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Ghaly TM, Tetu SG, Penesyan A, Qi Q, Rajabal V, Gillings MR. Discovery of integrons in Archaea: Platforms for cross-domain gene transfer. SCIENCE ADVANCES 2022; 8:eabq6376. [PMID: 36383678 PMCID: PMC9668308 DOI: 10.1126/sciadv.abq6376] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Accepted: 10/19/2022] [Indexed: 06/16/2023]
Abstract
Horizontal gene transfer between different domains of life is increasingly being recognized as an important evolutionary driver, with the potential to increase the pace of biochemical innovation and environmental adaptation. However, the mechanisms underlying the recruitment of exogenous genes from foreign domains are mostly unknown. Integrons are a family of genetic elements that facilitate this process within Bacteria. However, they have not been reported outside Bacteria, and thus their potential role in cross-domain gene transfer has not been investigated. Here, we discover that integrons are also present in 75 archaeal metagenome-assembled genomes from nine phyla, and are particularly enriched among Asgard archaea. Furthermore, we provide experimental evidence that integrons can facilitate the recruitment of archaeal genes by bacteria. Our findings establish a previously unknown mechanism of cross-domain gene transfer whereby bacteria can incorporate archaeal genes from their surrounding environment via integron activity. These findings have important implications for prokaryotic ecology and evolution.
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Affiliation(s)
- Timothy M. Ghaly
- School of Natural Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Sasha G. Tetu
- School of Natural Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Anahit Penesyan
- School of Natural Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Qin Qi
- School of Natural Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Vaheesan Rajabal
- School of Natural Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, New South Wales 2109, Australia
| | - Michael R. Gillings
- School of Natural Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, New South Wales 2109, Australia
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Ghaly TM, Gillings MR, Penesyan A, Qi Q, Rajabal V, Tetu SG. The Natural History of Integrons. Microorganisms 2021; 9:2212. [PMID: 34835338 PMCID: PMC8618304 DOI: 10.3390/microorganisms9112212] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2021] [Revised: 10/22/2021] [Accepted: 10/23/2021] [Indexed: 11/17/2022] Open
Abstract
Integrons were first identified because of their central role in assembling and disseminating antibiotic resistance genes in commensal and pathogenic bacteria. However, these clinically relevant integrons represent only a small proportion of integron diversity. Integrons are now known to be ancient genetic elements that are hotspots for genomic diversity, helping to generate adaptive phenotypes. This perspective examines the diversity, functions, and activities of integrons within both natural and clinical environments. We show how the fundamental properties of integrons exquisitely pre-adapted them to respond to the selection pressures imposed by the human use of antimicrobial compounds. We then follow the extraordinary increase in abundance of one class of integrons (class 1) that has resulted from its acquisition by multiple mobile genetic elements, and subsequent colonisation of diverse bacterial species, and a wide range of animal hosts. Consequently, this class of integrons has become a significant pollutant in its own right, to the extent that it can now be detected in most ecosystems. As human activities continue to drive environmental instability, integrons will likely continue to play key roles in bacterial adaptation in both natural and clinical settings. Understanding the ecological and evolutionary dynamics of integrons can help us predict and shape these outcomes that have direct relevance to human and ecosystem health.
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Affiliation(s)
- Timothy M. Ghaly
- Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia; (T.M.G.); (A.P.); (Q.Q.); (V.R.)
| | - Michael R. Gillings
- Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia; (T.M.G.); (A.P.); (Q.Q.); (V.R.)
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW 2109, Australia;
| | - Anahit Penesyan
- Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia; (T.M.G.); (A.P.); (Q.Q.); (V.R.)
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW 2109, Australia;
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Qin Qi
- Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia; (T.M.G.); (A.P.); (Q.Q.); (V.R.)
| | - Vaheesan Rajabal
- Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia; (T.M.G.); (A.P.); (Q.Q.); (V.R.)
