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Zheng L, Shen J, Chen R, Hu Y, Zhao W, Leung ELH, Dai L. Genome engineering of the human gut microbiome. J Genet Genomics 2024; 51:479-491. [PMID: 38218395 DOI: 10.1016/j.jgg.2024.01.002] [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: 10/08/2023] [Revised: 01/02/2024] [Accepted: 01/03/2024] [Indexed: 01/15/2024]
Abstract
The human gut microbiome, a complex ecosystem, significantly influences host health, impacting crucial aspects such as metabolism and immunity. To enhance our comprehension and control of the molecular mechanisms orchestrating the intricate interplay between gut commensal bacteria and human health, the exploration of genome engineering for gut microbes is a promising frontier. Nevertheless, the complexities and diversities inherent in the gut microbiome pose substantial challenges to the development of effective genome engineering tools for human gut microbes. In this comprehensive review, we provide an overview of the current progress and challenges in genome engineering of human gut commensal bacteria, whether executed in vitro or in situ. A specific focus is directed towards the advancements and prospects in cargo DNA delivery and high-throughput techniques. Additionally, we elucidate the immense potential of genome engineering methods to enhance our understanding of the human gut microbiome and engineer the microorganisms to enhance human health.
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Affiliation(s)
- Linggang Zheng
- Dr Neher's Biophysics Laboratory for Innovative Drug Discovery/State Key Laboratory of Quality Research in Chinese Medicine, Macau University of Science and Technology, Taipa, Macau 999078, China; CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Juntao Shen
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Ruiyue Chen
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yucan Hu
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wei Zhao
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Elaine Lai-Han Leung
- Cancer Center, Faculty of Health Science, University of Macau, Macau 999078, China; MOE Frontiers Science Center for Precision Oncology, University of Macau, Macau 999078, China.
| | - Lei Dai
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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Tan Y, Liang J, Lai M, Wan S, Luo X, Li F. Advances in synthetic biology toolboxes paving the way for mechanistic understanding and strain engineering of gut commensal Bacteroides spp. and Clostridium spp. Biotechnol Adv 2023; 69:108272. [PMID: 37844770 DOI: 10.1016/j.biotechadv.2023.108272] [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: 08/13/2023] [Revised: 10/10/2023] [Accepted: 10/13/2023] [Indexed: 10/18/2023]
Abstract
The gut microbiota plays a significant role in influencing human immunity, metabolism, development, and behavior by producing a wide range of metabolites. While there is accumulating data on several microbiota-derived small molecules that contribute to host health and disease, our knowledge regarding the molecular mechanisms underlying metabolite-mediated microbe-host interactions remains limited. This is primarily due to the lack of efficient genetic tools for most commensal bacteria, especially those belonging to the dominant phyla Bacteroides spp. and Clostridium spp., which hinders the application of synthetic biology to these gut commensal bacteria. In this review, we provide an overview of recent advances in synthetic biology tools developed for the two dominant genera, as well as their applications in deciphering the mechanisms of microbe-host interactions mediated by microbiota-derived small molecules. We also discuss the potential biomedical applications of engineering commensal bacteria using these toolboxes. Finally, we share our perspective on the future development of synthetic biology tools for a better understanding of small molecule-mediated microbe-host interactions and their engineering for biomedical purposes.
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Affiliation(s)
- Yang Tan
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China; Shandong Energy Institute, Qingdao 266101, China; Qingdao New Energy Shandong Laboratory, Qingdao 266101, China.
| | - Jing Liang
- Center for Synthetic Biochemistry, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Mingchi Lai
- College of Life Sciences, Qingdao Agricultural University, Qingdao 266109, China
| | - Sai Wan
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China; Shandong Energy Institute, Qingdao 266101, China; Qingdao New Energy Shandong Laboratory, Qingdao 266101, China
| | - Xiaozhou Luo
- Center for Synthetic Biochemistry, Shenzhen Institute of Synthetic Biology, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China
| | - Fuli Li
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao C1 Refinery Engineering Research Center, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China; Shandong Energy Institute, Qingdao 266101, China; Qingdao New Energy Shandong Laboratory, Qingdao 266101, China.
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Qiu X, Feng M, Zhou G, Wang H. Effects of mineral additives on antibiotic resistance genes and related mechanisms during chicken manure composting. BIORESOURCE TECHNOLOGY 2022; 346:126631. [PMID: 34971779 DOI: 10.1016/j.biortech.2021.126631] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 12/20/2021] [Accepted: 12/22/2021] [Indexed: 06/14/2023]
Abstract
In this study, two typical minerals (diatomite and bentonite) were applied during composting, and their influences on antibiotics, antibiotic resistance genes (ARGs), intI1 and the bacterial communities were investigated. The relative abundance of total ARGs decreased by 53.72% and 59.54% in diatomite and bentonite addition compared with control on day 42. The minerals addition also reduced the relative abundance of intI1, as much as 41.41% and 59.81% in diatomite and bentonite treatments. Proteobacteria and Firmicutes were the dominant candidate hosts of the major ARGs. There was a significant correlation between total ARGs and intI1 during the composting. Structural equation models further demonstrated that intI1 and antibiotics were the predominant direct factors responsible for ARG variations, and composting properties and bacterial community composition also shifted the variation of ARG profiles by influencing intI1. Overall, these findings suggest that diatomite and bentonite could decrease the potential proliferation of ARGs in chicken manure.
