Xiang Chen
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China
| | - Xin'an Jiao
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou University, Yangzhou, 225009, Jiangsu, China; Jiangsu Key Laboratory of Zoonosis, Yangzhou University, Yangzhou, 225009, Jiangsu, China
| |
Collapse
|
37
|
Handa S, Jiang Y, Tao S, Foreman R, Schinazi RF, Miller JF, Ghosh P. Template-assisted synthesis of adenine-mutagenized cDNA by a retroelement protein complex. Nucleic Acids Res 2019; 46:9711-9725. [PMID: 30007279 PMCID: PMC6182149 DOI: 10.1093/nar/gky620] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 06/27/2018] [Indexed: 12/28/2022] Open
Abstract
Diversity-generating retroelements (DGRs) create unparalleled levels of protein sequence variation through mutagenic retrohoming. Sequence information is transferred from an invariant template region (TR), through an RNA intermediate, to a protein-coding variable region. Selective infidelity at adenines during transfer is a hallmark of DGRs from disparate bacteria, archaea, and microbial viruses. We recapitulated selective infidelity in vitro for the prototypical Bordetella bacteriophage DGR. A complex of the DGR reverse transcriptase bRT and pentameric accessory variability determinant (Avd) protein along with DGR RNA were necessary and sufficient for synthesis of template-primed, covalently linked RNA–cDNA molecules, as observed in vivo. We identified RNA–cDNA molecules to be branched and most plausibly linked through 2′-5′ phosphodiester bonds. Adenine-mutagenesis was intrinsic to the bRT-Avd complex, which displayed unprecedented promiscuity while reverse transcribing adenines of either DGR or non-DGR RNA templates. In contrast, bRT-Avd processivity was strictly dependent on the template, occurring only for the DGR RNA. This restriction was mainly due to a noncoding segment downstream of TR, which specifically bound Avd and created a privileged site for processive polymerization. Restriction to DGR RNA may protect the host genome from damage. These results define the early steps in a novel pathway for massive sequence diversification.
Collapse
Affiliation(s)
- Sumit Handa
- Department of Chemistry & Biochemistry, University of California, San Diego, CA 92093, USA
| | - Yong Jiang
- Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Sijia Tao
- Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Robert Foreman
- Department of Chemistry & Biochemistry, University of California, San Diego, CA 92093, USA
| | - Raymond F Schinazi
- Center for AIDS Research, Laboratory of Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Jeff F Miller
- Departments of Microbiology, Immunology, and Molecular Genetics, Molecular Biology Institute, and California NanoSystems Institute, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Partho Ghosh
- Department of Chemistry & Biochemistry, University of California, San Diego, CA 92093, USA
| |
Collapse
|
38
|
Yan F, Yu X, Duan Z, Lu J, Jia B, Qiao Y, Sun C, Wei C. Discovery and characterization of the evolution, variation and functions of diversity-generating retroelements using thousands of genomes and metagenomes. BMC Genomics 2019; 20:595. [PMID: 31324156 PMCID: PMC6642488 DOI: 10.1186/s12864-019-5951-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 07/02/2019] [Indexed: 12/31/2022] Open
Abstract
Background Diversity-generating retroelements (DGRs) are a unique family of retroelements that generate sequence diversity of DNA to benefit their hosts by introducing variations and accelerating the evolution of target proteins. They exist widely in bacteria, archaea, phage and plasmid. However, our understanding about DGRs in natural environments was still very limited. Results We developed an efficient computational algorithm to identify DGRs, and applied it to characterize DGRs in more than 80,000 sequenced bacterial genomes as well as more than 4,000 human metagenome datasets. In total, we identified 948 non-redundant DGRs, which expanded the number of known DGRs in bacterial genomes and human microbiomes by about 55%, and provided a much more comprehensive reference for the study of DGRs. Phylogenetic analysis was done for identified DGRs. The putative target genes of DGRs were searched, and the functions of these target genes were investigated with a comprehensive alignment against the nr database. Conclusions DGR system is a powerful and universal mechanism to generate diversity. DGR evolution is closely associated with the living environment and their cassette structures. Furthermore, it may impact a wide range of functional processes in addition to receptor-binding. These results significantly improved our understanding about DGRs. Electronic supplementary material The online version of this article (10.1186/s12864-019-5951-3) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Fazhe Yan
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Xuelin Yu
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Zhongqu Duan
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Jinyuan Lu
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Ben Jia
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China.,Shanghai Center for Bioinformation Technology, 1278 Keyuan Road, Pudong District, Shanghai, 201203, China
| | - Yuyang Qiao
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Chen Sun
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China
| | - Chaochun Wei
- School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai, 200240, China. .,Shanghai Center for Bioinformation Technology, 1278 Keyuan Road, Pudong District, Shanghai, 201203, China.
