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Torrance EL, Diop A, Bobay LM. Homologous Recombination Shapes the Architecture and Evolution of Bacterial Genomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.31.596828. [PMID: 38895235 PMCID: PMC11185547 DOI: 10.1101/2024.05.31.596828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Homologous recombination is a key evolutionary force that varies considerably across bacterial species. However, how the landscape of homologous recombination varies across genes and within individual genomes has only been studied in a few species. Here, we used Approximate Bayesian Computation to estimate the recombination rate along the genomes of 145 bacterial species. Our results show that homologous recombination varies greatly along bacterial genomes and shapes many aspects of genome architecture and evolution. The genomic landscape of recombination presents several key signatures: rates are highest near the origin of replication in most species, patterns of recombination generally appear symmetrical in both replichores (i.e. replicational halves of circular chromosomes) and most species have genomic hotpots of recombination. Furthermore, many closely related species share conserved landscapes of recombination across orthologs indicating that recombination landscapes are conserved over significant evolutionary distances. We show evidence that recombination drives the evolution of GC-content through increasing the effectiveness of selection and not through biased gene conversion, thereby contributing to an ongoing debate. Finally, we demonstrate that the rate of recombination varies across gene function and that many hotspots of recombination are associated with adaptive and mobile regions often encoding genes involved in pathogenicity.
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Affiliation(s)
- Ellis L Torrance
- Dept. of Biology, University of North Carolina Greensboro, Greensboro, NC 27412
- Systems Biology Dept., Sandia National Laboratories, Livermore, CA 94551
| | - Awa Diop
- Dept. of Biological Sciences, North Carolina State University, Raleigh, NC 27695
| | - Louis-Marie Bobay
- Dept. of Biology, University of North Carolina Greensboro, Greensboro, NC 27412
- Dept. of Biological Sciences, North Carolina State University, Raleigh, NC 27695
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2
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Liu Z, Good BH. Dynamics of bacterial recombination in the human gut microbiome. PLoS Biol 2024; 22:e3002472. [PMID: 38329938 PMCID: PMC10852326 DOI: 10.1371/journal.pbio.3002472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 12/14/2023] [Indexed: 02/10/2024] Open
Abstract
Horizontal gene transfer (HGT) is a ubiquitous force in microbial evolution. Previous work has shown that the human gut is a hotspot for gene transfer between species, but the more subtle exchange of variation within species-also known as recombination-remains poorly characterized in this ecosystem. Here, we show that the genetic structure of the human gut microbiome provides an opportunity to measure recent recombination events from sequenced fecal samples, enabling quantitative comparisons across diverse commensal species that inhabit a common environment. By analyzing recent recombination events in the core genomes of 29 human gut bacteria, we observed widespread heterogeneities in the rates and lengths of transferred fragments, which are difficult to explain by existing models of ecological isolation or homology-dependent recombination rates. We also show that natural selection helps facilitate the spread of genetic variants across strain backgrounds, both within individual hosts and across the broader population. These results shed light on the dynamics of in situ recombination, which can strongly constrain the adaptability of gut microbial communities.
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Affiliation(s)
- Zhiru Liu
- Department of Applied Physics, Stanford University, Stanford, California, United States of America
| | - Benjamin H. Good
- Department of Applied Physics, Stanford University, Stanford, California, United States of America
- Department of Biology, Stanford University, Stanford, California, United States of America
- Chan Zuckerberg Biohub–San Francisco, San Francisco, California, United States of America
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3
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Coluzzi C, Guillemet M, Mazzamurro F, Touchon M, Godfroid M, Achaz G, Glaser P, Rocha EPC. Chance Favors the Prepared Genomes: Horizontal Transfer Shapes the Emergence of Antibiotic Resistance Mutations in Core Genes. Mol Biol Evol 2023; 40:msad217. [PMID: 37788575 PMCID: PMC10575684 DOI: 10.1093/molbev/msad217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 09/08/2023] [Accepted: 09/19/2023] [Indexed: 10/05/2023] Open
Abstract
Bacterial lineages acquire novel traits at diverse rates in part because the genetic background impacts the successful acquisition of novel genes by horizontal transfer. Yet, how horizontal transfer affects the subsequent evolution of core genes remains poorly understood. Here, we studied the evolution of resistance to quinolones in Escherichia coli accounting for population structure. We found 60 groups of genes whose gain or loss induced an increase in the probability of subsequently becoming resistant to quinolones by point mutations in the gyrase and topoisomerase genes. These groups include functions known to be associated with direct mitigation of the effect of quinolones, with metal uptake, cell growth inhibition, biofilm formation, and sugar metabolism. Many of them are encoded in phages or plasmids. Although some of the chronologies may reflect epidemiological trends, many of these groups encoded functions providing latent phenotypes of antibiotic low-level resistance, tolerance, or persistence under quinolone treatment. The mutations providing resistance were frequent and accumulated very quickly. Their emergence was found to increase the rate of acquisition of other antibiotic resistances setting the path for multidrug resistance. Hence, our findings show that horizontal gene transfer shapes the subsequent emergence of adaptive mutations in core genes. In turn, these mutations further affect the subsequent evolution of resistance by horizontal gene transfer. Given the substantial gene flow within bacterial genomes, interactions between horizontal transfer and point mutations in core genes may be a key to the success of adaptation processes.
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Affiliation(s)
- Charles Coluzzi
- Institut Pasteur, Université Paris Cité, CNRS, UMR3525, Microbial Evolutionary Genomics, Paris, France
| | - Martin Guillemet
- Institut Pasteur, Université Paris Cité, CNRS, UMR3525, Microbial Evolutionary Genomics, Paris, France
| | - Fanny Mazzamurro
- Institut Pasteur, Université Paris Cité, CNRS, UMR3525, Microbial Evolutionary Genomics, Paris, France
- Collège Doctoral, Sorbonne Université, Paris, France
| | - Marie Touchon
- Institut Pasteur, Université Paris Cité, CNRS, UMR3525, Microbial Evolutionary Genomics, Paris, France
| | - Maxime Godfroid
- SMILE Group, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Guillaume Achaz
- SMILE Group, Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS, INSERM, Université PSL, Paris, France
| | - Philippe Glaser
- Institut Pasteur, Université de Paris Cité, CNRS, UMR6047, Unité EERA, Paris, France
| | - Eduardo P C Rocha
- Institut Pasteur, Université Paris Cité, CNRS, UMR3525, Microbial Evolutionary Genomics, Paris, France
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4
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Lee IPA, Eldakar OT, Gogarten JP, Andam CP. Recombination as an enforcement mechanism of prosocial behavior in cooperating bacteria. iScience 2023; 26:107344. [PMID: 37554437 PMCID: PMC10405257 DOI: 10.1016/j.isci.2023.107344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 04/11/2023] [Accepted: 07/06/2023] [Indexed: 08/10/2023] Open
Abstract
Prosocial behavior is ubiquitous in nature despite the relative fitness costs carried by cooperative individuals. However, the stability of cooperation in populations is fragile and often maintained through enforcement. We propose that homologous recombination provides such a mechanism in bacteria. Using an agent-based model of recombination in bacteria playing a public goods game, we demonstrate how changes in recombination rates affect the proportion of cooperating cells. In our model, recombination converts cells to a different strategy, either freeloading (cheaters) or cooperation, based on the strategies of neighboring cells and recombination rate. Increasing the recombination rate expands the parameter space in which cooperators outcompete freeloaders. However, increasing the recombination rate alone is neither sufficient nor necessary. Intermediate benefits of cooperation, lower population viscosity, and greater population size can promote the evolution of cooperation from within populations of cheaters. Our findings demonstrate how recombination influences the persistence of cooperative behavior in bacteria.
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Affiliation(s)
- Isaiah Paolo A. Lee
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, NH 03824, USA
- National Institute of Molecular Biology and Biotechnology, University of the Philippines–Diliman, Quezon City 1101, Philippines
| | - Omar Tonsi Eldakar
- Department of Biological Sciences, Nova Southeastern University, Fort Lauderdale, FL 33328, USA
| | - J. Peter Gogarten
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA
| | - Cheryl P. Andam
- Department of Biological Sciences, University at Albany, State University of New York, Albany, NY 12222, USA
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5
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Lauterbur ME, Cavassim MIA, Gladstein AL, Gower G, Pope NS, Tsambos G, Adrion J, Belsare S, Biddanda A, Caudill V, Cury J, Echevarria I, Haller BC, Hasan AR, Huang X, Iasi LNM, Noskova E, Obsteter J, Pavinato VAC, Pearson A, Peede D, Perez MF, Rodrigues MF, Smith CCR, Spence JP, Teterina A, Tittes S, Unneberg P, Vazquez JM, Waples RK, Wohns AW, Wong Y, Baumdicker F, Cartwright RA, Gorjanc G, Gutenkunst RN, Kelleher J, Kern AD, Ragsdale AP, Ralph PL, Schrider DR, Gronau I. Expanding the stdpopsim species catalog, and lessons learned for realistic genome simulations. eLife 2023; 12:RP84874. [PMID: 37342968 DOI: 10.7554/elife.84874] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/23/2023] Open
Abstract
Simulation is a key tool in population genetics for both methods development and empirical research, but producing simulations that recapitulate the main features of genomic datasets remains a major obstacle. Today, more realistic simulations are possible thanks to large increases in the quantity and quality of available genetic data, and the sophistication of inference and simulation software. However, implementing these simulations still requires substantial time and specialized knowledge. These challenges are especially pronounced for simulating genomes for species that are not well-studied, since it is not always clear what information is required to produce simulations with a level of realism sufficient to confidently answer a given question. The community-developed framework stdpopsim seeks to lower this barrier by facilitating the simulation of complex population genetic models using up-to-date information. The initial version of stdpopsim focused on establishing this framework using six well-characterized model species (Adrion et al., 2020). Here, we report on major improvements made in the new release of stdpopsim (version 0.2), which includes a significant expansion of the species catalog and substantial additions to simulation capabilities. Features added to improve the realism of the simulated genomes include non-crossover recombination and provision of species-specific genomic annotations. Through community-driven efforts, we expanded the number of species in the catalog more than threefold and broadened coverage across the tree of life. During the process of expanding the catalog, we have identified common sticking points and developed the best practices for setting up genome-scale simulations. We describe the input data required for generating a realistic simulation, suggest good practices for obtaining the relevant information from the literature, and discuss common pitfalls and major considerations. These improvements to stdpopsim aim to further promote the use of realistic whole-genome population genetic simulations, especially in non-model organisms, making them available, transparent, and accessible to everyone.
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Affiliation(s)
- M Elise Lauterbur
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, United States
| | - Maria Izabel A Cavassim
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, Los Angeles, United States
| | | | - Graham Gower
- Section for Molecular Ecology and Evolution, Globe Institute, University of Copenhagen, Copenhagen, Denmark
| | - Nathaniel S Pope
- Institute of Ecology and Evolution, University of Oregon, Eugene, United States
| | - Georgia Tsambos
- School of Mathematics and Statistics, University of Melbourne, Melbourne, Australia
| | - Jeffrey Adrion
- Institute of Ecology and Evolution, University of Oregon, Eugene, United States
- Ancestry DNA, San Francisco, United States
| | - Saurabh Belsare
- Institute of Ecology and Evolution, University of Oregon, Eugene, United States
| | | | - Victoria Caudill
- Institute of Ecology and Evolution, University of Oregon, Eugene, United States
| | - Jean Cury
- Universite Paris-Saclay, CNRS, INRIA, Laboratoire Interdisciplinaire des Sciences du Numerique, Orsay, France
| | | | - Benjamin C Haller
- Department of Computational Biology, Cornell University, Ithaca, United States
| | - Ahmed R Hasan
- Department of Cell and Systems Biology, University of Toronto, Toronto, Canada
- Department of Biology, University of Toronto Mississauga, Mississauga, Canada
| | - Xin Huang
- Department of Evolutionary Anthropology, University of Vienna, Vienna, Austria
- Human Evolution and Archaeological Sciences (HEAS), University of Vienna, Vienna, Austria
| | | | - Ekaterina Noskova
- Computer Technologies Laboratory, ITMO University, St Petersburg, Russian Federation
| | - Jana Obsteter
- Agricultural Institute of Slovenia, Department of Animal Science, Ljubljana, Slovenia
| | | | - Alice Pearson
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - David Peede
- Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, United States
- Center for Computational Molecular Biology, Brown University, Providence, United States
| | - Manolo F Perez
- Department of Genetics and Evolution, Federal University of Sao Carlos, Sao Carlos, Brazil
| | - Murillo F Rodrigues
- Institute of Ecology and Evolution, University of Oregon, Eugene, United States
| | - Chris C R Smith
- Institute of Ecology and Evolution, University of Oregon, Eugene, United States
| | - Jeffrey P Spence
- Department of Genetics, Stanford University School of Medicine, Stanford, United States
| | - Anastasia Teterina
- Institute of Ecology and Evolution, University of Oregon, Eugene, United States
| | - Silas Tittes
- Institute of Ecology and Evolution, University of Oregon, Eugene, United States
| | - Per Unneberg
- Department of Cell and Molecular Biology, National Bioinformatics Infrastructure Sweden, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Juan Manuel Vazquez
- Department of Integrative Biology, University of California, Berkeley, Berkeley, United States
| | - Ryan K Waples
- Department of Biostatistics, University of Washington, Seattle, United States
| | | | - Yan Wong
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
| | - Franz Baumdicker
- Cluster of Excellence - Controlling Microbes to Fight Infections, Eberhard Karls Universit¨at Tubingen, Tubingen, Germany
| | - Reed A Cartwright
- School of Life Sciences and The Biodesign Institute, Arizona State University, Tempe, United States
| | - Gregor Gorjanc
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh, Edinburgh, United Kingdom
| | - Ryan N Gutenkunst
- Department of Molecular and Cellular Biology, University of Arizona, Tucson, United States
| | - Jerome Kelleher
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
| | - Andrew D Kern
- Institute of Ecology and Evolution, University of Oregon, Eugene, United States
| | - Aaron P Ragsdale
- Department of Integrative Biology, University of Wisconsin-Madison, Madison, United States
| | - Peter L Ralph
- Institute of Ecology and Evolution, University of Oregon, Eugene, United States
- Department of Mathematics, University of Oregon, Eugene, United States
| | - Daniel R Schrider
- Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, United States
| | - Ilan Gronau
- Efi Arazi School of Computer Science, Reichman University, Herzliya, Israel
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6
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Cobo-Simón M, Hart R, Ochman H. Escherichia Coli: What Is and Which Are? Mol Biol Evol 2023; 40:msac273. [PMID: 36585846 PMCID: PMC9830988 DOI: 10.1093/molbev/msac273] [Citation(s) in RCA: 4] [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: 09/21/2022] [Revised: 12/11/2022] [Accepted: 12/15/2022] [Indexed: 01/01/2023] Open
Abstract
Escherichia coli have served as important model organisms for over a century-used to elucidate key aspects of genetics, evolution, molecular biology, and pathogenesis. However, defining which strains actually belong to this species is erratic and unstable due to shifts in the characters and criteria used to distinguish bacterial species. Additionally, many isolates designated as E. coli are genetically more closely related to strains of Shigella than to other E. coli, creating a situation in which the entire genus of Shigella and its four species are encompassed within the single species E. coli. We evaluated all complete genomes assigned to E. coli and its closest relatives according to the biological species concept (BSC), using evidence of reproductive isolation and gene flow (i.e., homologous recombination in the case of asexual bacteria) to ascertain species boundaries. The BSC establishes a uniform, consistent, and objective principle that allows species-level classification across all domains of life and does not rely on either phenotypic or genotypic similarity to a defined type-specimen for species membership. Analyzing a total of 1,887 sequenced genomes and comparing our results to other genome-based classification methods, we found few barriers to gene flow among the strains, clades, phylogroups, or species within E. coli and Shigella. Due to the utility in recognizing which strains constitute a true biological species, we designate genomes that form a genetic cohesive group as members of E. coliBIO.