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Affiliation(s)
- Xiuwen Qiu
- Jiangxi Yangtze River Economic Zone Research Institute, Jiujiang University, Jiujiang 332005, PR China; Jiangxi Key Laboratory of Industrial Ecological Simulation and Environmental Health in Yangtze River Basin, Jiujiang University, Jiujiang 332005, PR China
| | - Mengting Feng
- Jiangxi Key Laboratory of Industrial Ecological Simulation and Environmental Health in Yangtze River Basin, Jiujiang University, Jiujiang 332005, PR China; College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang 330045, PR China
| | - Guixiang Zhou
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China.
| | - Huijuan Wang
- Jiangxi Key Laboratory of Industrial Ecological Simulation and Environmental Health in Yangtze River Basin, Jiujiang University, Jiujiang 332005, PR China
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Arai T, Aikawa S, Sudesh K, Kondo T, Kosugi A. Electrotransformation of thermophilic bacterium Caldimonas manganoxidans. J Microbiol Methods 2021; 192:106375. [PMID: 34793853 DOI: 10.1016/j.mimet.2021.106375] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/12/2021] [Accepted: 11/12/2021] [Indexed: 12/22/2022]
Abstract
Caldimonas manganoxidans is a Gram-negative, thermophilic, bioplastic-producing bacterium that is a promising strain to overcome the drawbacks of existing bioplastic manufacturing methods. However, genetic manipulation of this species has not previously been studied. Here, we developed an optimized electrotransformation protocol for C. manganoxidans by screening conditions, including the bacterial growth phase, electroporation buffer, pulse strength, and recovery time. The optimized transformation protocol obtained (3.1 ± 0.78) × 108 colony-forming units/μg DNA of plasmid pBBR1MCS-2. High transformation efficiency was observed when using plasmid DNA isolated from C. manganoxidans. The DNA methylases of Escherichia coli did not affect the transformation efficiency of C. manganoxidans. The electrotransformation technique proposed here will be beneficial for the genetic manipulation of thermophilic Caldimonas species.
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Affiliation(s)
- Takamitsu Arai
- Japan International Research Center for Agricultural Sciences, 1-1 Ohwashi Tsukuba, Ibaraki 305-8686, Japan
| | - Shimpei Aikawa
- Japan International Research Center for Agricultural Sciences, 1-1 Ohwashi Tsukuba, Ibaraki 305-8686, Japan
| | - Kumar Sudesh
- School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia
| | - Toshiaki Kondo
- Japan International Research Center for Agricultural Sciences, 1-1 Ohwashi Tsukuba, Ibaraki 305-8686, Japan
| | - Akihiko Kosugi
- Japan International Research Center for Agricultural Sciences, 1-1 Ohwashi Tsukuba, Ibaraki 305-8686, Japan.
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du Toit JP, Lea-Smith DJ, Git A, Hervey JRD, Howe CJ, Pott RWM. Expression of Alternative Nitrogenases in Rhodopseudomonas palustris Is Enhanced Using an Optimized Genetic Toolset for Rapid, Markerless Modifications. ACS Synth Biol 2021; 10:2167-2178. [PMID: 34431288 DOI: 10.1021/acssynbio.0c00496] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The phototrophic bacterium Rhodopseudomonas palustris is emerging as a promising biotechnological chassis organism, due to its resilience to a range of harsh conditions, a wide metabolic repertoire, and the ability to quickly regenerate ATP using light. However, realization of this promise is impeded by a lack of efficient, rapid methods for genetic modification. Here, we present optimized tools for generating chromosomal insertions and deletions employing electroporation as a means of transformation. Generation of markerless strains can be completed in 12 days, approximately half the time for previous conjugation-based methods. This system was used for overexpression of alternative nitrogenase isozymes with the aim of improving biohydrogen productivity. Insertion of the pucBa promoter upstream of vnf and anf nitrogenase operons drove robust overexpression up to 4000-fold higher than wild-type. Transcript quantification was facilitated by an optimized high-quality RNA extraction protocol employing lysis using detergent and heat. Overexpression resulted in increased nitrogenase protein levels, extending to superior hydrogen productivity in bioreactor studies under nongrowing conditions, where promoter-modified strains better utilized the favorable energy state created by reduced competition from cell division. Robust heterologous expression driven by the pucBa promoter is thus attractive for energy-intensive biosyntheses suited to the capabilities of R. palustris. Development of this genetic modification toolset will accelerate the advancement of R. palustris as a biotechnological chassis organism, and insights into the effects of nitrogenase overexpression will guide future efforts in engineering strains for improved hydrogen production.
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Affiliation(s)
- Jan-Pierre du Toit
- Department of Process Engineering, Stellenbosch University, Banghoek Road, Stellenbosch, 7600, South Africa
| | - David J. Lea-Smith
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, United Kingdom
- Department of Biochemistry, University of Cambridge, Hopkins Building, Downing Site, Tennis Court Road, Cambridge, CB2 1QW, United Kingdom
| | - Anna Git
- Department of Biochemistry, University of Cambridge, Hopkins Building, Downing Site, Tennis Court Road, Cambridge, CB2 1QW, United Kingdom
| | - John R. D. Hervey
- Department of Biochemistry, University of Cambridge, Hopkins Building, Downing Site, Tennis Court Road, Cambridge, CB2 1QW, United Kingdom
| | - Christopher J. Howe
- Department of Biochemistry, University of Cambridge, Hopkins Building, Downing Site, Tennis Court Road, Cambridge, CB2 1QW, United Kingdom
| | - Robert W. M. Pott
- Department of Process Engineering, Stellenbosch University, Banghoek Road, Stellenbosch, 7600, South Africa
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The Human Gut Microbe Bacteroides thetaiotaomicron Suppresses Toxin Release from Clostridium difficile by Inhibiting Autolysis. Antibiotics (Basel) 2021; 10:antibiotics10020187. [PMID: 33671889 PMCID: PMC7918992 DOI: 10.3390/antibiotics10020187] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 02/11/2021] [Accepted: 02/13/2021] [Indexed: 01/05/2023] Open
Abstract
Disruption of the human gut microbiota by antibiotics can lead to Clostridium difficile (CD)-associated diarrhea. CD overgrowth and elevated CD toxins result in gut inflammation. Herein, we report that a gut symbiont, Bacteroides thetaiotaomicron (BT), suppressed CD toxin production. The suppressive components are present in BT culture supernatant and are both heat- and proteinase K-resistant. Transposon-based mutagenesis indicated that the polysaccharide metabolism of BT is involved in the inhibitory effect. Among the genes identified, we focus on the methylerythritol 4-phosphate pathway gene gcpE, which supplies the isoprenoid backbone to produce the undecaprenyl phosphate lipid carrier that transports oligosaccharides across the membrane. Polysaccharide fractions prepared from the BT culture suppressed CD toxin production in vitro; the inhibitory effect of polysaccharide fractions was reduced in the gcpE mutant (ΔgcpE). The inhibitory effect of BT-derived polysaccharide fraction was abrogated by lysozyme treatment, indicating that cellwall-associated glycans are attributable to the inhibitory effect. BT-derived polysaccharide fraction did not affect CD toxin gene expression or intracellular toxin levels. An autolysis assay showed that CD cell autolysis was suppressed by BT-derived polysaccharide fraction, but the effect was reduced with that of ΔgcpE. These results indicate that cell wall-associated glycans of BT suppress CD toxin release by inhibiting cell autolysis.
