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Bustamante P, Ramos-Corominas MN, Martinez-Medina M. Contribution of Toxin-Antitoxin Systems to Adherent-Invasive E. coli Pathogenesis. Microorganisms 2024; 12:1158. [PMID: 38930540 PMCID: PMC11205521 DOI: 10.3390/microorganisms12061158] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 05/24/2024] [Accepted: 06/05/2024] [Indexed: 06/28/2024] Open
Abstract
Pathobionts have been implicated in various chronic diseases, including Crohn's disease (CD), a multifactorial chronic inflammatory condition that primarily affects the gastrointestinal tract, causing inflammation and damage to the digestive system. While the exact cause of CD remains unclear, adherent-invasive Escherichia coli (AIEC) strains have emerged as key contributors to its pathogenesis. AIEC are characterized by their ability to adhere to and invade intestinal epithelial cells and survive and replicate inside macrophages. However, the mechanisms underlying the virulence and persistence of AIEC within their host remain the subject of intensive research. Toxin-antitoxin systems (TAs) play a potential role in AIEC pathogenesis and may be therapeutic targets. These systems generally consist of two components: a toxin harmful to the cell and an antitoxin that neutralizes the toxin's effects. They contribute to bacterial survival in adverse conditions and regulate bacterial growth and behavior, affecting various cellular processes in bacterial pathogens. This review focuses on the current information available to determine the roles of TAs in the pathogenicity of AIEC. Their contribution to the AIEC stress response, biofilm formation, phage inhibition, the maintenance of mobile genetic elements, and host lifestyles is discussed.
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Affiliation(s)
- Paula Bustamante
- Molecular and Cellular Microbiology Laboratory, Instituto de Ciencias Biomédicas, Facultad de Ciencias de la Salud, Universidad Autónoma de Chile, Santiago 8910060, Chile
| | - María Núria Ramos-Corominas
- Microbiology of Intestinal Diseases, Biology Department, Universitat de Girona, 17003 Girona, Spain; (M.N.R.-C.); (M.M.-M.)
| | - Margarita Martinez-Medina
- Microbiology of Intestinal Diseases, Biology Department, Universitat de Girona, 17003 Girona, Spain; (M.N.R.-C.); (M.M.-M.)
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2
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Valadbeigi H, Sadeghifard N, Kaviar VH, Haddadi MH, Ghafourian S, Maleki A. Effect of ZnO nanoparticles on biofilm formation and gene expression of the toxin-antitoxin system in clinical isolates of Pseudomonas aeruginosa. Ann Clin Microbiol Antimicrob 2023; 22:89. [PMID: 37798613 PMCID: PMC10557154 DOI: 10.1186/s12941-023-00639-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Accepted: 09/25/2023] [Indexed: 10/07/2023] Open
Abstract
BACKGROUND Biofilm formation by Pseudomonas aeruginosa (P. aeruginosa) is known to be characteristic of this organism. This bacterium is considered one of the most life-threatening bacteria and has been identified as a priority pathogen for research by WHO. Biofilm-producing P. aeruginosa is a concern in many parts of the world due to antibiotic resistance. Alginate also plays an important role in the biofilm formation of P. aeruginosa as well as the emergence of antibiotic resistance in biofilms. In addition, the systems of toxin-antitoxin( TA) play an important role in biofilm formation. Metal nanoparticle(NP) such as zinc oxide (ZnO) also have extensive biological properties, especially anti-biofilm properties. Therefore, this study was conducted in relation to the importance of zinc oxide nanoparticles (ZnO NPs) in biofilm formation and also the correlation of gene expression of TA systems in clinical isolates of P. aeruginosa. METHODS A total of 52 P. aeruginosa isolates were collected from burns (n = 15), UTI (n = 31), and trachea (n = 6) in hospitals in Ilam between May 2020 and October 2020. Biofilm formation was assessed using a microtiter plate assay. MIC and sub-MIC concentrations of ZnO NPs (10-30 nm with purity greater than 99.8%) in P. aeruginosa were determined. Subsequently, biofilm formation was investigated using sub-MIC concentrations of ZnO NPs. Finally, total RNA was extracted and RT- qPCR was used to determine the expression levels of genes of mazEF, mqsRA, and higBA of TA systems. RESULTS Six isolates of P. aeruginosa were found to form strong biofilms. The results showed that ZnO NPs were able to inhibit biofilm formation. In our experiments, we found that the sub-MIC concentration of ZnO NPs increased the gene expression of antitoxins mazE and mqsA and toxin higB of TA systems treated with ZnO NPs. CONCLUSIONS In the present study, ZnO NPs were shown to effectively inhibit biofilm formation in P. aeruginosa. Our results support the relationship between TA systems and ZnO NPs in biofilm formation in P. aeruginosa. Importantly, the expression of antitoxins mazE and mqsA was high after treatment with ZnO NPs, but not that of antitoxin higA.
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Affiliation(s)
- Hassan Valadbeigi
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran.
| | - Nourkhoda Sadeghifard
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran
| | - Vahab Hassan Kaviar
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran
| | | | - Sobhan Ghafourian
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran
- Department of Microbiology, School of Medicine, Ilam University of Medical Sciences, Ilam, Iran
| | - Abbas Maleki
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran
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Berkvens A, Chauhan P, Bruggeman FJ. Integrative biology of persister cell formation: molecular circuitry, phenotypic diversification and fitness effects. JOURNAL OF THE ROYAL SOCIETY, INTERFACE 2022; 19:20220129. [PMID: 36099930 PMCID: PMC9470271 DOI: 10.1098/rsif.2022.0129] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Microbial populations often contain persister cells, which reduce the extinction risk upon sudden stresses. Persister cell formation is deeply intertwined with physiology. Due to this complexity, it cannot be satisfactorily understood by focusing only on mechanistic, physiological or evolutionary aspects. In this review, we take an integrative biology perspective to identify common principles of persister cell formation, which might be applicable across evolutionary-distinct microbes. Persister cells probably evolved to cope with a fundamental trade-off between cellular stress and growth tasks, as any biosynthetic resource investment in growth-supporting proteins is at the expense of stress tasks and vice versa. Natural selection probably favours persister cell subpopulation formation over a single-phenotype strategy, where each cell is prepared for growth and stress to a suboptimal extent, since persister cells can withstand harsher environments and their coexistence with growing cells leads to a higher fitness. The formation of coexisting phenotypes requires bistable molecular circuitry. Bistability probably emerges from growth-modulated, positive feedback loops in the cell's growth versus stress control network, involving interactions between sigma factors, guanosine pentaphosphate and toxin-antitoxin (TA) systems. We conclude that persister cell formation is most likely a response to a sudden reduction in growth rate, which can be achieved by antibiotic addition, nutrient starvation, sudden stresses, nutrient transitions or activation of a TA system.