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW 2109, Australia;
| | - Sasha G. Tetu
- ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney, NSW 2109, Australia;
- Department of Molecular Sciences, Macquarie University, Sydney, NSW 2109, Australia
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Buongermino Pereira M, Österlund T, Eriksson KM, Backhaus T, Axelson-Fisk M, Kristiansson E. A comprehensive survey of integron-associated genes present in metagenomes. BMC Genomics 2020; 21:495. [PMID: 32689930 PMCID: PMC7370490 DOI: 10.1186/s12864-020-06830-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 06/15/2020] [Indexed: 12/19/2022] Open
Abstract
Background Integrons are genomic elements that mediate horizontal gene transfer by inserting and removing genetic material using site-specific recombination. Integrons are commonly found in bacterial genomes, where they maintain a large and diverse set of genes that plays an important role in adaptation and evolution. Previous studies have started to characterize the wide range of biological functions present in integrons. However, the efforts have so far mainly been limited to genomes from cultivable bacteria and amplicons generated by PCR, thus targeting only a small part of the total integron diversity. Metagenomic data, generated by direct sequencing of environmental and clinical samples, provides a more holistic and unbiased analysis of integron-associated genes. However, the fragmented nature of metagenomic data has previously made such analysis highly challenging. Results Here, we present a systematic survey of integron-associated genes in metagenomic data. The analysis was based on a newly developed computational method where integron-associated genes were identified by detecting their associated recombination sites. By processing contiguous sequences assembled from more than 10 terabases of metagenomic data, we were able to identify 13,397 unique integron-associated genes. Metagenomes from marine microbial communities had the highest occurrence of integron-associated genes with levels more than 100-fold higher than in the human microbiome. The identified genes had a large functional diversity spanning over several functional classes. Genes associated with defense mechanisms and mobility facilitators were most overrepresented and more than five times as common in integrons compared to other bacterial genes. As many as two thirds of the genes were found to encode proteins of unknown function. Less than 1% of the genes were associated with antibiotic resistance, of which several were novel, previously undescribed, resistance gene variants. Conclusions Our results highlight the large functional diversity maintained by integrons present in unculturable bacteria and significantly expands the number of described integron-associated genes.
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Affiliation(s)
- Mariana Buongermino Pereira
- Department of Mathematical Sciences, Chalmers University of Technology, Gothenburg, Sweden.,Centre for Antibiotic Resistance Research (CARe) at University of Gothenburg, Gothenburg, Sweden
| | - Tobias Österlund
- Department of Mathematical Sciences, Chalmers University of Technology, Gothenburg, Sweden.,Centre for Antibiotic Resistance Research (CARe) at University of Gothenburg, Gothenburg, Sweden
| | - K Martin Eriksson
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.,Gothenburg Centre for Sustainable Development, Chalmers University of Technology, Gothenburg, Sweden
| | - Thomas Backhaus
- Centre for Antibiotic Resistance Research (CARe) at University of Gothenburg, Gothenburg, Sweden.,Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden
| | - Marina Axelson-Fisk
- Department of Mathematical Sciences, Chalmers University of Technology, Gothenburg, Sweden
| | - Erik Kristiansson
- Department of Mathematical Sciences, Chalmers University of Technology, Gothenburg, Sweden. .,Centre for Antibiotic Resistance Research (CARe) at University of Gothenburg, Gothenburg, Sweden.
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The Peril and Promise of Integrons: Beyond Antibiotic Resistance. Trends Microbiol 2020; 28:455-464. [PMID: 31948729 DOI: 10.1016/j.tim.2019.12.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 11/13/2019] [Accepted: 12/09/2019] [Indexed: 12/11/2022]
Abstract
Integrons are bacterial genetic elements that can capture, rearrange, and express mobile gene cassettes. They are best known for their role in disseminating antibiotic-resistance genes among pathogens. Their ability to rapidly spread resistance phenotypes makes it important to consider what other integron-mediated traits might impact human health in the future, such as increased virulence, pathogenicity, or resistance to novel antimicrobial strategies. Exploring the functional diversity of cassettes and understanding their de novo creation will allow better pre-emptive management of bacterial growth, while also facilitating development of technologies that could harness integron activity. If we can control integrons and cassette formation, we could use integrons as a platform for enzyme discovery and to construct novel biochemical pathways, with applications in bioremediation or biosynthesis of industrial and therapeutic molecules. Integron activity thus holds both peril and promise for humans.
