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Stindt KR, McClean MN. Tuning interdomain conjugation to enable in situ population modification in yeasts. mSystems 2024; 9:e0005024. [PMID: 38747597 DOI: 10.1128/msystems.00050-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Accepted: 04/15/2024] [Indexed: 05/28/2024] Open
Abstract
The ability to modify and control natural and engineered microbiomes is essential for biotechnology and biomedicine. Fungi are critical members of most microbiomes, yet technology for modifying the fungal members of a microbiome has lagged far behind that for bacteria. Interdomain conjugation (IDC) is a promising approach, as DNA transfer from bacterial cells to yeast enables in situ modification. While such genetic transfers have been known to naturally occur in a wide range of eukaryotes and are thought to contribute to their evolution, IDC has been understudied as a technique to control fungal or fungal-bacterial consortia. One major obstacle to the widespread use of IDC is its limited efficiency. In this work, we manipulated metabolic and physical interactions between genetically tractable Escherichia coli and Saccharomyces cerevisiae to control the incidence of IDC. We test the landscape of population interactions between the bacterial donors and yeast recipients to find that bacterial commensalism leads to maximized IDC, both in culture and in mixed colonies. We demonstrate the capacity of cell-to-cell binding via mannoproteins to assist both IDC incidence and bacterial commensalism in culture and model how these tunable controls can predictably yield a range of IDC outcomes. Furthermore, we demonstrate that these controls can be utilized to irreversibly alter a recipient yeast population, by both "rescuing" a poor-growing recipient population and collapsing a stable population via a novel IDC-mediated CRISPR/Cas9 system.IMPORTANCEFungi are important but often unaddressed members of most natural and synthetic microbial communities. This work highlights opportunities for modifying yeast microbiome populations through bacterial conjugation. While conjugation has been recognized for its capacity to deliver engineerable DNA to a range of cells, its dependence on cell contact has limited its efficiency. Here, we find "knobs" to control DNA transfer, by engineering the metabolic dependence between bacterial donors and yeast recipients and by changing their ability to physically adhere to each other. Importantly, we functionally validate these "knobs" by irreversibly altering yeast populations. We use these controls to "rescue" a failing yeast population, demonstrate the capacity of conjugated CRISPR/Cas9 to depress or collapse populations, and show that conjugation can be easily interrupted by disrupting cell-to-cell binding. These results offer building blocks toward in situ mycobiome editing, with significant implications for clinical treatments of fungal pathogens and other fungal system engineering.
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Affiliation(s)
- Kevin R Stindt
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA
- Doctoral Program in Biophysics, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Megan N McClean
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, USA
- University of Wisconsin Carbone Cancer Center, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
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2
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Stindt KR, McClean MN. Tuning Interdomain Conjugation Toward in situ Population Modification in Yeast. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.12.557379. [PMID: 37745509 PMCID: PMC10515866 DOI: 10.1101/2023.09.12.557379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/26/2023]
Abstract
The ability to modify and control natural and engineered microbiomes is essential for biotechnology and biomedicine. Fungi are critical members of most microbiomes, yet technology for modifying the fungal members of a microbiome has lagged far behind that for bacteria. Interdomain conjugation (IDC) is a promising approach, as DNA transfer from bacterial cells to yeast enables in situ modification. While such genetic transfers have been known to naturally occur in a wide range of eukaryotes, and are thought to contribute to their evolution, IDC has been understudied as a technique to control fungal or fungal-bacterial consortia. One major obstacle to widespread use of IDC is its limited efficiency. In this work, we utilize interactions between genetically tractable Escherichia coli and Saccharomyces cerevisiae to control the incidence of IDC. We test the landscape of population interactions between the bacterial donors and yeast recipients to find that bacterial commensalism leads to maximized IDC, both in culture and in mixed colonies. We demonstrate the capacity of cell-to-cell binding via mannoproteins to assist both IDC incidence and bacterial commensalism in culture, and model how these tunable controls can predictably yield a range of IDC outcomes. Further, we demonstrate that these lessons can be utilized to lastingly alter a recipient yeast population, by both "rescuing" a poor-growing recipient population and collapsing a stable population via a novel IDC-mediated CRISPR/Cas9 system.
