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A Comparative Genomic Approach to Determine the Virulence Factors and Horizontal Gene Transfer Events of Clinical Acanthamoeba Isolates. Microbiol Spectr 2022; 10:e0002522. [PMID: 35416714 PMCID: PMC9045148 DOI: 10.1128/spectrum.00025-22] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Acanthamoeba species are among the most ubiquitous protists that are widespread in soil and water and act as both a replicative niche and vectors for dispersal. They are the most important human intracellular pathogens, causing Acanthamoeba keratitis (AK) and severely damaging the human cornea. The sympatric lifestyle within the host and amoeba-resisting microorganisms (ARMs) promotes horizontal gene transfer (HGT). However, the genomic diversity of only A. castellanii and A. polyphaga has been widely studied, and the pathogenic mechanisms remain unknown. Thus, we examined 7 clinically pathogenic strains by comparative genomic, phylogenetic, and rhizome gene mosaicism analyses to explore amoeba-symbiont interactions that possibly contribute to pathogenesis. Genetic characterization and phylogenetic analysis showed differences in functional characteristics between the "open" state of T3 and T4 isolates, which may contribute to the differences in virulence and pathogenicity. Through comparative genomic analysis, we identified potential genes related to virulence, such as metalloprotease, laminin-binding protein, and HSP, that were specific to the genus Acanthamoeba. Then, analysis of putative sequence trafficking between Acanthamoeba and Pandoraviruses or Acanthamoeba castellanii medusaviruses provided the best hits with viral genes; among bacteria, Pseudomonas had the most significant numbers. The most parsimonious evolutionary scenarios were between Acanthamoeba and endosymbionts; nevertheless, in most cases, the scenarios are more complex. In addition, the differences in exchanged genes were limited to the same family. In brief, this study provided extensive data to suggest the existence of HGT between Acanthamoeba and ARMs, explaining the occurrence of diseases and challenging Darwin's concept of eukaryotic evolution. IMPORTANCE Acanthamoeba has the ability to cause serious blinding keratitis. Although the prevalence of this phenomenon has increased in recent years, our knowledge of the underlying opportunistic pathogenic mechanism maybe remains incomplete. In this study, we highlighted the importance of Pseudomonas in the pathogenesis pathway using comprehensive a whole genomics approach of clinical isolates. The horizontal gene transfer events help to explain how endosymbionts contribute Acanthamoeba to act as an opportunistic pathogen. Our study opens up several potential avenues for future research on the differences in pathogenicity and interactions among clinical strains.
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Salomon M, Dassy B. Partitional Classification: A Complement to Phylogeny. Evol Bioinform Online 2016; 12:149-56. [PMID: 27346943 PMCID: PMC4912232 DOI: 10.4137/ebo.s38288] [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: 12/24/2015] [Revised: 03/21/2016] [Accepted: 03/27/2016] [Indexed: 11/30/2022] Open
Abstract
The tree of life is currently an active object of research, though next to vertical gene transmission non vertical gene transfers proved to play a significant role in the evolutionary process. To overcome this difficulty, trees of life are now constructed from genes hypothesized vital, on the assumption that these are all transmitted vertically. This view has been challenged. As a frame for this discussion, we developed a partitional taxonomical system clustering taxa at a high taxonomical rank. Our analysis (1) selects RNase P RNA sequences of bacterial, archaeal, and eucaryal genera from genetic databases, (2) submits the sequences, aligned, to k-medoid analysis to obtain clusters, (3) establishes the correspondence between clusters and taxa, (4) constructs from the taxa a new type of taxon, the genetic community (GC), and (5) classifies the GCs: Archaea-Eukaryotes contrastingly different from the six others, all bacterial. The GCs would be the broadest frame to carry out the phylogenies.