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Abstract
Tsetse flies are the insect vectors of T. brucei, the causative agent of African sleeping sickness—a zoonotic disease that inflicts a substantial economic cost on a broad region of sub-Saharan Africa. Notably, tsetse flies can be infected with the bacterium S. glossinidius to establish an asymptomatic chronic infection. This infection can be inherited by future generations of tsetse flies, allowing S. glossinidius to spread and persist within populations. To this effect, S. glossinidius has been considered a potential expression platform to create flies which reduce T. brucei stasis and lower overall parasite transmission to humans and animals. However, the efficient genetic manipulation of S. glossinidius has remained a technical challenge due to its complex growth requirements and uncharacterized physiology. Here, we exploit a natural mechanism of DNA transfer among bacteria and develop an efficient technique to genetically manipulate S. glossinidius for future studies in reducing trypanosome transmission. Stable associations between insects and bacterial species are widespread in nature. This is the case for many economically important insects, such as tsetse flies. Tsetse flies are the vectors of Trypanosoma brucei, the etiological agent of African trypanosomiasis—a zoonotic disease that incurs a high socioeconomic cost in regions of endemicity. Populations of tsetse flies are often infected with the bacterium Sodalis glossinidius. Following infection, S. glossinidius establishes a chronic, stable association characterized by vertical (maternal) and horizontal (paternal) modes of transmission. Due to the stable nature of this association, S. glossinidius has been long sought as a means for the implementation of anti-Trypanosoma paratransgenesis in tsetse flies. However, the lack of tools for the genetic modification of S. glossinidius has hindered progress in this area. Here, we establish that S. glossinidius is amenable to DNA uptake by conjugation. We show that conjugation can be used as a DNA delivery method to conduct forward and reverse genetic experiments in this bacterium. This study serves as an important step in the development of genetic tools for S. glossinidius. The methods highlighted here should guide the implementation of genetics for the study of the tsetse-Sodalis association and the evaluation of S. glossinidius-based tsetse fly paratransgenesis strategies. IMPORTANCE Tsetse flies are the insect vectors of T. brucei, the causative agent of African sleeping sickness—a zoonotic disease that inflicts a substantial economic cost on a broad region of sub-Saharan Africa. Notably, tsetse flies can be infected with the bacterium S. glossinidius to establish an asymptomatic chronic infection. This infection can be inherited by future generations of tsetse flies, allowing S. glossinidius to spread and persist within populations. To this effect, S. glossinidius has been considered a potential expression platform to create flies which reduce T. brucei stasis and lower overall parasite transmission to humans and animals. However, the efficient genetic manipulation of S. glossinidius has remained a technical challenge due to its complex growth requirements and uncharacterized physiology. Here, we exploit a natural mechanism of DNA transfer among bacteria and develop an efficient technique to genetically manipulate S. glossinidius for future studies in reducing trypanosome transmission.
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Pierce JV, Fellows JD, Anderson DE, Bernstein HD. A clostripain-like protease plays a major role in generating the secretome of enterotoxigenic Bacteroides fragilis. Mol Microbiol 2020; 115:290-304. [PMID: 32996200 DOI: 10.1111/mmi.14616] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 09/21/2020] [Accepted: 09/23/2020] [Indexed: 11/27/2022]
Abstract
Bacteroides fragilis toxin (BFT) is a protein secreted by enterotoxigenic (ETBF) strains of B. fragilis. BFT is synthesized as a proprotein (proBFT) that is predicted to be a lipoprotein and that is cleaved into two discrete fragments by a clostripain-like protease called fragipain (Fpn). In this study, we obtained evidence that Fpn cleaves proBFT following its transport across the outer membrane. Remarkably, we also found that the disruption of the fpn gene led to a strong reduction in the level of >100 other proteins, many of which are predicted to be lipoproteins, in the culture medium of an ETBF strain. Experiments performed with purified Fpn provided direct evidence that the protease releases at least some of these proteins from the cell surface. The observation that wild-type cells outcompeted an fpn- strain in co-cultivation assays also supported the notion that Fpn plays an important role in cell physiology and is not simply dedicated to toxin biogenesis. Finally, we found that purified Fpn altered the adhesive properties of HT29 intestinal epithelial cells. Our results suggest that Fpn is a broad-spectrum protease that not only catalyzes the protein secretion on a wide scale but that also potentially cleaves host cell proteins during colonization.
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Affiliation(s)
- Jessica V Pierce
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Justin D Fellows
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - D Eric Anderson
- Advanced Mass Spectrometry Facility, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Harris D Bernstein
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
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Ozyigit II. Gene transfer to plants by electroporation: methods and applications. Mol Biol Rep 2020; 47:3195-3210. [PMID: 32242300 DOI: 10.1007/s11033-020-05343-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 02/22/2020] [Indexed: 01/09/2023]
Abstract
Developing gene transfer technologies enables the genetic manipulation of the living organisms more efficiently. The methods used for gene transfer fall into two main categories; natural and artificial transformation. The natural methods include the conjugation, transposition, bacterial transformation as well as phage and retroviral transductions, contain the physical methods whereas the artificial methods can physically alter and transfer genes from one to another organisms' cell using, for instance, biolistic transformation, micro- and macroinjection, and protoplast fusion etc. The artificial gene transformation can also be conducted through chemical methods which include calcium phosphate-mediated, polyethylene glycol-mediated, DEAE-Dextran, and liposome-mediated transfers. Electrical methods are also artificial ways to transfer genes that can be done by electroporation and electrofusion. Comparatively, among all the above-mentioned methods, electroporation is being widely used owing to its high efficiency and broader applicability. Electroporation is an electrical transformation method by which transient electropores are produced in the cell membranes. Based on the applications, process can be either reversible where electropores in membrane are resealable and cells preserve the vitality or irreversible where membrane is not able to reseal, and cell eventually dies. This problem can be minimized by developing numerical models to iteratively optimize the field homogeneity considering the cell size, shape, number, and electrode positions supplemented by real-time measurements. In modern biotechnology, numerical methods have been used in electrotransformation, electroporation-based inactivation, electroextraction, and electroporative biomass drying. Moreover, current applications of electroporation also point to some other uncovered potentials for various exploitations in future.