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Affiliation(s)
- Alicia Berkvens
- Systems Biology Lab, AIMMS, VU University, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands
| | - Priyanka Chauhan
- Systems Biology Lab, AIMMS, VU University, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands
| | - Frank J Bruggeman
- Systems Biology Lab, AIMMS, VU University, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands
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Fu S, Wang Q, Wang R, Zhang Y, Lan R, He F, Yang Q. Horizontal transfer of antibiotic resistance genes within the bacterial communities in aquacultural environment. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 820:153286. [PMID: 35074363 DOI: 10.1016/j.scitotenv.2022.153286] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 01/13/2022] [Accepted: 01/16/2022] [Indexed: 06/14/2023]
Abstract
Very little is known about how microbiome interactions shape the horizontal transfer of antibiotic resistance genes in aquacultural environment. To this end, we first conducted 16S rRNA gene amplicon sequencing to monitor the dynamics of bacterial community compositions in one shrimp farm from 2019 to 2020. Next, co-occurrence analysis was then conducted to reveal the interactions network between Vibrio spp. and other species. Subsequently, 21 V. parahaemolyticus isolates and 15 related bacterial species were selected for whole-genome sequencing (WGS). The 16S rDNA amplicon sequencing results identified a remarkable increase of Vibrio and Providencia in September-2019 and a significant rise of Enterobacter and Shewanella in Septtember-2020. Co-occurrence analysis revealed that Vibrio spp. positively interacted with the above species, leading to the sequencing of their isolates to further understand the sharing of the resistant genomic islands (GIs). Subsequent pan-genomic analysis of V. parahaemolyticus genomes identified 278 horizontally transferred genes in 10 GIs, most of which were associated with antibiotic resistance, virulence, and fitness of metabolism. Most of the GIs have also been identified in Providencia, and Enterobacter, suggesting that exchange of genetic traits might occur in V. parahaemolyticus and other cooperative species in a specific niche. No genetic exchange was found between the species with negative relationships. The knowledge generated from this study would greatly improve our capacity to predict and mitigate the emergence of new resistant population and provide practical guidance on the microbial management during the aquacultural activities.
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Affiliation(s)
- Songzhe Fu
- College of Marine Science and Environment, Dalian Ocean University, Dalian, China.
| | - Qingyao Wang
- College of Marine Science and Environment, Dalian Ocean University, Dalian, China; Key Laboratory of Environment Controlled Aquaculture, Dalian Ocean University, Ministry of Education, 116023 Dalian, China
| | - Rui Wang
- College of Marine Science and Environment, Dalian Ocean University, Dalian, China; Key Laboratory of Environment Controlled Aquaculture, Dalian Ocean University, Ministry of Education, 116023 Dalian, China
| | - Yixiang Zhang
- CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institutes for Biological Sciences (SIBS), Chinese Academy of Sciences, Shanghai, China; University of Chinese Academy of Sciences, Shanghai, China
| | - Ruiting Lan
- School of Biotechnology and Biomolecular Sciences, University of New South Wales (UNSW), Sydney, NSW, Australia
| | - Fenglan He
- The Collaboration Unit for Field Epidemiology of State Key Laboratory for Infectious Disease Prevention and Control, Nanchang Center for Disease Control and Prevention, Nanchang, China
| | - Qian Yang
- Center for Microbial Ecology and Technology (CMET), Ghent University, Coupure Links 653, 9000 Gent, Belgium.
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de Souza-Neto RR, Carvalho IGB, Martins PMM, Picchi SC, Tomaz JP, Caserta R, Takita MA, de Souza AA. MqsR toxin as a biotechnological tool for plant pathogen bacterial control. Sci Rep 2022; 12:2794. [PMID: 35181693 PMCID: PMC8857320 DOI: 10.1038/s41598-022-06690-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Accepted: 12/23/2021] [Indexed: 11/09/2022] Open
Abstract
Type II toxin-antitoxin (TA) systems are widespread in bacteria and are involved in important cell features, such as cell growth inhibition and antimicrobial tolerance, through the induction of persister cells. Overall, these characteristics are associated with bacterial survival under stress conditions and represent a significant genetic mechanism to be explored for antibacterial molecules. We verified that even though Xylella fastidiosa and Xanthomonas citri subsp. citri share closely related genomes, they have different Type II TA system contents. One important difference is the absence of mqsRA in X. citri. The toxin component of this TA system has been shown to inhibit the growth of X. fastidiosa. Thus, the absence of mqsRA in X. citri led us to explore the possibility of using the MqsR toxin to impair X. citri growth. We purified MqsR and confirmed that the toxin was able to inhibit X. citri. Subsequently, transgenic citrus plants producing MqsR showed a significant reduction in citrus canker and citrus variegated chlorosis symptoms caused, respectively, by X. citri and X. fastidiosa. This study demonstrates that the use of toxins from TA systems is a promising strategy to be explored aiming bacterial control.