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Affiliation(s)
- Marc Salomon
- Sorbonne Universités, UPMC Université Paris 06, Faculté de Biologie, Paris, France
| | - Bruno Dassy
- Sorbonne Universités, UPMC Université Paris 06, Faculté de Biologie, Paris, France
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Dhanani AS, Block G, Dewar K, Forgetta V, Topp E, Beiko RG, Diarra MS. Genomic Comparison of Non-Typhoidal Salmonella enterica Serovars Typhimurium, Enteritidis, Heidelberg, Hadar and Kentucky Isolates from Broiler Chickens. PLoS One 2015; 10:e0128773. [PMID: 26083489 PMCID: PMC4470630 DOI: 10.1371/journal.pone.0128773] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 05/01/2015] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Non-typhoidal Salmonella enterica serovars, associated with different foods including poultry products, are important causes of bacterial gastroenteritis worldwide. The colonization of the chicken gut by S. enterica could result in the contamination of the environment and food chain. The aim of this study was to compare the genomes of 25 S. enterica serovars isolated from broiler chicken farms to assess their intra- and inter-genetic variability, with a focus on virulence and antibiotic resistance characteristics. METHODOLOGY/PRINCIPAL FINDING The genomes of 25 S. enterica isolates covering five serovars (ten Typhimurium including three monophasic 4,[5],12:i:, four Enteritidis, three Hadar, four Heidelberg and four Kentucky) were sequenced. Most serovars were clustered in strongly supported phylogenetic clades, except for isolates of serovar Enteritidis that were scattered throughout the tree. Plasmids of varying sizes were detected in several isolates independently of serovars. Genes associated with the IncF plasmid and the IncI1 plasmid were identified in twelve and four isolates, respectively, while genes associated with the IncQ plasmid were found in one isolate. The presence of numerous genes associated with Salmonella pathogenicity islands (SPIs) was also confirmed. Components of the type III and IV secretion systems (T3SS and T4SS) varied in different isolates, which could explain in part, differences of their pathogenicity in humans and/or persistence in broilers. Conserved clusters of genes in the T3SS were detected that could be used in designing effective strategies (diagnostic, vaccination or treatments) to combat Salmonella. Antibiotic resistance genes (CMY, aadA, ampC, florR, sul1, sulI, tetAB, and srtA) and class I integrons were detected in resistant isolates while all isolates carried multidrug efflux pump systems regardless of their antibiotic susceptibility profile. CONCLUSIONS/SIGNIFICANCE This study showed that the predominant Salmonella serovars in broiler chickens harbor genes encoding adhesins, flagellar proteins, T3SS, iron acquisition systems, and antibiotic and metal resistance genes that may explain their pathogenicity, colonization ability and persistence in chicken. The existence of mobile genetic elements indicates that isolates from a given serovar could acquire and transfer genetic material. Conserved genes in the T3SS and T4SS that we have identified are promising candidates for identification of diagnostic, antimicrobial or vaccine targets for the control of Salmonella in broiler chickens.
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Affiliation(s)
- Akhilesh S. Dhanani
- Faculty of Computer Science, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Glenn Block
- Pacific Agri-Food Research Center, Agriculture and Agri-Food Canada (AAFC), Agassiz, British Columbia, V0M 1A0, Canada
| | - Ken Dewar
- McGill University and Genome Quebec Innovation Centre, Montreal, Quebec, H3A 1A4, Canada
| | - Vincenzo Forgetta
- Lady Davis Institute for Medical Research, Montréal, Québec, H3T 1E2, Canada
| | - Edward Topp
- Southern Crop Protection and Food Research Centre, AAFC, London, Ontario, N5V 4T3, Canada
| | - Robert G. Beiko
- Faculty of Computer Science, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada
| | - Moussa S. Diarra
- Pacific Agri-Food Research Center, Agriculture and Agri-Food Canada (AAFC), Agassiz, British Columbia, V0M 1A0, Canada
- * E-mail:
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Abstract
Bacterial genomes are remarkably stable from one generation to the next but are plastic on an evolutionary time scale, substantially shaped by horizontal gene transfer, genome rearrangement, and the activities of mobile DNA elements. This implies the existence of a delicate balance between the maintenance of genome stability and the tolerance of genome instability. In this review, we describe the specialized genetic elements and the endogenous processes that contribute to genome instability. We then discuss the consequences of genome instability at the physiological level, where cells have harnessed instability to mediate phase and antigenic variation, and at the evolutionary level, where horizontal gene transfer has played an important role. Indeed, this ability to share DNA sequences has played a major part in the evolution of life on Earth. The evolutionary plasticity of bacterial genomes, coupled with the vast numbers of bacteria on the planet, substantially limits our ability to control disease.