| |
Collapse
|
39
|
Wu L, Gingery M, Abebe M, Arambula D, Czornyj E, Handa S, Khan H, Liu M, Pohlschroder M, Shaw KL, Du A, Guo H, Ghosh P, Miller JF, Zimmerly S. Diversity-generating retroelements: natural variation, classification and evolution inferred from a large-scale genomic survey. Nucleic Acids Res 2019; 46:11-24. [PMID: 29186518 PMCID: PMC5758913 DOI: 10.1093/nar/gkx1150] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Accepted: 11/04/2017] [Indexed: 01/12/2023] Open
Abstract
Diversity-generating retroelements (DGRs) are novel genetic elements that use reverse transcription to generate vast numbers of sequence variants in specific target genes. Here, we present a detailed comparative bioinformatic analysis that depicts the landscape of DGR sequences in nature as represented by data in GenBank. Over 350 unique DGRs are identified, which together form a curated reference set of putatively functional DGRs. We classify target genes, variable repeats and DGR cassette architectures, and identify two new accessory genes. The great variability of target genes implies roles of DGRs in many undiscovered biological processes. There is much evidence for horizontal transfers of DGRs, and we identify lineages of DGRs that appear to have specialized properties. Because GenBank contains data from only 10% of described species, the compilation may not be wholly representative of DGRs present in nature. Indeed, many DGR subtypes are present only once in the set and DGRs of the candidate phylum radiation bacteria, and Diapherotrites, Parvarchaeota, Aenigmarchaeota, Nanoarchaeota, Nanohaloarchaea archaea, are exceptionally diverse in sequence, with little information available about functions of their target genes. Nonetheless, this study provides a detailed framework for classifying and studying DGRs as they are uncovered and studied in the future.
Collapse
Affiliation(s)
- Li Wu
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Mari Gingery
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Michael Abebe
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Diego Arambula
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Elizabeth Czornyj
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Sumit Handa
- Department of Chemistry and Biochemistry, University of California, San Diego, CA 92093, USA
| | - Hamza Khan
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Minghsun Liu
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | | | - Kharissa L Shaw
- Department of Chemistry and Biochemistry, University of California, San Diego, CA 92093, USA
| | - Amy Du
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| | - Huatao Guo
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA.,Department of Molecular Microbiology and Immunology, University of Missouri, Columbia, MO 65212, USA
| | - Partho Ghosh
- Department of Chemistry and Biochemistry, University of California, San Diego, CA 92093, USA
| | - Jeff F Miller
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Steven Zimmerly
- Department of Biological Sciences, University of Calgary, Calgary, Alberta T2N 1N4, Canada
| |
Collapse
|
40
|
Sharifi F, Ye Y. MyDGR: a server for identification and characterization of diversity-generating retroelements. Nucleic Acids Res 2019; 47:W289-W294. [PMID: 31049585 PMCID: PMC6602519 DOI: 10.1093/nar/gkz329] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Revised: 04/05/2019] [Accepted: 04/23/2019] [Indexed: 01/18/2023] Open
Abstract
MyDGR is a web server providing integrated prediction and visualization of Diversity-Generating Retroelements (DGR) systems in query nucleotide sequences. It is built upon an enhanced version of DGRscan, a tool we previously developed for identification of DGR systems. DGR systems are remarkable genetic elements that use error-prone reverse transcriptases to generate vast sequence variants in specific target genes, which have been shown to benefit their hosts (bacteria, archaea or phages). As the first web server for annotation of DGR systems, myDGR is freely available on the web at http://omics.informatics.indiana.edu/myDGR with all major browsers supported. MyDGR accepts query nucleotide sequences in FASTA format, and outputs all the important features of a predicted DGR system, including a reverse transcriptase, a template repeat and one (or more) variable repeats and their alignment featuring A-to-N (N can be C, T or G) substitutions, and VR-containing target gene(s). In addition to providing the results as text files for download, myDGR generates a visual summary of the results for users to explore the predicted DGR systems. Users can also directly access pre-calculated, putative DGR systems identified in currently available reference bacterial genomes and a few other collections of sequences (including human microbiomes).