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Affiliation(s)
- Reinaldo Rodrigues de Souza-Neto
- Citrus Research Center, Agronomic Institute - IAC, Cordeirópolis, SP, Brazil.,Department of Genetics, Evolution, Microbiology, and Immunology, Institute of Biology, University of Campinas - UNICAMP, Campinas, SP, Brazil
| | | | | | | | - Juarez Pires Tomaz
- Rural Development Institute of Parana - IAPAR-EMATER, Londrina, PR, Brazil
| | - Raquel Caserta
- Citrus Research Center, Agronomic Institute - IAC, Cordeirópolis, SP, Brazil
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Bhowmik P, Rajagopal S, Hmar RV, Singh P, Saxena P, Amar P, Thomas T, Ravishankar R, Nagaraj S, Katagihallimath N, Sarangapani RK, Ramachandran V, Datta S. Validated In Silico Model for Biofilm Formation in Escherichia coli. ACS Synth Biol 2022; 11:713-731. [PMID: 35025506 DOI: 10.1021/acssynbio.1c00445] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using Escherichia coli as the representative biofilm former, we report here the development of an in silico model built by simulating events that transform a free-living bacterial entity into self-encased multicellular biofilms. Published literature on ∼300 genes associated with pathways involved in biofilm formation was curated, static maps were created, and suitably interconnected with their respective metabolites using ordinary differential equations. Precise interplay of genetic networks that regulate the transitory switching of bacterial growth pattern in response to environmental changes and the resultant multicomponent synthesis of the extracellular matrix were appropriately represented. Subsequently, the in silico model was analyzed by simulating time-dependent changes in the concentration of components by using the R and python environment. The model was validated by simulating and verifying the impact of key gene knockouts (KOs) and systematic knockdowns on biofilm formation, thus ensuring the outcomes were comparable with the reported literature. Similarly, specific gene KOs in laboratory and pathogenic E. coli were constructed and assessed. MiaA, YdeO, and YgiV were found to be crucial in biofilm development. Furthermore, qRT-PCR confirmed the elevation of expression in biofilm-forming clinical isolates. Findings reported in this study offer opportunities for identifying biofilm inhibitors with applications in multiple industries. The application of this model can be extended to the health care sector specifically to develop novel adjunct therapies that prevent biofilms in medical implants and reduce emergence of biofilm-associated resistant polymicrobial-chronic infections. The in silico framework reported here is open source and accessible for further enhancements.
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Affiliation(s)
- Purnendu Bhowmik
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
- The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bengaluru, Karnataka 560064, India
| | - Sreenath Rajagopal
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
| | - Rothangamawi Victoria Hmar
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
| | - Purnima Singh
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
| | - Pragya Saxena
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
| | - Prakruthi Amar
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
| | - Teby Thomas
- St. John’s Research Institute, Bengaluru, Karnataka 560034, India
| | - Rajani Ravishankar
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
| | - Savitha Nagaraj
- St. John’s Medical College, Bengaluru, Karnataka 560034, India
| | - Nainesh Katagihallimath
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
- The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bengaluru, Karnataka 560064, India
| | - Ramanujan Kadambi Sarangapani
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
| | - Vasanthi Ramachandran
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
- The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bengaluru, Karnataka 560064, India
| | - Santanu Datta
- Bugworks Research India Pvt. Ltd., Centre for Cellular and Molecular Platforms, National Centre for Biological Sciences, GKVK, Bellary Road, Bengaluru, Karnataka 560065, India
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Karimaei S, Kazem Aghamir SM, Foroushani AR, Pourmand MR. Antibiotic tolerance in biofilm persister cells of Staphylococcus aureus and expression of toxin-antitoxin system genes. Microb Pathog 2021; 159:105126. [PMID: 34384900 DOI: 10.1016/j.micpath.2021.105126] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 06/04/2021] [Accepted: 08/05/2021] [Indexed: 11/17/2022]
Abstract
The ability of Staphylococcus aureus to form biofilm and persister cells is the main cause of recurrent infections. This study aimed to evaluate the expression of toxin-antitoxin (TA) systems in persister cells within S. aureus biofilms. Time-dependent variation in the persister population present in biofilms of S. aureus was examined after treatment with bactericidal antibiotics. Then, the relative expression level of type II TA system (mazF, relE1, and relE2), type I TA system (sprG), and clpP protease genes in S. aureus strains were assessed by Real _Time PCR. Among the sixteen isolates, two isolates were found to be the strongest biofilm producers. The established biofilm of these isolates showed a comparable biphasic pattern at the lethal dose of the antibiotics. The expression level of TA system genes was increased and strain-specific expression patterns were observed under antibiotics stress conditions. Persisters within a biofilm may establish a reservoir for relapsing infection and could contribute to treatment failures. Hence, the possible role of the TA systems should be considered in biofilm and persister cell formation.
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Affiliation(s)
- Samira Karimaei
- Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | | | - Abbas Rahimi Foroushani
- Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
| | - Mohammad Reza Pourmand
- Department of Pathobiology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran.
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Abstract
Bacterial endoribonuclease toxins belong to a protein family that inhibits bacterial growth by degrading mRNA or rRNA sequences. The toxin genes are organized in pairs with its cognate antitoxins in the chromosome and thus the activities of the toxins are antagonized by antitoxin proteins or RNAs during active translation. In response to a variety of cellular stresses, the endoribonuclease toxins appear to be released from antitoxin molecules via proteolytic cleavage of antitoxin proteins or preferential degradation of antitoxin RNAs and cleave a diverse range of mRNA or rRNA sequences in a sequence-specific or codon-specific manner, resulting in various biological phenomena such as antibiotic tolerance and persister cell formation. Given that substrate specificity of each endoribonuclease toxin is determined by its structure and the composition of active site residues, we summarize the biology, structure, and substrate specificity of the updated bacterial endoribonuclease toxins.
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Affiliation(s)
- Yoontak Han
- Department of Life Sciences, Korea University, Seoul 02481, Korea
| | - Eun-Jin Lee
- Department of Life Sciences, Korea University, Seoul 02481, Korea
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Narimisa N, Amraei F, Kalani BS, Azarnezhad A, Jazi FM. Biofilm establishment, biofilm persister cell formation, and relative gene expression analysis of type II toxin-antitoxin system in Klebsiella pneumoniae. GENE REPORTS 2020. [DOI: 10.1016/j.genrep.2020.100846] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Targeting Type II Toxin-Antitoxin Systems as Antibacterial Strategies. Toxins (Basel) 2020; 12:toxins12090568. [PMID: 32899634 PMCID: PMC7551001 DOI: 10.3390/toxins12090568] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 08/31/2020] [Accepted: 08/31/2020] [Indexed: 12/13/2022] Open
Abstract
The identification of novel targets for antimicrobial agents is crucial for combating infectious diseases caused by evolving bacterial pathogens. Components of bacterial toxin–antitoxin (TA) systems have been recognized as promising therapeutic targets. These widespread genetic modules are usually composed of two genes that encode a toxic protein targeting an essential cellular process and an antitoxin that counteracts the activity of the toxin. Uncontrolled toxin expression may elicit a bactericidal effect, so they may be considered “intracellular molecular bombs” that can lead to elimination of their host cells. Based on the molecular nature of antitoxins and their mode of interaction with toxins, TA systems have been classified into six groups. The most prevalent are type II TA systems. Due to their ubiquity among clinical isolates of pathogenic bacteria and the essential processes targeted, they are promising candidates for the development of novel antimicrobial strategies. In this review, we describe the distribution of type II TA systems in clinically relevant human pathogens, examine how these systems could be developed as the targets for novel antibacterials, and discuss possible undesirable effects of such therapeutic intervention, such as the induction of persister cells, biofilm formation and toxicity to eukaryotic cells.