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Sleator RD. A beginner's guide to phylogenetics. MICROBIAL ECOLOGY 2013; 66:1-4. [PMID: 23624570 DOI: 10.1007/s00248-013-0236-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 04/17/2013] [Indexed: 06/02/2023]
Abstract
Metagenomics and the development of high throughput next generation sequencing capabilities have forced significant development in the field of phylogenetics: the study of the evolutionary relatedness of the planet's inhabitants. Herein, I review the major tree-building strategies, challenges and opportunities which exist in this rapidly expanding field of evolutionary biology.
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Bapteste E, Dupré J. Towards a processual microbial ontology. BIOLOGY & PHILOSOPHY 2013; 28:379-404. [PMID: 23487350 PMCID: PMC3591535 DOI: 10.1007/s10539-012-9350-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 10/17/2012] [Indexed: 05/26/2023]
Abstract
Standard microbial evolutionary ontology is organized according to a nested hierarchy of entities at various levels of biological organization. It typically detects and defines these entities in relation to the most stable aspects of evolutionary processes, by identifying lineages evolving by a process of vertical inheritance from an ancestral entity. However, recent advances in microbiology indicate that such an ontology has important limitations. The various dynamics detected within microbiological systems reveal that a focus on the most stable entities (or features of entities) over time inevitably underestimates the extent and nature of microbial diversity. These dynamics are not the outcome of the process of vertical descent alone. Other processes, often involving causal interactions between entities from distinct levels of biological organisation, or operating at different time scales, are responsible not only for the destabilisation of pre-existing entities, but also for the emergence and stabilisation of novel entities in the microbial world. In this article we consider microbial entities as more or less stabilised functional wholes, and sketch a network-based ontology that can represent a diverse set of processes including, for example, as well as phylogenetic relations, interactions that stabilise or destabilise the interacting entities, spatial relations, ecological connections, and genetic exchanges. We use this pluralistic framework for evaluating (i) the existing ontological assumptions in evolution (e.g. whether currently recognized entities are adequate for understanding the causes of change and stabilisation in the microbial world), and (ii) for identifying hidden ontological kinds, essentially invisible from within a more limited perspective. We propose to recognize additional classes of entities that provide new insights into the structure of the microbial world, namely "processually equivalent" entities, "processually versatile" entities, and "stabilized" entities.
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Affiliation(s)
- Eric Bapteste
- />UMR CNRS 7138, Université Pierre et Marie Curie, 75005 Paris, France
| | - John Dupré
- />ESRC Centre for Genomics in Society (Egenis), University of Exeter, Exeter, UK
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Bertelli C, Greub G. Lateral gene exchanges shape the genomes of amoeba-resisting microorganisms. Front Cell Infect Microbiol 2012; 2:110. [PMID: 22919697 PMCID: PMC3423634 DOI: 10.3389/fcimb.2012.00110] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Accepted: 08/01/2012] [Indexed: 12/05/2022] Open
Abstract
Based on Darwin's concept of the tree of life, vertical inheritance was thought to be dominant, and mutations, deletions, and duplication were streaming the genomes of living organisms. In the current genomic era, increasing data indicated that both vertical and lateral gene inheritance interact in space and time to trigger genome evolution, particularly among microorganisms sharing a given ecological niche. As a paradigm to their diversity and their survival in a variety of cell types, intracellular microorganisms, and notably intracellular bacteria, were considered as less prone to lateral genetic exchanges. Such specialized microorganisms generally have a smaller gene repertoire because they do rely on their host's factors for some basic regulatory and metabolic functions. Here we review events of lateral gene transfer (LGT) that illustrate the genetic exchanges among intra-amoebal microorganisms or between the microorganism and its amoebal host. We tentatively investigate the functions of laterally transferred genes in the light of the interaction with their host as they should confer a selective advantage and success to the amoeba-resisting microorganisms (ARMs).