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Affiliation(s)
- Ibrahim Ilker Ozyigit
- Department of Biology, Faculty of Science and Arts, Marmara University, Goztepe, 34722, Istanbul, Turkey. .,Department of Biology, Faculty of Science, Kyrgyz-Turkish Manas University, 720038, Bishkek, Kyrgyzstan.
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10
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Verma R, Lee C, Jeun EJ, Yi J, Kim KS, Ghosh A, Byun S, Lee CG, Kang HJ, Kim GC, Jun CD, Jan G, Suh CH, Jung JY, Sprent J, Rudra D, De Castro C, Molinaro A, Surh CD, Im SH. Cell surface polysaccharides of Bifidobacterium bifidum induce the generation of Foxp3 + regulatory T cells. Sci Immunol 2019; 3:3/28/eaat6975. [PMID: 30341145 DOI: 10.1126/sciimmunol.aat6975] [Citation(s) in RCA: 127] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 08/14/2018] [Indexed: 12/29/2022]
Abstract
Dysregulation of intestinal microflora is linked to inflammatory disorders associated with compromised immunosuppressive functions of Foxp3+ T regulatory (Treg) cells. Although mucosa-associated commensal microbiota has been implicated in Treg generation, molecular identities of the "effector" components controlling this process remain largely unknown. Here, we have defined Bifidobacterium bifidum as a potent inducer of Foxp3+ Treg cells with diverse T cell receptor specificity to dietary antigens, commensal bacteria, and B. bifidum itself. Cell surface β-glucan/galactan (CSGG) polysaccharides of B. bifidum were identified as key components responsible for Treg induction. CSGG efficiently recapitulated the activity of whole bacteria and acted via regulatory dendritic cells through a partially Toll-like receptor 2-mediated mechanism. Treg cells induced by B. bifidum or purified CSGG display stable and robust suppressive capacity toward experimental colitis. By identifying CSGG as a functional component of Treg-inducing bacteria, our studies highlight the immunomodulatory potential of CSGG and CSGG-producing microbes.
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Affiliation(s)
- Ravi Verma
- Academy of Immunology and Microbiology, Institute for Basic Science, Pohang 37673, Republic of Korea
| | - Changhon Lee
- Division of Integrative Biosciences and Biotechnology, Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Eun-Ji Jeun
- Division of Integrative Biosciences and Biotechnology, Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Jaeu Yi
- Division of Integrative Biosciences and Biotechnology, Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Kwang Soon Kim
- Academy of Immunology and Microbiology, Institute for Basic Science, Pohang 37673, Republic of Korea
| | - Ambarnil Ghosh
- Academy of Immunology and Microbiology, Institute for Basic Science, Pohang 37673, Republic of Korea
| | - Seohyun Byun
- Division of Integrative Biosciences and Biotechnology, Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Choong-Gu Lee
- Academy of Immunology and Microbiology, Institute for Basic Science, Pohang 37673, Republic of Korea
| | - Hye-Ji Kang
- Academy of Immunology and Microbiology, Institute for Basic Science, Pohang 37673, Republic of Korea
| | - Gi-Cheon Kim
- Academy of Immunology and Microbiology, Institute for Basic Science, Pohang 37673, Republic of Korea
| | - Chang-Duk Jun
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 61005, Republic of Korea
| | - Gwenaël Jan
- INRA-Agrocampus Ouest Rennes, UMR 1253 STLO, Rennes, France
| | - Chang-Hee Suh
- Department of Rheumatology, Ajou University School of Medicine,164 Worldcup-ro, Yeongtong-gu, Suwon 16499, Republic of Korea
| | - Ju-Yang Jung
- Department of Rheumatology, Ajou University School of Medicine,164 Worldcup-ro, Yeongtong-gu, Suwon 16499, Republic of Korea
| | - Jonathan Sprent
- Division of Integrative Biosciences and Biotechnology, Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Republic of Korea.,Immunology Research Program, Garvan Institute of Medical Research, Darlinghurst, New South Wales 2010, Australia
| | - Dipayan Rudra
- Academy of Immunology and Microbiology, Institute for Basic Science, Pohang 37673, Republic of Korea.,Division of Integrative Biosciences and Biotechnology, Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Cristina De Castro
- Department of Agricultural Sciences, University of Napoli, 80055 Portici, Italy.,Department of Chemical Sciences, University of Napoli, 80126 Napoli, Italy
| | - Antonio Molinaro
- Department of Chemical Sciences, University of Napoli, 80126 Napoli, Italy.,Task Force on Microbiome Studies, University of Naples Federico II, Naples, Italy
| | - Charles D Surh
- Academy of Immunology and Microbiology, Institute for Basic Science, Pohang 37673, Republic of Korea.,Division of Integrative Biosciences and Biotechnology, Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
| | - Sin-Hyeog Im
- Academy of Immunology and Microbiology, Institute for Basic Science, Pohang 37673, Republic of Korea. .,Division of Integrative Biosciences and Biotechnology, Department of Life Sciences, Pohang University of Science and Technology, Pohang 37673, Republic of Korea
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Sakanaka M, Sugiyama Y, Nara M, Kitakata A, Kurihara S. Functional analysis of arginine decarboxylase gene speA of Bacteroides dorei by markerless gene deletion. FEMS Microbiol Lett 2019; 365:4793251. [PMID: 29319802 DOI: 10.1093/femsle/fny003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Accepted: 01/03/2018] [Indexed: 12/18/2022] Open
Abstract
Polyamine concentrations in the intestine are regulated by their biosynthesis by hundreds of gut microbial species and these polyamines are involved in host health and disease. However, polyamine biosynthesis has not been sufficiently analyzed in major members of the human gut microbiota, possibly owing to a lack of gene manipulation systems. In this study, we successfully performed markerless gene deletion in Bacteroides dorei, one of the major members of the human gut microbiota. The combination of a thymidine kinase gene (tdk) deletion mutant and a counter-selection marker tdk, which has been applied in other Bacteroides species, was used for the markerless gene deletion. Deletion of tdk in B. dorei caused 5-fluoro-2΄-deoxyuridine resistance, suggesting the utility of B. dorei Δtdk as the host for future markerless gene deletions. Compared to parental strains, an arginine decarboxylase gene (speA) deletion mutant generated in this system showed a severe growth defect and decreased concentration of spermidine in the cells and culture supernatant. Collectively, our results indicate the accessibility of gene deletion and the important role of speA in polyamine biosynthesis in B. dorei.