Collapse
Affiliation(s)
- Fatemeh Sharifi
- School of Informatics, Computing, and Engineering, Indiana University, Bloomington, IN 47405, USA
| | - Yuzhen Ye
- School of Informatics, Computing, and Engineering, Indiana University, Bloomington, IN 47405, USA
| |
Collapse
|
41
|
García-López R, Pérez-Brocal V, Moya A. Beyond cells - The virome in the human holobiont. MICROBIAL CELL (GRAZ, AUSTRIA) 2019; 6:373-396. [PMID: 31528630 PMCID: PMC6717880 DOI: 10.15698/mic2019.09.689] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 03/14/2019] [Accepted: 04/03/2019] [Indexed: 01/01/2023]
Abstract
Viromics, or viral metagenomics, is a relatively new and burgeoning field of research that studies the complete collection of viruses forming part of the microbiota in any given niche. It has strong foundations rooted in over a century of discoveries in the field of virology and recent advances in molecular biology and sequencing technologies. Historically, most studies have deconstructed the concept of viruses into a simplified perception of viral agents as mere pathogens, which demerits the scope of large-scale viromic analyses. Viruses are, in fact, much more than regular parasites. They are by far the most dynamic and abundant entity and the greatest killers on the planet, as well as the most effective geo-transforming genetic engineers and resource recyclers, acting on all life strata in any habitat. Yet, most of this uncanny viral world remains vastly unexplored to date, greatly hindered by the bewildering complexity inherent to such studies and the methodological and conceptual limitations. Viromic studies are just starting to address some of these issues but they still lag behind microbial metagenomics. In recent years, however, higher-throughput analysis and resequencing have rekindled interest in a field that is just starting to show its true potential. In this review, we take a look at the scientific and technological developments that led to the advent of viral and bacterial metagenomics with a particular, but not exclusive, focus on human viromics from an ecological perspective. We also address some of the most relevant challenges that current viral studies face and ponder on the future directions of the field.
Collapse
Affiliation(s)
- Rodrigo García-López
- Institute of Evolutionary Systems Biology (I2Sysbio), Universitat de València and CSIC, València, Spain
- CIBER in Epidemiology and Public Health (CIBEResp), Madrid, Spain
- Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO), València, Spain
| | - Vicente Pérez-Brocal
- Institute of Evolutionary Systems Biology (I2Sysbio), Universitat de València and CSIC, València, Spain
- CIBER in Epidemiology and Public Health (CIBEResp), Madrid, Spain
- Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO), València, Spain
| | - Andrés Moya
- Institute of Evolutionary Systems Biology (I2Sysbio), Universitat de València and CSIC, València, Spain
- CIBER in Epidemiology and Public Health (CIBEResp), Madrid, Spain
- Fundación para el Fomento de la Investigación Sanitaria y Biomédica de la Comunidad Valenciana (FISABIO), València, Spain
| |
Collapse
|
42
|
Abstract
The combination of modern biotechnologies such as DNA synthesis, λ red recombineering, CRISPR-based editing and next-generation high-throughput sequencing increasingly enables precise manipulation of genes and genomes. Beyond rational design, these technologies also enable the targeted, and potentially continuous, introduction of multiple mutations. While this might seem to be merely a return to natural selection, the ability to target evolution greatly reduces fitness burdens and focuses mutation and selection on those genes and traits that best contribute to a desired phenotype, ultimately throwing evolution into fast forward.
Collapse
|
43
|
Abstract
Abstract
The development of clustered regularly interspaced short-palindromic repeat (CRISPR)-Cas systems for genome editing has transformed the way life science research is conducted and holds enormous potential for the treatment of disease as well as for many aspects of biotechnology. Here, I provide a personal perspective on the development of CRISPR-Cas9 for genome editing within the broader context of the field and discuss our work to discover novel Cas effectors and develop them into additional molecular tools. The initial demonstration of Cas9-mediated genome editing launched the development of many other technologies, enabled new lines of biological inquiry, and motivated a deeper examination of natural CRISPR-Cas systems, including the discovery of new types of CRISPR-Cas systems. These new discoveries in turn spurred further technological developments. I review these exciting discoveries and technologies as well as provide an overview of the broad array of applications of these technologies in basic research and in the improvement of human health. It is clear that we are only just beginning to unravel the potential within microbial diversity, and it is quite likely that we will continue to discover other exciting phenomena, some of which it may be possible to repurpose as molecular technologies. The transformation of mysterious natural phenomena to powerful tools, however, takes a collective effort to discover, characterize, and engineer them, and it has been a privilege to join the numerous researchers who have contributed to this transformation of CRISPR-Cas systems.