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11
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Jahanshahi S, Li Y. An Effective Method for Quantifying RNA Expression of IbsC-SibC, a Type I Toxin-Antitoxin System in Escherichia coli. Chembiochem 2020; 21:3120-3130. [PMID: 32516493 DOI: 10.1002/cbic.202000280] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 06/04/2020] [Indexed: 01/28/2023]
Abstract
Toxin and antitoxin (TA) systems are small genetic modules consisting of a toxin protein and an RNA or protein antitoxin. It is difficult to study their functions in a large part due to the lack of effective methods to study toxin RNAs, which usually exist at exceptionally low levels. Herein, we describe a sensitive reverse transcription quantitative PCR (RT-qPCR) method that is able to quantitate such RNA species. The method was directed at detection of the toxin mRNA of the ibsC-sibC TA pair, and its high specificity was validated by sequencing. The approach was used to determine relative expression of the IbsC and SibC RNAs at different cell-growth phases; this revealed an expression pattern that cannot be explained by the prevailing notion of growth stasis by the toxin and rescue by the antitoxin. The usefulness of the method was further showcased by the determination of average cellular copy numbers of the IbsC-SibC RNAs in wild-type E. coli cells and RNA abundance in E. coli cells engineered with extra copies of the ibsC-sibC genes. With a robust method to quantitate cellular small RNAs at very low concentrations, we are now equipped to study the expression of TA systems under different conditions to gain useful insights about their functions.
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Affiliation(s)
- Shahrzad Jahanshahi
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, DeGroote School of Medicine, School of Biomedical Engineering, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4 K1, Canada
| | - Yingfu Li
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, DeGroote School of Medicine, School of Biomedical Engineering, McMaster University, 1280 Main Street West, Hamilton, ON, L8S 4 K1, Canada
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12
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Wu AY, Kamruzzaman M, Iredell JR. Specialised functions of two common plasmid mediated toxin-antitoxin systems, ccdAB and pemIK, in Enterobacteriaceae. PLoS One 2020; 15:e0230652. [PMID: 32603331 PMCID: PMC7326226 DOI: 10.1371/journal.pone.0230652] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 06/17/2020] [Indexed: 12/17/2022] Open
Abstract
Toxin-antitoxin systems (TAS) are commonly found on bacterial plasmids and are generally involved in plasmid maintenance. In addition to plasmid maintenance, several plasmid-mediated TAS are also involved in bacterial stress response and virulence. Even though the same TAS are present in a variety of plasmid types and bacterial species, differences in their sequences, expression and functions are not well defined. Here, we aimed to identify commonly occurring plasmid TAS in Escherichia coli and Klebsiella pneumoniae and compare the sequence, expression and plasmid stability function of their variants. 27 putative type II TAS were identified from 1063 plasmids of Klebsiella pneumoniae in GenBank. Among these, ccdAB and pemIK were found to be most common, also occurring in plasmids of E. coli. Comparisons of ccdAB variants, taken from E. coli and K. pneumoniae, revealed sequence differences, while pemIK variants from IncF and IncL/M plasmids were almost identical. Similarly, the expression and plasmid stability functions of ccdAB variants varied according to the host strain and species, whereas the expression and functions of pemIK variants were consistent among host strains. The specialised functions of some TAS may determine the host specificity and epidemiology of major antibiotic resistance plasmids.
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Affiliation(s)
- Alma Y. Wu
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, New South Wales, Australia
| | - Muhammad Kamruzzaman
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, New South Wales, Australia
- * E-mail: (MK); (JI)
| | - Jonathan R. Iredell
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead, New South Wales, Australia
- Westmead Hospital, Westmead, New South Wales, Australia
- * E-mail: (MK); (JI)
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Bustamante P, Iredell JR. The roles of HicBA and a novel toxin-antitoxin-like system, TsxAB, in the stability of IncX4 resistance plasmids in Escherichia coli. J Antimicrob Chemother 2020; 74:553-556. [PMID: 30535076 DOI: 10.1093/jac/dky491] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2018] [Revised: 11/05/2018] [Accepted: 11/06/2018] [Indexed: 11/13/2022] Open
Abstract
OBJECTIVES To identify toxin-antitoxin (TA)-like plasmid stability loci on IncX4 plasmids. METHODS TA-like loci were identified bioinformatically and their contribution to stability of the IncX4 plasmid pJIE143 was tested in optimal growth conditions in vitro. The conservation of the TA-like loci identified was analysed within an updated IncX plasmid database. RESULTS A novel TA-like locus, tsxAB, was identified on the IncX4 plasmid pJIE143, carrying the important plasmid-borne antibiotic resistance gene blaCTX-M-15. pJIE143 (the WT plasmid) and its tsxA mutant are stable for 80 bacterial generations in the absence of selective pressure but a tsxB deletion mutant of pJIE143 is relatively quickly lost without positive selection (91.1% ± 1.5% loss after 50 generations). Nine IncX subclasses were identified among 272 fully sequenced IncX plasmids, dominated by those identified as IncX3, IncX1 and IncX4 subclasses in PlasmidFinder. The novel TA-like locus, tsxAB, appears to be a feature of IncX4 plasmids, being present in 64 of 67 so identified, but only present in a single IncX1 plasmid (of 79 identified) and present in no other IncX plasmids. CONCLUSIONS tsxAB, a novel TA-like stability locus, is highly conserved in IncX4 plasmids associated with transmission of important antibiotic resistance genes. Previous in silico analysis indicated that IncX4 encodes only HicBA among the known TA systems. Here we show that HicBA does not contribute to plasmid stability in optimal growth conditions for Escherichia coli and instead demonstrate this role for a completely novel TA-like system, TsxAB, that appears both necessary and sufficient for E. coli addiction to IncX4 resistance plasmids.
