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Gibert M, Jiménez CJ, Comas J, Zechner EL, Madrid C, Balsalobre C. In Situ Monitoring and Quantitative Determination of R27 Plasmid Conjugation. LIFE (BASEL, SWITZERLAND) 2022; 12:life12081212. [PMID: 36013391 PMCID: PMC9410318 DOI: 10.3390/life12081212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 08/06/2022] [Accepted: 08/07/2022] [Indexed: 11/16/2022]
Abstract
Horizontal gene transfer (HGT) by plasmid conjugation is a major driving force in the spread of antibiotic resistance among Enterobacteriaceae. Most of the conjugation studies are based on calculation of conjugation ratios (number of transconjugants/number of donors) after viable counting of transconjugant and donor cells. The development of robust, fast and reliable techniques for in situ monitoring and quantification of conjugation ratios might accelerate progress in understanding the impact of this cellular process in the HGT. The IncHI1 plasmids, involved in multiresistance phenotypes of relevant pathogens such as Salmonella and E. coli, are distinguished by the thermosensitivity of their conjugative transfer. Conjugation mediated by IncHI1 plasmids is more efficient at temperatures lower than 30 °C, suggesting that the transfer process takes place during the environmental transit of the bacteria. In this report, we described a methodology to monitor in situ the conjugation process during agar surface matings of the IncHI1 plasmid R27 and its derepressed derivative drR27 at different temperatures. A three-color-labeling strategy was used to visualize the spatial distribution of transconjugants within the heterogeneous environment by epifluorescence and confocal microscopy. Moreover, the fluorescent labelling was also used to quantify conjugation frequencies in liquid media by flow cytometry.
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Affiliation(s)
- Marta Gibert
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Avda, Diagonal 643, 08028 Barcelona, Spain
| | - Carlos J. Jiménez
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Avda, Diagonal 643, 08028 Barcelona, Spain
| | - Jaume Comas
- Laboratori de Citometria/Genòmica CCiT, Parc Científic de Barcelona, Baldiri Reixac 10, 08024 Barcelona, Spain
| | - Ellen L. Zechner
- Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50, A-8010 Graz, Austria
| | - Cristina Madrid
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Avda, Diagonal 643, 08028 Barcelona, Spain
- Correspondence: (C.M.); (C.B.); Tel.: +34-934-039-382 (C.M.); +34-934-034-622 (C.B.)
| | - Carlos Balsalobre
- Departament de Genètica, Microbiologia i Estadística, Universitat de Barcelona, Avda, Diagonal 643, 08028 Barcelona, Spain
- Correspondence: (C.M.); (C.B.); Tel.: +34-934-039-382 (C.M.); +34-934-034-622 (C.B.)
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PixR, a Novel Activator of Conjugative Transfer of IncX4 Resistance Plasmids, Mitigates the Fitness Cost of mcr-1 Carriage in Escherichia coli. mBio 2022; 13:e0320921. [PMID: 35089067 PMCID: PMC8725589 DOI: 10.1128/mbio.03209-21] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The emergence of the plasmid-borne colistin resistance gene mcr-1 threatens public health. IncX4-type plasmids are one of the most epidemiologically successful vehicles for spreading mcr-1 worldwide. Since MCR-1 is known for imposing a fitness cost to its host bacterium, the successful spread of mcr-1-bearing plasmids might be linked to high conjugation frequency, which would enhance the maintenance of the plasmid in the host without antibiotic selection. However, the mechanism of IncX4 plasmid conjugation remains unclear. In this study, we used high-density transposon mutagenesis to identify factors required for IncX4 plasmid transfer. Eighteen essential transfer genes were identified, including five with annotations unrelated to conjugation. Cappable-seq, transcriptome sequencing (RNA-seq), electrophoretic mobility shift assay, and β-galactosidase assay confirmed that a novel transcriptional regulator gene, pixR, directly regulates the transfer of IncX4 plasmids by binding the promoter of 13 essential transfer genes to increase their transcription. PixR is not active under nonmating conditions, while the expression of the pixR, pilX3-4, and pilX11 genes increased 3- to 6-fold upon contact with recipient Escherichia coli C600. Plasmid invasion and coculture competition assays revealed the essentiality of pixR for spreading and persistence of mcr-1-bearing IncX4 plasmids in bacterial populations. Effective conjugation is crucial for alleviating the fitness cost exerted by mcr-1 carriage. The existence of the IncX4-specific pixR gene increases plasmid transmissibility while promoting the invasion and persistence of mcr-1-bearing plasmids in bacterial populations, which helps explain their global prevalence. IMPORTANCE The spread of clinically relevant antibiotic resistance genes is often linked to the dissemination of epidemic plasmids. However, the underlying molecular mechanisms contributing to the successful spread of epidemic plasmids remain unclear. In this report, we shine a light on the transfer activation of IncX4 plasmids. We show how conjugation promotes the invasion and persistence of IncX4 plasmids within a bacterial population. The dissection of the regulatory network of conjugation helps explain the rapid spread of epidemic plasmids in nature. It also reveals potential targets for the development of conjugation inhibitors.