Collapse
|
44
|
Jariah ROA, Hakim MS. Interaction of phages, bacteria, and the human immune system: Evolutionary changes in phage therapy. Rev Med Virol 2019; 29:e2055. [PMID: 31145517 DOI: 10.1002/rmv.2055] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 05/01/2019] [Accepted: 05/02/2019] [Indexed: 12/26/2022]
Abstract
Phages and bacteria are known to undergo dynamic and co-evolutionary arms race interactions in order to survive. Recent advances from in vitro and in vivo studies have improved our understanding of the complex interactions between phages, bacteria, and the human immune system. This insight is essential for the development of phage therapy to battle the growing problems of antibiotic resistance. It is also pivotal to prevent the development of phage-resistance during the implementation of phage therapy in the clinic. In this review, we discuss recent progress of the interactions between phages, bacteria, and the human immune system and its clinical application for phage therapy. Proper phage therapy design will ideally produce large burst sizes, short latent periods, broad host ranges, and a low tendency to select resistance.
Collapse
Affiliation(s)
- Rizka O A Jariah
- Department of Health Science, Faculty of Vocational Studies, Universitas Airlangga, Surabaya, Indonesia
| | - Mohamad S Hakim
- Department of Microbiology, Faculty of Medicine, Public Health and Nursing, Universitas Gadjah Mada, Yogyakarta, Indonesia
| |
Collapse
|
45
|
Nasko DJ, Ferrell BD, Moore RM, Bhavsar JD, Polson SW, Wommack KE. CRISPR Spacers Indicate Preferential Matching of Specific Virioplankton Genes. mBio 2019; 10:e02651-18. [PMID: 30837341 PMCID: PMC6401485 DOI: 10.1128/mbio.02651-18] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Accepted: 12/14/2018] [Indexed: 01/21/2023] Open
Abstract
Viral infection exerts selection pressure on marine microbes, as virus-induced cell lysis causes 20 to 50% of cell mortality, resulting in fluxes of biomass into oceanic dissolved organic matter. Archaeal and bacterial populations can defend against viral infection using the clustered regularly interspaced short palindromic repeat (CRISPR)-associated (Cas) system, which relies on specific matching between a spacer sequence and a viral gene. If a CRISPR spacer match to any gene within a viral genome is equally effective in preventing lysis, no viral genes should be preferentially matched by CRISPR spacers. However, if there are differences in effectiveness, certain viral genes may demonstrate a greater frequency of CRISPR spacer matches. Indeed, homology search analyses of bacterioplankton CRISPR spacer sequences against virioplankton sequences revealed preferential matching of replication proteins, nucleic acid binding proteins, and viral structural proteins. Positive selection pressure for effective viral defense is one parsimonious explanation for these observations. CRISPR spacers from virioplankton metagenomes preferentially matched methyltransferase and phage integrase genes within virioplankton sequences. These virioplankton CRISPR spacers may assist infected host cells in defending against competing phage. Analyses also revealed that half of the spacer-matched viral genes were unknown, some genes matched several spacers, and some spacers matched multiple genes, a many-to-many relationship. Thus, CRISPR spacer matching may be an evolutionary algorithm, agnostically identifying those genes under stringent selection pressure for sustaining viral infection and lysis. Investigating this subset of viral genes could reveal those genetic mechanisms essential to virus-host interactions and provide new technologies for optimizing CRISPR defense in beneficial microbes.IMPORTANCE The CRISPR-Cas system is one means by which bacterial and archaeal populations defend against viral infection which causes 20 to 50% of cell mortality in the ocean. We tested the hypothesis that certain viral genes are preferentially targeted for the initial attack of the CRISPR-Cas system on a viral genome. Using CASC, a pipeline for CRISPR spacer discovery, and metagenome data from oceanic microbes and viruses, we found a clear subset of viral genes with high match frequencies to CRISPR spacers. Moreover, we observed a many-to-many relationship of spacers and viral genes. These high-match viral genes were involved in nucleotide metabolism, DNA methylation, and viral structure. It is possible that CRISPR spacer matching is an evolutionary algorithm pointing to those viral genes most important to sustaining infection and lysis. Studying these genes may advance the understanding of virus-host interactions in nature and provide new technologies for leveraging CRISPR-Cas systems in beneficial microbes.