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Affiliation(s)
- Paula Bustamante
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead Hospital, Westmead, NSW, Australia
| | - Jonathan R Iredell
- Centre for Infectious Diseases and Microbiology, The Westmead Institute for Medical Research, The University of Sydney, Westmead Hospital, Westmead, NSW, Australia
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14
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Fuller GG, Han T, Freeberg MA, Moresco JJ, Ghanbari Niaki A, Roach NP, Yates JR, Myong S, Kim JK. RNA promotes phase separation of glycolysis enzymes into yeast G bodies in hypoxia. eLife 2020; 9:e48480. [PMID: 32298230 PMCID: PMC7162659 DOI: 10.7554/elife.48480] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 03/31/2020] [Indexed: 12/20/2022] Open
Abstract
In hypoxic stress conditions, glycolysis enzymes assemble into singular cytoplasmic granules called glycolytic (G) bodies. G body formation in yeast correlates with increased glucose consumption and cell survival. However, the physical properties and organizing principles that define G body formation are unclear. We demonstrate that glycolysis enzymes are non-canonical RNA binding proteins, sharing many common mRNA substrates that are also integral constituents of G bodies. Targeting nonspecific endoribonucleases to G bodies reveals that RNA nucleates G body formation and maintains its structural integrity. Consistent with a phase separation mechanism of biogenesis, recruitment of glycolysis enzymes to G bodies relies on multivalent homotypic and heterotypic interactions. Furthermore, G bodies fuse in vivo and are largely insensitive to 1,6-hexanediol, consistent with a hydrogel-like composition. Taken together, our results elucidate the biophysical nature of G bodies and demonstrate that RNA nucleates phase separation of the glycolysis machinery in response to hypoxic stress.
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Affiliation(s)
- Gregory G Fuller
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - Ting Han
- National Institute of Biological SciencesBeijingChina
| | | | - James J Moresco
- Department of Chemical Physiology, The Scripps Research InstituteLa JollaUnited States
| | | | - Nathan P Roach
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
| | - John R Yates
- Department of Chemical Physiology, The Scripps Research InstituteLa JollaUnited States
| | - Sua Myong
- Department of Biophysics, Johns Hopkins UniversityBaltimoreUnited States
| | - John K Kim
- Department of Biology, Johns Hopkins UniversityBaltimoreUnited States
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15
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Reassessing the Role of the Type II MqsRA Toxin-Antitoxin System in Stress Response and Biofilm Formation: mqsA Is Transcriptionally Uncoupled from mqsR. mBio 2019; 10:mBio.02678-19. [PMID: 31848281 PMCID: PMC6918082 DOI: 10.1128/mbio.02678-19] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Toxin-antitoxin (TA) systems are broadly distributed modules whose biological roles remain mostly unknown. The mqsRA system is a noncanonical TA system in which the toxin and antitoxins genes are organized in operon but with the particularity that the toxin gene precedes that of the antitoxin. This system was shown to regulate global processes such as resistance to bile salts, motility, and biofilm formation. In addition, the MqsA antitoxin was shown to be a master regulator that represses the transcription of the csgD, cspD, and rpoS global regulator genes, thereby displaying a pleiotropic regulatory role. Here, we identified two promoters located in the toxin sequence driving the constitutive expression of mqsA, allowing thereby excess production of the MqsA antitoxin compared to the MqsR toxin. Our results show that both antitoxin-specific and operon promoters are not regulated by stresses such as amino acid starvation, oxidative shock, or bile salts. Moreover, we show that the MqsA antitoxin is not a global regulator as suggested, since the expression of csgD, cspD and rpoS is similar in wild-type and ΔmqsRA mutant strains. Moreover, these two strains behave similarly in terms of biofilm formation and sensitivity to oxidative stress or bile salts.IMPORTANCE There is growing controversy regarding the role of chromosomal toxin-antitoxin systems in bacterial physiology. mqsRA is a peculiar toxin-antitoxin system, as the gene encoding the toxin precedes that of the antitoxin. This system was previously shown to play a role in stress response and biofilm formation. In this work, we identified two promoters specifically driving the constitutive expression of the antitoxin, thereby decoupling the expression of antitoxin from the toxin. We also showed that mqsRA contributes neither to the regulation of biofilm formation nor to the sensitivity to oxidative stress and bile salts. Finally, we were unable to confirm that the MqsA antitoxin is a global regulator. Altogether, our data are ruling out the involvement of the mqsRA system in Escherichia coli regulatory networks.
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16
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Shivaee A, Mohammadzadeh R, Shahbazi S, Pardakhtchi E, Ohadi E, Kalani BS. Time-variable expression levels of mazF, atlE, sdrH, and bap genes during biofilm formation in Staphylococcus epidermidis. Acta Microbiol Immunol Hung 2019; 66:499-508. [PMID: 31198057 DOI: 10.1556/030.66.2019.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Staphylococcus epidermidis is an opportunistic pathogen causing infections related to the usage of implants and medical devices. Pathogenicity of this microorganism is mainly linked to its capability to form biofilm structures. Biofilm formation vastly depends on several factors including different proteins. We studied the expression levels of three proteins including SdrH, Bap, AtlE, and MazF at different time intervals during the course of biofilm formation. In this study, a catheter-derived S. epidermidis isolate with strong ability of biofilm formation was selected. PCR assay was used to detect sdrH, bap, atlE, and mazF genes in this isolate. Real-time PCR was used to determine the expression levels of these genes after 4, 8, and 20 h during the course of biofilm formation. The studied genes showed different expression levels at different time intervals during biofilm formation by real-time PCR method. Expression levels of atlE and sdrH genes were the highest at 4 h, whereas bap gene showed the highest expression level at 8 h during the course of biofilm formation. In addition, the expression level of mazF gene peaked at 4 h and then progressively decreased at 8 and 20 h. Our results suggest the importance of AtlE, SdrH, and MazF proteins in the establishment and development of the biofilm structure. In addition, our results showed the important role of protein Bap in the accumulation of biofilm structure. Future studies are required to understand the exact role of MazF in the process of biofilm formation.