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3
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Vink JNA, Hayhurst M, Gerth ML. Harnessing CRISPR-Cas for oomycete genome editing. Trends Microbiol 2023; 31:947-958. [PMID: 37127441 DOI: 10.1016/j.tim.2023.03.017] [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: 10/20/2022] [Revised: 03/08/2023] [Accepted: 03/29/2023] [Indexed: 05/03/2023]
Abstract
Oomycetes are a group of microorganisms that include pathogens responsible for devastating diseases in plants and animals worldwide. Despite their importance, the development of genome editing techniques for oomycetes has progressed more slowly than for model microorganisms. Here, we review recent breakthroughs in clustered regularly interspaced short palindromic repeats (CRISPR)-Cas technologies that are expanding the genome editing toolbox for oomycetes - from the original Cas9 study to Cas12a editing, ribonucleoprotein (RNP) delivery, and complementation. We also discuss some of the challenges to applying CRISPR-Cas in oomycetes and potential ways to overcome them. Advances in CRISPR-Cas technologies are being used to illuminate the biology of oomycetes, which ultimately can guide the development of tools for managing oomycete diseases.
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Affiliation(s)
- Jochem N A Vink
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Max Hayhurst
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand
| | - Monica L Gerth
- School of Biological Sciences, Victoria University of Wellington, Wellington 6012, New Zealand; Bioprotection Aotearoa National Centre of Research Excellence, New Zealand.
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Ryan ME, Damke PP, Shaffer CL. DNA Transport through the Dynamic Type IV Secretion System. Infect Immun 2023; 91:e0043622. [PMID: 37338415 PMCID: PMC10353360 DOI: 10.1128/iai.00436-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2023] Open
Abstract
The versatile type IV secretion system (T4SS) nanomachine plays a pivotal role in bacterial pathogenesis and the propagation of antibiotic resistance determinants throughout microbial populations. In addition to paradigmatic DNA conjugation machineries, diverse T4SSs enable the delivery of multifarious effector proteins to target prokaryotic and eukaryotic cells, mediate DNA export and uptake from the extracellular milieu, and in rare examples, facilitate transkingdom DNA translocation. Recent advances have identified new mechanisms underlying unilateral nucleic acid transport through the T4SS apparatus, highlighting both functional plasticity and evolutionary adaptations that enable novel capabilities. In this review, we describe the molecular mechanisms underscoring DNA translocation through diverse T4SS machineries, emphasizing the architectural features that implement DNA exchange across the bacterial membrane and license transverse DNA release across kingdom boundaries. We further detail how recent studies have addressed outstanding questions surrounding the mechanisms by which nanomachine architectures and substrate recruitment strategies contribute to T4SS functional diversity.
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Affiliation(s)
- Mackenzie E. Ryan
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Prashant P. Damke
- Department of Veterinary Sciences, University of Kentucky College of Agriculture, Lexington, Kentucky, USA
| | - Carrie L. Shaffer
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
- Department of Veterinary Sciences, University of Kentucky College of Agriculture, Lexington, Kentucky, USA
- Department of Pharmaceutical Sciences, University of Kentucky College of Pharmacy, Lexington, Kentucky, USA
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky, USA
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5
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Cochrane RR, Shrestha A, Severo de Almeida MM, Agyare-Tabbi M, Brumwell SL, Hamadache S, Meaney JS, Nucifora DP, Say HH, Sharma J, Soltysiak MPM, Tong C, Van Belois K, Walker EJL, Lachance MA, Gloor GB, Edgell DR, Shapiro RS, Karas BJ. Superior Conjugative Plasmids Delivered by Bacteria to Diverse Fungi. BIODESIGN RESEARCH 2022; 2022:9802168. [PMID: 37850145 PMCID: PMC10521675 DOI: 10.34133/2022/9802168] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Accepted: 07/28/2022] [Indexed: 10/19/2023] Open
Abstract
Fungi are nature's recyclers, allowing for ecological nutrient cycling and, in turn, the continuation of life on Earth. Some fungi inhabit the human microbiome where they can provide health benefits, while others are opportunistic pathogens that can cause disease. Yeasts, members of the fungal kingdom, have been domesticated by humans for the production of beer, bread, and, recently, medicine and chemicals. Still, the great untapped potential exists within the diverse fungal kingdom. However, many yeasts are intractable, preventing their use in biotechnology or in the development of novel treatments for pathogenic fungi. Therefore, as a first step for the domestication of new fungi, an efficient DNA delivery method needs to be developed. Here, we report the creation of superior conjugative plasmids and demonstrate their transfer via conjugation from bacteria to 7 diverse yeast species including the emerging pathogen Candida auris. To create our superior plasmids, derivatives of the 57 kb conjugative plasmid pTA-Mob 2.0 were built using designed gene deletions and insertions, as well as some unintentional mutations. Specifically, a cluster mutation in the promoter of the conjugative gene traJ had the most significant effect on improving conjugation to yeasts. In addition, we created Golden Gate assembly-compatible plasmid derivatives that allow for the generation of custom plasmids to enable the rapid insertion of designer genetic cassettes. Finally, we demonstrated that designer conjugative plasmids harboring engineered restriction endonucleases can be used as a novel antifungal agent, with important applications for the development of next-generation antifungal therapeutics.