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Affiliation(s)
- Mikiyasu Sakanaka
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan
| | - Yuta Sugiyama
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan
| | - Misaki Nara
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan
| | - Aya Kitakata
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan
| | - Shin Kurihara
- Faculty of Bioresources and Environmental Sciences, Ishikawa Prefectural University, Nonoichi, Ishikawa 921-8836, Japan
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Streamlined Genetic Manipulation of Diverse Bacteroides and Parabacteroides Isolates from the Human Gut Microbiota. mBio 2019; 10:mBio.01762-19. [PMID: 31409684 PMCID: PMC6692515 DOI: 10.1128/mbio.01762-19] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
We have entered an era when studies of the gut microbiota are transitioning from basic questions of composition and host effects to understanding the microbial molecules that underlie compositional shifts and mediate health and disease processes. The importance of the gut Bacteroidales to human health and disease and their potential as a source of engineered live biotherapeutics make these bacteria of particular interest for in-depth mechanistic study. However, there are still barriers to the genetic analysis of diverse Bacteroidales strains, limiting our ability to study important host and community phenotypes identified in these strains. Here, we have overcome many of these obstacles by constructing a series of vectors that allow easy genetic manipulation in diverse gut Bacteroides and Parabacteroides strains. These constructs fill a critical need and allow streamlined allelic replacement in diverse gut Bacteroidales, including the growing number of multiantibiotic-resistant strains present in the modern-day human intestine. Studies of the gut microbiota have dramatically increased in recent years as the importance of this microbial ecosystem to human health and disease is better appreciated. The Bacteroidales are the most abundant order of bacteria in the healthy human gut and induce both health-promoting and disease-promoting effects. There are more than 55 species of gut Bacteroidales with extensive intraspecies genetic diversity, especially in regions involved in the synthesis of molecules that interact with other bacteria, the host, and the diet. This property necessitates the study of diverse species and strains. In recent years, the genetic toolkit to study these bacteria has greatly expanded, but we still lack a facile system for creating deletion mutants and allelic replacements in diverse strains, especially with the rapid increase in resistance to the two antibiotics used for genetic manipulation. Here, we present a new versatile and highly efficient vector suite that allows the creation of allelic deletions and replacements in multiresistant strains of Bacteroides and Parabacteroides using a gain-of-function system based on polysaccharide utilization. These vectors also allow for easy counterselection independent of creating a mutant background strain, using a toxin from a type VI secretion system of Bacteroides fragilis. Toxin production during counterselection is induced with one of two different molecules, providing flexibility based on strain phenotypes. This family of vectors greatly facilitates functional genetic analyses and extends the range of gut Bacteroidales strains that can be genetically modified to include multiresistant strains that are currently genetically intractable with existing genetic tools.
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The gut bacterium and pathobiont Bacteroides vulgatus activates NF-κB in a human gut epithelial cell line in a strain and growth phase dependent manner. Anaerobe 2017; 47:209-217. [DOI: 10.1016/j.anaerobe.2017.06.002] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 05/17/2017] [Accepted: 06/01/2017] [Indexed: 01/06/2023]
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14
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Hashimoto M, Waki J, Nakayama-Imaohji H, Ozono M, Hashiguchi S, Kuwahara T. TLR2-stimulating contaminants in glycoconjugate fractions prepared from Bacteroides fragilis. Innate Immun 2017; 23:449-458. [PMID: 28606014 DOI: 10.1177/1753425917714313] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Bacteroides fragilis is a member of the normal intestinal flora and is involved in host immunostimulation via TLR2. On the bacterial cell surface, glycoconjugates, such as LPS and capsular polysaccharide A (PSA), have been reported to participate in host immunostimulation via TLR2. Previously, we identified a TLR2-stimulating lipoprotein in B. fragilis cells. In this study, we demonstrated that TLR2-stimulating principal molecules in glycoconjugate fractions prepared from B. fragilis are contaminating proteinous molecules, which may also be lipoproteins. The glycoconjugate fractions were prepared by phenol-hot water extraction of B. fragilis wild type and PSA-deficient strains, followed by hydrophobic interaction chromatography. TLR2-stimilating activities of the fractions were not affected by PSA deficiency. By in-gel TLR2-stimulation assay, molecules in high-molecular-mass area, where capsular polysaccharides were migrated, were found not to stimulate TLR2, but those in the range of 15-40 kDa were active. Further, proteinase K could digest the latter molecules and the TLR2-stimulating activities were migrated to the area of below 15 kDa. These results support that proteinous molecules, which are estimated to be lipoproteins, are responsible for almost all TLR2-stimulating activity in the glycoconjugate fractions prepared from B. fragilis.