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Affiliation(s)
- Ali Shivaee
- 1 Department of Microbiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Rokhsareh Mohammadzadeh
- 1 Department of Microbiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Shahla Shahbazi
- 2 Department of Bacteriology, Pasteur Institute of Iran, Teheran, Iran
| | - Elahe Pardakhtchi
- 3 Microbial Biotechnology Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Elnaz Ohadi
- 1 Department of Microbiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Behrooz Sadeghi Kalani
- 1 Department of Microbiology, Faculty of Medicine, Iran University of Medical Sciences, Tehran, Iran
- 3 Microbial Biotechnology Research Center, Iran University of Medical Sciences, Tehran, Iran
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17
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Towards Exploring Toxin-Antitoxin Systems in Geobacillus: A Screen for Type II Toxin-Antitoxin System Families in a Thermophilic Genus. Int J Mol Sci 2019; 20:ijms20235869. [PMID: 31771094 PMCID: PMC6929052 DOI: 10.3390/ijms20235869] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Revised: 11/12/2019] [Accepted: 11/20/2019] [Indexed: 12/19/2022] Open
Abstract
The toxin-antitoxin (TA) systems have been attracting attention due to their role in regulating stress responses in prokaryotes and their biotechnological potential. Much recognition has been given to type II TA system of mesophiles, while thermophiles have received merely limited attention. Here, we are presenting the putative type II TA families encoded on the genomes of four Geobacillus strains. We employed the TA finder tool to mine for TA-coding genes and manually curated the results using protein domain analysis tools. We also used the NCBI BLAST, Operon Mapper, ProOpDB, and sequence alignment tools to reveal the geobacilli TA features. We identified 28 putative TA pairs, distributed over eight TA families. Among the identified TAs, 15 represent putative novel toxins and antitoxins, belonging to the MazEF, MNT-HEPN, ParDE, RelBE, and XRE-COG2856 TA families. We also identified a potentially new TA composite, AbrB-ParE. Furthermore, we are suggesting the Geobacillus acetyltransferase TA (GacTA) family, which potentially represents one of the unique TA families with a reverse gene order. Moreover, we are proposing a hypothesis on the xre-cog2856 gene expression regulation, which seems to involve the c-di-AMP. This study aims for highlighting the significance of studying TAs in Geobacillus and facilitating future experimental research.
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18
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Nikolic N. Autoregulation of bacterial gene expression: lessons from the MazEF toxin-antitoxin system. Curr Genet 2019; 65:133-138. [PMID: 30132188 PMCID: PMC6343021 DOI: 10.1007/s00294-018-0879-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 08/13/2018] [Accepted: 08/14/2018] [Indexed: 11/30/2022]
Abstract
Autoregulation is the direct modulation of gene expression by the product of the corresponding gene. Autoregulation of bacterial gene expression has been mostly studied at the transcriptional level, when a protein acts as the cognate transcriptional repressor. A recent study investigating dynamics of the bacterial toxin-antitoxin MazEF system has shown how autoregulation at both the transcriptional and post-transcriptional levels affects the heterogeneity of Escherichia coli populations. Toxin-antitoxin systems hold a crucial but still elusive part in bacterial response to stress. This perspective highlights how these modules can also serve as a great model system for investigating basic concepts in gene regulation. However, as the genomic background and environmental conditions substantially influence toxin activation, it is important to study (auto)regulation of toxin-antitoxin systems in well-defined setups as well as in conditions that resemble the environmental niche.
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Affiliation(s)
- Nela Nikolic
- Institute of Science and Technology (IST) Austria, 3400, Klosterneuburg, Austria.
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19
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Mets T, Kasvandik S, Saarma M, Maiväli Ü, Tenson T, Kaldalu N. Fragmentation of Escherichia coli mRNA by MazF and MqsR. Biochimie 2019; 156:79-91. [DOI: 10.1016/j.biochi.2018.10.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 10/06/2018] [Indexed: 01/21/2023]
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20
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Nikolic N, Bergmiller T, Vandervelde A, Albanese TG, Gelens L, Moll I. Autoregulation of mazEF expression underlies growth heterogeneity in bacterial populations. Nucleic Acids Res 2018; 46:2918-2931. [PMID: 29432616 PMCID: PMC5888573 DOI: 10.1093/nar/gky079] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 12/30/2017] [Accepted: 01/27/2018] [Indexed: 01/24/2023] Open
Abstract
The MazF toxin sequence-specifically cleaves single-stranded RNA upon various stressful conditions, and it is activated as a part of the mazEF toxin-antitoxin module in Escherichia coli. Although autoregulation of mazEF expression through the MazE antitoxin-dependent transcriptional repression has been biochemically characterized, less is known about post-transcriptional autoregulation, as well as how both of these autoregulatory features affect growth of single cells during conditions that promote MazF production. Here, we demonstrate post-transcriptional autoregulation of mazF expression dynamics by MazF cleaving its own transcript. Single-cell analyses of bacterial populations during ectopic MazF production indicated that two-level autoregulation of mazEF expression influences cell-to-cell growth rate heterogeneity. The increase in growth rate heterogeneity is governed by the MazE antitoxin, and tuned by the MazF-dependent mazF mRNA cleavage. Also, both autoregulatory features grant rapid exit from the stress caused by mazF overexpression. Time-lapse microscopy revealed that MazF-mediated cleavage of mazF mRNA leads to increased temporal variability in length of individual cells during ectopic mazF overexpression, as explained by a stochastic model indicating that mazEF mRNA cleavage underlies temporal fluctuations in MazF levels during stress.
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Affiliation(s)
- Nela Nikolic
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Tobias Bergmiller
- Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria
| | - Alexandra Vandervelde
- Laboratory of Dynamics in Biological Systems, Department of Cellular and Molecular Medicine, University of Leuven, 3000 Leuven, Belgium
| | - Tanino G Albanese
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Lendert Gelens
- Laboratory of Dynamics in Biological Systems, Department of Cellular and Molecular Medicine, University of Leuven, 3000 Leuven, Belgium
| | - Isabella Moll
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, University of Vienna, Vienna BioCenter (VBC), 1030 Vienna, Austria
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21
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Yao J, Guo Y, Wang P, Zeng Z, Li B, Tang K, Liu X, Wang X. Type II toxin/antitoxin system ParE SO /CopA SO stabilizes prophage CP4So in Shewanella oneidensis. Environ Microbiol 2018; 20:1224-1239. [PMID: 29411516 DOI: 10.1111/1462-2920.14068] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Revised: 02/03/2018] [Accepted: 02/04/2018] [Indexed: 12/15/2022]
Abstract
Toxin/antitoxin (TA) loci are commonly found in mobile genetic elements such as plasmids and prophages. However, the physiological functions of these TA loci in prophages and cross-regulation among these TA loci remain largely unexplored. Here, we characterized a newly discovered type II TA pair, ParESO /CopASO , in the CP4So prophage in Shewanella oneidensis. We demonstrated that ParESO /CopASO plays a critical role in the maintenance of CP4So in host cells after its excision. The toxin ParESO inhibited cell growth, resulting in filamentous growth and eventually cell death. The antitoxin CopASO neutralized the toxicity of ParESO through direct protein-protein interactions and repressed transcription of the TA operon by binding to a DNA motif in the promoter region containing two inverted repeats [5'-GTANTAC (N)3 GTANTAC-3']. CopASO also repressed transcription of another TA system PemKSO /PemISO in megaplasmid pMR-1 of S. oneidensis through binding to a highly similar DNA motif in its promoter region. CopASO homologs are widely spread in Shewanella and other Proteobacteria, either as a component of a TA pair or as orphan antitoxins. Our study thus illustrated the cross-regulation of the TA systems in different mobile genetic elements and expanded our understanding of the physiological function of TA systems.