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Affiliation(s)
- Ryan R. Cochrane
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada, N6A 5C1
| | - Arina Shrestha
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada, N6A 5C1
| | - Mariana M. Severo de Almeida
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada, N6A 5C1
| | - Michelle Agyare-Tabbi
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Stephanie L. Brumwell
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada, N6A 5C1
| | - Samir Hamadache
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada, N6A 5C1
| | - Jordyn S. Meaney
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada, N6A 5C1
| | - Daniel P. Nucifora
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada, N6A 5C1
| | - Henry Heng Say
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada, N6A 5C1
| | - Jehoshua Sharma
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | | | - Cheryl Tong
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada, N6A 5C1
| | - Katherine Van Belois
- Department of Biology, The University of Western Ontario, London, Ontario, Canada, N6A 5B7
| | - Emma J. L. Walker
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada, N6A 5C1
| | - Marc-André Lachance
- Department of Biology, The University of Western Ontario, London, Ontario, Canada, N6A 5B7
| | - Gregory B. Gloor
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada, N6A 5C1
| | - David R. Edgell
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada, N6A 5C1
| | - Rebecca S. Shapiro
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada, N1G 2W1
| | - Bogumil J. Karas
- Department of Biochemistry, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada, N6A 5C1
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6
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Zoolkefli FIRM, Moriguchi K, Cho Y, Kiyokawa K, Yamamoto S, Suzuki K. Isolation and Analysis of Donor Chromosomal Genes Whose Deficiency Is Responsible for Accelerating Bacterial and Trans-Kingdom Conjugations by IncP1 T4SS Machinery. Front Microbiol 2021; 12:620535. [PMID: 34093458 PMCID: PMC8174662 DOI: 10.3389/fmicb.2021.620535] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Accepted: 04/06/2021] [Indexed: 11/13/2022] Open
Abstract
Conjugal transfer is a major driving force of genetic exchange in eubacteria, and the system in IncP1-type broad-host-range plasmids transfers DNA even to eukaryotes and archaea in a process known as trans-kingdom conjugation (TKC). Although conjugation factors encoded on plasmids have been extensively analyzed, those on the donor chromosome have not. To identify the potential conjugation factor(s), a genome-wide survey on a comprehensive collection of Escherichia coli gene knockout mutants (Keio collection) as donors to Saccharomyces cerevisiae recipients was performed using a conjugal transfer system mediated by the type IV secretion system (T4SS) of the IncP1α plasmid. Out of 3,884 mutants, three mutants (ΔfrmR, ΔsufA, and ΔiscA) were isolated, which showed an increase by one order of magnitude in both E. coli-E. coli and E. coli-yeast conjugations without an increase in the mRNA accumulation level for the conjugation related genes examined. The double-knockout mutants for these genes (ΔfrmRΔsufA and ΔiscAΔfrmR) did not show synergistic effects on the conjugation efficiency, suggesting that these factors affect a common step in the conjugation machinery. The three mutants demonstrated increased conjugation efficiency in IncP1β-type but not in IncN- and IncW-type broad-host-range plasmid transfers, and the homologous gene knockout mutants against the three genes in Agrobacterium tumefaciens also showed increased TKC efficiency. These results suggest the existence of a specific regulatory system in IncP1 plasmids that enables the control of conjugation efficiency in different hosts, which could be utilized for the development of donor strains as gene introduction tools into bacteria, eukaryotes, and archaea.