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Affiliation(s)
- Masahito Hashimoto
- 1 Department of Chemistry, Biotechnology, and Chemical Engineering, Kagoshima University, Kagoshima, Japan
| | - Junpei Waki
- 1 Department of Chemistry, Biotechnology, and Chemical Engineering, Kagoshima University, Kagoshima, Japan
| | | | - Mami Ozono
- 1 Department of Chemistry, Biotechnology, and Chemical Engineering, Kagoshima University, Kagoshima, Japan
| | - Shuhei Hashiguchi
- 1 Department of Chemistry, Biotechnology, and Chemical Engineering, Kagoshima University, Kagoshima, Japan
| | - Tomomi Kuwahara
- 2 Department of Microbiology, Faculty of Medicine, Kagawa University, Kagawa, Japan
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15
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Counterselection employing mutated pheS for markerless genetic deletion in Bacteroides species. Anaerobe 2016; 42:81-88. [PMID: 27639596 DOI: 10.1016/j.anaerobe.2016.09.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 09/12/2016] [Accepted: 09/13/2016] [Indexed: 02/04/2023]
Abstract
Markerless gene deletion is necessary for multiple gene disruptions due to the limited number of antibiotic resistant markers for some bacteria. However, even in transformable strains, obtaining the expected mutation without a marker requires laborious screening of a large number of colonies. Previous studies had success in various bacteria with a counter-selection system where a conditional lethal gene was incorporated into the vector. We examined the efficacy of the mutated pheS gene (pheS*) as a counter-selective marker for gene deletion in Bacteroides. This mutation produces an amino acid substitution (A303G) in the alpha subunit of Bacteroides phenylalanyl tRNA synthetase, which in E. coli alters the specificity of the tRNA synthetase resulting in a conditional lethal mutation due to the incorporation of p-chloro-phenylalanine (p-Cl-Phe) into protein. B. fragilis YCH46 and B. thetaiotaomicron VPI-5482 transformed with a pheS*-harboring shuttle vector were clearly growth-inhibited in the presence of >5 mM p-Cl-Phe in liquid defined minimal media (DMM) and on DMM agar plates. A targeting plasmid was constructed to delete the genetic region for capsular polysaccharide PS2 in B. fragilis or PS1 in B. thetaiotaomicron. After counterselection, p-Cl-Phe-resistant colonies were generated at a frequency of 8.1 × 10-3 for B. fragilis and 1.7 × 10-3 for B. thetaiotaomicron. Of the p-Cl-Phe-resistant colonies, 4.2% and 72% harbored the correct genetic deletion for B. fragilis and B. thetaiotaomicron, respectively. These results indicate that mutated pheS is a useful counter-selective gene to construct markerless genetic deletions in Bacteroides.
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Yildirim S, Thompson MG, Jacobs AC, Zurawski DV, Kirkup BC. Evaluation of Parameters for High Efficiency Transformation of Acinetobacter baumannii. Sci Rep 2016; 6:22110. [PMID: 26911658 PMCID: PMC4766488 DOI: 10.1038/srep22110] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2015] [Accepted: 02/03/2016] [Indexed: 11/09/2022] Open
Abstract
Acinetobacter baumannii is an emerging, nosocomial pathogen that is poorly characterized due to a paucity of genetic tools and methods. While whole genome sequence data from several epidemic and environmental strains have recently become available, the functional characterization of genes is significantly lagging. Efficient transformation is one of the first steps to develop molecular tools that can be used to address these shortcomings. Here we report parameters allowing high efficiency transformation of A. baumannii. Using a multi-factorial experimental design we found that growth phase, voltage, and resistance all significantly contribute to transformation efficiency. The highest efficiency (4.3 × 10(8) Transformants/μg DNA) was obtained at the stationary growth phase of the bacterium (OD 6.0) using 25 ng of plasmid DNA under 100 Ohms resistance and 1.7 kV/cm voltage. The optimized electroporation parameters reported here provide a useful tool for genetic manipulation of A. baumannii.
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Affiliation(s)
- Suleyman Yildirim
- Department of Wound Infections, Bacterial Diseases Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | - Mitchell G Thompson
- Department of Wound Infections, Bacterial Diseases Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | - Anna C Jacobs
- Department of Wound Infections, Bacterial Diseases Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | - Daniel V Zurawski
- Department of Wound Infections, Bacterial Diseases Walter Reed Army Institute of Research, Silver Spring, Maryland, USA
| | - Benjamin C Kirkup
- Department of Wound Infections, Bacterial Diseases Walter Reed Army Institute of Research, Silver Spring, Maryland, USA.,Department of Medicine, Infectious Diseases Division, Uniformed Services University of the Health Sciences, F. Edward Hebert School of Medicine, Bethesda, Maryland, USA
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17
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Nakayama-Imaohji H, Hirota K, Yamasaki H, Yoneda S, Nariya H, Suzuki M, Secher T, Miyake Y, Oswald E, Hayashi T, Kuwahara T. DNA Inversion Regulates Outer Membrane Vesicle Production in Bacteroides fragilis. PLoS One 2016; 11:e0148887. [PMID: 26859882 PMCID: PMC4747536 DOI: 10.1371/journal.pone.0148887] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 01/25/2016] [Indexed: 02/06/2023] Open
Abstract
Phase changes in Bacteroides fragilis, a member of the human colonic microbiota, mediate variations in a vast array of cell surface molecules, such as capsular polysaccharides and outer membrane proteins through DNA inversion. The results of the present study show that outer membrane vesicle (OMV) formation in this anaerobe is also controlled by DNA inversions at two distantly localized promoters, IVp-I and IVp-II that are associated with extracellular polysaccharide biosynthesis and the expression of outer membrane proteins. These promoter inversions are mediated by a single tyrosine recombinase encoded by BF2766 (orthologous to tsr19 in strain NCTC9343) in B. fragilis YCH46, which is located near IVp-I. A series of BF2766 mutants were constructed in which the two promoters were locked in different configurations (IVp-I/IVp-II = ON/ON, OFF/OFF, ON/OFF or OFF/ON). ON/ON B. fragilis mutants exhibited hypervesiculating, whereas the other mutants formed only a trace amount of OMVs. The hypervesiculating ON/ON mutants showed higher resistance to treatment with bile, LL-37, and human β-defensin 2. Incubation of wild-type cells with 5% bile increased the population of cells with the ON/ON genotype. These results indicate that B. fragilis regulates the formation of OMVs through DNA inversions at two distantly related promoter regions in response to membrane stress, although the mechanism underlying the interplay between the two regions controlled by the invertible promoters remains unknown.