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Delgado-Blas JF, Ovejero CM, David S, Montero N, Calero-Caceres W, Garcillan-Barcia MP, de la Cruz F, Muniesa M, Aanensen DM, Gonzalez-Zorn B. Population genomics and antimicrobial resistance dynamics of Escherichia coli in wastewater and river environments. Commun Biol 2021; 4:457. [PMID: 33846529 PMCID: PMC8041779 DOI: 10.1038/s42003-021-01949-x] [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: 08/05/2020] [Accepted: 03/02/2021] [Indexed: 12/17/2022] Open
Abstract
Aquatic environments are key niches for the emergence, evolution and dissemination of antimicrobial resistance. However, the population diversity and the genetic elements that drive the dynamics of resistant bacteria in different aquatic environments are still largely unknown. The aim of this study was to understand the population genomics and evolutionary events of Escherichia coli resistant to clinically important antibiotics including aminoglycosides, in anthropogenic and natural water ecosystems. Here we show that less different E. coli sequence types (STs) are identified in wastewater than in rivers, albeit more resistant to antibiotics, and with significantly more plasmids/cell (6.36 vs 3.72). However, the genomic diversity within E. coli STs in both aquatic environments is similar. Wastewater environments favor the selection of conserved chromosomal structures associated with diverse flexible plasmids, unraveling promiscuous interplasmidic resistance genes flux. On the contrary, the key driver for river E. coli adaptation is a mutable chromosome along with few plasmid types shared between diverse STs harboring a limited resistance gene content.
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Affiliation(s)
- Jose F Delgado-Blas
- Antimicrobial Resistance Unit (ARU), Animal Health Department, Faculty of Veterinary Medicine and VISAVET Health Surveillance Centre, Complutense University of Madrid, Madrid, Spain
| | - Cristina M Ovejero
- Antimicrobial Resistance Unit (ARU), Animal Health Department, Faculty of Veterinary Medicine and VISAVET Health Surveillance Centre, Complutense University of Madrid, Madrid, Spain
| | - Sophia David
- Centre for Genomic Pathogen Surveillance (CGPS), Wellcome Sanger Institute, Hinxton, UK
| | - Natalia Montero
- Antimicrobial Resistance Unit (ARU), Animal Health Department, Faculty of Veterinary Medicine and VISAVET Health Surveillance Centre, Complutense University of Madrid, Madrid, Spain
| | - William Calero-Caceres
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain
- UTA RAM One Health, Faculty of Food Science, Engineering and Biotechnology, Technical University of Ambato, Ambato, Ecuador
| | - M Pilar Garcillan-Barcia
- Institute of Biomedicine and Biotechnology (IBBTEC), CSIC, University of Cantabria, Santander, Spain
| | - Fernando de la Cruz
- Institute of Biomedicine and Biotechnology (IBBTEC), CSIC, University of Cantabria, Santander, Spain
| | - Maite Muniesa
- Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - David M Aanensen
- Centre for Genomic Pathogen Surveillance (CGPS), Wellcome Sanger Institute, Hinxton, UK
| | - Bruno Gonzalez-Zorn
- Antimicrobial Resistance Unit (ARU), Animal Health Department, Faculty of Veterinary Medicine and VISAVET Health Surveillance Centre, Complutense University of Madrid, Madrid, Spain.