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Oliveira-Pinto C, Costa PS, Reis MP, Chartone-Souza E, Nascimento AMA. Diversity of gene cassettes and the abundance of the class 1 integron-integrase gene in sediment polluted by metals. Extremophiles 2016; 20:283-9. [PMID: 26961777 DOI: 10.1007/s00792-016-0820-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 02/23/2016] [Indexed: 11/25/2022]
Abstract
The integron-gene cassette system has typically been associated with antibiotic-resistant pathogens. However, the diversity of gene cassettes and the abundance of class 1 integrons outside of the clinical context are not fully explored. Primers targeting the conserved segments of attC recombination sites were used to amplify gene cassettes from the sediment of the Mina stream, which exhibited a higher degree of stress to metal pollution in the dry season than the rainy season. Of the 143 total analyzed sequences, 101 had no matches to proteins in the database, where cassette open reading frames could be identified by homology with database entries. There was a predominance of sequences encoding essential cellular functions. Each season that was sampled yielded a specific pool of gene cassettes. Real-time PCR revealed that 8.5 and 41.6 % of bacterial cells potentially harbored a class 1 integron in the rainy and dry seasons, respectively. In summary, our findings demonstrate that most of the gene cassettes have no ascribable function and, apparently, historically metal-contaminated sediment favors the maintenance of bacteria containing the intI1 gene. Thus, the diversity of gene cassettes is far from being fully explored deserving further attention.
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Affiliation(s)
- Clarisse Oliveira-Pinto
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, Belo Horizonte, Minas Gerais, 31270-901, Brazil
| | - Patrícia S Costa
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, Belo Horizonte, Minas Gerais, 31270-901, Brazil
| | - Mariana P Reis
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, Belo Horizonte, Minas Gerais, 31270-901, Brazil
| | - Edmar Chartone-Souza
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, Belo Horizonte, Minas Gerais, 31270-901, Brazil
| | - Andréa M A Nascimento
- Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antônio Carlos 6627, Belo Horizonte, Minas Gerais, 31270-901, Brazil.
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Abella J, Fahy A, Duran R, Cagnon C. Integron diversity in bacterial communities of freshwater sediments at different contamination levels. FEMS Microbiol Ecol 2015; 91:fiv140. [DOI: 10.1093/femsec/fiv140] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/04/2015] [Indexed: 12/29/2022] Open
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Abella J, Bielen A, Huang L, Delmont TO, Vujaklija D, Duran R, Cagnon C. Integron diversity in marine environments. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2015. [PMID: 26213132 DOI: 10.1007/s11356-015-5085-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Integrons are bacterial genetic elements known to be active vectors of antibiotic resistance among clinical bacteria. They are also found in bacterial communities from natural environments. Although integrons have become especially efficient for bacterial adaptation in the particular context of antibiotic usage, their role in natural environments in other contexts is still unknown. Indeed, most studies have focused on integrons and the spread of antibiotic resistance in freshwater or soil impacted by anthropogenic activities, with only few on marine environments. Notably, integrons show a wider diversity of both gene cassettes and integrase gene in natural environments than in clinical environments, suggesting a general role of integrons in bacterial adaptation. This article reviews the current knowledge on integrons in marine environments. We also present conclusions of our studies on polluted and nonpolluted backgrounds.