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Affiliation(s)
- Marta Cobo-Simón
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX
| | - Rowan Hart
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX
| | - Howard Ochman
- Department of Molecular Biosciences, University of Texas at Austin, Austin, TX
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7
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Didelot X, Helekal D, Kendall M, Ribeca P. Distinguishing imported cases from locally acquired cases within a geographically limited genomic sample of an infectious disease. Bioinformatics 2022; 39:6849542. [PMID: 36440957 PMCID: PMC9805578 DOI: 10.1093/bioinformatics/btac761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 11/17/2022] [Accepted: 11/24/2022] [Indexed: 11/30/2022] Open
Abstract
MOTIVATION The ability to distinguish imported cases from locally acquired cases has important consequences for the selection of public health control strategies. Genomic data can be useful for this, for example, using a phylogeographic analysis in which genomic data from multiple locations are compared to determine likely migration events between locations. However, these methods typically require good samples of genomes from all locations, which is rarely available. RESULTS Here, we propose an alternative approach that only uses genomic data from a location of interest. By comparing each new case with previous cases from the same location, we are able to detect imported cases, as they have a different genealogical distribution than that of locally acquired cases. We show that, when variations in the size of the local population are accounted for, our method has good sensitivity and excellent specificity for the detection of imports. We applied our method to data simulated under the structured coalescent model and demonstrate relatively good performance even when the local population has the same size as the external population. Finally, we applied our method to several recent genomic datasets from both bacterial and viral pathogens, and show that it can, in a matter of seconds or minutes, deliver important insights on the number of imports to a geographically limited sample of a pathogen population. AVAILABILITY AND IMPLEMENTATION The R package DetectImports is freely available from https://github.com/xavierdidelot/DetectImports. SUPPLEMENTARY INFORMATION Supplementary data are available at Bioinformatics online.
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Affiliation(s)
| | - David Helekal
- Centre for Doctoral Training in Mathematics for Real-World Systems, University of Warwick, Coventry CV4 7AL, UK
| | - Michelle Kendall
- School of Life Sciences and Department of Statistics, University of Warwick, Coventry CV4 7AL, UK
| | - Paolo Ribeca
- Gastrointestinal Bacteria Reference Unit, UK Health Security Agency, London NW9 5EQ, UK,Biomathematics and Statistics Scotland, The James Hutton Institute, Edinburgh EH9 3FD, UK
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8
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Diop A, Torrance EL, Stott CM, Bobay LM. Gene flow and introgression are pervasive forces shaping the evolution of bacterial species. Genome Biol 2022; 23:239. [PMID: 36357919 PMCID: PMC9650840 DOI: 10.1186/s13059-022-02809-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 10/24/2022] [Indexed: 11/11/2022] Open
Abstract
BACKGROUND Although originally thought to evolve clonally, studies have revealed that most bacteria exchange DNA. However, it remains unclear to what extent gene flow shapes the evolution of bacterial genomes and maintains the cohesion of species. RESULTS Here, we analyze the patterns of gene flow within and between >2600 bacterial species. Our results show that fewer than 10% of bacterial species are truly clonal, indicating that purely asexual species are rare in nature. We further demonstrate that the taxonomic criterion of ~95% genome sequence identity routinely used to define bacterial species does not accurately represent a level of divergence that imposes an effective barrier to gene flow across bacterial species. Interruption of gene flow can occur at various sequence identities across lineages, generally from 90 to 98% genome identity. This likely explains why a ~95% genome sequence identity threshold has empirically been judged as a good approximation to define bacterial species. Our results support a universal mechanism where the availability of identical genomic DNA segments required to initiate homologous recombination is the primary determinant of gene flow and species boundaries in bacteria. We show that these barriers of gene flow remain porous since many distinct species maintain some level of gene flow, similar to introgression in sexual organisms. CONCLUSIONS Overall, bacterial evolution and speciation are likely shaped by similar forces driving the evolution of sexual organisms. Our findings support a model where the interruption of gene flow-although not necessarily the initial cause of speciation-leads to the establishment of permanent and irreversible species borders.
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Affiliation(s)
- Awa Diop
- grid.266860.c0000 0001 0671 255XDepartment of Biology, University of North Carolina Greensboro, Greensboro, North Carolina, 321 McIver Street, PO Box 26170, Greensboro, NC 27402 USA
| | - Ellis L. Torrance
- grid.266860.c0000 0001 0671 255XDepartment of Biology, University of North Carolina Greensboro, Greensboro, North Carolina, 321 McIver Street, PO Box 26170, Greensboro, NC 27402 USA
| | - Caroline M. Stott
- grid.266860.c0000 0001 0671 255XDepartment of Biology, University of North Carolina Greensboro, Greensboro, North Carolina, 321 McIver Street, PO Box 26170, Greensboro, NC 27402 USA
| | - Louis-Marie Bobay
- grid.266860.c0000 0001 0671 255XDepartment of Biology, University of North Carolina Greensboro, Greensboro, North Carolina, 321 McIver Street, PO Box 26170, Greensboro, NC 27402 USA
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9
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Preska Steinberg A, Lin M, Kussell E. Core genes can have higher recombination rates than accessory genes within global microbial populations. eLife 2022; 11:78533. [PMID: 35801696 PMCID: PMC9444244 DOI: 10.7554/elife.78533] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 06/30/2022] [Indexed: 11/24/2022] Open
Abstract
Recombination is essential to microbial evolution, and is involved in the spread of antibiotic resistance, antigenic variation, and adaptation to the host niche. However, assessing the impact of homologous recombination on accessory genes which are only present in a subset of strains of a given species remains challenging due to their complex phylogenetic relationships. Quantifying homologous recombination for accessory genes (which are important for niche-specific adaptations) in comparison to core genes (which are present in all strains and have essential functions) is critical to understanding how selection acts on variation to shape species diversity and genome structures of bacteria. Here, we apply a computationally efficient, non-phylogenetic approach to measure homologous recombination rates in the core and accessory genome using >100,000 whole genome sequences from Streptococcus pneumoniae and several additional species. By analyzing diverse sets of sequence clusters, we show that core genes often have higher recombination rates than accessory genes, and for some bacterial species the associated effect sizes for these differences are pronounced. In a subset of species, we find that gene frequency and homologous recombination rate are positively correlated. For S. pneumoniae and several additional species, we find that while the recombination rate is higher for the core genome, the mutational divergence is lower, indicating that divergence-based homologous recombination barriers could contribute to differences in recombination rates between the core and accessory genome. Homologous recombination may therefore play a key role in increasing the efficiency of selection in the most conserved parts of the genome.
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Affiliation(s)
| | - Mingzhi Lin
- Department of Biology, New York University, New York, United States
| | - Edo Kussell
- Department of Biology, New York University, New York, United States
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10
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Foster-Nyarko E, Pallen MJ. OUP accepted manuscript. FEMS Microbiol Rev 2022; 46:6522174. [PMID: 35134909 PMCID: PMC9075585 DOI: 10.1093/femsre/fuac008] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 01/31/2022] [Accepted: 02/01/2022] [Indexed: 11/13/2022] Open
Abstract
Escherichia coli has a rich history as biology's ‘rock star’, driving advances across many fields. In the wild, E. coli resides innocuously in the gut of humans and animals but is also a versatile pathogen commonly associated with intestinal and extraintestinal infections and antimicrobial resistance—including large foodborne outbreaks such as the one that swept across Europe in 2011, killing 54 individuals and causing approximately 4000 infections and 900 cases of haemolytic uraemic syndrome. Given that most E. coli are harmless gut colonizers, an important ecological question plaguing microbiologists is what makes E. coli an occasionally devastating pathogen? To address this question requires an enhanced understanding of the ecology of the organism as a commensal. Here, we review how our knowledge of the ecology and within-host diversity of this organism in the vertebrate gut has progressed in the 137 years since E. coli was first described. We also review current approaches to the study of within-host bacterial diversity. In closing, we discuss some of the outstanding questions yet to be addressed and prospects for future research.
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Affiliation(s)
- Ebenezer Foster-Nyarko
- Corresponding author: Department of Infection Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom. E-mail:
| | - Mark J Pallen
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UQ, United Kingdom
- School of Veterinary Medicine, University of Surrey, Guildford, Surrey, GU2 7AL, United Kingdom
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TU, United Kingdom
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11
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Colquhoun RM, Hall MB, Lima L, Roberts LW, Malone KM, Hunt M, Letcher B, Hawkey J, George S, Pankhurst L, Iqbal Z. Pandora: nucleotide-resolution bacterial pan-genomics with reference graphs. Genome Biol 2021; 22:267. [PMID: 34521456 PMCID: PMC8442373 DOI: 10.1186/s13059-021-02473-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 08/19/2021] [Indexed: 12/21/2022] Open
Abstract
We present pandora, a novel pan-genome graph structure and algorithms for identifying variants across the full bacterial pan-genome. As much bacterial adaptability hinges on the accessory genome, methods which analyze SNPs in just the core genome have unsatisfactory limitations. Pandora approximates a sequenced genome as a recombinant of references, detects novel variation and pan-genotypes multiple samples. Using a reference graph of 578 Escherichia coli genomes, we compare 20 diverse isolates. Pandora recovers more rare SNPs than single-reference-based tools, is significantly better than picking the closest RefSeq reference, and provides a stable framework for analyzing diverse samples without reference bias.
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Affiliation(s)
- Rachel M Colquhoun
- European Bioinformatics Institute, Hinxton, Cambridge, CB10 1SD, UK
- Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, UK
- Institute of Evolutionary Biology, Ashworth Laboratories, University of Edinburgh, Edinburgh, UK
| | - Michael B Hall
- European Bioinformatics Institute, Hinxton, Cambridge, CB10 1SD, UK
| | - Leandro Lima
- European Bioinformatics Institute, Hinxton, Cambridge, CB10 1SD, UK
| | - Leah W Roberts
- European Bioinformatics Institute, Hinxton, Cambridge, CB10 1SD, UK
| | - Kerri M Malone
- European Bioinformatics Institute, Hinxton, Cambridge, CB10 1SD, UK
| | - Martin Hunt
- European Bioinformatics Institute, Hinxton, Cambridge, CB10 1SD, UK
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Brice Letcher
- European Bioinformatics Institute, Hinxton, Cambridge, CB10 1SD, UK
| | - Jane Hawkey
- Department of Infectious Diseases, Central Clinical School, Monash University, Melbourne, Victoria, 3004, Australia
| | - Sophie George
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
| | - Louise Pankhurst
- Nuffield Department of Medicine, University of Oxford, Oxford, UK
- Department of Zoology, University of Oxford, Mansfield Road, Oxford, UK
| | - Zamin Iqbal
- European Bioinformatics Institute, Hinxton, Cambridge, CB10 1SD, UK.
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12
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Horesh G, Blackwell GA, Tonkin-Hill G, Corander J, Heinz E, Thomson NR. A comprehensive and high-quality collection of Escherichia coli genomes and their genes. Microb Genom 2021; 7:000499. [PMID: 33417534 PMCID: PMC8208696 DOI: 10.1099/mgen.0.000499] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 12/07/2020] [Indexed: 01/25/2023] Open
Abstract
Escherichia coli is a highly diverse organism that includes a range of commensal and pathogenic variants found across a range of niches and worldwide. In addition to causing severe intestinal and extraintestinal disease, E. coli is considered a priority pathogen due to high levels of observed drug resistance. The diversity in the E. coli population is driven by high genome plasticity and a very large gene pool. All these have made E. coli one of the most well-studied organisms, as well as a commonly used laboratory strain. Today, there are thousands of sequenced E. coli genomes stored in public databases. While data is widely available, accessing the information in order to perform analyses can still be a challenge. Collecting relevant available data requires accessing different sources, where data may be stored in a range of formats, and often requires further manipulation and processing to apply various analyses and extract useful information. In this study, we collated and intensely curated a collection of over 10 000 E. coli and Shigella genomes to provide a single, uniform, high-quality dataset. Shigella were included as they are considered specialized pathovars of E. coli. We provide these data in a number of easily accessible formats that can be used as the foundation for future studies addressing the biological differences between E. coli lineages and the distribution and flow of genes in the E. coli population at a high resolution. The analysis we present emphasizes our lack of understanding of the true diversity of the E. coli species, and the biased nature of our current understanding of the genetic diversity of such a key pathogen.
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Affiliation(s)
- Gal Horesh
- Parasites and Microbes, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire CB10 1RQ, UK
| | - Grace A. Blackwell
- Parasites and Microbes, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire CB10 1RQ, UK
- EMBL-EBI, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Gerry Tonkin-Hill
- Parasites and Microbes, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire CB10 1RQ, UK
| | - Jukka Corander
- Parasites and Microbes, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire CB10 1RQ, UK
- Department of Biostatistics, University of Oslo, Oslo, Norway
- Department of Mathematics and Statistics, Helsinki Institute for Information Technology (HIIT), University of Helsinki, Helsinki, Finland
| | - Eva Heinz
- Department of Vector Biology and Clinical Sciences, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK
| | - Nicholas R. Thomson
- Parasites and Microbes, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire CB10 1RQ, UK
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
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13
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Sakoparnig T, Field C, van Nimwegen E. Whole genome phylogenies reflect the distributions of recombination rates for many bacterial species. eLife 2021; 10:e65366. [PMID: 33416498 PMCID: PMC7884076 DOI: 10.7554/elife.65366] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 01/07/2021] [Indexed: 12/26/2022] Open
Abstract
Although recombination is accepted to be common in bacteria, for many species robust phylogenies with well-resolved branches can be reconstructed from whole genome alignments of strains, and these are generally interpreted to reflect clonal relationships. Using new methods based on the statistics of single-nucleotide polymorphism (SNP) splits, we show that this interpretation is incorrect. For many species, each locus has recombined many times along its line of descent, and instead of many loci supporting a common phylogeny, the phylogeny changes many thousands of times along the genome alignment. Analysis of the patterns of allele sharing among strains shows that bacterial populations cannot be approximated as either clonal or freely recombining but are structured such that recombination rates between lineages vary over several orders of magnitude, with a unique pattern of rates for each lineage. Thus, rather than reflecting clonal ancestry, whole genome phylogenies reflect distributions of recombination rates.