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Affiliation(s)
- Jianyun Yao
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, People's Republic of China.,University of Chinese Academy of Sciences, Beijing 100049, People's Republic of China
| | - Yunxue Guo
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, People's Republic of China
| | - Pengxia Wang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, People's Republic of China
| | - Zhenshun Zeng
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, People's Republic of China
| | - Baiyuan Li
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, People's Republic of China
| | - Kaihao Tang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, People's Republic of China
| | - Xiaoxiao Liu
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, People's Republic of China
| | - Xiaoxue Wang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, People's Republic of China
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22
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Nikolic N, Didara Z, Moll I. MazF activation promotes translational heterogeneity of the grcA mRNA in Escherichia coli populations. PeerJ 2017; 5:e3830. [PMID: 28948108 PMCID: PMC5610899 DOI: 10.7717/peerj.3830] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Accepted: 08/29/2017] [Indexed: 12/04/2022] Open
Abstract
Bacteria adapt to adverse environmental conditions by altering gene expression patterns. Recently, a novel stress adaptation mechanism has been described that allows Escherichia coli to alter gene expression at the post-transcriptional level. The key player in this regulatory pathway is the endoribonuclease MazF, the toxin component of the toxin-antitoxin module mazEF that is triggered by various stressful conditions. In general, MazF degrades the majority of transcripts by cleaving at ACA sites, which results in the retardation of bacterial growth. Furthermore, MazF can process a small subset of mRNAs and render them leaderless by removing their ribosome binding site. MazF concomitantly modifies ribosomes, making them selective for the translation of leaderless mRNAs. In this study, we employed fluorescent reporter-systems to investigate mazEF expression during stressful conditions, and to infer consequences of the mRNA processing mediated by MazF on gene expression at the single-cell level. Our results suggest that mazEF transcription is maintained at low levels in single cells encountering adverse conditions, such as antibiotic stress or amino acid starvation. Moreover, using the grcA mRNA as a model for MazF-mediated mRNA processing, we found that MazF activation promotes heterogeneity in the grcA reporter expression, resulting in a subpopulation of cells with increased levels of GrcA reporter protein.
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Affiliation(s)
- Nela Nikolic
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, Vienna Biocenter (VBC), University of Vienna, Vienna, Austria
- Current affiliation: Institute of Science and Technology Austria (IST Austria), Klosterneuburg, Austria
| | - Zrinka Didara
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, Vienna Biocenter (VBC), University of Vienna, Vienna, Austria
- Current affiliation: Department of Life Sciences, IMC University of Applied Sciences Krems, Krems an der Donau, Austria
| | - Isabella Moll
- Department of Microbiology, Immunobiology and Genetics, Max F. Perutz Laboratories, Vienna Biocenter (VBC), University of Vienna, Vienna, Austria
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23
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Rossi E, Cimdins A, Lüthje P, Brauner A, Sjöling Å, Landini P, Römling U. "It's a gut feeling" - Escherichia coli biofilm formation in the gastrointestinal tract environment. Crit Rev Microbiol 2017; 44:1-30. [PMID: 28485690 DOI: 10.1080/1040841x.2017.1303660] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Escherichia coli can commonly be found, either as a commensal, probiotic or a pathogen, in the human gastrointestinal (GI) tract. Biofilm formation and its regulation is surprisingly variable, although distinct regulatory pattern of red, dry and rough (rdar) biofilm formation arise in certain pathovars and even clones. In the GI tract, environmental conditions, signals from the host and from commensal bacteria contribute to shape E. coli biofilm formation within the multi-faceted multicellular communities in a complex and integrated fashion. Although some major regulatory networks, adhesion factors and extracellular matrix components constituting E. coli biofilms have been recognized, these processes have mainly been characterized in vitro and in the context of interaction of E. coli strains with intestinal epithelial cells. However, direct observation of E. coli cells in situ, and the vast number of genes encoding surface appendages on the core or accessory genome of E. coli suggests the complexity of the biofilm process to be far from being fully understood. In this review, we summarize biofilm formation mechanisms of commensal, probiotic and pathogenic E. coli in the context of the gastrointestinal tract.