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Affiliation(s)
- Claire Bertelli
- Center for Research on Intracellular Bacteria, Institute of Microbiology, University Hospital Center and University of Lausanne Lausanne, Switzerland
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The role of reticulate evolution in creating innovation and complexity. INTERNATIONAL JOURNAL OF EVOLUTIONARY BIOLOGY 2012; 2012:418964. [PMID: 22844638 PMCID: PMC3403396 DOI: 10.1155/2012/418964] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 05/08/2012] [Accepted: 05/10/2012] [Indexed: 12/31/2022]
Abstract
Reticulate evolution encompasses processes that conflict with traditional Tree of Life efforts. These processes, horizontal gene transfer (HGT), gene and whole-genome duplications through allopolyploidization, are some of the main driving forces for generating innovation and complexity. HGT has a profound impact on prokaryotic and eukaryotic evolution. HGTs can lead to the invention of new metabolic pathways and the expansion and enhancement of previously existing pathways. It allows for organismal adaptation into new ecological niches and new host ranges. Although many HGTs appear to be selected for because they provide some benefit to their recipient lineage, other HGTs may be maintained by chance through random genetic drift. Moreover, some HGTs that may initially seem parasitic in nature can cause complexity to arise through pathways of neutral evolution. Another mechanism for generating innovation and complexity, occurring more frequently in eukaryotes than in prokaryotes, is gene and genome duplications, which often occur through allopolyploidizations. We discuss how these different evolutionary processes contribute to generating innovation and complexity.
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Diemer GS, Stedman KM. A novel virus genome discovered in an extreme environment suggests recombination between unrelated groups of RNA and DNA viruses. Biol Direct 2012; 7:13. [PMID: 22515485 PMCID: PMC3372434 DOI: 10.1186/1745-6150-7-13] [Citation(s) in RCA: 114] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2012] [Accepted: 04/19/2012] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Viruses are known to be the most abundant organisms on earth, yet little is known about their collective origin and evolutionary history. With exceptionally high rates of genetic mutation and mosaicism, it is not currently possible to resolve deep evolutionary histories of the known major virus groups. Metagenomics offers a potential means of establishing a more comprehensive view of viral evolution as vast amounts of new sequence data becomes available for comparative analysis. RESULTS Bioinformatic analysis of viral metagenomic sequences derived from a hot, acidic lake revealed a circular, putatively single-stranded DNA virus encoding a major capsid protein similar to those found only in single-stranded RNA viruses. The presence and circular configuration of the complete virus genome was confirmed by inverse PCR amplification from native DNA extracted from lake sediment. The virus genome appears to be the result of a RNA-DNA recombination event between two ostensibly unrelated virus groups. Environmental sequence databases were examined for homologous genes arranged in similar configurations and three similar putative virus genomes from marine environments were identified. This result indicates the existence of a widespread but previously undetected group of viruses. CONCLUSIONS This unique viral genome carries implications for theories of virus emergence and evolution, as no mechanism for interviral RNA-DNA recombination has yet been identified, and only scant evidence exists that genetic exchange occurs between such distinct virus lineages. REVIEWERS This article was reviewed by EK, MK (nominated by PF) and AM. For the full reviews, please go to the Reviewers' comments section.