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Affiliation(s)
- Thomas Sakoparnig
- Biozentrum, University of Basel, and Swiss Institute of BioinformaticsBaselSwitzerland
| | - Chris Field
- Biozentrum, University of Basel, and Swiss Institute of BioinformaticsBaselSwitzerland
| | - Erik van Nimwegen
- Biozentrum, University of Basel, and Swiss Institute of BioinformaticsBaselSwitzerland
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14
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Kang Y, Yuan L, Shi X, Chu Y, He Z, Jia X, Lin Q, Ma Q, Wang J, Xiao J, Hu S, Gao Z, Chen F, Yu J. A fine-scale map of genome-wide recombination in divergent Escherichia coli population. Brief Bioinform 2020; 22:6034796. [PMID: 33319232 DOI: 10.1093/bib/bbaa335] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/19/2020] [Accepted: 10/23/2020] [Indexed: 01/09/2023] Open
Abstract
Recombination is one of the most important molecular mechanisms of prokaryotic genome evolution, but its exact roles are still in debate. Here we try to infer genome-wide recombination within a species, utilizing a dataset of 149 complete genomes of Escherichia coli from diverse animal hosts and geographic origins, including 45 in-house sequenced with the single-molecular real-time platform. Two major clades identified based on physiological, clinical and ecological characteristics form distinct genetic lineages based on scarcity of interclade gene exchanges. By defining gene-based syntenies for genomic segments within and between the two clades, we build a fine-scale recombination map for this representative global E. coli population. The map suggests extensive within-clade recombination that often breaks physical linkages among individual genes but seldom interrupts the structure of genome organizational frameworks as well as primary metabolic portfolios supported by the framework integrity, possibly due to strong natural selection for both physiological compatibility and ecological fitness. In contrast, the between-clade recombination declines drastically when phylogenetic distance increases to the extent where a 10-fold reduction can be observed, establishing a firm genetic barrier between clades. Our empirical data suggest a critical role for such recombination events in the early stage of speciation where recombination rate is associated with phylogenetic distance in addition to sequence and gene variations. The extensive intraclade recombination binds sister strains into a quasisexual group and optimizes genes or alleles to streamline physiological activities, whereas the sharply declined interclade recombination split the population into clades adaptive to divergent ecological niches.
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Affiliation(s)
- Yu Kang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, 100101, Beijing, PR China.,China National Center for Bioinformation, Beijing 100101, PR China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Lina Yuan
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, 100101, Beijing, PR China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xing Shi
- Department of Respiratory & Critical Care Medicine, Peking University People's Hospital, Beijing, 100044, PR China
| | - Yanan Chu
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, 100101, Beijing, PR China.,China National Center for Bioinformation, Beijing 100101, PR China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zilong He
- Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Interdisciplinary Innovation Institute of Medicine and Engineering, Beihang University, Beijing, 100191, PR China
| | - Xinmiao Jia
- Medical Research Center, Peking Union Medical College Hospital, Peking Union Medical College & Chinese Academy of Medical Sciences, Beijing 100730, PR China
| | - Qiang Lin
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China
| | - Qin Ma
- Department of Agronomy, Horticulture, and Plant Science, South Dakota State University, Brookings, SD, 57007, USA
| | - Jian Wang
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, 100101, Beijing, PR China.,China National Center for Bioinformation, Beijing 100101, PR China
| | - Jingfa Xiao
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, 100101, Beijing, PR China.,China National Center for Bioinformation, Beijing 100101, PR China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Songnian Hu
- University of Chinese Academy of Sciences, Beijing 100049, China.,State Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, 100101, Beijing, PR China
| | - Zhancheng Gao
- Department of Respiratory & Critical Care Medicine, Peking University People's Hospital, Beijing, 100044, PR China
| | - Fei Chen
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, 100101, Beijing, PR China.,China National Center for Bioinformation, Beijing 100101, PR China.,University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jun Yu
- CAS Key Laboratory of Genome Sciences and Information, Beijing Institute of Genomics, Chinese Academy of Sciences, 100101, Beijing, PR China.,China National Center for Bioinformation, Beijing 100101, PR China.,University of Chinese Academy of Sciences, Beijing 100049, China
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15
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Stott CM, Bobay LM. Impact of homologous recombination on core genome phylogenies. BMC Genomics 2020; 21:829. [PMID: 33238876 PMCID: PMC7691112 DOI: 10.1186/s12864-020-07262-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 11/19/2020] [Indexed: 01/14/2023] Open
Abstract
BACKGROUND Core genome phylogenies are widely used to build the evolutionary history of individual prokaryote species. By using hundreds or thousands of shared genes, these approaches are the gold standard to reconstruct the relationships of large sets of strains. However, there is growing evidence that bacterial strains exchange DNA through homologous recombination at rates that vary widely across prokaryote species, indicating that core genome phylogenies might not be able to reconstruct true phylogenies when recombination rate is high. Few attempts have been made to evaluate the robustness of core genome phylogenies to recombination, but some analyses suggest that reconstructed trees are not always accurate. RESULTS In this study, we tested the robustness of core genome phylogenies to various levels of recombination rates. By analyzing simulated and empirical data, we observed that core genome phylogenies are relatively robust to recombination rates; nevertheless, our results suggest that many reconstructed trees are not completely accurate even when bootstrap supports are high. We found that some core genome phylogenies are highly robust to recombination whereas others are strongly impacted by it, and we identified that the robustness of core genome phylogenies to recombination is highly linked to the levels of selective pressures acting on a species. Stronger selective pressures lead to less accurate tree reconstructions, presumably because selective pressures more strongly bias the routes of DNA transfers, thereby causing phylogenetic artifacts. CONCLUSIONS Overall, these results have important implications for the application of core genome phylogenies in prokaryotes.
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Affiliation(s)
- Caroline M Stott
- Department of Biology, University of North Carolina Greensboro, 321 McIver Street, PO Box 26170, Greensboro, NC, 27402, USA
| | - Louis-Marie Bobay
- Department of Biology, University of North Carolina Greensboro, 321 McIver Street, PO Box 26170, Greensboro, NC, 27402, USA.
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16
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Homologous Recombination in Clostridioides difficile Mediates Diversification of Cell Surface Features and Transport Systems. mSphere 2020; 5:5/6/e00799-20. [PMID: 33208516 PMCID: PMC7677006 DOI: 10.1128/msphere.00799-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Infections with C. difficile result in up to half a million illnesses and tens of thousands of deaths annually in the United States. The severity of C. difficile illness is dependent on both host and bacterial factors. Illness caused by the pathogen Clostridioides difficile is widespread and can range in severity from mild diarrhea to sepsis and death. Strains of C. difficile isolated from human infections exhibit great genetic diversity, leading to the hypothesis that the genetic background of the infecting strain at least partially determines a patient’s clinical course. However, although certain strains of C. difficile have been suggested to be associated with increased severity, strain typing alone has proved insufficient to explain infection severity. The limited explanatory power of strain typing has been hypothesized to be due to genetic variation within strain types, as well as genetic elements shared between strain types. Homologous recombination is an evolutionary mechanism that can result in large genetic differences between two otherwise clonal isolates, and also lead to convergent genotypes in distantly related strains. More than 400 C. difficile genomes were analyzed here to assess the effect of homologous recombination within and between C. difficile clades. Almost three-quarters of single nucleotide variants in the C. difficile phylogeny are predicted to be due to homologous recombination events. Furthermore, recombination events were enriched in genes previously reported to be important to virulence and host-pathogen interactions, such as flagella, cell wall proteins, and sugar transport and metabolism. Thus, by exploring the landscape of homologous recombination in C. difficile, we identified genetic loci whose elevated rates of recombination mediated diversification, making them strong candidates for being mediators of host-pathogen interaction in diverse strains of C. difficile. IMPORTANCE Infections with C. difficile result in up to half a million illnesses and tens of thousands of deaths annually in the United States. The severity of C. difficile illness is dependent on both host and bacterial factors. Studying the evolutionary history of C. difficile pathogens is important for understanding the variation in pathogenicity of these bacteria. This study examines the extent and targets of homologous recombination, a mechanism by which distant strains of bacteria can share genetic material, in hundreds of C. difficile strains and identifies hot spots of realized recombination events. The results of this analysis reveal the importance of homologous recombination in the diversification of genetic loci in C. difficile that are significant in its pathogenicity and host interactions, such as flagellar construction, cell wall proteins, and sugar transport and metabolism.
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17
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Decano AG, Tran N, Al-Foori H, Al-Awadi B, Campbell L, Ellison K, Mirabueno LP, Nelson M, Power S, Smith G, Smyth C, Vance Z, Woods C, Rahm A, Downing T. Plasmids shape the diverse accessory resistomes of Escherichia coli ST131. Access Microbiol 2020; 3:acmi000179. [PMID: 33997610 PMCID: PMC8115979 DOI: 10.1099/acmi.0.000179] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 10/27/2020] [Indexed: 12/22/2022] Open
Abstract
The human gut microbiome includes beneficial, commensal and pathogenic bacteria that possess antimicrobial resistance (AMR) genes and exchange these predominantly through conjugative plasmids. Escherichia coli is a significant component of the gastrointestinal microbiome and is typically non-pathogenic in this niche. In contrast, extra-intestinal pathogenic E. coli (ExPEC) including ST131 may occupy other environments like the urinary tract or bloodstream where they express genes enabling AMR and host cell adhesion like type 1 fimbriae. The extent to which commensal E. coli and uropathogenic ExPEC ST131 share AMR genes remains understudied at a genomic level, and we examined this here using a preterm infant resistome. We found that individual ST131 had small differences in AMR gene content relative to a larger shared resistome. Comparisons with a range of plasmids common in ST131 showed that AMR gene composition was driven by conjugation, recombination and mobile genetic elements. Plasmid pEK499 had extended regions in most ST131 Clade C isolates, and it had evidence of a co-evolutionary signal based on protein-level interactions with chromosomal gene products, as did pEK204 that had a type IV fimbrial pil operon. ST131 possessed extensive diversity of selective type 1, type IV, P and F17-like fimbriae genes that was highest in subclade C2. The structure and composition of AMR genes, plasmids and fimbriae vary widely in ST131 Clade C and this may mediate pathogenicity and infection outcomes.
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Affiliation(s)
- Arun Gonzales Decano
- School of Biotechnology, Dublin City University, Ireland.,Present address: School of Medicine, University of St., Andrews, UK
| | - Nghia Tran
- School of Maths, Applied Maths and Statistics, National University of Ireland Galway, Ireland
| | | | | | | | - Kevin Ellison
- School of Biotechnology, Dublin City University, Ireland
| | - Louisse Paolo Mirabueno
- School of Biotechnology, Dublin City University, Ireland.,Present address: National Institute of Agricultural Botany - East Malling Research, Kent, UK
| | - Maddy Nelson
- School of Biotechnology, Dublin City University, Ireland
| | - Shane Power
- School of Biotechnology, Dublin City University, Ireland
| | | | - Cian Smyth
- School of Biotechnology, Dublin City University, Ireland.,Present address: Dept of Biology, Maynooth University, Dublin, Ireland
| | - Zoe Vance
- School of Genetics & Microbiology, Trinity College Dublin, Ireland
| | | | - Alexander Rahm
- School of Maths, Applied Maths and Statistics, National University of Ireland Galway, Ireland.,Present address: GAATI Lab, Université de la Polynésie Française, Puna'auia, French Polynesia
| | - Tim Downing
- School of Biotechnology, Dublin City University, Ireland
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18
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Abstract
Escherichia coli is a commensal of the vertebrate gut that is increasingly involved in various intestinal and extra-intestinal infections as an opportunistic pathogen. Numerous pathotypes that represent groups of strains with specific pathogenic characteristics have been described based on heterogeneous and complex criteria. The democratization of whole-genome sequencing has led to an accumulation of genomic data that render possible a population phylogenomic approach to the emergence of virulence. Few lineages are responsible for the pathologies compared with the diversity of commensal strains. These lineages emerged multiple times during E. coli evolution, mainly by acquiring virulence genes located on mobile elements, but in a specific chromosomal phylogenetic background. This repeated emergence of stable and cosmopolitan lineages argues for an optimization of strain fitness through epistatic interactions between the virulence determinants and the remaining genome.
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19
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Kc R, Leong KWC, Harkness NM, Lachowicz J, Gautam SS, Cooley LA, McEwan B, Petrovski S, Karupiah G, O'Toole RF. Whole-genome analyses reveal gene content differences between nontypeable Haemophilus influenzae isolates from chronic obstructive pulmonary disease compared to other clinical phenotypes. Microb Genom 2020; 6. [PMID: 32706329 PMCID: PMC7641420 DOI: 10.1099/mgen.0.000405] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Nontypeable Haemophilus influenzae (NTHi) colonizes human upper respiratory airways and plays a key role in the course and pathogenesis of acute exacerbations of chronic obstructive pulmonary disease (COPD). Currently, it is not possible to distinguish COPD isolates of NTHi from other clinical isolates of NTHi using conventional genotyping methods. Here, we analysed the core and accessory genome of 568 NTHi isolates, including 40 newly sequenced isolates, to look for genetic distinctions between NTHi isolates from COPD with respect to other illnesses, including otitis media, meningitis and pneumonia. Phylogenies based on polymorphic sites in the core-genome did not show discrimination between NTHi strains collected from different clinical phenotypes. However, pan-genome-wide association studies identified 79 unique NTHi accessory genes that were significantly associated with COPD. Furthermore, many of the COPD-related NTHi genes have known or predicted roles in virulence, transmembrane transport of metal ions and nutrients, cellular respiration and maintenance of redox homeostasis. This indicates that specific genes may be required by NTHi for its survival or virulence in the COPD lung. These results advance our understanding of the pathogenesis of NTHi infection in COPD lungs.
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Affiliation(s)
- Rajendra Kc
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Tasmania, Australia
| | - Kelvin W C Leong
- Department of Pharmacy and Biomedical Sciences, School of Molecular Sciences, College of Science, Health and Engineering, La Trobe University, Victoria, Australia
| | - Nicholas M Harkness
- Department of Respiratory and Sleep Medicine, Royal Hobart Hospital, Tasmania, Australia
| | - Julia Lachowicz
- Department of Respiratory and Sleep Medicine, Royal Hobart Hospital, Tasmania, Australia
| | - Sanjay S Gautam
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Tasmania, Australia
| | - Louise A Cooley
- Department of Microbiology and Infectious Diseases, Royal Hobart Hospital, Tasmania, Australia
| | - Belinda McEwan
- Department of Microbiology and Infectious Diseases, Royal Hobart Hospital, Tasmania, Australia
| | - Steve Petrovski
- Department of Physiology, Anatomy and Microbiology, School of Life Sciences, La Trobe University, Victoria, Australia
| | - Gunasegaran Karupiah
- Tasmanian School of Medicine, College of Health and Medicine, University of Tasmania, Tasmania, Australia
| | - Ronan F O'Toole
- Department of Pharmacy and Biomedical Sciences, School of Molecular Sciences, College of Science, Health and Engineering, La Trobe University, Victoria, Australia
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20
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Touchon M, Perrin A, de Sousa JAM, Vangchhia B, Burn S, O’Brien CL, Denamur E, Gordon D, Rocha EPC. Phylogenetic background and habitat drive the genetic diversification of Escherichia coli. PLoS Genet 2020; 16:e1008866. [PMID: 32530914 PMCID: PMC7314097 DOI: 10.1371/journal.pgen.1008866] [Citation(s) in RCA: 99] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2020] [Revised: 06/24/2020] [Accepted: 05/18/2020] [Indexed: 12/15/2022] Open
Abstract
Escherichia coli is mostly a commensal of birds and mammals, including humans, where it can act as an opportunistic pathogen. It is also found in water and sediments. We investigated the phylogeny, genetic diversification, and habitat-association of 1,294 isolates representative of the phylogenetic diversity of more than 5,000 isolates from the Australian continent. Since many previous studies focused on clinical isolates, we investigated mostly other isolates originating from humans, poultry, wild animals and water. These strains represent the species genetic diversity and reveal widespread associations between phylogroups and isolation sources. The analysis of strains from the same sequence types revealed very rapid change of gene repertoires in the very early stages of divergence, driven by the acquisition of many different types of mobile genetic elements. These elements also lead to rapid variations in genome size, even if few of their genes rise to high frequency in the species. Variations in genome size are associated with phylogroup and isolation sources, but the latter determine the number of MGEs, a marker of recent transfer, suggesting that gene flow reinforces the association of certain genetic backgrounds with specific habitats. After a while, the divergence of gene repertoires becomes linear with phylogenetic distance, presumably reflecting the continuous turnover of mobile element and the occasional acquisition of adaptive genes. Surprisingly, the phylogroups with smallest genomes have the highest rates of gene repertoire diversification and fewer but more diverse mobile genetic elements. This suggests that smaller genomes are associated with higher, not lower, turnover of genetic information. Many of these genomes are from freshwater isolates and have peculiar traits, including a specific capsule, suggesting adaptation to this environment. Altogether, these data contribute to explain why epidemiological clones tend to emerge from specific phylogenetic groups in the presence of pervasive horizontal gene transfer across the species. Previous large scale studies on the evolution of E. coli focused on clinical isolates emphasizing virulence and antibiotic resistance in medically important lineages. Yet, most E. coli strains are either human commensals or not associated with humans at all. Here, we analyzed a large collection of non-clinical isolates of the species to assess the mechanisms of gene repertoire diversification in the light of isolation sources and phylogeny. We show that gene repertoires evolve so rapidly by the high turnover of mobile genetic elements that epidemiologically indistinguishable strains can be phenotypically extremely heterogeneous, illustrating the velocity of bacterial adaptation and the importance of accounting for the information on the whole genome at the epidemiological scale. Phylogeny and habitat shape the genetic diversification of E. coli to similar extents. Surprisingly, freshwater strains seem specifically adapted to this environment, breaking the paradigm that E. coli environmental isolates are systematically fecal contaminations. As a consequence, the evolution of this species is also shaped by environmental habitats, and it may diversify by acquiring genes and mobile elements from environmental bacteria (and not just from gut bacteria). This may facilitate the acquisition of virulence factors and antibiotic resistance in the strains that become pathogenic.
