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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.
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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
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2
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Zajkowski T, Lee MD, Sharma S, Vallota-Eastman A, Kuska M, Malczewska M, Rothschild LJ. Conserved functions of prion candidates suggest a primeval role of protein self-templating. Proteins 2023; 91:1298-1315. [PMID: 37519023 DOI: 10.1002/prot.26558] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 06/14/2023] [Accepted: 07/07/2023] [Indexed: 08/01/2023]
Abstract
Amyloid-based prions have simple structures, a wide phylogenetic distribution, and a plethora of functions in contemporary organisms, suggesting they may be an ancient phenomenon. However, this hypothesis has yet to be addressed with a systematic, computational, and experimental approach. Here we present a framework to help guide future experimental verification of candidate prions with conserved functions to understand their role in the early stages of evolution and potentially in the origins of life. We identified candidate prions in all high-quality proteomes available in UniProt computationally, assessed their phylogenomic distributions, and analyzed candidate-prion functional annotations. Of the 27 980 560 proteins scanned, 228 561 were identified as candidate prions (~0.82%). Among these candidates, there were 84 Gene Ontology (GO) terms conserved across the three domains of life. We found that candidate prions with a possible role in adaptation were particularly well-represented within this group. We discuss unifying features of candidate prions to elucidate the primeval roles of prions and their associated functions. Candidate prions annotated as transcription factors, DNA binding, and kinases are particularly well suited to generating diverse responses to changes in their environment and could allow for adaptation and population expansion into more diverse environments. We hypothesized that a relationship between these functions and candidate prions could be evolutionarily ancient, even if individual prion domains themselves are not evolutionarily conserved. Candidate prions annotated with these universally occurring functions potentially represent the oldest extant prions on Earth and are therefore excellent experimental targets.
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Affiliation(s)
- Tomasz Zajkowski
- Universities Space Research Association at NASA Ames Research Center, Mountain View, California, USA
- Polish Astrobiology Society, Warsaw, Poland
- Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California, USA
- Centre of New Technologies, University of Warsaw, Warsaw, Poland
| | - Michael D Lee
- Blue Marble Space Institute of Science, Seattle, Washington, USA
- KBR, NASA Ames Research Center, Mountain View, California, USA
| | - Siddhant Sharma
- Blue Marble Space Institute of Science, Seattle, Washington, USA
- School of Chemistry, University of New South Wales, Sydney, Australia
| | - Alec Vallota-Eastman
- Department of Earth Science, University of California, Santa Barbara, California, USA
| | - Mikołaj Kuska
- Polish Astrobiology Society, Warsaw, Poland
- Department of Biophysics, Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - Małgorzata Malczewska
- Polish Astrobiology Society, Warsaw, Poland
- Department of Biophysics, Faculty of Physics, University of Warsaw, Warsaw, Poland
| | - Lynn J Rothschild
- Space Science and Astrobiology Division, NASA Ames Research Center, Mountain View, California, USA
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3
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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.
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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
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4
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Qu PP, Fu FX, Wang XW, Kling JD, Elghazzawy M, Huh M, Zhou QQ, Wang C, Mak EWK, Lee MD, Yang N, Hutchins DA. Two co-dominant nitrogen-fixing cyanobacteria demonstrate distinct acclimation and adaptation responses to cope with ocean warming. ENVIRONMENTAL MICROBIOLOGY REPORTS 2022; 14:203-217. [PMID: 35023627 DOI: 10.1111/1758-2229.13041] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Revised: 12/17/2021] [Accepted: 12/18/2021] [Indexed: 05/28/2023]
Abstract
The globally dominant N2 -fixing cyanobacteria Trichodesmium and Crocosphaera provide vital nitrogen supplies to subtropical and tropical oceans, but little is known about how they will be affected by long-term ocean warming. We tested their thermal responses using experimental evolution methods during 2 years of selection at optimal (28°C), supra-optimal (32°C) and suboptimal (22°C) temperatures. After several hundred generations under thermal selection, changes in growth parameters, as well as N and C fixation rates, suggested that Trichodesmium did not adapt to the three selection temperature regimes during the 2-year evolution experiment, but could instead rapidly and reversibly acclimate to temperature shifts from 20°C to 34°C. In contrast, over the same timeframe apparent thermal adaptation was observed in Crocosphaera, as evidenced by irreversible phenotypic changes as well as whole-genome sequencing and variant analysis. Especially under stressful warming conditions (34°C), 32°C-selected Crocosphaera cells had an advantage in survival and nitrogen fixation over cell lines selected at 22°C and 28°C. The distinct strategies of phenotypic plasticity versus irreversible adaptation in these two sympatric diazotrophs are both viable ways to maintain fitness despite long-term temperature changes, and so could help to stabilize key ocean nitrogen cycle functions under future warming scenarios.