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Affiliation(s)
- Haruyuki Nakayama-Imaohji
- Department of Microbiology, Faculty of Medicine, Kagawa University, 1750–1 Miki, Kagawa 761–0793, Japan
| | - Katsuhiko Hirota
- Department of Oral Microbiology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770–8503, Japan
| | - Hisashi Yamasaki
- Department of Cellular and Molecular Medicine, Wakayama Medical University Graduate School of Medicine, Wakayama 641–8509, Japan
| | - Saori Yoneda
- Department of Microbiology, Faculty of Medicine, Kagawa University, 1750–1 Miki, Kagawa 761–0793, Japan
| | - Hirofumi Nariya
- Department of Microbiology, Faculty of Medicine, Kagawa University, 1750–1 Miki, Kagawa 761–0793, Japan
| | - Motoo Suzuki
- Department of Microbiology, Faculty of Medicine, Kagawa University, 1750–1 Miki, Kagawa 761–0793, Japan
| | - Thomas Secher
- Inserm UMR1043 Toulouse, France
- INRA USC 1360 Toulouse, France
- CNRS UMR5282 Toulouse, France
- Université de Toulouse, UPS, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, France
| | - Yoichiro Miyake
- Department of Oral Microbiology, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima 770–8503, Japan
| | - Eric Oswald
- Inserm UMR1043 Toulouse, France
- INRA USC 1360 Toulouse, France
- CNRS UMR5282 Toulouse, France
- Université de Toulouse, UPS, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, France
- CHU Toulouse, Hôpital Purpan, Service de bactériologie-hygiène, Toulouse, France
| | - Tetsuya Hayashi
- Department of Bacteriology, Faculty of Medical Sciences, Kyushu University, Fukuoka 812–8582, Japan
| | - Tomomi Kuwahara
- Department of Microbiology, Faculty of Medicine, Kagawa University, 1750–1 Miki, Kagawa 761–0793, Japan
- * E-mail:
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18
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Ichimura M, Uchida K, Nakayama-Imaohji H, Hirakawa H, Tada T, Morita H, Yasutomo K, Okazaki K, Kuwahara T. Mariner-based transposon mutagenesis forBacteroidesspecies. J Basic Microbiol 2013; 54:558-67. [DOI: 10.1002/jobm.201200763] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 01/26/2013] [Indexed: 11/06/2022]
Affiliation(s)
- Minoru Ichimura
- Department of Microbiology; Faculty of Medicine, Kagawa University; Miki Kagawa Japan
- Department of Immunology and Parasitology; Institute of Health Biosciences, The University of Tokushima Graduate School; Kuramoto-cho Tokushima Japan
| | - Keiko Uchida
- Department of Microbiology; Faculty of Medicine, Kagawa University; Miki Kagawa Japan
- Department of Applied Bioscience; Faculty of Agriculture, Kagawa University; Miki Kagawa Japan
| | | | - Hideki Hirakawa
- Kazusa DNA Research Institute, Kazusa-Kamatari; Kisarazu Chiba Japan
| | - Tomoyo Tada
- Department of Microbiology; Faculty of Medicine, Kagawa University; Miki Kagawa Japan
| | - Hidetoshi Morita
- School of Veterinary Medicine; Azabu University; Fuchinobe Sagamihara Japan
| | - Koji Yasutomo
- Department of Immunology and Parasitology; Institute of Health Biosciences, The University of Tokushima Graduate School; Kuramoto-cho Tokushima Japan
| | - Katsuichiro Okazaki
- Department of Applied Bioscience; Faculty of Agriculture, Kagawa University; Miki Kagawa Japan
| | - Tomomi Kuwahara
- Department of Microbiology; Faculty of Medicine, Kagawa University; Miki Kagawa Japan
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Kotnik T. Lightning-triggered electroporation and electrofusion as possible contributors to natural horizontal gene transfer. Phys Life Rev 2013; 10:351-70. [PMID: 23787374 DOI: 10.1016/j.plrev.2013.05.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 05/06/2013] [Indexed: 12/29/2022]
Abstract
Phylogenetic studies show that horizontal gene transfer (HGT) is a significant contributor to genetic variability of prokaryotes, and was perhaps even more abundant during the early evolution. Hitherto, research of natural HGT has mainly focused on three mechanisms of DNA transfer: conjugation, natural competence, and viral transduction. This paper discusses the feasibility of a fourth such mechanism--cell electroporation and/or electrofusion triggered by atmospheric electrostatic discharges (lightnings). A description of electroporation as a phenomenon is followed by a review of experimental evidence that electroporation of prokaryotes in aqueous environments can result in release of non-denatured DNA, as well as uptake of DNA from the surroundings and transformation. Similarly, a description of electrofusion is followed by a review of experiments showing that prokaryotes devoid of cell wall can electrofuse into hybrids expressing the genes of their both precursors. Under sufficiently fine-tuned conditions, electroporation and electrofusion are efficient tools for artificial transformation and hybridization, respectively, but the quantitative analysis developed here shows that conditions for electroporation-based DNA release, DNA uptake and transformation, as well as for electrofusion are also present in many natural aqueous environments exposed to lightnings. Electroporation is thus a plausible contributor to natural HGT among prokaryotes, and could have been particularly important during the early evolution, when the other mechanisms might have been scarcer or nonexistent. In modern prokaryotes, natural absence of the cell wall is rare, but it is reasonable to assume that the wall has formed during a certain stage of evolution, and at least prior to this, electrofusion could also have contributed to natural HGT. The concluding section outlines several guidelines for assessment of the feasibility of lightning-triggered HGT.
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Affiliation(s)
- Tadej Kotnik
- Department of Biomedical Engineering, Faculty of Electrical Engineering, University of Ljubljana, Tržaška 25, SI-1000 Ljubljana, Slovenia.