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Affiliation(s)
- Marie Touchon
- Microbial Evolutionary Genomics, Institut Pasteur, CNRS, UMR3525, 25-28 rue Dr Roux, Paris, 75015, France
- * E-mail:
| | - Amandine Perrin
- Microbial Evolutionary Genomics, Institut Pasteur, CNRS, UMR3525, 25-28 rue Dr Roux, Paris, 75015, France
- Sorbonne Université, Collège doctoral, F-75005 Paris, France
| | - Jorge André Moura de Sousa
- Microbial Evolutionary Genomics, Institut Pasteur, CNRS, UMR3525, 25-28 rue Dr Roux, Paris, 75015, France
| | - Belinda Vangchhia
- Ecology and Evolution, Research School of Biology, The Australian National University, Acton, ACT, Australia
- Department of Veterinary Microbiology, College of Veterinary Sciences & Animal Husbandry, Central Agricultural University, Selesih, Aizawl, Mizoram, India
| | - Samantha Burn
- Ecology and Evolution, Research School of Biology, The Australian National University, Acton, ACT, Australia
| | - Claire L. O’Brien
- School of Medicine, University of Wollongong, Northfields Ave Wollongong, Australia
| | - Erick Denamur
- Université de Paris, IAME, UMR 1137, INSERM, Paris, 75018, France
- AP-HP, Laboratoire de Génétique Moléculaire, Hôpital Bichat, 75018, Paris, France
| | - David Gordon
- Ecology and Evolution, Research School of Biology, The Australian National University, Acton, ACT, Australia
| | - Eduardo PC Rocha
- Microbial Evolutionary Genomics, Institut Pasteur, CNRS, UMR3525, 25-28 rue Dr Roux, Paris, 75015, France
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21
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Patiño-Navarrete R, Rosinski-Chupin I, Cabanel N, Gauthier L, Takissian J, Madec JY, Hamze M, Bonnin RA, Naas T, Glaser P. Stepwise evolution and convergent recombination underlie the global dissemination of carbapenemase-producing Escherichia coli. Genome Med 2020; 12:10. [PMID: 31955713 PMCID: PMC6970295 DOI: 10.1186/s13073-019-0699-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2019] [Accepted: 11/21/2019] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Carbapenem-resistant Enterobacteriaceae are considered by WHO as "critical" priority pathogens for which novel antibiotics are urgently needed. The dissemination of carbapenemase-producing Escherichia coli (CP-Ec) in the community is a major public health concern. However, the global molecular epidemiology of CP-Ec isolates remains largely unknown as well as factors contributing to the acquisition of carbapenemase genes. METHODS We first analyzed the whole-genome sequence and the evolution of the E. coli sequence type (ST) 410 and its disseminated clade expressing the carbapenemase OXA-181. We reconstructed the phylogeny of 19 E. coli ST enriched in CP-Ec and corresponding to a total of 2026 non-redundant isolates. Using the EpiCs software, we determined the significance of the association between specific mutations and the acquisition of a carbapenemase gene and the most probable order of events. The impact of the identified mutations was assessed experimentally by genetic manipulations and phenotypic testing. RESULTS In 13 of the studied STs, acquisition of carbapenemase genes occurred in multidrug-resistant lineages characterized by a combination of mutations in ftsI encoding the penicillin-binding protein 3 and in the porin genes ompC and ompF. Mutated ftsI genes and a specific ompC allele related to that from ST38 inducing reduced susceptibility to diverse β-lactams spread across the species by recombination. We showed that these mutations precede in most cases the acquisition of a carbapenemase gene. The ompC allele from ST38 might have contributed to the selection of CP-Ec disseminated lineages within this ST. On the other hand, in the pandemic ST131 lineage, CP-Ec were not associated with mutations in ompC or ftsI and show no signs of dissemination. CONCLUSIONS Lineages of CP-Ec have started to disseminate globally. However, their selection is a multistep process involving mutations, recombination, acquisition of antibiotic resistance genes, and selection by β-lactams from diverse families. This process did not yet occur in the high-risk lineage ST131.
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Affiliation(s)
- Rafael Patiño-Navarrete
- Unité EERA, Institut Pasteur, APHP, Université Paris Saclay, 28 Rue du Dr Roux, 75015, Paris, France.,UMR3525, CNRS, 28 rue du Dr Roux, 75015, Paris, France
| | - Isabelle Rosinski-Chupin
- Unité EERA, Institut Pasteur, APHP, Université Paris Saclay, 28 Rue du Dr Roux, 75015, Paris, France.,UMR3525, CNRS, 28 rue du Dr Roux, 75015, Paris, France
| | - Nicolas Cabanel
- Unité EERA, Institut Pasteur, APHP, Université Paris Saclay, 28 Rue du Dr Roux, 75015, Paris, France.,UMR3525, CNRS, 28 rue du Dr Roux, 75015, Paris, France
| | - Lauraine Gauthier
- Unité EERA, Institut Pasteur, APHP, Université Paris Saclay, 28 Rue du Dr Roux, 75015, Paris, France.,EA7361 Faculty of Medicine of University Paris-Sud, Le Kremlin-Bicêtre, France.,Department of Bacteriology-Hygiene, Bicêtre Hospital, APHP, Le Kremlin-Bicêtre, France.,Associated French National Reference Center for Antibiotic Resistance, Le Kremlin-Bicêtre, France
| | - Julie Takissian
- Unité EERA, Institut Pasteur, APHP, Université Paris Saclay, 28 Rue du Dr Roux, 75015, Paris, France.,Associated French National Reference Center for Antibiotic Resistance, Le Kremlin-Bicêtre, France
| | - Jean-Yves Madec
- Université de Lyon - Agence Nationale de Sécurité Sanitaire (ANSES), Unité Antibiorésistance et Virulence Bactériennes, Lyon, France
| | - Monzer Hamze
- Laboratoire Microbiologie Santé et Environnement (LMSE), Ecole Doctorale des Sciences et de Technologie, Faculté de Santé Publique, Université Libanaise, Tripoli, Lebanon
| | - Remy A Bonnin
- Unité EERA, Institut Pasteur, APHP, Université Paris Saclay, 28 Rue du Dr Roux, 75015, Paris, France.,Department of Bacteriology-Hygiene, Bicêtre Hospital, APHP, Le Kremlin-Bicêtre, France.,Associated French National Reference Center for Antibiotic Resistance, Le Kremlin-Bicêtre, France
| | - Thierry Naas
- Unité EERA, Institut Pasteur, APHP, Université Paris Saclay, 28 Rue du Dr Roux, 75015, Paris, France.,EA7361 Faculty of Medicine of University Paris-Sud, Le Kremlin-Bicêtre, France.,Department of Bacteriology-Hygiene, Bicêtre Hospital, APHP, Le Kremlin-Bicêtre, France.,Associated French National Reference Center for Antibiotic Resistance, Le Kremlin-Bicêtre, France
| | - Philippe Glaser
- Unité EERA, Institut Pasteur, APHP, Université Paris Saclay, 28 Rue du Dr Roux, 75015, Paris, France. .,UMR3525, CNRS, 28 rue du Dr Roux, 75015, Paris, France.
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22
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Yang C, Pei X, Wu Y, Yan L, Yan Y, Song Y, Coyle NM, Martinez-Urtaza J, Quince C, Hu Q, Jiang M, Feil E, Yang D, Song Y, Zhou D, Yang R, Falush D, Cui Y. Recent mixing of Vibrio parahaemolyticus populations. THE ISME JOURNAL 2019; 13:2578-2588. [PMID: 31235840 PMCID: PMC6775990 DOI: 10.1038/s41396-019-0461-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 06/04/2019] [Accepted: 06/07/2019] [Indexed: 02/07/2023]
Abstract
Humans have profoundly affected the ocean environment but little is known about anthropogenic effects on the distribution of microbes. Vibrio parahaemolyticus is found in warm coastal waters and causes gastroenteritis in humans and economically significant disease in shrimps. Based on data from 1103 genomes of environmental and clinical isolates, we show that V. parahaemolyticus is divided into four diverse populations, VppUS1, VppUS2, VppX and VppAsia. The first two are largely restricted to the US and Northern Europe, while the others are found worldwide, with VppAsia making up the great majority of isolates in the seas around Asia. Patterns of diversity within and between the populations are consistent with them having arisen by progressive divergence via genetic drift during geographical isolation. However, we find that there is substantial overlap in their current distribution. These observations can be reconciled without requiring genetic barriers to exchange between populations if long-range dispersal has increased dramatically in the recent past. We found that VppAsia isolates from the US have an average of 1.01% more shared ancestry with VppUS1 and VppUS2 isolates than VppAsia isolates from Asia itself. Based on time calibrated trees of divergence within epidemic lineages, we estimate that recombination affects about 0.017% of the genome per year, implying that the genetic mixture has taken place within the last few decades. These results suggest that human activity, such as shipping, aquatic products trade and increased human migration between continents, are responsible for the change of distribution pattern of this species.
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Affiliation(s)
- Chao Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China
| | - Xiaoyan Pei
- National Center for Food Safety Risk Assessment, Beijing, 100022, China
| | - Yarong Wu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China
| | - Lin Yan
- National Center for Food Safety Risk Assessment, Beijing, 100022, China
| | - Yanfeng Yan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China
| | - Yuqin Song
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China
| | | | | | | | - Qinghua Hu
- Shenzhen Centre for Disease Control and Prevention, Shenzhen, 518055, China
| | - Min Jiang
- Shenzhen Centre for Disease Control and Prevention, Shenzhen, 518055, China
| | | | - Dajin Yang
- National Center for Food Safety Risk Assessment, Beijing, 100022, China
| | - Yajun Song
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China
| | - Dongsheng Zhou
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China
| | - Ruifu Yang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China.
| | | | - Yujun Cui
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, 100071, China.
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23
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Rates of Molecular Evolution in a Marine Synechococcus Phage Lineage. Viruses 2019; 11:v11080720. [PMID: 31390807 PMCID: PMC6722890 DOI: 10.3390/v11080720] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 07/27/2019] [Accepted: 07/31/2019] [Indexed: 12/30/2022] Open
Abstract
Cyanophages are characterized by vast genomic diversity and the formation of stable ecotypes over time. The evolution of phage diversity includes vertical processes, such as mutation, and horizontal processes, such as recombination and gene transfer. Here, we study the contribution of vertical and horizontal processes to short-term evolution of marine cyanophages. Analyzing time series data of Synechococcus-infecting Myoviridae ecotypes spanning up to 17 years, we found a high contribution of recombination relative to mutation (r/m) in all ecotypes. Additionally, we found a molecular clock of substitution and recombination in one ecotype, RIM8. The estimated RIM8 evolutionary rates are 2.2 genome-wide substitutions per year (1.275 × 10−5 substitutions/site/year) and 29 genome-wide nucleotide alterations due to recombination per year. We found 26 variable protein families, of which only two families have a predicted functional annotation, suggesting that they are auxiliary metabolic genes with bacterial homologs. A comparison of our rate estimates to other phage evolutionary rate estimates in the literature reveals a negative correlation of phage substitution rates with their genome size. A comparison to evolutionary rates in bacterial organisms further shows that phages have high rates of mutation and recombination compared to their bacterial hosts. We conclude that the increased recombination rate in phages likely contributes to their vast genomic diversity.
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24
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Tchesnokova V, Radey M, Chattopadhyay S, Larson L, Weaver JL, Kisiela D, Sokurenko EV. Pandemic fluoroquinolone resistant Escherichia coli clone ST1193 emerged via simultaneous homologous recombinations in 11 gene loci. Proc Natl Acad Sci U S A 2019; 116:14740-14748. [PMID: 31262826 PMCID: PMC6642405 DOI: 10.1073/pnas.1903002116] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Global growth in antibiotic resistance is a major social problem. A high level of resistance to fluoroquinolones requires the concurrent presence of at least 3 mutations in the target proteins-2 in DNA gyrase (GyrA) and 1 in topoisomerase IV (ParC), which occur in a stepwise manner. In the Escherichia coli chromosome, the gyrA and parC loci are positioned about 1 Mb away from each other. Here we show that the 3 fluoroquinolone resistance mutations are tightly associated genetically in naturally occurring strains. In the latest pandemic uropathogenic and multidrug-resistant E. coli clonal group ST1193, the mutant variants of gyrA and parC were acquired not by a typical gradual, stepwise evolution but all at once. This happened as part of 11 simultaneous homologous recombination events involving 2 phylogenetically distant strains of E. coli, from an uropathogenic clonal complex ST14 and fluoroquinolone-resistant ST10. The gene exchanges swapped regions between 0.5 and 139 Kb in length (183 Kb total) spread along 976 Kb of chromosomal DNA around and between gyrA and parC loci. As a result, all 3 fluoroquinolone resistance mutations in GyrA and ParC have simultaneously appeared in ST1193. Based on molecular clock estimates, this potentially happened as recently as <12 y ago. Thus, naturally occurring homologous recombination events between 2 strains can involve numerous chromosomal gene locations simultaneously, resulting in the transfer of distant but tightly associated genetic mutations and emergence of a both highly pathogenic and antibiotic-resistant strain with a rapid global spread capability.