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Affiliation(s)
- Justine Abella
- Equipe Environnement et Microbiologie, MELODY Group, Université de Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013, Pau, Cedex, France
| | - Ana Bielen
- Laboratory for Molecular Genetics, Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, 10000, Zagreb, Croatia
- Laboratory for Biology and Microbial Genetics, Department of Biochemical Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, 10000, Zagreb, Croatia
| | - Lionel Huang
- Equipe Environnement et Microbiologie, MELODY Group, Université de Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013, Pau, Cedex, France
- Euro Engineering, Technopole Hélioparc Bât Newton, 4 rue Jules Ferry, CS N 99207, 64053, Pau, Cedex 09, France
| | - Tom O Delmont
- Equipe Environnement et Microbiologie, MELODY Group, Université de Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013, Pau, Cedex, France
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biology Laboratory, Woods Hole, MA, USA
| | - Dušica Vujaklija
- Laboratory for Molecular Genetics, Division of Molecular Biology, Ruđer Bošković Institute, Bijenička 54, 10000, Zagreb, Croatia
| | - Robert Duran
- Equipe Environnement et Microbiologie, MELODY Group, Université de Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013, Pau, Cedex, France
| | - Christine Cagnon
- Equipe Environnement et Microbiologie, MELODY Group, Université de Pau et des Pays de l'Adour, IPREM UMR CNRS 5254, BP 1155, 64013, Pau, Cedex, France.
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Abstract
Integrons are versatile gene acquisition systems commonly found in bacterial genomes. They are ancient elements that are a hot spot for genomic complexity, generating phenotypic diversity and shaping adaptive responses. In recent times, they have had a major role in the acquisition, expression, and dissemination of antibiotic resistance genes. Assessing the ongoing threats posed by integrons requires an understanding of their origins and evolutionary history. This review examines the functions and activities of integrons before the antibiotic era. It shows how antibiotic use selected particular integrons from among the environmental pool of these elements, such that integrons carrying resistance genes are now present in the majority of Gram-negative pathogens. Finally, it examines the potential consequences of widespread pollution with the novel integrons that have been assembled via the agency of human antibiotic use and speculates on the potential uses of integrons as platforms for biotechnology.
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Rapa RA, Labbate M. The function of integron-associated gene cassettes in Vibrio species: the tip of the iceberg. Front Microbiol 2013; 4:385. [PMID: 24367362 PMCID: PMC3856429 DOI: 10.3389/fmicb.2013.00385] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Accepted: 11/25/2013] [Indexed: 12/17/2022] Open
Abstract
The integron is a genetic element that incorporates mobile genes termed gene cassettes into a reserved genetic site via site-specific recombination. It is best known for its role in antibiotic resistance with one type of integron, the class 1 integron, a major player in the dissemination of antibiotic resistance genes across Gram negative pathogens and commensals. However, integrons are ancient structures with over 100 classes (including class 1) present in bacteria from the broader environment. While, the class 1 integron is only one example of an integron being mobilized into the clinical environment, it is by far the most successful. Unlike clinical class 1 integrons which are largely found on plasmids, other integron classes are found on the chromosomes of bacteria and carry diverse gene cassettes indicating a non-antibiotic resistance role(s). However, there is very limited knowledge on what these alternative roles are. This is particularly relevant to Vibrio species where gene cassettes make up approximately 1-3% of their entire genome. In this review, we discuss how emphasis on class 1 integron research has resulted in a limited understanding by the wider research community on the role of integrons in the broader environment. This has the capacity to be counterproductive in solving or improving the antibiotic resistance problem into the future. Furthermore, there is still a significant lack of knowledge on how gene cassettes in Vibrio species drive adaptation and evolution. From research in Vibrio rotiferianus DAT722, new insight into how gene cassettes affect cellular physiology offers new alternative roles for the gene cassette resource. At least a subset of gene cassettes are involved in host surface polysaccharide modification suggesting that gene cassettes may be important in processes such as bacteriophage resistance, adhesion/biofilm formation, protection from grazers and bacterial aggregation.
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Affiliation(s)
- Rita A Rapa
- ithree Institute, University of Technology Sydney, NSW, Australia ; Department of Medical and Molecular Biosciences, University of Technology Sydney, NSW, Australia
| | - Maurizio Labbate
- ithree Institute, University of Technology Sydney, NSW, Australia ; Department of Medical and Molecular Biosciences, University of Technology Sydney, NSW, Australia
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