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Affiliation(s)
| | - Kazuki Moriguchi
- Department of Biological Science, Graduate School of Science, Hiroshima University, Higashihiroshima, Japan.,Program of Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Japan
| | - Yunjae Cho
- Department of Biological Science, Faculty of Science, Hiroshima University, Higashihiroshima, Japan
| | - Kazuya Kiyokawa
- Program of Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Japan
| | - Shinji Yamamoto
- Department of Biological Science, Graduate School of Science, Hiroshima University, Higashihiroshima, Japan
| | - Katsunori Suzuki
- Department of Biological Science, Graduate School of Science, Hiroshima University, Higashihiroshima, Japan.,Program of Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Japan
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7
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Moriguchi K, Zoolkefli FIRM, Abe M, Kiyokawa K, Yamamoto S, Suzuki K. Targeting Antibiotic Resistance Genes Is a Better Approach to Block Acquisition of Antibiotic Resistance Than Blocking Conjugal Transfer by Recipient Cells: A Genome-Wide Screening in Escherichia coli. Front Microbiol 2020; 10:2939. [PMID: 31969865 PMCID: PMC6960129 DOI: 10.3389/fmicb.2019.02939] [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: 09/26/2019] [Accepted: 12/06/2019] [Indexed: 11/21/2022] Open
Abstract
The conjugal transfer is a major driving force in the spread of antibiotic resistance genes. Nevertheless, an effective approach has not yet been developed to target conjugal transfer to prevent the acquisition of antibiotic resistance by this mechanism. This study aimed to identify potential targets for plasmid transfer blockade by isolating mutants defective in the completion of the acquisition of antibiotic resistance via conjugal transfer. We performed genome-wide screening by combining an IncP1α-type broad host range plasmid conjugation system with a comprehensive collection of Escherichia coli gene knockout mutants (Keio collection; 3884 mutants). We followed a six-step screening procedure to identify the mutants showing conjugation deficiency precisely. No mutants defective in the conjugal transfer were isolated, strongly suggesting that E. coli cannot escape from being a recipient organism for P1α plasmid transfer. However, several mutants with low viability were identified, as well as mutants defective in establishing resistance to chloramphenicol, which was used for transconjugant selection. These results suggest that developing drugs capable of inhibiting the establishment of antibiotic resistance is a better approach than attempting to prevent the conjugal transfer to block the spread of antibiotic resistance genes. Our screening system based on the IncP1α-type plasmid transfer can be extended to isolation of target genes for other drugs. This study could be the foundation for further research to understand its underlying molecular mechanism through functional analysis of the identified genes.
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Affiliation(s)
- Kazuki Moriguchi
- Program of Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Japan.,Department of Biological Science, Graduate School of Science, Hiroshima University, Higashihiroshima, Japan
| | | | - Masanobu Abe
- Division for Health Service Promotion, University of Tokyo, Tokyo, Japan
| | - Kazuya Kiyokawa
- Program of Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Japan.,Department of Biological Science, Graduate School of Science, Hiroshima University, Higashihiroshima, Japan
| | - Shinji Yamamoto
- Department of Biological Science, Graduate School of Science, Hiroshima University, Higashihiroshima, Japan
| | - Katsunori Suzuki
- Program of Basic Biology, Graduate School of Integrated Sciences for Life, Hiroshima University, Higashihiroshima, Japan.,Department of Biological Science, Graduate School of Science, Hiroshima University, Higashihiroshima, Japan
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8
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Transfer of plasmid into the pentose-fermenting yeast Pachysolen tannophilus. J Microbiol Methods 2018; 148:97-103. [DOI: 10.1016/j.mimet.2018.03.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Accepted: 03/13/2018] [Indexed: 01/13/2023]
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9
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Moriguchi K, Yamamoto S, Ohmine Y, Suzuki K. A Fast and Practical Yeast Transformation Method Mediated by Escherichia coli Based on a Trans-Kingdom Conjugal Transfer System: Just Mix Two Cultures and Wait One Hour. PLoS One 2016; 11:e0148989. [PMID: 26849654 PMCID: PMC4744038 DOI: 10.1371/journal.pone.0148989] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2015] [Accepted: 01/26/2016] [Indexed: 11/18/2022] Open
Abstract
Trans-kingdom conjugation is a phenomenon by which DNA is transferred into a eukaryotic cell by a bacterial conjugal transfer system. Improvement in this method to facilitate the rapid co-cultivation of donor bacterial and recipient eukaryotic cell cultures could make it the simplest transformation method, requiring neither isolation of vector DNA nor preparation of competent recipient cells. To evaluate this potential advantage of trans-kingdom conjugation, we examined this simple transformation method using vector combinations, helper plasmids, and recipient Saccharomyces cerevisiae strains. Mixing donor Escherichia coli and recipient S. cerevisiae overnight cultures (50 μL each) consistently yielded on the order of 10(1) transformants using the popular experimental strain BY4742 derived from S288c and a shuttle vector for trans-kingdom conjugation. Transformation efficiency increased to the order of 10(2) using a high receptivity trans-kingdom conjugation strain. In addition, either increasing the amount of donor cells or pretreating the recipient cells with thiols such as dithiothreitol improved the transformation efficiency by one order of magnitude. This simple trans-kingdom conjugation-mediated transformation method could be used as a practical yeast transformation method upon enrichment of available vectors and donor E. coli strains.