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Affiliation(s)
| | - Matthew Radey
- Department of Microbiology, University of Washington, Seattle, WA 98105
| | - Sujay Chattopadhyay
- Institute of Advanced Studies and Research, JIS University, Kolkata 700091, India
| | - Lydia Larson
- Department of Microbiology, University of Washington, Seattle, WA 98105
| | - Jamie Lee Weaver
- Department of Microbiology, University of Washington, Seattle, WA 98105
| | - Dagmara Kisiela
- Department of Microbiology, University of Washington, Seattle, WA 98105
| | - Evgeni V Sokurenko
- Department of Microbiology, University of Washington, Seattle, WA 98105;
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25
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Nanayakkara BS, O'Brien CL, Gordon DM. Diversity and distribution of Klebsiella capsules in Escherichia coli. ENVIRONMENTAL MICROBIOLOGY REPORTS 2019; 11:107-117. [PMID: 30411512 DOI: 10.1111/1758-2229.12710] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 10/31/2018] [Accepted: 11/03/2018] [Indexed: 06/08/2023]
Abstract
E. coli strains responsible for elevated counts (blooms) in freshwater reservoirs in Australia carry a capsule originating from Klebsiella. The occurrence of Klebsiella capsules in E. coli was about 7% overall and 23 different capsule types were detected. Capsules were observed in strains from phylogroups A, B1 and C, but were absent from phylogroup B2, D, E and F strains. In general, few A, B1 or C lineages were capsule-positive, but when a lineage was encapsulated multiple different capsule types were present. All Klebsiella capsule-positive strains were of serogroups O8, O9 and O89. Regardless of the phylogroup, O9 strains were more likely to be capsule-positive than O8 strains. Given the sequence similarity, it appears that both the capsule region and the O-antigen gene region are transferred to E. coli from Klebsiella as a single block via horizontal gene transfer events. Pan genome analysis indicated that there were only modest differences between encapsulated and non-encapsulated strains belonging to phylogroup A. The possession of a Klebsiella capsule, but not the type of capsule, is likely a key determinant of the bloom status of a strain.
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Affiliation(s)
- Buddhie S Nanayakkara
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
- Department of Botany, Faculty of Science, University of Peradeniya, Peradeniya, 20400, Sri Lanka
| | - Claire L O'Brien
- Medical School, The Australian National University, Canberra, ACT 2601, Australia
- Gastroenterology and Hepatology Unit, Canberra Hospital, Canberra, ACT, Australia
| | - David M Gordon
- Division of Ecology and Evolution, Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
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26
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Park CJ, Andam CP. Within-Species Genomic Variation and Variable Patterns of Recombination in the Tetracycline Producer Streptomyces rimosus. Front Microbiol 2019; 10:552. [PMID: 30949149 PMCID: PMC6437091 DOI: 10.3389/fmicb.2019.00552] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 03/04/2019] [Indexed: 01/09/2023] Open
Abstract
Streptomyces rimosus is best known as the primary source of the tetracycline class of antibiotics, most notably oxytetracycline, which have been widely used against many gram-positive and gram-negative pathogens and protozoan parasites. However, despite the medical and agricultural importance of S. rimosus, little is known of its evolutionary history and genome dynamics. In this study, we aim to elucidate the pan-genome characteristics and phylogenetic relationships of 32 S. rimosus genomes. The S. rimosus pan-genome contains more than 22,000 orthologous gene clusters, and approximately 8.8% of these genes constitutes the core genome. A large part of the accessory genome is composed of 9,646 strain-specific genes. S. rimosus exhibits an open pan-genome (decay parameter α = 0.83) and high gene diversity between strains (genomic fluidity φ = 0.12). We also observed strain-level variation in the distribution and abundance of biosynthetic gene clusters (BGCs) and that each individual S. rimosus genome has a unique repertoire of BGCs. Lastly, we observed variation in recombination, with some strains donating or receiving DNA more often than others, strains that tend to frequently recombine with specific partners, genes that often experience recombination more than others, and variable sizes of recombined DNA sequences. We conclude that the high levels of inter-strain genomic variation in S. rimosus is partly explained by differences in recombination among strains. These results have important implications on current efforts for natural drug discovery, the ecological role of strain-level variation in microbial populations, and addressing the fundamental question of why microbes have pan-genomes.
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Affiliation(s)
- Cooper J Park
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, United States
| | - Cheryl P Andam
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, Durham, NH, United States
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27
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Garud NR, Good BH, Hallatschek O, Pollard KS. Evolutionary dynamics of bacteria in the gut microbiome within and across hosts. PLoS Biol 2019; 17:e3000102. [PMID: 30673701 PMCID: PMC6361464 DOI: 10.1371/journal.pbio.3000102] [Citation(s) in RCA: 186] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2018] [Revised: 02/04/2019] [Accepted: 12/19/2018] [Indexed: 12/16/2022] Open
Abstract
Gut microbiota are shaped by a combination of ecological and evolutionary forces. While the ecological dynamics have been extensively studied, much less is known about how species of gut bacteria evolve over time. Here, we introduce a model-based framework for quantifying evolutionary dynamics within and across hosts using a panel of metagenomic samples. We use this approach to study evolution in approximately 40 prevalent species in the human gut. Although the patterns of between-host diversity are consistent with quasi-sexual evolution and purifying selection on long timescales, we identify new genealogical signatures that challenge standard population genetic models of these processes. Within hosts, we find that genetic differences that accumulate over 6-month timescales are only rarely attributable to replacement by distantly related strains. Instead, the resident strains more commonly acquire a smaller number of putative evolutionary changes, in which nucleotide variants or gene gains or losses rapidly sweep to high frequency. By comparing these mutations with the typical between-host differences, we find evidence that some sweeps may be seeded by recombination, in addition to new mutations. However, comparisons of adult twins suggest that replacement eventually overwhelms evolution over multi-decade timescales, hinting at fundamental limits to the extent of local adaptation. Together, our results suggest that gut bacteria can evolve on human-relevant timescales, and they highlight the connections between these short-term evolutionary dynamics and longer-term evolution across hosts.
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Affiliation(s)
- Nandita R. Garud
- Gladstone Institutes, San Francisco, California, United States of America
| | - Benjamin H. Good
- Department of Physics, University of California, Berkeley, Berkeley, California, United States of America
- Department of Bioengineering, University of California, Berkeley, Berkeley, California, United States of America
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, Santa Barbara, California, United States of America
| | - Oskar Hallatschek
- Department of Physics, University of California, Berkeley, Berkeley, California, United States of America
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, Santa Barbara, California, United States of America
- Department of Integrative Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - Katherine S. Pollard
- Gladstone Institutes, San Francisco, California, United States of America
- Department of Epidemiology and Biostatistics, Institute for Human Genetics, Quantitative Biology Institute, and Institute for Computational Health Sciences, University of California, San Francisco, San Francisco, California, United States of America
- Chan-Zuckerberg Biohub, San Francisco, California, United States of America
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28
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Pattabiraman V, Katz LS, Chen JC, McCullough AE, Trees E. Genome wide characterization of enterotoxigenic Escherichia coli serogroup O6 isolates from multiple outbreaks and sporadic infections from 1975-2016. PLoS One 2018; 13:e0208735. [PMID: 30596673 PMCID: PMC6312315 DOI: 10.1371/journal.pone.0208735] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 11/22/2018] [Indexed: 02/07/2023] Open
Abstract
Enterotoxigenic Escherichia coli (ETEC) are an important cause of diarrhea globally, particularly among children under the age of five in developing countries. ETEC O6 is the most common ETEC serogroup, yet the genome wide population structure of isolates of this serogroup is yet to be determined. In this study, we have characterized 40 ETEC O6 isolates collected between 1975–2016 by whole genome sequencing (WGS) and by phenotypic antimicrobial susceptibility testing. To determine the relatedness of isolates, we evaluated two methods—whole genome high-quality single nucleotide polymorphism (whole genome-hqSNP) and core genome SNP analyses using Lyve-SET and Parsnp respectively. All isolates were tested for antimicrobial susceptibility using a panel of 14 antibiotics. ResFinder 2.1 and a custom quinolone resistance determinants workflow were used for resistance determinant detection. VirulenceFinder 1.5 was used for prediction of the virulence genes. Thirty-seven isolates clustered into three major clades (I, II, III) by whole genome-hqSNP and core genome SNP analyses, while three isolates included in the whole genome-hqSNP analysis only did not cluster with clades I-III by both analyses and formed a distantly related outgroup, designated clade IV. Median number of pairwise whole genome-hqSNPs in clonal ETEC O6 outbreaks ranged from 0 to 5. Of the 40 isolates tested for antimicrobial susceptibility, 18 isolates were pansusceptible. Twenty-two isolates were resistant to at least one antibiotic, nine of which were multidrug resistant. Phenotypic antimicrobial resistance (AR) correlated with AR determinants in 22 isolates. Thirty-two isolates harbored both enterotoxin virulence genes while the remaining 8 isolates had only one of the two virulence genes. In summary, whole genome-hqSNP and core genome SNP analyses from this study revealed similar evolutionary relationships and an overall diversity of ETEC O6 isolates independent of time of isolation. Less than 5 pairwise hqSNPs between ETEC O6 isolates is circumstantially indicative of an outbreak cluster. Findings from this study will be a basis for quicker outbreak detection and control by efficient subtyping by WGS.
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Affiliation(s)
- Vaishnavi Pattabiraman
- Centers for Disease Control and Prevention, Atlanta, GA, United States of America
- * E-mail:
| | - Lee S. Katz
- Centers for Disease Control and Prevention, Atlanta, GA, United States of America
- Center for Food Safety, College of Agricultural and Environmental Sciences, University of Georgia, Griffin, GA, United States of America
| | - Jessica C. Chen
- Centers for Disease Control and Prevention, Atlanta, GA, United States of America
| | | | - Eija Trees
- Centers for Disease Control and Prevention, Atlanta, GA, United States of America
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29
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Beghain J, Bridier-Nahmias A, Le Nagard H, Denamur E, Clermont O. ClermonTyping: an easy-to-use and accurate in silico method for Escherichia genus strain phylotyping. Microb Genom 2018. [PMID: 29916797 DOI: 10.1099/mgen.1090.000192] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/17/2023] Open
Abstract
The genus Escherichia is composed of Escherichia albertii, E. fergusonii, five cryptic Escherichia clades and E. coli sensu stricto. Furthermore, the E. coli species can be divided into seven main phylogroups termed A, B1, B2, C, D, E and F. As specific lifestyles and/or hosts can be attributed to these species/phylogroups, their identification is meaningful for epidemiological studies. Classical phenotypic tests fail to identify non-sensu stricto E. coli as well as phylogroups. Clermont and colleagues have developed PCR assays that allow the identification of most of these species/phylogroups, the triplex/quadruplex PCR for E. coli phylogroup determination being the most popular. With the growing availability of whole genome sequences, we have developed the ClermonTyping method and its associated web-interface, the ClermonTyper, that allows a given strain sequence to be assigned to E. albertii, E. fergusonii, Escherichia clades I-V, E. coli sensu stricto as well as to the seven main E. coli phylogroups. The ClermonTyping is based on the concept of in vitro PCR assays and maintains the principles of ease of use and speed that prevailed during the development of the in vitro assays. This in silico approach shows 99.4 % concordance with the in vitro PCR assays and 98.8 % with the Mash genome-clustering tool. The very few discrepancies result from various errors occurring mainly from horizontal gene transfers or SNPs in the primers. We propose the ClermonTyper as a freely available resource to the scientific community at: http://clermontyping.iame-research.center/.
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Affiliation(s)
- Johann Beghain
- 1IAME, UMR 1137, INSERM, Université Paris Diderot, Sorbonne Paris Cité, F-75018 Paris, France
| | - Antoine Bridier-Nahmias
- 1IAME, UMR 1137, INSERM, Université Paris Diderot, Sorbonne Paris Cité, F-75018 Paris, France
| | - Hervé Le Nagard
- 1IAME, UMR 1137, INSERM, Université Paris Diderot, Sorbonne Paris Cité, F-75018 Paris, France
| | - Erick Denamur
- 1IAME, UMR 1137, INSERM, Université Paris Diderot, Sorbonne Paris Cité, F-75018 Paris, France
- 2Assistance Publique-Hôpitaux de Paris, Hôpital Bichat, Laboratoire de Génétique Moléculaire, F-75018 Paris, France
| | - Olivier Clermont
- 1IAME, UMR 1137, INSERM, Université Paris Diderot, Sorbonne Paris Cité, F-75018 Paris, France
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30
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Kiel M, Sagory-Zalkind P, Miganeh C, Stork C, Leimbach A, Sekse C, Mellmann A, Rechenmann F, Dobrindt U. Identification of Novel Biomarkers for Priority Serotypes of Shiga Toxin-Producing Escherichia coli and the Development of Multiplex PCR for Their Detection. Front Microbiol 2018; 9:1321. [PMID: 29997582 PMCID: PMC6028524 DOI: 10.3389/fmicb.2018.01321] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 05/30/2018] [Indexed: 12/22/2022] Open
Abstract
It would be desirable to have an unambiguous scheme for the typing of Shiga toxin-producing Escherichia coli (STEC) isolates to subpopulations. Such a scheme should take the high genomic plasticity of E. coli into account and utilize the stratification of STEC into subgroups, based on serotype or phylogeny. Therefore, our goal was to identify specific marker combinations for improved classification of STEC subtypes. We developed and evaluated two bioinformatic pipelines for genomic marker identification from larger sets of bacterial genome sequences. Pipeline A performed all-against-all BLASTp analyses of gene products predicted in STEC genome test sets against a set of control genomes. Pipeline B identified STEC marker genes by comparing the STEC core proteome and the "pan proteome" of a non-STEC control group. Both pipelines defined an overlapping, but not identical set of discriminative markers for different STEC subgroups. Differential marker prediction resulted from differences in genome assembly, ORF finding and inclusion cut-offs in both workflows. Based on the output of the pipelines, we defined new specific markers for STEC serogroups and phylogenetic groups frequently associated with outbreaks and cases of foodborne illnesses. These included STEC serogroups O157, O26, O45, O103, O111, O121, and O145, Shiga toxin-positive enteroaggregative E. coli O104:H4, and HUS-associated sequence type (ST)306. We evaluated these STEC marker genes for their presence in whole genome sequence data sets. Based on the identified discriminative markers, we developed a multiplex PCR (mPCR) approach for detection and typing of the targeted STEC. The specificity of the mPCR primer pairs was verified using well-defined clinical STEC isolates as well as isolates from the ECOR, DEC, and HUSEC collections. The application of the STEC mPCR for food analysis was tested with inoculated milk. In summary, we evaluated two different strategies to screen large genome sequence data sets for discriminative markers and implemented novel marker genes found in this genome-wide approach into a DNA-based typing tool for STEC that can be used for the characterization of STEC from clinical and food samples.