Collapse
Affiliation(s)
- Daniel J Nasko
- Delaware Biotechnology Institute, University of Delaware, Newark, Delaware, USA
| | - Barbra D Ferrell
- Delaware Biotechnology Institute, University of Delaware, Newark, Delaware, USA
| | - Ryan M Moore
- Delaware Biotechnology Institute, University of Delaware, Newark, Delaware, USA
| | - Jaysheel D Bhavsar
- Delaware Biotechnology Institute, University of Delaware, Newark, Delaware, USA
| | - Shawn W Polson
- Delaware Biotechnology Institute, University of Delaware, Newark, Delaware, USA
| | - K Eric Wommack
- Delaware Biotechnology Institute, University of Delaware, Newark, Delaware, USA
| |
Collapse
|
46
|
Abstract
Bacteriophages, discovered about a century ago, have been pivotal as models for understanding the fundamental principles of molecular biology. While interest in phage biology declined after the phage "golden era," key recent developments, including advances in phage genomics, microscopy, and the discovery of the CRISPR-Cas anti-phage defense system, have sparked a renaissance in phage research in the past decade. This review highlights recently discovered unexpected complexities in phage biology, describes a new arsenal of phage genes that help them overcome bacterial defenses, and discusses advances toward documentation of the phage biodiversity on a global scale.
Collapse
Affiliation(s)
- Gal Ofir
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Rotem Sorek
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
| |
Collapse
|
47
|
Handa S, Shaw KL, Ghosh P. Crystal structure of a Thermus aquaticus diversity-generating retroelement variable protein. PLoS One 2019; 14:e0205618. [PMID: 30629599 PMCID: PMC6328139 DOI: 10.1371/journal.pone.0205618] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 12/21/2018] [Indexed: 01/01/2023] Open
Abstract
Diversity-generating retroelements (DGRs) are widely distributed in bacteria, archaea, and microbial viruses, and bring about unparalleled levels of sequence variation in target proteins. While DGR variable proteins share low sequence identity, the structures of several such proteins have revealed the C-type lectin (CLec)-fold as a conserved scaffold for accommodating massive sequence variation. This conservation has led to the suggestion that the CLec-fold may be useful in molecular surface display applications. Thermostability is an attractive feature in such applications, and thus we studied the variable protein of a DGR encoded by a prophage of the thermophile Thermus aquaticus. We report here the 2.8 Å resolution crystal structure of the variable protein from the T. aquaticus DGR, called TaqVP, and confirm that it has a CLec-fold. Remarkably, its variable region is nearly identical in structure to those of several other CLec-fold DGR variable proteins despite low sequence identity among these. TaqVP was found to be thermostable, which appears to be a property shared by several CLec-fold DGR variable proteins. These results provide impetus for the pursuit of the DGR variable protein CLec-fold in molecular display applications.
Collapse
Affiliation(s)
- Sumit Handa
- Department of Chemistry & Biochemistry, University of California San Diego, La Jolla, CA, United States of America
| | - Kharissa L. Shaw
- Department of Chemistry & Biochemistry, University of California San Diego, La Jolla, CA, United States of America
| | - Partho Ghosh
- Department of Chemistry & Biochemistry, University of California San Diego, La Jolla, CA, United States of America
- * E-mail:
| |
Collapse
|
48
|
Dombrowski N, Lee JH, Williams TA, Offre P, Spang A. Genomic diversity, lifestyles and evolutionary origins of DPANN archaea. FEMS Microbiol Lett 2019; 366:5281434. [PMID: 30629179 PMCID: PMC6349945 DOI: 10.1093/femsle/fnz008] [Citation(s) in RCA: 103] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 01/07/2019] [Indexed: 12/16/2022] Open
Abstract
Archaea-a primary domain of life besides Bacteria-have for a long time been regarded as peculiar organisms that play marginal roles in biogeochemical cycles. However, this picture changed with the discovery of a large diversity of archaea in non-extreme environments enabled by the use of cultivation-independent methods. These approaches have allowed the reconstruction of genomes of uncultivated microorganisms and revealed that archaea are diverse and broadly distributed in the biosphere and seemingly include a large diversity of putative symbiotic organisms, most of which belong to the tentative archaeal superphylum referred to as DPANN. This archaeal group encompasses at least 10 different lineages and includes organisms with extremely small cell and genome sizes and limited metabolic capabilities. Therefore, many members of DPANN may be obligately dependent on symbiotic interactions with other organisms and may even include novel parasites. In this contribution, we review the current knowledge of the gene repertoires and lifestyles of members of this group and discuss their placement in the tree of life, which is the basis for our understanding of the deep microbial roots and the role of symbiosis in the evolution of life on Earth.