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Affiliation(s)
- Kazuki Moriguchi
- Department of Biological Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739–8526, Japan
- * E-mail:
| | - Shinji Yamamoto
- Department of Biological Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739–8526, Japan
| | - Yuta Ohmine
- Department of Biological Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739–8526, Japan
| | - Katsunori Suzuki
- Department of Biological Science, Graduate School of Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739–8526, Japan
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Hernández–Montañez Z, López–Ramírez MP, Delgado–Balbuena L, Dendooven L, Bello–López JM. Mesophilic strains of Aeromonas spp. can acquire the multidrug resistance plasmid pRAS1 in horizontal transfer experiments at low temperatures. ANN MICROBIOL 2015. [DOI: 10.1007/s13213-014-0923-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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11
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Moriguchi K, Yamamoto S, Tanaka K, Kurata N, Suzuki K. Trans-kingdom horizontal DNA transfer from bacteria to yeast is highly plastic due to natural polymorphisms in auxiliary nonessential recipient genes. PLoS One 2013; 8:e74590. [PMID: 24058593 PMCID: PMC3772842 DOI: 10.1371/journal.pone.0074590] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2013] [Accepted: 08/05/2013] [Indexed: 11/30/2022] Open
Abstract
With the rapid accumulation of genomic information from various eukaryotes in the last decade, genes proposed to have been derived from recent horizontal gene transfer (HGT) events have been reported even in non-phagotrophic unicellular and multicellular organisms, but the molecular pathways underlying HGT remain to be explained. The development of in vitro HGT detection systems, which permit the molecular and genetic analyses of donor and recipient organisms and quantify HGT, are helpful in order to gain insight into mechanisms that may contribute to contemporary HGT events or may have contributed to past HGT events. We applied a horizontal DNA transfer system model based on conjugal gene transfer called trans-kingdom conjugation (TKC) from the prokaryote Escherichia coli to the eukaryote Saccharomyces cerevisiae, and assessed whether and to what extent genetic variations in the eukaryotic recipient affect its receptivity to TKC. Strains from a collection of 4,823 knock-out mutants of S. cerevisiae MAT-α haploids were tested for their individual TKC receptivity. Two types of mutants, an ssd1 mutant and respiratory mutants, which are also found in experimental strains and in nature widely, were identified as highly receptive mutants. The TKC efficiency for spontaneously accrued petite (rho−/0) mutants of the functional allele (SSD1-V) strain showed increased receptivity. The TKC efficiency of the ssd1Δ mutant was 36% for bacterial conjugation, while that of the petite/ssd1Δ double mutants was even higher (220% in average) compared to bacterial conjugation. This increased TKC receptivity was also observed when other conjugal transfer systems were applied and the donor bacterium was changed to Agrobacterium tumefaciens. These results support the idea that the genomes of certain eukaryotes have been exposed to exogenous DNA more frequently and continuously than previously thought.
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Affiliation(s)
- Kazuki Moriguchi
- Department of Biological Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
- * E-mail:
| | - Shinji Yamamoto
- Department of Biological Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
| | - Katsuyuki Tanaka
- Department of Biological Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
| | - Nori Kurata
- Plant Genetics, National Institute of Genetics, Mishima, Shizuoka, Japan
| | - Katsunori Suzuki
- Department of Biological Science, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
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