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Affiliation(s)
- Matthias Kiel
- Institute of Hygiene, University of Münster, Münster, Germany
| | | | - Céline Miganeh
- Genostar Bioinformatics, Montbonnot-Saint-Martin, France
| | - Christoph Stork
- Institute of Hygiene, University of Münster, Münster, Germany
| | | | | | | | | | - Ulrich Dobrindt
- Institute of Hygiene, University of Münster, Münster, Germany
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31
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Beghain J, Bridier-Nahmias A, Le Nagard H, Denamur E, Clermont O. ClermonTyping: an easy-to-use and accurate in silico method for Escherichia genus strain phylotyping. Microb Genom 2018; 4. [PMID: 29916797 PMCID: PMC6113867 DOI: 10.1099/mgen.0.000192] [Citation(s) in RCA: 240] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The genus Escherichia is composed of Escherichia albertii, E. fergusonii, five cryptic Escherichia clades and E. coli sensu stricto. Furthermore, the E. coli species can be divided into seven main phylogroups termed A, B1, B2, C, D, E and F. As specific lifestyles and/or hosts can be attributed to these species/phylogroups, their identification is meaningful for epidemiological studies. Classical phenotypic tests fail to identify non-sensu stricto E. coli as well as phylogroups. Clermont and colleagues have developed PCR assays that allow the identification of most of these species/phylogroups, the triplex/quadruplex PCR for E. coli phylogroup determination being the most popular. With the growing availability of whole genome sequences, we have developed the ClermonTyping method and its associated web-interface, the ClermonTyper, that allows a given strain sequence to be assigned to E. albertii, E. fergusonii, Escherichia clades I-V, E. coli sensu stricto as well as to the seven main E. coli phylogroups. The ClermonTyping is based on the concept of in vitro PCR assays and maintains the principles of ease of use and speed that prevailed during the development of the in vitro assays. This in silico approach shows 99.4 % concordance with the in vitro PCR assays and 98.8 % with the Mash genome-clustering tool. The very few discrepancies result from various errors occurring mainly from horizontal gene transfers or SNPs in the primers. We propose the ClermonTyper as a freely available resource to the scientific community at: http://clermontyping.iame-research.center/.
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Affiliation(s)
- Johann Beghain
- IAME, UMR 1137, INSERM, Université Paris Diderot, Sorbonne Paris Cité, F-75018 Paris, France
| | - Antoine Bridier-Nahmias
- IAME, UMR 1137, INSERM, Université Paris Diderot, Sorbonne Paris Cité, F-75018 Paris, France
| | - Hervé Le Nagard
- IAME, UMR 1137, INSERM, Université Paris Diderot, Sorbonne Paris Cité, F-75018 Paris, France
| | - Erick Denamur
- IAME, UMR 1137, INSERM, Université Paris Diderot, Sorbonne Paris Cité, F-75018 Paris, France
- Assistance Publique-Hôpitaux de Paris, Hôpital Bichat, Laboratoire de Génétique Moléculaire, F-75018 Paris, France
| | - Olivier Clermont
- IAME, UMR 1137, INSERM, Université Paris Diderot, Sorbonne Paris Cité, F-75018 Paris, France
- *Correspondence: Olivier Clermont,
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32
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Rocha EPC. Neutral Theory, Microbial Practice: Challenges in Bacterial Population Genetics. Mol Biol Evol 2018; 35:1338-1347. [DOI: 10.1093/molbev/msy078] [Citation(s) in RCA: 51] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Affiliation(s)
- Eduardo P C Rocha
- Microbial Evolutionary Genomics, Institut Pasteur, Paris, France
- CNRS, UMR3525, Paris, France
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Chu HY, Sprouffske K, Wagner A. Assessing the benefits of horizontal gene transfer by laboratory evolution and genome sequencing. BMC Evol Biol 2018; 18:54. [PMID: 29673327 PMCID: PMC5909237 DOI: 10.1186/s12862-018-1164-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 03/22/2018] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND Recombination is widespread across the tree of life, because it helps purge deleterious mutations and creates novel adaptive traits. In prokaryotes, it often takes the form of horizontal gene transfer from a donor to a recipient bacterium. While such transfer is widespread in natural communities, its immediate fitness benefits are usually unknown. We asked whether any such benefits depend on the environment, and on the identity of donor and recipient strains. To this end, we adapted Escherichia coli to two novel carbon sources over several hundred generations of laboratory evolution, exposing evolving populations to various DNA donors. RESULTS At the end of these experiments, we measured fitness and sequenced the genomes of 65 clones from 34 replicate populations to study the genetic changes associated with adaptive evolution. Furthermore, we identified candidate de novo beneficial mutations. During adaptive evolution on the first carbon source, 4-Hydroxyphenylacetic acid (HPA), recombining populations adapted better, which was likely mediated by acquiring the hpa operon from the donor. In contrast, recombining populations did not adapt better to the second carbon source, butyric acid, even though they suffered fewer extinctions than non-recombining populations. The amount of DNA transferred, but not its benefit, strongly depended on the donor-recipient strain combination. CONCLUSIONS To our knowledge, our study is the first to investigate the genomic consequences of prokaryotic recombination and horizontal gene transfer during laboratory evolution. It shows that the benefits of recombination strongly depend on the environment and the foreign DNA donor.
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Affiliation(s)
- Hoi Yee Chu
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - Kathleen Sprouffske
- The Swiss Institute of Bioinformatics, Quartier Sorge – Batiment Genopode, 1015 Lausanne, Switzerland
| | - Andreas Wagner
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
- The Swiss Institute of Bioinformatics, Quartier Sorge – Batiment Genopode, 1015 Lausanne, Switzerland
- Santa Fe Institute, Santa Fe, New Mexico USA
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Duchaud E, Rochat T, Habib C, Barbier P, Loux V, Guérin C, Dalsgaard I, Madsen L, Nilsen H, Sundell K, Wiklund T, Strepparava N, Wahli T, Caburlotto G, Manfrin A, Wiens GD, Fujiwara-Nagata E, Avendaño-Herrera R, Bernardet JF, Nicolas P. Genomic Diversity and Evolution of the Fish Pathogen Flavobacterium psychrophilum. Front Microbiol 2018; 9:138. [PMID: 29467746 PMCID: PMC5808330 DOI: 10.3389/fmicb.2018.00138] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Accepted: 01/22/2018] [Indexed: 12/04/2022] Open
Abstract
Flavobacterium psychrophilum, the etiological agent of rainbow trout fry syndrome and bacterial cold-water disease in salmonid fish, is currently one of the main bacterial pathogens hampering the productivity of salmonid farming worldwide. In this study, the genomic diversity of the F. psychrophilum species is analyzed using a set of 41 genomes, including 30 newly sequenced isolates. These were selected on the basis of available MLST data with the two-fold objective of maximizing the coverage of the species diversity and of allowing a focus on the main clonal complex (CC-ST10) infecting farmed rainbow trout (Oncorhynchus mykiss) worldwide. The results reveal a bacterial species harboring a limited genomic diversity both in terms of nucleotide diversity, with ~0.3% nucleotide divergence inside CDSs in pairwise genome comparisons, and in terms of gene repertoire, with the core genome accounting for ~80% of the genes in each genome. The pan-genome seems nevertheless “open” according to the scaling exponent of a power-law fitted on the rate of new gene discovery when genomes are added one-by-one. Recombination is a key component of the evolutionary process of the species as seen in the high level of apparent homoplasy in the core genome. Using a Hidden Markov Model to delineate recombination tracts in pairs of closely related genomes, the average recombination tract length was estimated to ~4.0 Kbp and the typical ratio of the contributions of recombination and mutations to nucleotide-level differentiation (r/m) was estimated to ~13. Within CC-ST10, evolutionary distances computed on non-recombined regions and comparisons between 22 isolates sampled up to 27 years apart suggest a most recent common ancestor in the second half of the nineteenth century in North America with subsequent diversification and transmission of this clonal complex coinciding with the worldwide expansion of rainbow trout farming. With the goal to promote the development of tools for the genetic manipulation of F. psychrophilum, a particular attention was also paid to plasmids. Their extraction and sequencing to completion revealed plasmid diversity that remained hidden to classical plasmid profiling due to size similarities.
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Affiliation(s)
- Eric Duchaud
- Unité de Virologie et Immunologie Moléculaires (VIM), Institut National de la Recherche Agronomique, Université Paris-Saclay, Jouy-en-Josas, France
| | - Tatiana Rochat
- Unité de Virologie et Immunologie Moléculaires (VIM), Institut National de la Recherche Agronomique, Université Paris-Saclay, Jouy-en-Josas, France
| | - Christophe Habib
- Unité de Virologie et Immunologie Moléculaires (VIM), Institut National de la Recherche Agronomique, Université Paris-Saclay, Jouy-en-Josas, France.,Unité Mathématiques et Informatique Appliquées du Génome à l'Environnement (MaIAGE), Institut National de la Recherche Agronomique, Université Paris-Saclay, Jouy-en-Josas, France
| | - Paul Barbier
- Unité de Virologie et Immunologie Moléculaires (VIM), Institut National de la Recherche Agronomique, Université Paris-Saclay, Jouy-en-Josas, France
| | - Valentin Loux
- Unité Mathématiques et Informatique Appliquées du Génome à l'Environnement (MaIAGE), Institut National de la Recherche Agronomique, Université Paris-Saclay, Jouy-en-Josas, France
| | - Cyprien Guérin
- Unité Mathématiques et Informatique Appliquées du Génome à l'Environnement (MaIAGE), Institut National de la Recherche Agronomique, Université Paris-Saclay, Jouy-en-Josas, France
| | - Inger Dalsgaard
- Section for Bacteriology and Pathology, National Veterinary Institute, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Lone Madsen
- Section for Bacteriology and Pathology, National Veterinary Institute, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Hanne Nilsen
- Department of Aquatic Animal health, Norwegian Veterinary Institute, Bergen, Norway
| | - Krister Sundell
- Laboratory of Aquatic Pathobiology, Environmental and Marine Biology, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Tom Wiklund
- Laboratory of Aquatic Pathobiology, Environmental and Marine Biology, Faculty of Science and Engineering, Åbo Akademi University, Turku, Finland
| | - Nicole Strepparava
- Laboratory of Applied Microbiology, Department for Environment Constructions and Design, University of Applied Sciences and Arts of Southern Switzerland (SUPSI), Bellinzona, Switzerland
| | - Thomas Wahli
- Centre for Fish and Wildlife Health (FIWI), University of Bern, Bern, Switzerland
| | - Greta Caburlotto
- Department of Fish Pathology, Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, Italy
| | - Amedeo Manfrin
- Department of Fish Pathology, Istituto Zooprofilattico Sperimentale delle Venezie, Legnaro, Italy
| | - Gregory D Wiens
- National Center for Cool and Cold Water Aquaculture, Agricultural Research Service, United States Department of Agriculture, Kearneysville, WV, United States
| | | | - Ruben Avendaño-Herrera
- Departamento Facultad de Ciencias Biológicas, Universidad Andres Bello, Universidad Andres BelloViña del Mar, Interdisciplinary Center for Aquaculture Research, Concepción, Chile
| | - Jean-François Bernardet
- Unité de Virologie et Immunologie Moléculaires (VIM), Institut National de la Recherche Agronomique, Université Paris-Saclay, Jouy-en-Josas, France
| | - Pierre Nicolas
- Unité Mathématiques et Informatique Appliquées du Génome à l'Environnement (MaIAGE), Institut National de la Recherche Agronomique, Université Paris-Saclay, Jouy-en-Josas, France
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Basra P, Alsaadi A, Bernal-Astrain G, O’Sullivan ML, Hazlett B, Clarke LM, Schoenrock A, Pitre S, Wong A. Fitness Tradeoffs of Antibiotic Resistance in Extraintestinal Pathogenic Escherichia coli. Genome Biol Evol 2018; 10:667-679. [PMID: 29432584 PMCID: PMC5817949 DOI: 10.1093/gbe/evy030] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/06/2018] [Indexed: 12/21/2022] Open
Abstract
Evolutionary trade-offs occur when selection on one trait has detrimental effects on other traits. In pathogenic microbes, it has been hypothesized that antibiotic resistance trades off with fitness in the absence of antibiotic. Although studies of single resistance mutations support this hypothesis, it is unclear whether trade-offs are maintained over time, due to compensatory evolution and broader effects of genetic background. Here, we leverage natural variation in 39 extraintestinal clinical isolates of Escherichia coli to assess trade-offs between growth rates and resistance to fluoroquinolone and cephalosporin antibiotics. Whole-genome sequencing identifies a broad range of clinically relevant resistance determinants in these strains. We find evidence for a negative correlation between growth rate and antibiotic resistance, consistent with a persistent trade-off between resistance and growth. However, this relationship is sometimes weak and depends on the environment in which growth rates are measured. Using in vitro selection experiments, we find that compensatory evolution in one environment does not guarantee compensation in other environments. Thus, even in the face of compensatory evolution and other genetic background effects, resistance may be broadly costly, supporting the use of drug restriction protocols to limit the spread of resistance. Furthermore, our study demonstrates the power of using natural variation to study evolutionary trade-offs in microbes.
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Affiliation(s)
- Prabh Basra
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Ahlam Alsaadi
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | | | | | - Bryn Hazlett
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | | | - Andrew Schoenrock
- School of Computer Science, Carleton University, Ottawa, Ontario, Canada
- Research Computing Services, Carleton University, Ottawa, Ontario, Canada
| | - Sylvain Pitre
- Research Computing Services, Carleton University, Ottawa, Ontario, Canada
| | - Alex Wong
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
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36
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Kim BJ, Kim BR, Kook YH, Kim BJ. Role of the DNA Mismatch Repair Gene MutS4 in Driving the Evolution of Mycobacterium yongonense Type I via Homologous Recombination. Front Microbiol 2017; 8:2578. [PMID: 29326683 PMCID: PMC5742357 DOI: 10.3389/fmicb.2017.02578] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 12/11/2017] [Indexed: 11/13/2022] Open
Abstract
We recently showed that Mycobacterium yongonense could be divided into two genotypes: Type I, in which the rpoB gene has been transferred from Mycobacterium parascrofulaceum, and Type II, in which the rpoB gene has not been transferred. Comparative genome analysis of three M. yongonense Type I, two M. yongonense Type II and M. parascrofulaceum type strains were performed in this study to gain insight into gene transfer from M. parascrofulaceum into M. yongonense Type I strains. We found two genome regions transferred from M. parascrofulaceum: one contained 3 consecutive genes, including the rpoBC operon, and the other contained 57 consecutive genes that had been transferred into M. yongonense Type I genomes via homologous recombination. Further comparison between the M. yongonense Type I and II genomes revealed that Type I, but not Type II has a distinct DNA mismatch repair gene (MutS4 subfamily) that was possibly transferred via non-homologous recombination from other actinomycetes. We hypothesized that it could facilitate homologous recombination from the M. parascrofulaceum to the M. yongonense Type I genomes. We therefore generated recombinant Mycobacterium smegmatis containing a MutS4 operon of M. yongonense. We found that the M. tuberculosis rpoB fragment with a rifampin resistance-conferring mutation was more frequently inserted into recombinant M. smegmatis than the wild type, suggesting that MutS4 is a driving force in the gene transfer from M. parascrofulaceum to M. yongonense Type I strains via homologous recombination. In conclusion, our data indicated that MutS4 in M. yongonense Type I genomes may drive gene transfer from M. parascrofulaceum via homologous recombination, resulting in division of M. yongonense into two genotypes, Type I and II.