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Affiliation(s)
- Geoffrey S Diemer
- Department of Biology, and the Center for Life in Extreme Environments, Portland State University, 1719 SW 10th Avenue, SRTC room 246, Portland, OR 97201, USA
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Georgiades K, Raoult D. How microbiology helps define the rhizome of life. Front Cell Infect Microbiol 2012; 2:60. [PMID: 22919651 PMCID: PMC3417629 DOI: 10.3389/fcimb.2012.00060] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2012] [Accepted: 04/16/2012] [Indexed: 01/24/2023] Open
Abstract
In contrast to the tree of life (TOF) theory, species are mosaics of gene sequences with different origins. Observations of the extensive lateral sequence transfers in all organisms have demonstrated that the genomes of all life forms are collections of genes with different evolutionary histories that cannot be represented by a single TOF. Moreover, genes themselves commonly have several origins due to recombination. The human genome is not free from recombination events, so it is a mosaic like other organisms' genomes. Recent studies have demonstrated evidence for the integration of parasitic DNA into the human genome. Lateral transfer events have been accepted as major contributors of genome evolution in free-living bacteria. Furthermore, the accumulation of genomic sequence data provides evidence for extended genetic exchanges in intracellular bacteria and suggests that such events constitute an agent that promotes and maintains all bacterial species. Archaea and viruses also form chimeras containing primarily bacterial but also eukaryotic sequences. In addition to lateral transfers, orphan genes are indicative of the fact that gene creation is a permanent and unsettled phenomenon. Currently, a rhizome may more adequately represent the multiplicity and de novo creation of a genome. We wanted to confirm that the term “rhizome” in evolutionary biology applies to the entire cellular life history. This view of evolution should resemble a clump of roots representing the multiple origins of the repertoires of the genes of each species.
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Affiliation(s)
- Kalliopi Georgiades
- Faculté de Médecine La Timone, Unité de Recherche en Maladies Infectieuses Tropical Emergentes (URMITE), CNRS-IRD UMR 6236-198, Université de la Méditerranée Marseille, France
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Bapteste E, Bouchard F, Burian RM. Philosophy and evolution: minding the gap between evolutionary patterns and tree-like patterns. Methods Mol Biol 2012; 856:81-110. [PMID: 22399456 DOI: 10.1007/978-1-61779-585-5_4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Ever since Darwin, the familiar genealogical pattern known as the Tree of Life (TOL) has been prominent in evolutionary thinking and has dominated not only systematics, but also the analysis of the units of evolution. However, recent findings indicate that the evolution of DNA, especially in prokaryotes and such DNA vehicles as viruses and plasmids, does not follow a unique tree-like pattern. Because evolutionary patterns track a greater range of processes than those captured in genealogies, genealogical patterns are in fact only a subset of a broader set of evolutionary patterns. This fact suggests that evolutionists who focus exclusively on genealogical patterns are blocked from providing a significant range of genuine evolutionary explanations. Consequently, we highlight challenges to tree-based approaches, and point the way toward more appropriate methods to study evolution (although we do not present them in technical detail). We argue that there is significant benefit in adopting wider range of models, evolutionary representations, and evolutionary explanations, based on an analysis of the full range of evolutionary processes. We introduce an ecosystem orientation into evolutionary thinking that highlights the importance of "type 1 coalitions" (functionally related units with genetic exchanges, aka "friends with genetic benefits"), "type 2 coalitions" (functionally related units without genetic exchanges), "communal interactions," and "emergent evolutionary properties." On this basis, we seek to promote the study of (especially prokaryotic) evolution with dynamic evolutionary networks, which are less constrained than the TOL, and to provide new ways to analyze an expanded range of evolutionary units (genetic modules, recombined genes, plasmids, phages and prokaryotic genomes, pangenomes, microbial communities) and evolutionary processes. Finally, we discuss some of the conceptual and practical questions raised by such network-based representation.
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Zhi XY, Zhao W, Li WJ, Zhao GP. Prokaryotic systematics in the genomics era. Antonie van Leeuwenhoek 2011; 101:21-34. [PMID: 22116211 DOI: 10.1007/s10482-011-9667-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 10/24/2011] [Indexed: 11/29/2022]
Abstract
As an essential and basic biological discipline, prokaryotic systematics is entering the era of genomics. This paradigmatic shift is significant not only for understanding molecular phylogeny at the whole genome level but also in revealing the genetic or epigenetic basis that accounts for the phenotypic criteria used to classify and identify species. These developments provide an opportunity and a challenge for systematists to reanalyze the molecular mechanisms underlying the taxonomic characteristics of prokaryotes by drawing the knowledge from studies of genomics and/or functional genomics employing platform technologies and related bioinformatics tools. It is expected that taxonomic books, such as Bergey's Manual of Systematic Bacteriology may evolve into a systematics library indexed by phylogenomic information with an comprehensive understanding of prokaryotic speciation and associated increasing knowledge of biological phenomena.