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20
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Wakimoto S, Nakayama-Imaohji H, Ichimura M, Morita H, Hirakawa H, Hayashi T, Yasutomo K, Kuwahara T. PhoB regulates the survival of Bacteroides fragilis in peritoneal abscesses. PLoS One 2013; 8:e53829. [PMID: 23342014 PMCID: PMC3547664 DOI: 10.1371/journal.pone.0053829] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2012] [Accepted: 12/03/2012] [Indexed: 12/22/2022] Open
Abstract
In response to phosphate limitation, bacteria employ the Pho regulon, a specific regulatory network for phosphate acquisition. The two-component signal transduction system of PhoRB plays a crucial role in the induction of Pho regulon genes, leading to the adaptation to phosphate starvation. Herein, we identified the PhoRB system in Bacteroides fragilis, a commensal gut bacterium, and evaluated its role in gut colonization and survival in peritoneal abscesses. BF1575 and BF1576 encoded PhoR (sensor histidine kinase) and PhoB (response regulator) in the sequenced B. fragilis strain YCH46, respectively. Transcriptome analysis revealed that deletion of phoB affected the expression of 585 genes (more than 4-fold change) in B. fragilis, which included genes for stress response (chaperons and heat shock proteins), virulence (capsular polysaccharide biosynthesis) and phosphate metabolism. Deletion of phoB reduced the ability of the bacterium to persist in peritoneal abscesses induced by an intra-abdominal challenge of B. fragilis. Furthermore, PhoB was necessary for survival of this anaerobe in peritoneal abscesses but not for in vitro growth in rich media or in intestinal colonization. These results indicate that PhoB plays an important role in the survival of B. fragilis under stressful extraintestinal conditions.
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Affiliation(s)
- Shin Wakimoto
- Department of Immunology and Parasitology, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan
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21
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Letzel AC, Pidot SJ, Hertweck C. A genomic approach to the cryptic secondary metabolome of the anaerobic world. Nat Prod Rep 2012; 30:392-428. [PMID: 23263685 DOI: 10.1039/c2np20103h] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
A total of 211 complete and published genomes from anaerobic bacteria are analysed for the presence of secondary metabolite biosynthesis gene clusters, in particular those tentatively coding for polyketide synthases (PKS) and non-ribosomal peptide synthetases (NRPS). We investigate the distribution of these gene clusters according to bacterial phylogeny and, if known, correlate these to the type of metabolic pathways they encode. The potential of anaerobes as secondary metabolite producers is highlighted.
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Affiliation(s)
- Anne-Catrin Letzel
- Leibniz Institute for Natural Product Research and Infection Biology HKI, Beutenbergstr. 11a, Jena, 07745, Germany
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22
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Nakayama-Imaohji H, Ichimura M, Iwasa T, Okada N, Ohnishi Y, Kuwahara T. Characterization of a gene cluster for sialoglycoconjugate utilization in Bacteroides fragilis. THE JOURNAL OF MEDICAL INVESTIGATION 2012; 59:79-94. [PMID: 22449996 DOI: 10.2152/jmi.59.79] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Recent analysis of the whole genome sequence of Bacteroides fragilis revealed extensive duplication of polysaccharide utilization genes in this anaerobe. Here we analyzed a unique 27-kb gene cluster (sgu) comprised of the 13 sialoglycoconjugates-utilization genes, which include the sialidase gene (nanH1) in B. fragilis strain YCH46. The genes were tightly organized and transcribed polycistronically. Comparative PCR scanning demonstrated that the sgu locus was conserved among the Bacteroides strains tested. Based on the transcriptional profiles generated by reverse transcriptase PCR, the sgu locus can be classified into at least three regulatory units: 1) sialic acid- or sialooligosaccharide-inducible genes, 2) constitutively expressed genes that can be down-regulated by catabolite repression, and 3) constitutively expressed genes. In vitro comparison of the growth of a sgu locus deletion mutant (SGUM172941) with a wild type strain indicates that this locus is necessary for B. fragilis to efficiently utilize mucin as a carbon source. Furthermore, SGUM172941 was defective in colonization of the intestines of germ-free mice under competitive conditions. These data indicate that the sgu locus in B. fragilis plays a crucial role in the utilization of host-derived sialoglycoconjugates and the stable colonization of this anaerobe in the human gut.
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Affiliation(s)
- Haruyuki Nakayama-Imaohji
- Department of Immunology and Parasitology, Institute of Health Biosciences, the University of Tokushima Graduate School, Tokushima, Japan
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Development of a double-crossover markerless gene deletion system in Bifidobacterium longum: functional analysis of the α-galactosidase gene for raffinose assimilation. Appl Environ Microbiol 2012; 78:4984-94. [PMID: 22582061 DOI: 10.1128/aem.00588-12] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Functional analysis of Bifidobacterium genes is essential for understanding host-Bifidobacterium interactions with beneficial effects on human health; however, the lack of an effective targeted gene inactivation system in bifidobacteria has prevented the development of functional genomics in this bacterium. Here, we report the development of a markerless gene deletion system involving a double crossover in Bifidobacterium longum. Incompatible plasmid vectors were used to facilitate a second crossover step. The conditional replication vector pBS423-ΔrepA, which lacks the plasmid replication gene repA, was integrated into the target gene by a first crossover event. Subsequently, the replicative plasmid pTBR101-CM, which harbors repA, was introduced into this integrant to facilitate the second crossover step and subsequent elimination of the excised conditional replication vector from the cells by plasmid incompatibility. The proposed system was confirmed to work as expected in B. longum 105-A using the chromosomal full-length β-galactosidase gene as a target. Markerless gene deletion was tested using the aga gene, which encodes α-galactosidase, whose substrates include raffinose. Almost all the pTBR101-CM-transformed strains became double-crossover recombinants after subculture, and 4 out of the 270 double-crossover recombinants had lost the ability to assimilate raffinose. Genotype analysis of these strains revealed markerless gene deletion of aga. Carbohydrate assimilation analysis and α-galactosidase activity measurement were conducted using both the representative mutant and a plasmid-based aga-complemented strain. These functional analyses revealed that aga is the only gene encoding a functional α-galactosidase enzyme in B. longum 105-A.
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Development of replicative oriC plasmids and their versatile use in genetic manipulation of Cytophaga hutchinsonii. Appl Microbiol Biotechnol 2011; 93:697-705. [DOI: 10.1007/s00253-011-3572-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 08/15/2011] [Accepted: 09/08/2011] [Indexed: 10/17/2022]
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