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Affiliation(s)
- Byoung-Jun Kim
- Department of Microbiology and Immunology, Biomedical Sciences, Liver Research Institute and Cancer Research Institute, College of Medicine, Seoul National University, Seoul, South Korea
| | - Bo-Ram Kim
- Department of Microbiology and Immunology, Biomedical Sciences, Liver Research Institute and Cancer Research Institute, College of Medicine, Seoul National University, Seoul, South Korea
| | - Yoon-Hoh Kook
- Department of Microbiology and Immunology, Biomedical Sciences, Liver Research Institute and Cancer Research Institute, College of Medicine, Seoul National University, Seoul, South Korea
| | - Bum-Joon Kim
- Department of Microbiology and Immunology, Biomedical Sciences, Liver Research Institute and Cancer Research Institute, College of Medicine, Seoul National University, Seoul, South Korea
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Hoetzinger M, Hahn MW. Genomic divergence and cohesion in a species of pelagic freshwater bacteria. BMC Genomics 2017; 18:794. [PMID: 29037158 PMCID: PMC5644125 DOI: 10.1186/s12864-017-4199-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 10/08/2017] [Indexed: 11/15/2022] Open
Abstract
Background In many prokaryotic genera a clustered phylogeny is observed, akin to the occurrence of species in sexually reproducing organisms. For some taxa, homologous recombination has been invoked as the underlying mechanism providing genomic cohesion among conspecific individuals. Whether this mechanism is applicable to prokaryotes in freshwaters with low habitat connectivity – i.e. elevated geographic barriers to gene flow – is unclear. To investigate further we studied genomic trends within the globally abundant PnecC cluster (genus Polynucleobacter, Betaproteobacteria) and analyzed homologous recombination within the affiliated species P. asymbioticus. Results Comparisons among 20 PnecC genomes revealed a clearly discontinuous distribution of nucleotide sequence similarities. Among the nine conspecific individuals (P. asymbioticus) all average nucleotide identity (ANI) values were greater than 97%, whereas all other comparisons exhibited ANI values lower than 85%. The reconstruction of recombination and mutation events for the P. asymbioticus core genomes yielded an r/m ratio of 7.4, which is clearly above estimated thresholds for recombination to act as a cohesive force. Hotspots of recombination were found to be located in the flanking regions of genomic islands. Even between geographically separated habitats a high flux of recombination was evident. While a biogeographic population structure was suggested from MLST data targeting rather conserved loci, such a structure was barely visible when whole genome data was considered. However, both MLST and whole genome data showed evidence of differentiation between two lineages of P. asymbioticus. The ratios of non-synonymous to synonymous substitution rates as well as growth rates in transplantation experiments suggested that this divergence was not selectively neutral. Conclusions The high extent of homologous recombination among P. asymbioticus bacteria can act as a cohesive force that effectively counteracts genetic divergence. At least on a regional scale, homologous recombination can act across geographically separated ecosystems and therefore plays an important role in the evolution and consistency of bacterial freshwater species. A species model akin to the biological species concept may be applicable for P. asymbioticus. Nonetheless, two genetically distinct lineages have emerged and further research may clarify if their divergence has been initiated by reinforced geographical barriers or has been evolving in sympatry. Electronic supplementary material The online version of this article (10.1186/s12864-017-4199-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Matthias Hoetzinger
- Research Institute for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310, Mondsee, Austria.
| | - Martin W Hahn
- Research Institute for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310, Mondsee, Austria
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38
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Recombination-Driven Genome Evolution and Stability of Bacterial Species. Genetics 2017; 207:281-295. [PMID: 28751420 DOI: 10.1534/genetics.117.300061] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 07/18/2017] [Indexed: 01/21/2023] Open
Abstract
While bacteria divide clonally, horizontal gene transfer followed by homologous recombination is now recognized as an important contributor to their evolution. However, the details of how the competition between clonality and recombination shapes genome diversity remains poorly understood. Using a computational model, we find two principal regimes in bacterial evolution and identify two composite parameters that dictate the evolutionary fate of bacterial species. In the divergent regime, characterized by either a low recombination frequency or strict barriers to recombination, cohesion due to recombination is not sufficient to overcome the mutational drift. As a consequence, the divergence between pairs of genomes in the population steadily increases in the course of their evolution. The species lacks genetic coherence with sexually isolated clonal subpopulations continuously formed and dissolved. In contrast, in the metastable regime, characterized by a high recombination frequency combined with low barriers to recombination, genomes continuously recombine with the rest of the population. The population remains genetically cohesive and temporally stable. Notably, the transition between these two regimes can be affected by relatively small changes in evolutionary parameters. Using the Multi Locus Sequence Typing (MLST) data, we classify a number of bacterial species to be either the divergent or the metastable type. Generalizations of our framework to include selection, ecologically structured populations, and horizontal gene transfer of nonhomologous regions are discussed as well.
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39
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Chu HY, Sprouffske K, Wagner A. The role of recombination in evolutionary adaptation of Escherichia coli to a novel nutrient. J Evol Biol 2017; 30:1692-1711. [PMID: 28612351 DOI: 10.1111/jeb.13132] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 05/11/2017] [Accepted: 06/05/2017] [Indexed: 12/11/2022]
Abstract
The benefits and detriments of recombination for adaptive evolution have been studied both theoretically and experimentally, with conflicting predictions and observations. Most pertinent experiments examine recombination's effects in an unchanging environment and do not study its genomewide effects. Here, we evolved six replicate populations of either highly recombining R+ or lowly recombining R- E. coli strains in a changing environment, by introducing the novel nutrients L-arabinose or indole into the environment. The experiment's ancestral strains are not viable on these nutrients, but 130 generations of adaptive evolution were sufficient to render them viable. Recombination conferred a more pronounced advantage to populations adapting to indole. To study the genomic changes associated with this advantage, we sequenced the genomes of 384 clones isolated from selected replicates at the end of the experiment. These genomes harbour complex changes that range from point mutations to large-scale DNA amplifications. Among several candidate adaptive mutations, those in the tryptophanase regulator tnaC stand out, because the tna operon in which it resides has a known role in indole metabolism. One of the highly recombining populations also shows a significant excess of large-scale segmental DNA amplifications that include the tna operon. This lineage also shows a unique and potentially adaptive combination of point mutations and DNA amplifications that may have originated independently from one another, to be joined later by recombination. Our data illustrate that the advantages of recombination for adaptive evolution strongly depend on the environment and that they can be associated with complex genomic changes.
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Affiliation(s)
- H-Y Chu
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - K Sprouffske
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland
| | - A Wagner
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.,The Swiss Institute of Bioinformatics, Quartier Sorge, Batiment Genopode, Lausanne, Switzerland.,The Santa Fe Institute, Santa Fe, NM, USA
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40
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David S, Sánchez-Busó L, Harris SR, Marttinen P, Rusniok C, Buchrieser C, Harrison TG, Parkhill J. Dynamics and impact of homologous recombination on the evolution of Legionella pneumophila. PLoS Genet 2017. [PMID: 28650958 PMCID: PMC5507463 DOI: 10.1371/journal.pgen.1006855] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Legionella pneumophila is an environmental bacterium and the causative agent of Legionnaires' disease. Previous genomic studies have shown that recombination accounts for a high proportion (>96%) of diversity within several major disease-associated sequence types (STs) of L. pneumophila. This suggests that recombination represents a potentially important force shaping adaptation and virulence. Despite this, little is known about the biological effects of recombination in L. pneumophila, particularly with regards to homologous recombination (whereby genes are replaced with alternative allelic variants). Using newly available population genomic data, we have disentangled events arising from homologous and non-homologous recombination in six major disease-associated STs of L. pneumophila (subsp. pneumophila), and subsequently performed a detailed characterisation of the dynamics and impact of homologous recombination. We identified genomic "hotspots" of homologous recombination that include regions containing outer membrane proteins, the lipopolysaccharide (LPS) region and Dot/Icm effectors, which provide interesting clues to the selection pressures faced by L. pneumophila. Inference of the origin of the recombined regions showed that isolates have most frequently imported DNA from isolates belonging to their own clade, but also occasionally from other major clades of the same subspecies. This supports the hypothesis that the possibility for horizontal exchange of new adaptations between major clades of the subspecies may have been a critical factor in the recent emergence of several clinically important STs from diverse genomic backgrounds. However, acquisition of recombined regions from another subspecies, L. pneumophila subsp. fraseri, was rarely observed, suggesting the existence of a recombination barrier and/or the possibility of ongoing speciation between the two subspecies. Finally, we suggest that multi-fragment recombination may occur in L. pneumophila, whereby multiple non-contiguous segments that originate from the same molecule of donor DNA are imported into a recipient genome during a single episode of recombination.
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Affiliation(s)
- Sophia David
- Pathogen Genomics, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
- Respiratory and Vaccine Preventable Bacteria Reference Unit, Public Health England, London, United Kingdom
| | - Leonor Sánchez-Busó
- Pathogen Genomics, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Simon R. Harris
- Pathogen Genomics, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Pekka Marttinen
- Helsinki Institute for Information Technology HIIT, Department of Computer Science, Aalto University, Aalto, Espoo, Finland
| | - Christophe Rusniok
- Institut Pasteur, Biologie des Bactéries Intracellulaires, Paris, France
- CNRS UMR 3525, Paris, France
| | - Carmen Buchrieser
- Institut Pasteur, Biologie des Bactéries Intracellulaires, Paris, France
- CNRS UMR 3525, Paris, France
| | - Timothy G. Harrison
- Respiratory and Vaccine Preventable Bacteria Reference Unit, Public Health England, London, United Kingdom
| | - Julian Parkhill
- Pathogen Genomics, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
- * E-mail:
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41
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Fernandez-Lopez R, Redondo S, Garcillan-Barcia MP, de la Cruz F. Towards a taxonomy of conjugative plasmids. Curr Opin Microbiol 2017; 38:106-113. [PMID: 28586714 DOI: 10.1016/j.mib.2017.05.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 05/10/2017] [Accepted: 05/17/2017] [Indexed: 01/14/2023]
Abstract
Conjugative plasmids are the keystone of horizontal gene transfer. Metagenomic research and clinical understanding of plasmid transmission beg for a taxonomical approach to conjugative plasmid classification. Up to now, a meaningful classification was difficult to achieve for lack of appropriate analytical tools. The advent of the genomic era revolutionized the landscape, offering a plethora of plasmid sequences as well as bioinformatic analytical tools. Given the need and the opportunity, in view of the available evidence, a taxonomy of conjugative plasmids is proposed in the hope that it will leverage plasmid studies.
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Affiliation(s)
- Raul Fernandez-Lopez
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria, Santander, Spain
| | - Santiago Redondo
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria, Santander, Spain
| | - M Pilar Garcillan-Barcia
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria, Santander, Spain
| | - Fernando de la Cruz
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria, Santander, Spain.
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Leimbach A, Poehlein A, Vollmers J, Görlich D, Daniel R, Dobrindt U. No evidence for a bovine mastitis Escherichia coli pathotype. BMC Genomics 2017; 18:359. [PMID: 28482799 PMCID: PMC5422975 DOI: 10.1186/s12864-017-3739-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 04/27/2017] [Indexed: 11/30/2022] Open
Abstract
Background Escherichia coli bovine mastitis is a disease of significant economic importance in the dairy industry. Molecular characterization of mastitis-associated E. coli (MAEC) did not result in the identification of common traits. Nevertheless, a mammary pathogenic E. coli (MPEC) pathotype has been proposed suggesting virulence traits that differentiate MAEC from commensal E. coli. The present study was designed to investigate the MPEC pathotype hypothesis by comparing the genomes of MAEC and commensal bovine E. coli. Results We sequenced the genomes of eight E. coli isolated from bovine mastitis cases and six fecal commensal isolates from udder-healthy cows. We analyzed the phylogenetic history of bovine E. coli genomes by supplementing this strain panel with eleven bovine-associated E. coli from public databases. The majority of the isolates originate from phylogroups A and B1, but neither MAEC nor commensal strains could be unambiguously distinguished by phylogenetic lineage. The gene content of both MAEC and commensal strains is highly diverse and dominated by their phylogenetic background. Although individual strains carry some typical E. coli virulence-associated genes, no traits important for pathogenicity could be specifically attributed to MAEC. Instead, both commensal strains and MAEC have very few gene families enriched in either pathotype. Only the aerobactin siderophore gene cluster was enriched in commensal E. coli within our strain panel. Conclusions This is the first characterization of a phylogenetically diverse strain panel including several MAEC and commensal isolates. With our comparative genomics approach we could not confirm previous studies that argue for a positive selection of specific traits enabling MAEC to elicit bovine mastitis. Instead, MAEC are facultative and opportunistic pathogens recruited from the highly diverse bovine gastrointestinal microbiota. Virulence-associated genes implicated in mastitis are a by-product of commensalism with the primary function to enhance fitness in the bovine gastrointestinal tract. Therefore, we put the definition of the MPEC pathotype into question and suggest to designate corresponding isolates as MAEC. Electronic supplementary material The online version of this article (doi:10.1186/s12864-017-3739-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andreas Leimbach
- Institute of Hygiene, University of Münster, Mendelstrasse 7, 48149, Münster, Germany. .,Department of Genomic and Applied Microbiology, Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University of Göttingen, Göttingen, Germany. .,Institute for Molecular Infection Biology, Julius-Maximilians-University of Würzburg, Würzburg, Germany.
| | - Anja Poehlein
- Department of Genomic and Applied Microbiology, Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University of Göttingen, Göttingen, Germany
| | - John Vollmers
- Leibniz Institute DSMZ, German Collection of Microorganisms and Cell Cultures, Braunschweig, Germany
| | - Dennis Görlich
- Institute of Biostatistics and Clinical Research, University of Münster, Münster, Germany
| | - Rolf Daniel
- Department of Genomic and Applied Microbiology, Göttingen Genomics Laboratory, Institute of Microbiology and Genetics, Georg-August-University of Göttingen, Göttingen, Germany
| | - Ulrich Dobrindt
- Institute of Hygiene, University of Münster, Mendelstrasse 7, 48149, Münster, Germany. .,Institute for Molecular Infection Biology, Julius-Maximilians-University of Würzburg, Würzburg, Germany.
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Kingston AW, Ponkratz C, Raleigh EA. Rpn (YhgA-Like) Proteins of Escherichia coli K-12 and Their Contribution to RecA-Independent Horizontal Transfer. J Bacteriol 2017; 199:e00787-16. [PMID: 28096446 PMCID: PMC5350276 DOI: 10.1128/jb.00787-16] [Citation(s) in RCA: 16] [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: 11/14/2016] [Accepted: 01/09/2017] [Indexed: 01/21/2023] Open
Abstract
Bacteria use a variety of DNA-mobilizing enzymes to facilitate environmental niche adaptation via horizontal gene transfer. This has led to real-world problems, like the spread of antibiotic resistance, yet many mobilization proteins remain undefined. In the study described here, we investigated the uncharacterized family of YhgA-like transposase_31 (Pfam PF04754) proteins. Our primary focus was the genetic and biochemical properties of the five Escherichia coli K-12 members of this family, which we designate RpnA to RpnE, where Rpn represents recombination-promoting nuclease. We employed a conjugal system developed by our lab that demanded RecA-independent recombination following transfer of chromosomal DNA. Overexpression of RpnA (YhgA), RpnB (YfcI), RpnC (YadD), and RpnD (YjiP) increased RecA-independent recombination, reduced cell viability, and induced the expression of reporter of DNA damage. For the exemplar of the family, RpnA, mutational changes in proposed catalytic residues reduced or abolished all three phenotypes in concert. In vitro, RpnA displayed magnesium-dependent, calcium-stimulated DNA endonuclease activity with little, if any, sequence specificity and a preference for double-strand cleavage. We propose that Rpn/YhgA-like family nucleases can participate in gene acquisition processes.IMPORTANCE Bacteria adapt to new environments by obtaining new genes from other bacteria. Here, we characterize a set of genes that can promote the acquisition process by a novel mechanism. Genome comparisons had suggested the horizontal spread of the genes for the YhgA-like family of proteins through bacteria. Although annotated as transposase_31, no member of the family has previously been characterized experimentally. We show that four Escherichia coli K-12 paralogs contribute to a novel RecA-independent recombination mechanism in vivo For RpnA, we demonstrate in vitro action as a magnesium-dependent, calcium-stimulated nonspecific DNA endonuclease. The cleavage products are capable of providing priming sites for DNA polymerase, which can enable DNA joining by primer-template switching.