Collapse
Affiliation(s)
- Nina Dombrowski
- NIOZ, Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, and Utrecht University, P.O. Box 59, NL-1790 AB Den Burg, The Netherlands
- Department of Marine Science, University of Texas at Austin, Marine Science Institute, 750 Channel View Drive, Port Aransas, TX 78373, USA
| | - Jun-Hoe Lee
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, P.O. Box 596, Husargatan 3, SE-75123 Uppsala, Sweden
| | - Tom A Williams
- School of Biological Sciences, University of Bristol, Life Sciences Building, 24 Tyndall Avenue, Bristol, Bristol BS8 1TQ, UK
| | - Pierre Offre
- NIOZ, Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, and Utrecht University, P.O. Box 59, NL-1790 AB Den Burg, The Netherlands
| | - Anja Spang
- NIOZ, Royal Netherlands Institute for Sea Research, Department of Marine Microbiology and Biogeochemistry, and Utrecht University, P.O. Box 59, NL-1790 AB Den Burg, The Netherlands
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, P.O. Box 596, Husargatan 3, SE-75123 Uppsala, Sweden
| |
Collapse
|
49
|
Benler S, Cobián-Güemes AG, McNair K, Hung SH, Levi K, Edwards R, Rohwer F. A diversity-generating retroelement encoded by a globally ubiquitous Bacteroides phage. MICROBIOME 2018; 6:191. [PMID: 30352623 PMCID: PMC6199706 DOI: 10.1186/s40168-018-0573-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 10/08/2018] [Indexed: 05/23/2023]
Abstract
BACKGROUND Diversity-generating retroelements (DGRs) are genetic cassettes that selectively mutate target genes to produce hypervariable proteins. First characterized in Bordetella bacteriophage BPP-1, the DGR creates a hypervariable phage tail fiber that enables host tropism switching. Subsequent surveys for DGRs conclude that the majority identified to date are bacterial or archaeal in origin. This work examines bacteriophage and bacterial genomes for novel phage-encoded DGRs. RESULTS This survey discovered 92 DGRs that were only found in phages exhibiting a temperate lifestyle. The majority of phage-encoded DGRs were identified as prophages in bacterial hosts from the phyla Bacteroidetes, Proteobacteria, and Firmicutes. Sequence reads from these previously unidentified prophages were present in viral metagenomes (viromes), indicating these prophages can produce functional viruses. Five phages possessed hypervariable proteins with structural similarity to the tail fiber of BPP-1, whereas the functions of the remaining DGR target proteins were unknown. A novel temperate phage that harbors a DGR cassette targeting a protein of unknown function was induced from Bacteroides dorei. This phage, here named Bacteroides dorei Hankyphage, lysogenizes 13 different Bacteroides species and was present in 34% and 21% of whole-community metagenomes and human-associated viromes, respectively. CONCLUSIONS Here, the number of known DGR-containing phages is increased from four to 92. All of these phages exhibit a temperate lifestyle, including a cosmopolitan human-associated phage. Targeted hypervariation by temperate phages may be a ubiquitous mechanism underlying phage-bacteria interaction in the human microbiome.
Collapse
Affiliation(s)
- Sean Benler
- Department of Biology, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182 USA
| | | | - Katelyn McNair
- Department of Computer Science, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182 USA
| | - Shr-Hau Hung
- Department of Biology, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182 USA
| | - Kyle Levi
- Department of Computer Science, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182 USA
| | - Rob Edwards
- Department of Computer Science, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182 USA
| | - Forest Rohwer
- Department of Biology, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182 USA
| |
Collapse
|
50
|
Core Concepts: How diversity-generating retroelements promote mutation and adaptation in myriad microbes. Proc Natl Acad Sci U S A 2018; 114:10509-10511. [PMID: 29073036 DOI: 10.1073/pnas.1714687114] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
|