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Affiliation(s)
- Xiao-Yang Zhi
- Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education and the Laboratory for Conservation and Utilization of Bio-Resources, Yunnan Institute of Microbiology, Yunnan University, Kunming, China
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Carbonell P, Lecointre G, Faulon JL. Origins of specificity and promiscuity in metabolic networks. J Biol Chem 2011; 286:43994-44004. [PMID: 22052908 DOI: 10.1074/jbc.m111.274050] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
How enzymes have evolved to their present form is linked to the question of how pathways emerged and evolved into extant metabolic networks. To investigate this mechanism, we have explored the chemical diversity present in a largely unbiased data set of catalytic reactions processed by modern enzymes across the tree of life. In order to get a quantitative estimate of enzyme chemical diversity, we measure enzyme multispecificity or promiscuity using the reaction molecular signatures. Our main finding is that reactions that are catalyzed by a highly specific enzyme are shared by poorly divergent species, suggesting a later emergence of this function during evolution. In contrast, reactions that are catalyzed by highly promiscuous enzymes are more likely to appear uniformly distributed across species in the tree of life. From a functional point of view, promiscuous enzymes are mainly involved in amino acid and lipid metabolisms, which might be associated with the earliest form of biochemical reactions. In this way, results presented in this paper might assist us with the identification of primeval promiscuous catalytic functions contributing to life's minimal metabolism.
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Affiliation(s)
- Pablo Carbonell
- Institute of Systems and Synthetic Biology, University of Evry, 91030 Evry, France
| | - Guillaume Lecointre
- UMR 7138 Systématique Adaptation Evolution, Département Systématique et Evolution, Muséum National d'Histoire Naturelle, 75005 Paris, France
| | - Jean-Loup Faulon
- Institute of Systems and Synthetic Biology, University of Evry, 91030 Evry, France.
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Beauregard-Racine J, Bicep C, Schliep K, Lopez P, Lapointe FJ, Bapteste E. Of woods and webs: possible alternatives to the tree of life for studying genomic fluidity in E. coli. Biol Direct 2011; 6:39; discussion 39. [PMID: 21774799 PMCID: PMC3160433 DOI: 10.1186/1745-6150-6-39] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2011] [Accepted: 07/20/2011] [Indexed: 12/26/2022] Open
Abstract
Background We introduce several forest-based and network-based methods for exploring microbial evolution, and apply them to the study of thousands of genes from 30 strains of E. coli. This case study illustrates how additional analyses could offer fast heuristic alternatives to standard tree of life (TOL) approaches. Results We use gene networks to identify genes with atypical modes of evolution, and genome networks to characterize the evolution of genetic partnerships between E. coli and mobile genetic elements. We develop a novel polychromatic quartet method to capture patterns of recombination within E. coli, to update the clanistic toolkit, and to search for the impact of lateral gene transfer and of pathogenicity on gene evolution in two large forests of trees bearing E. coli. We unravel high rates of lateral gene transfer involving E. coli (about 40% of the trees under study), and show that both core genes and shell genes of E. coli are affected by non-tree-like evolutionary processes. We show that pathogenic lifestyle impacted the structure of 30% of the gene trees, and that pathogenic strains are more likely to transfer genes with one another than with non-pathogenic strains. In addition, we propose five groups of genes as candidate mobile modules of pathogenicity. We also present strong evidence for recent lateral gene transfer between E. coli and mobile genetic elements. Conclusions Depending on which evolutionary questions biologists want to address (i.e. the identification of modules, genetic partnerships, recombination, lateral gene transfer, or genes with atypical evolutionary modes, etc.), forest-based and network-based methods are preferable to the reconstruction of a single tree, because they provide insights and produce hypotheses about the dynamics of genome evolution, rather than the relative branching order of species and lineages. Such a methodological pluralism - the use of woods and webs - is to be encouraged to analyse the evolutionary processes at play in microbial evolution. This manuscript was reviewed by: Ford Doolittle, Tal Pupko, Richard Burian, James McInerney, Didier Raoult, and Yan Boucher
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Abstract
The recent rapid expansion in the DNA and protein databases, arising from large-scale genomic and metagenomic sequence projects, has forced significant development in the field of phylogenetics: the study of the evolutionary relatedness of the planet's inhabitants. Advances in phylogenetic analysis have greatly transformed our view of the landscape of evolutionary biology, transcending the view of the tree of life that has shaped evolutionary theory since Darwinian times. Indeed, modern phylogenetic analysis no longer focuses on the restricted Darwinian-Mendelian model of vertical gene transfer, but must also consider the significant degree of lateral gene transfer, which connects and shapes almost all living things. Herein, I review the major tree-building methods, their strengths, weaknesses and future prospects.