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Okura M, Nozawa T, Watanabe T, Murase K, Nakagawa I, Takamatsu D, Osaki M, Sekizaki T, Gottschalk M, Hamada S, Maruyama F. A Locus Encoding Variable Defense Systems against Invading DNA Identified in Streptococcus suis. Genome Biol Evol 2017; 9:1000-1012. [PMID: 28379509 PMCID: PMC5398294 DOI: 10.1093/gbe/evx062] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/03/2017] [Indexed: 12/21/2022] Open
Abstract
Streptococcus suis, an important zoonotic pathogen, is known to have an open pan-genome and to develop a competent state. In S. suis, limited genetic lineages are suggested to be associated with zoonosis. However, little is known about the evolution of diversified lineages and their respective phenotypic or ecological characteristics. In this study, we performed comparative genome analyses of S. suis, with a focus on the competence genes, mobile genetic elements, and genetic elements related to various defense systems against exogenous DNAs (defense elements) that are associated with gene gain/loss/exchange mediated by horizontal DNA movements and their restrictions. Our genome analyses revealed a conserved competence-inducing peptide type (pherotype) of the competence system and large-scale genome rearrangements in certain clusters based on the genome phylogeny of 58 S. suis strains. Moreover, the profiles of the defense elements were similar or identical to each other among the strains belonging to the same genomic clusters. Our findings suggest that these genetic characteristics of each cluster might exert specific effects on the phenotypic or ecological differences between the clusters. We also found certain loci that shift several types of defense elements in S. suis. Of note, one of these loci is a previously unrecognized variable region in bacteria, at which strains of distinct clusters code for different and various defense elements. This locus might represent a novel defense mechanism that has evolved through an arms race between bacteria and invading DNAs, mediated by mobile genetic elements and genetic competence.
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Affiliation(s)
- Masatoshi Okura
- Division of Bacterial and Parasitic Diseases, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Takashi Nozawa
- Department of Microbiology, Kyoto University Graduate School of Medicine, Japan
| | - Takayasu Watanabe
- Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan
| | - Kazunori Murase
- Department of Microbiology, Kyoto University Graduate School of Medicine, Japan
| | - Ichiro Nakagawa
- Department of Microbiology, Kyoto University Graduate School of Medicine, Japan
| | - Daisuke Takamatsu
- Division of Bacterial and Parasitic Diseases, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan.,The United Graduate School of Veterinary Sciences, Gifu University, Japan
| | - Makoto Osaki
- Division of Bacterial and Parasitic Diseases, National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Tsutomu Sekizaki
- Research Center for Food Safety, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Japan
| | - Marcelo Gottschalk
- Groupe de Recherche sur les Maladies Infectieuses du Porc, Faculté de Médecine Vétérinaire, Université de Montréal, St-Hyacinthe, Quebec, Canada
| | - Shigeyuki Hamada
- Research Institute for Microbial Diseases, Thailand-Japan Collaboration Center for Emerging and Re-emerging Infections, Osaka University, Suita-Osaka, Japan
| | - Fumito Maruyama
- Department of Microbiology, Kyoto University Graduate School of Medicine, Japan
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45
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Choudoir MJ, Panke-Buisse K, Andam CP, Buckley DH. Genome Surfing As Driver of Microbial Genomic Diversity. Trends Microbiol 2017; 25:624-636. [PMID: 28283403 DOI: 10.1016/j.tim.2017.02.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 02/03/2017] [Accepted: 02/10/2017] [Indexed: 01/20/2023]
Abstract
Historical changes in population size, such as those caused by demographic range expansions, can produce nonadaptive changes in genomic diversity through mechanisms such as gene surfing. We propose that demographic range expansion of a microbial population capable of horizontal gene exchange can result in genome surfing, a mechanism that can cause widespread increase in the pan-genome frequency of genes acquired by horizontal gene exchange. We explain that patterns of genetic diversity within Streptomyces are consistent with genome surfing, and we describe several predictions for testing this hypothesis both in Streptomyces and in other microorganisms.
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Affiliation(s)
- Mallory J Choudoir
- School of Integrative Plant Science, Cornell University, Ithaca, NY 14850 USA
| | - Kevin Panke-Buisse
- School of Integrative Plant Science, Cornell University, Ithaca, NY 14850 USA
| | - Cheryl P Andam
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham NH 03824, USA
| | - Daniel H Buckley
- School of Integrative Plant Science, Cornell University, Ithaca, NY 14850 USA.
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46
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Vaughan TG, Welch D, Drummond AJ, Biggs PJ, George T, French NP. Inferring Ancestral Recombination Graphs from Bacterial Genomic Data. Genetics 2017; 205:857-870. [PMID: 28007885 PMCID: PMC5289856 DOI: 10.1534/genetics.116.193425] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Accepted: 12/03/2016] [Indexed: 11/18/2022] Open
Abstract
Homologous recombination is a central feature of bacterial evolution, yet it confounds traditional phylogenetic methods. While a number of methods specific to bacterial evolution have been developed, none of these permit joint inference of a bacterial recombination graph and associated parameters. In this article, we present a new method which addresses this shortcoming. Our method uses a novel Markov chain Monte Carlo algorithm to perform phylogenetic inference under the ClonalOrigin model. We demonstrate the utility of our method by applying it to ribosomal multilocus sequence typing data sequenced from pathogenic and nonpathogenic Escherichia coli serotype O157 and O26 isolates collected in rural New Zealand. The method is implemented as an open source BEAST 2 package, Bacter, which is available via the project web page at http://tgvaughan.github.io/bacter.
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Affiliation(s)
- Timothy G Vaughan
- Centre for Computational Evolution, The University of Auckland, 1010, New Zealand
- Department of Computer Science, The University of Auckland, 1010, New Zealand
| | - David Welch
- Centre for Computational Evolution, The University of Auckland, 1010, New Zealand
- Department of Computer Science, The University of Auckland, 1010, New Zealand
| | - Alexei J Drummond
- Centre for Computational Evolution, The University of Auckland, 1010, New Zealand
- Department of Computer Science, The University of Auckland, 1010, New Zealand
| | - Patrick J Biggs
- Molecular Epidemiology and Public Health Laboratory, Infectious Disease Research Centre, Hopkirk Research Institute, Massey University, Palmerston North 4442, New Zealand
| | - Tessy George
- Molecular Epidemiology and Public Health Laboratory, Infectious Disease Research Centre, Hopkirk Research Institute, Massey University, Palmerston North 4442, New Zealand
| | - Nigel P French
- Molecular Epidemiology and Public Health Laboratory, Infectious Disease Research Centre, Hopkirk Research Institute, Massey University, Palmerston North 4442, New Zealand
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Collins C, Didelot X. Reconstructing the Ancestral Relationships Between Bacterial Pathogen Genomes. Methods Mol Biol 2017; 1535:109-137. [PMID: 27914076 DOI: 10.1007/978-1-4939-6673-8_8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Following recent developments in DNA sequencing technology, it is now possible to sequence hundreds of whole genomes from bacterial isolates at relatively low cost. Analyzing this growing wealth of genomic data in terms of ancestral relationships can reveal many interesting aspects of the evolution, ecology, and epidemiology of bacterial pathogens. However, reconstructing the ancestry of a sample of bacteria remains challenging, especially for the majority of species where recombination is frequent. Here, we review and describe the computational techniques currently available to infer ancestral relationships, including phylogenetic methods that either ignore or account for the effect of recombination, as well as model-based and model-free phylogeny-independent approaches.
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Affiliation(s)
- Caitlin Collins
- Department of Infectious Disease Epidemiology, Imperial College London, London, W2 1PG, UK.
| | - Xavier Didelot
- Department of Infectious Disease Epidemiology, Imperial College London, London, W2 1PG, UK.
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48
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Correlated Mutations and Homologous Recombination Within Bacterial Populations. Genetics 2016; 205:891-917. [PMID: 28007887 DOI: 10.1534/genetics.116.189621] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 12/15/2016] [Indexed: 11/18/2022] Open
Abstract
Inferring the rate of homologous recombination within a bacterial population remains a key challenge in quantifying the basic parameters of bacterial evolution. Due to the high sequence similarity within a clonal population, and unique aspects of bacterial DNA transfer processes, detecting recombination events based on phylogenetic reconstruction is often difficult, and estimating recombination rates using coalescent model-based methods is computationally expensive, and often infeasible for large sequencing data sets. Here, we present an efficient solution by introducing a set of mutational correlation functions computed using pairwise sequence comparison, which characterize various facets of bacterial recombination. We provide analytical expressions for these functions, which precisely recapitulate simulation results of neutral and adapting populations under different coalescent models. We used these to fit correlation functions measured at synonymous substitutions using whole-genome data on Escherichia coli and Streptococcus pneumoniae populations. We calculated and corrected for the effect of sample selection bias, i.e., the uneven sampling of individuals from natural microbial populations that exists in most datasets. Our method is fast and efficient, and does not employ phylogenetic inference or other computationally intensive numerics. By simply fitting analytical forms to measurements from sequence data, we show that recombination rates can be inferred, and the relative ages of different samples can be estimated. Our approach, which is based on population genetic modeling, is broadly applicable to a wide variety of data, and its computational efficiency makes it particularly attractive for use in the analysis of large sequencing datasets.
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A Novel Protective Vaccine Antigen from the Core Escherichia coli Genome. mSphere 2016; 1:mSphere00326-16. [PMID: 27904885 PMCID: PMC5120174 DOI: 10.1128/msphere.00326-16] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 10/27/2016] [Indexed: 12/21/2022] Open
Abstract
E. coli is a multifaceted pathogen of major significance to global human health and an important contributor to increasing antibiotic resistance. Given the paucity of therapies still effective against multidrug-resistant pathogenic E. coli strains, novel treatment and prevention strategies are urgently required. In this study, we defined the core and accessory components of the E. coli genome by examining a large collection of draft and completely sequenced strains available from public databases. This data set was mined by employing a reverse-vaccinology approach in combination with proteomics to identify putative broadly protective vaccine antigens. One such antigen was identified that was highly immunogenic and induced protection in a mouse model of bacteremia. Overall, our study provides a genomic and proteomic framework for the selection of novel vaccine antigens that could mediate broad protection against pathogenic E. coli. Escherichia coli is a versatile pathogen capable of causing intestinal and extraintestinal infections that result in a huge burden of global human disease. The diversity of E. coli is reflected by its multiple different pathotypes and mosaic genome composition. E. coli strains are also a major driver of antibiotic resistance, emphasizing the urgent need for new treatment and prevention measures. Here, we used a large data set comprising 1,700 draft and complete genomes to define the core and accessory genome of E. coli and demonstrated the overlapping relationship between strains from different pathotypes. In combination with proteomic investigation, this analysis revealed core genes that encode surface-exposed or secreted proteins that represent potential broad-coverage vaccine antigens. One of these antigens, YncE, was characterized as a conserved immunogenic antigen able to protect against acute systemic infection in mice after vaccination. Overall, this work provides a genomic blueprint for future analyses of conserved and accessory E. coli genes. The work also identified YncE as a novel antigen that could be exploited in the development of a vaccine against all pathogenic E. coli strains—an important direction given the high global incidence of infections caused by multidrug-resistant strains for which there are few effective antibiotics. IMPORTANCEE. coli is a multifaceted pathogen of major significance to global human health and an important contributor to increasing antibiotic resistance. Given the paucity of therapies still effective against multidrug-resistant pathogenic E. coli strains, novel treatment and prevention strategies are urgently required. In this study, we defined the core and accessory components of the E. coli genome by examining a large collection of draft and completely sequenced strains available from public databases. This data set was mined by employing a reverse-vaccinology approach in combination with proteomics to identify putative broadly protective vaccine antigens. One such antigen was identified that was highly immunogenic and induced protection in a mouse model of bacteremia. Overall, our study provides a genomic and proteomic framework for the selection of novel vaccine antigens that could mediate broad protection against pathogenic E. coli.
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50
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Merda D, Bonneau S, Guimbaud JF, Durand K, Brin C, Boureau T, Lemaire C, Jacques MA, Fischer-Le Saux M. Recombination-prone bacterial strains form a reservoir from which epidemic clones emerge in agroecosystems. ENVIRONMENTAL MICROBIOLOGY REPORTS 2016; 8:572-581. [PMID: 27059897 DOI: 10.1111/1758-2229.12397] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
The acquisition of virulence-related genes through horizontal gene transfer can modify the pathogenic profiles of strains and lead to the emergence of new diseases. Xanthomonas arboricola is a bacterial species largely known for the damage it causes to stone and nut fruit trees worldwide. In addition to these host-specific populations called pathovars, many nonpathogenic strains have been identified in this species. Their evolutionary significance in the context of pathogen emergence is unknown. We looked at seven housekeeping genes amplified from 187 pathogenic and nonpathogenic strains isolated from various plants worldwide to analyze population genetics and recombination dynamics. We also examined the dynamics of the gains and losses of genes associated with life history traits (LHTs) during X. arboricola evolution. We discovered that X. arboricola presents an epidemic population structure. Successful pathovars of trees (i.e. pruni, corylina and juglandis) are epidemic clones whose emergence appears to be linked to the acquisition of eight genes coding for Type III effectors. The other strains of this species are part of a recombinant network, within which LHT-associated genes might have been lost. We suggest that nonpathogenic strains, because of their high genetic diversity and propensity for recombination, may promote the emergence of pathogenic strains.
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Affiliation(s)
- Déborah Merda
- IRHS, Agrocampus-Ouest, INRA, Université d'Angers, SFR 4207 QuaSaV, 49071, Beaucouzé, France
| | - Sophie Bonneau
- IRHS, Agrocampus-Ouest, INRA, Université d'Angers, SFR 4207 QuaSaV, 49071, Beaucouzé, France
| | - Jean-François Guimbaud
- IRHS, Agrocampus-Ouest, INRA, Université d'Angers, SFR 4207 QuaSaV, 49071, Beaucouzé, France
| | - Karine Durand
- IRHS, Agrocampus-Ouest, INRA, Université d'Angers, SFR 4207 QuaSaV, 49071, Beaucouzé, France
| | - Chrystelle Brin
- IRHS, Agrocampus-Ouest, INRA, Université d'Angers, SFR 4207 QuaSaV, 49071, Beaucouzé, France
| | - Tristan Boureau
- IRHS, Agrocampus-Ouest, INRA, Université d'Angers, SFR 4207 QuaSaV, 49071, Beaucouzé, France
| | - Christophe Lemaire
- IRHS, Agrocampus-Ouest, INRA, Université d'Angers, SFR 4207 QuaSaV, 49071, Beaucouzé, France
| | - Marie-Agnès Jacques
- IRHS, Agrocampus-Ouest, INRA, Université d'Angers, SFR 4207 QuaSaV, 49071, Beaucouzé, France
| | - Marion Fischer-Le Saux
- IRHS, Agrocampus-Ouest, INRA, Université d'Angers, SFR 4207 QuaSaV, 49071, Beaucouzé, France
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