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Gibert M, Paytubi S, Madrid C, Balsalobre C. Temperature Dependent Control of the R27 Conjugative Plasmid Genes. Front Mol Biosci 2020; 7:124. [PMID: 32754612 PMCID: PMC7366339 DOI: 10.3389/fmolb.2020.00124] [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] [Received: 04/30/2020] [Accepted: 06/02/2020] [Indexed: 11/25/2022] Open
Abstract
Conjugation of R27 plasmid is thermoregulated, being promoted at 25°C and repressed at 37°C. Previous studies identified plasmid-encoded regulators, HtdA, TrhR and TrhY, that control expression of conjugation-related genes (tra). Moreover, the nucleoid-associated protein H-NS represses conjugation at non-permissive temperature. A transcriptomic approach has been used to characterize the effect of temperature on the expression of the 205 R27 genes. Many of the 35 tra genes, directly involved in plasmid-conjugation, were upregulated at 25°C. However, the majority of the non-tra R27 genes—many of them with unknown function—were more actively expressed at 37°C. The role of HtdA, a regulator that causes repression of the R27 conjugation by counteracting TrhR/TrhY mediated activation of tra genes, has been investigated. Most of the R27 genes are severely derepressed at 25°C in an htdA mutant, suggesting that HtdA is involved also in the repression of R27 genes other than the tra genes. Interestingly, the effect of htdA mutation was abolished at non-permissive temperature, indicating that the HtdA-TrhR/TrhY regulatory circuit mediates the environmental regulation of R27 gene expression. The role of H-NS in the proposed model is discussed.
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Affiliation(s)
- Marta Gibert
- Department of Genetics, Microbiology and Statistics, University of Barcelona, Barcelona, Spain
| | - Sonia Paytubi
- Department of Genetics, Microbiology and Statistics, University of Barcelona, Barcelona, Spain
| | - Cristina Madrid
- Department of Genetics, Microbiology and Statistics, University of Barcelona, Barcelona, Spain
| | - Carlos Balsalobre
- Department of Genetics, Microbiology and Statistics, University of Barcelona, Barcelona, Spain
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Luque A, Paytubi S, Sánchez-Montejo J, Gibert M, Balsalobre C, Madrid C. Crosstalk between bacterial conjugation and motility is mediated by plasmid-borne regulators. ENVIRONMENTAL MICROBIOLOGY REPORTS 2019; 11:708-717. [PMID: 31309702 DOI: 10.1111/1758-2229.12784] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Accepted: 07/12/2019] [Indexed: 06/10/2023]
Abstract
Plasmid conjugation is a major horizontal gene transfer mechanism. The acquisition of a plasmid may cause a perturbation of the cell functions in addition to provide advantageous properties for the recipient cell, such as the gaining of antibiotic resistances. The interplay between plasmid and chromosomal functions has been studied using the IncHI1 plasmid R27. Plasmids of the incompatibility group HI1, isolated from several Gram-negative pathogens, are associated with the spread of multidrug resistance. Their conjugation is tightly regulated by temperature, being repressed at temperatures within the host (37°C). In this report, we described that at permissive temperature, when conjugation of plasmid R27 is prompted, a reduction in the motility of the cells is observed. This reduction is mediated by the plasmid-encoded regulators TrhR/TrhY, which together with HtdA form a plasmid-borne regulatory circuit controlling R27 conjugation. TrhR/TrhY, required to induce R27 conjugation, is responsible for the downregulation of the flagella synthesis and the consequent decrease in motility. TrhR/TrhY repress, direct or indirectly, the expression of the specific flagellar sigma subunit FliA and, consequently, the expression of all genes located bellow in the flagellar expression cascade.
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Affiliation(s)
- Ainara Luque
- Secció de Microbiologia, Virologia i Biotecnologia. Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain
| | - Sonia Paytubi
- Secció de Microbiologia, Virologia i Biotecnologia. Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain
| | - Javier Sánchez-Montejo
- Secció de Microbiologia, Virologia i Biotecnologia. Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain
| | - Marta Gibert
- Secció de Microbiologia, Virologia i Biotecnologia. Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain
| | - Carlos Balsalobre
- Secció de Microbiologia, Virologia i Biotecnologia. Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain
| | - Cristina Madrid
- Secció de Microbiologia, Virologia i Biotecnologia. Departament de Genètica, Microbiologia i Estadística, Facultat de Biologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain
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Gibert M, Paytubi S, Beltrán S, Juárez A, Balsalobre C, Madrid C. Growth phase-dependent control of R27 conjugation is mediated by the interplay between the plasmid-encoded regulatory circuit TrhR/TrhY-HtdA and the cAMP regulon. Environ Microbiol 2016; 18:5277-5287. [PMID: 27768816 DOI: 10.1111/1462-2920.13579] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 10/14/2016] [Indexed: 01/06/2023]
Abstract
Plasmids of the incompatibility group HI1 (IncHI1) have been isolated from several Gram-negative pathogens and are associated with the spread of multidrug resistance. Their conjugation is tightly regulated and it is inhibited at temperatures higher than 30°C, indicating that conjugation occurs outside warm-blooded hosts. Using R27, the prototype of IncHI1 plasmids, we report that plasmid transfer efficiency in E. coli strongly depends on the physiological state of the donor cells. Conjugation frequency is high when cells are actively growing, dropping sharply when cells enter the stationary phase of growth. Accordingly, our transcriptomic assays show significant downregulation of numerous R27 genes during the stationary phase, including several tra (transfer) genes. Growth phase-dependent regulation of tra genes transcription is independent of H-NS, a silencer of horizontal gene transfer, and ppGpp and RpoS, regulators of the stationary phase, but highly dependent on the plasmid-encoded regulatory circuit TrhR/TrhY-HtdA. The metabolic sensor cAMP, whose synthesis is chromosomally encoded, is also involved in the growth phase regulation of R27 conjugation by modulating htdA expression. Our data suggest that the involvement of regulators encoded by both chromosome and plasmid are required for efficient physiological control of IncHI1 plasmid conjugation.