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Affiliation(s)
- Ping-Ping Qu
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA
| | - Fei-Xue Fu
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA
| | - Xin-Wei Wang
- School of Marine Sciences, Ningbo University, Ningbo, Zhejiang, 315211, China
| | - Joshua D Kling
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA
| | - Mariam Elghazzawy
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA
| | - Megan Huh
- Department of Preventative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA, 90089, USA
| | - Qian-Qian Zhou
- Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, Fujian, 361005, China
| | - Chunguang Wang
- Third Institute of Oceanography, Ministry of Natural Resources, Xiamen, Fujian, 361005, China
| | - Esther Wing Kwan Mak
- Department of Ocean Sciences and Institute of Marine Sciences, University of California, Santa Cruz, CA, 95064, USA
| | - Michael D Lee
- Exobiology Branch, NASA Ames Research Center, Mountain View, CA, 94035, USA
- Blue Marble Space Institute of Science, Seattle, WA, 98154, USA
| | - Nina Yang
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA
| | - David A Hutchins
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, USA
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5
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Benler S, Koonin EV. Recruitment of Mobile Genetic Elements for Diverse Cellular Functions in Prokaryotes. Front Mol Biosci 2022; 9:821197. [PMID: 35402511 PMCID: PMC8987985 DOI: 10.3389/fmolb.2022.821197] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 02/08/2022] [Indexed: 12/15/2022] Open
Abstract
Prokaryotic genomes are replete with mobile genetic elements (MGE) that span a continuum of replication autonomy. On numerous occasions during microbial evolution, diverse MGE lose their autonomy altogether but, rather than being quickly purged from the host genome, assume a new function that benefits the host, rendering the immobilized MGE subject to purifying selection, and resulting in its vertical inheritance. This mini-review highlights the diversity of the repurposed (exapted) MGE as well as the plethora of cellular functions that they perform. The principal contribution of the exaptation of MGE and their components is to the prokaryotic functional systems involved in biological conflicts, and in particular, defense against viruses and other MGE. This evolutionary entanglement between MGE and defense systems appears to stem both from mechanistic similarities and from similar evolutionary predicaments whereby both MGEs and defense systems tend to incur fitness costs to the hosts and thereby evolve mechanisms for survival including horizontal mobility, causing host addiction, and exaptation for functions beneficial to the host. The examples discussed demonstrate that the identity of an MGE, overall mobility and relationship with the host cell (mutualistic, symbiotic, commensal, or parasitic) are all factors that affect exaptation.
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6
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Paul BG, Eren AM. Eco-evolutionary significance of domesticated retroelements in microbial genomes. Mob DNA 2022; 13:6. [PMID: 35197094 PMCID: PMC8867640 DOI: 10.1186/s13100-022-00262-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 01/03/2022] [Indexed: 01/03/2023] Open
Abstract
Since the first discovery of reverse transcriptase in bacteria, and later in archaea, bacterial and archaeal retroelements have been defined by their common enzyme that coordinates diverse functions. Yet, evolutionary refinement has produced distinct retroelements across the tree of microbial life that are perhaps best described in terms of their programmed RNA—a compact sequence that preserves core information for a sophisticated mechanism. From this perspective, reverse transcriptase has been selected as the modular tool for carrying out nature’s instructions in various RNA templates. Beneficial retroelements—those that can provide a fitness advantage to their host—evolved to their extant forms in a wide array of microorganisms and their viruses, spanning nearly all habitats. Within each specialized retroelement class, several universal features seem to be shared across diverse taxa, while specific functional and mechanistic insights are based on only a few model retroelement systems from clinical isolates. Currently, little is known about the diversity of cellular functions and ecological significance of retroelements across different biomes. With increasing availability of isolate, metagenome-assembled, and single-amplified genomes, the taxonomic and functional breadth of prokaryotic retroelements is coming into clearer view. This review explores the recently characterized classes of beneficial, yet accessory retroelements of bacteria and archaea. We describe how these specialized mechanisms exploit a form of fixed mobility, whereby the retroelements do not appear to proliferate selfishly throughout the genome. Moreover, we discuss computational approaches for systematic identification of retroelements from vast sequence repositories and highlight recent discoveries in terms of their apparent distribution and ecological significance in nature. Lastly, we present a new perspective on the eco-evolutionary significance of these genetic elements in marine bacteria and demonstrate approaches that enable the characterization of their environmental diversity through metagenomics.