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Espinosa A. Introduction: protistan biology, horizontal gene transfer, and common descent uncover faulty logic in intelligent design. J Eukaryot Microbiol 2009; 57:1-2. [PMID: 20021545 DOI: 10.1111/j.1550-7408.2009.00459.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Avelina Espinosa
- Department of Biology, Roger Williams University, Bristol, Rhode Island 02809, USA.
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Paz-Y-Miño C G, Espinosa A. Integrating horizontal gene transfer and common descent to depict evolution and contrast it with "common design". J Eukaryot Microbiol 2009; 57:11-8. [PMID: 20021546 DOI: 10.1111/j.1550-7408.2009.00458.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Horizontal gene transfer (HGT) and common descent interact in space and time. Because events of HGT co-occur with phylogenetic evolution, it is difficult to depict evolutionary patterns graphically. Tree-like representations of life's diversification are useful, but they ignore the significance of HGT in evolutionary history, particularly of unicellular organisms, ancestors of multicellular life. Here we integrate the reticulated-tree model, ring of life, symbiogenesis whole-organism model, and eliminative pattern pluralism to represent evolution. Using Entamoeba histolytica alcohol dehydrogenase 2 (EhADH2), a bifunctional enzyme in the glycolytic pathway of amoeba, we illustrate how EhADH2 could be the product of both horizontally acquired features from ancestral prokaryotes (i.e. aldehyde dehydrogenase [ALDH] and alcohol dehydrogenase [ADH]), and subsequent functional integration of these enzymes into EhADH2, which is now inherited by amoeba via common descent. Natural selection has driven the evolution of EhADH2 active sites, which require specific amino acids (cysteine 252 in the ALDH domain; histidine 754 in the ADH domain), iron- and NAD(+) as cofactors, and the substrates acetyl-CoA for ALDH and acetaldehyde for ADH. Alternative views invoking "common design" (i.e. the non-naturalistic emergence of major taxa independent from ancestry) to explain the interaction between horizontal and vertical evolution are unfounded.
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Affiliation(s)
- Guillermo Paz-Y-Miño C
- Department of Biology, University of Massachusetts Dartmouth, North Dartmouth, Massachusetts 02747, USA
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Villarreal LP, Witzany G. Viruses are essential agents within the roots and stem of the tree of life. J Theor Biol 2009; 262:698-710. [PMID: 19833132 DOI: 10.1016/j.jtbi.2009.10.014] [Citation(s) in RCA: 107] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2009] [Revised: 09/28/2009] [Accepted: 10/08/2009] [Indexed: 02/06/2023]
Abstract
In contrast with former definitions of life limited to membrane-bound cellular life forms which feed, grow, metabolise and replicate (i) a role of viruses as genetic symbionts, (ii) along with peripheral phenomena such as cryptobiosis and (iii) the horizontal nature of genetic information acquisition and processing broaden our view of the tree of life. Some researchers insist on the traditional textbook conviction of what is part of the community of life. In a recent review [Moreira, D., Lopez-Garcia, P., 2009. Ten reasons to exclude viruses from the tree of life. Nat. Rev. Microbiol. 7, 306-311.] they assemble four main arguments which should exclude viruses from the tree of life because of their inability to self-sustain and self-replicate, their polyphyly, the cellular origin of their cell-like genes and the volatility of their genomes. In this article we will show that these features are not coherent with current knowledge about viruses but that viral agents play key roles within the roots and stem of the tree of life.
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Affiliation(s)
- Luis P Villarreal
- Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA
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