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Affiliation(s)
- Marta Gibert
- Departament de Microbiologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain
| | - Sonia Paytubi
- Departament de Microbiologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain
| | - Sergi Beltrán
- Centre Nacional d'Anàlisi Genòmica (CNAG), Parc Científic de Barcelona, Baldiri Reixac 4, Barcelona, 08028, Spain
| | - Antonio Juárez
- Departament de Microbiologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain.,Institut de Bioenginyeria de Catalunya (IBEC), Parc Científic de Barcelona, Baldiri Reixac 10, Barcelona, 08028, Spain
| | - Carlos Balsalobre
- Departament de Microbiologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain
| | - Cristina Madrid
- Departament de Microbiologia, Universitat de Barcelona, Avda. Diagonal 643, Barcelona, 08028, Spain
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Gruber CJ, Lang S, Rajendra VKH, Nuk M, Raffl S, Schildbach JF, Zechner EL. Conjugative DNA Transfer Is Enhanced by Plasmid R1 Partitioning Proteins. Front Mol Biosci 2016; 3:32. [PMID: 27486582 PMCID: PMC4949242 DOI: 10.3389/fmolb.2016.00032] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 07/01/2016] [Indexed: 11/22/2022] Open
Abstract
Bacterial conjugation is a form of type IV secretion used to transport protein and DNA directly to recipient bacteria. The process is cell contact-dependent, yet the mechanisms enabling extracellular events to trigger plasmid transfer to begin inside the cell remain obscure. In this study of plasmid R1 we investigated the role of plasmid proteins in the initiation of gene transfer. We find that TraI, the central regulator of conjugative DNA processing, interacts physically, and functionally with the plasmid partitioning proteins ParM and ParR. These interactions stimulate TraI catalyzed relaxation of plasmid DNA in vivo and in vitro and increase ParM ATPase activity. ParM also binds the coupling protein TraD and VirB4-like channel ATPase TraC. Together, these protein-protein interactions probably act to co-localize the transfer components intracellularly and promote assembly of the conjugation machinery. Importantly these data also indicate that the continued association of ParM and ParR at the conjugative pore is necessary for plasmid transfer to start efficiently. Moreover, the conjugative pilus and underlying secretion machinery assembled in the absence of Par proteins mediate poor biofilm formation and are completely dysfunctional for pilus specific R17 bacteriophage uptake. Thus, functional integration of Par components at the interface of relaxosome, coupling protein, and channel ATPases appears important for an optimal conformation and effective activation of the transfer machinery. We conclude that low copy plasmid R1 has evolved an active segregation system that optimizes both its vertical and lateral modes of dissemination.
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Affiliation(s)
- Christian J Gruber
- Institute of Molecular Biosciences, University of Graz, BioTechMed-Graz Graz, Austria
| | - Silvia Lang
- Institute of Molecular Biosciences, University of Graz, BioTechMed-Graz Graz, Austria
| | - Vinod K H Rajendra
- Institute of Molecular Biosciences, University of Graz, BioTechMed-Graz Graz, Austria
| | - Monika Nuk
- Institute of Molecular Biosciences, University of Graz, BioTechMed-Graz Graz, Austria
| | - Sandra Raffl
- Institute of Molecular Biosciences, University of Graz, BioTechMed-Graz Graz, Austria
| | | | - Ellen L Zechner
- Institute of Molecular Biosciences, University of Graz, BioTechMed-Graz Graz, Austria
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