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Affiliation(s)
- Blair G Paul
- Marine Biological Laboratory, Josephine Bay Paul Center, Woods Hole, MA, USA.
| | - A Murat Eren
- Marine Biological Laboratory, Josephine Bay Paul Center, Woods Hole, MA, USA. .,Department of Medicine, University of Chicago, Chicago, IL, USA.
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7
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Sharifi F, Ye Y. Identification and classification of reverse transcriptases in bacterial genomes and metagenomes. Nucleic Acids Res 2021; 50:e29. [PMID: 34904653 PMCID: PMC8934634 DOI: 10.1093/nar/gkab1207] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 11/17/2021] [Accepted: 11/22/2021] [Indexed: 02/07/2023] Open
Abstract
Reverse transcriptases (RTs) are found in different systems including group II introns, Diversity Generating Retroelements (DGRs), retrons, CRISPR-Cas systems, and Abortive Infection (Abi) systems in prokaryotes. Different classes of RTs can play different roles, such as template switching and mobility in group II introns, spacer acquisition in CRISPR-Cas systems, mutagenic retrohoming in DGRs, programmed cell suicide in Abi systems, and recently discovered phage defense in retrons. While some classes of RTs have been studied extensively, others remain to be characterized. There is a lack of computational tools for identifying and characterizing various classes of RTs. In this study, we built a tool (called myRT) for identification and classification of prokaryotic RTs. In addition, our tool provides information about the genomic neighborhood of each RT, providing potential functional clues. We applied our tool to predict RTs in all complete and draft bacterial genomes, and created a collection that can be used for exploration of putative RTs and their associated protein domains. Application of myRT to metagenomes showed that gut metagenomes encode proportionally more RTs related to DGRs, outnumbering retron-related RTs, as compared to the collection of reference genomes. MyRT is both available as a standalone software (https://github.com/mgtools/myRT) and also through a website (https://omics.informatics.indiana.edu/myRT/).
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Affiliation(s)
- Fatemeh Sharifi
- Luddy School of Informatics, Computing, and Engineering, Indiana University, Bloomington, IN 47408, USA
| | - Yuzhen Ye
- Luddy School of Informatics, Computing, and Engineering, Indiana University, Bloomington, IN 47408, USA
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8
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González-Delgado A, Mestre MR, Martínez-Abarca F, Toro N. Prokaryotic reverse transcriptases: from retroelements to specialized defense systems. FEMS Microbiol Rev 2021; 45:fuab025. [PMID: 33983378 PMCID: PMC8632793 DOI: 10.1093/femsre/fuab025] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 05/07/2021] [Indexed: 12/30/2022] Open
Abstract
Reverse transcriptases (RTs) catalyze the polymerization of DNA from an RNA template. These enzymes were first discovered in RNA tumor viruses in 1970, but it was not until 1989 that they were found in prokaryotes as a key component of retrons. Apart from RTs encoded by the 'selfish' mobile retroelements known as group II introns, prokaryotic RTs are extraordinarily diverse, but their function has remained elusive. However, recent studies have revealed that different lineages of prokaryotic RTs, including retrons, those associated with CRISPR-Cas systems, Abi-like RTs and other yet uncharacterized RTs, are key components of different lines of defense against phages and other mobile genetic elements. Prokaryotic RTs participate in various antiviral strategies, including abortive infection (Abi), in which the infected cell is induced to commit suicide to protect the host population, adaptive immunity, in which a memory of previous infection is used to build an efficient defense, and other as yet unidentified mechanisms. These prokaryotic enzymes are attracting considerable attention, both for use in cutting-edge technologies, such as genome editing, and as an emerging research topic. In this review, we discuss what is known about prokaryotic RTs, and the exciting evidence for their domestication from retroelements to create specialized defense systems.
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Affiliation(s)
- Alejandro González-Delgado
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Mario Rodríguez Mestre
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
- Department of Biochemistry, Universidad Autónoma de Madrid and Instituto de Investigaciones Biomédicas “Alberto Sols”, CSIC-UAM, Madrid, Spain
| | - Francisco Martínez-Abarca
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
| | - Nicolás Toro
- Department of Soil Microbiology and Symbiotic Systems, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Structure, Dynamics and Function of Rhizobacterial Genomes, Grupo de Ecología Genética de la Rizosfera, C/ Profesor Albareda 1, 18008 Granada, Spain
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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.
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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.
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10
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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.
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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
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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.
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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
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