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Affiliation(s)
- Elio Rossi
- a Department of Biosciences , Università degli Studi di Milano , Milan , Italy.,b Novo Nordisk Center for Biosustainabiliy , Technical University of Denmark , Kgs. Lyngby , Denmark
| | - Annika Cimdins
- c Department of Microbiology, Tumor and Cell Biology (MTC) , Karolinska Institutet , Stockholm , Sweden.,d Institute of Hygiene, University of Münster , Münster , Germany
| | - Petra Lüthje
- c Department of Microbiology, Tumor and Cell Biology (MTC) , Karolinska Institutet , Stockholm , Sweden.,e Division of Clinical Microbiology, Department of Laboratory Medicine , Karolinska Institutet and Karolinska University Hospital Huddinge , Stockholm , Sweden
| | - Annelie Brauner
- c Department of Microbiology, Tumor and Cell Biology (MTC) , Karolinska Institutet , Stockholm , Sweden
| | - Åsa Sjöling
- c Department of Microbiology, Tumor and Cell Biology (MTC) , Karolinska Institutet , Stockholm , Sweden
| | - Paolo Landini
- a Department of Biosciences , Università degli Studi di Milano , Milan , Italy
| | - Ute Römling
- c Department of Microbiology, Tumor and Cell Biology (MTC) , Karolinska Institutet , Stockholm , Sweden
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24
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Sun C, Guo Y, Tang K, Wen Z, Li B, Zeng Z, Wang X. MqsR/MqsA Toxin/Antitoxin System Regulates Persistence and Biofilm Formation in Pseudomonas putida KT2440. Front Microbiol 2017; 8:840. [PMID: 28536573 PMCID: PMC5422877 DOI: 10.3389/fmicb.2017.00840] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 04/24/2017] [Indexed: 11/23/2022] Open
Abstract
Bacterial toxin/antitoxin (TA) systems have received increasing attention due to their prevalence, diverse structures, and important physiological functions. In this study, we identified and characterized a type II TA system in a soil bacterium Pseudomonas putida KT2440. This TA system belongs to the MqsR/MqsA family. We found that PP_4205 (MqsR) greatly inhibits cell growth in P. putida KT2440 and Escherichia coli, the antitoxin PP_4204 (MqsA) neutralizes the toxicity of the toxin MqsR, and the two genes encoding them are co-transcribed. MqsR and MqsA interact with each other directly in vivo and MqsA is a negative regulator of the TA operon through binding to the promoter. Consistent with the MqsR/MqsA pair in E. coli, the binding of the toxin MqsR to MqsA inhibits the DNA binding ability of MqsA in P. putida KT2440. Disruption of the mqsA gene which induces mqsR expression increases persister cell formation 53-fold, while overexpressing mqsA which represses mqsR expression reduces persister cell formation 220-fold, suggesting an important role of MqsR in persistence in P. putida KT2440. Furthermore, both MqsR and MqsA promote biofilm formation. As a DNA binding protein, MqsA can also negatively regulate an ECF sigma factor AlgU and a universal stress protein PP_3288. Thus, we revealed an important regulatory role of MqsR/MqsA in persistence and biofilm formation in P. putida KT2440.
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Affiliation(s)
- Chenglong Sun
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of SciencesGuangzhou, China.,University of Chinese Academy of SciencesBeijing, China
| | - Yunxue Guo
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of SciencesGuangzhou, China
| | - Kaihao Tang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of SciencesGuangzhou, China
| | - Zhongling Wen
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of SciencesGuangzhou, China.,University of Chinese Academy of SciencesBeijing, China
| | - Baiyuan Li
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of SciencesGuangzhou, China
| | - Zhenshun Zeng
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of SciencesGuangzhou, China
| | - Xiaoxue Wang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of SciencesGuangzhou, China
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25
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Masuda H, Inouye M. Toxins of Prokaryotic Toxin-Antitoxin Systems with Sequence-Specific Endoribonuclease Activity. Toxins (Basel) 2017; 9:toxins9040140. [PMID: 28420090 PMCID: PMC5408214 DOI: 10.3390/toxins9040140] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 04/09/2017] [Accepted: 04/10/2017] [Indexed: 01/21/2023] Open
Abstract
Protein translation is the most common target of toxin-antitoxin system (TA) toxins. Sequence-specific endoribonucleases digest RNA in a sequence-specific manner, thereby blocking translation. While past studies mainly focused on the digestion of mRNA, recent analysis revealed that toxins can also digest tRNA, rRNA and tmRNA. Purified toxins can digest single-stranded portions of RNA containing recognition sequences in the absence of ribosome in vitro. However, increasing evidence suggests that in vivo digestion may occur in association with ribosomes. Despite the prevalence of recognition sequences in many mRNA, preferential digestion seems to occur at specific positions within mRNA and also in certain reading frames. In this review, a variety of tools utilized to study the nuclease activities of toxins over the past 15 years will be reviewed. A recent adaptation of an RNA-seq-based technique to analyze entire sets of cellular RNA will be introduced with an emphasis on its strength in identifying novel targets and redefining recognition sequences. The differences in biochemical properties and postulated physiological roles will also be discussed.
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Affiliation(s)
- Hisako Masuda
- School of Sciences, Indiana University Kokomo, Kokomo, IN 46902, USA.
| | - Masayori Inouye
- Department of Biochemistry, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, NJ 08854, USA.
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26
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Renbarger TL, Baker JM, Sattley WM. Slow and steady wins the race: an examination of bacterial persistence. AIMS Microbiol 2017; 3:171-185. [PMID: 31294156 PMCID: PMC6605009 DOI: 10.3934/microbiol.2017.2.171] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 03/21/2017] [Indexed: 12/02/2022] Open
Abstract
Bacterial persistence is a state of metabolic dormancy among a small fraction (<1%) of a genetically identical population of cells that, as a result, becomes transiently resistant to environmental stressors. Such cells, called persisters, are able to survive indeterminate periods of exposure to challenging and even hostile environmental conditions, including nutrient deprivation, oxidative stress, or the presence of an antibiotic to which the bacterium would normally be susceptible. Subpopulations of cells having the persister phenotype is also a common feature of biofilms, in which limited space, hypoxia, and nutrient deficiencies all contribute to the onset of persistence. Microbiologists have been aware of bacterial persistence since the early days of antibiotic development. However, in recent years the significance of this phenomenon has been brought into new focus, as persistent bacterial infections that require multiple rounds of antibiotic treatment are becoming a more widespread clinical challenge. Here, we provide an overview of the major features of bacterial persistence, including the various conditions that precipitate persister formation and a discussion of several of the better-characterized molecular mechanisms that trigger this distinctive mode of bacterial dormancy.
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Affiliation(s)
- Tara L Renbarger
- Division of Natural Sciences, Indiana Wesleyan University, Marion, Indiana 46953, USA
| | - Jennifer M Baker
- Division of Natural Sciences, Indiana Wesleyan University, Marion, Indiana 46953, USA
| | - W Matthew Sattley
- Division of Natural Sciences, Indiana Wesleyan University, Marion, Indiana 46953, USA
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Comparative Genome Analyses of Vibrio anguillarum Strains Reveal a Link with Pathogenicity Traits. mSystems 2017; 2:mSystems00001-17. [PMID: 28293680 PMCID: PMC5347184 DOI: 10.1128/msystems.00001-17] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 01/30/2017] [Indexed: 01/30/2023] Open
Abstract
Comparative genome analysis of strains of a pathogenic bacterial species can be a powerful tool to discover acquisition of mobile genetic elements related to virulence. Here, we compared 28 V. anguillarum strains that differed in virulence in fish larval models. By pan-genome analyses, we found that six of nine highly virulent strains had a unique core and accessory genome. In contrast, V. anguillarum strains that were medium to nonvirulent had low genomic diversity. Integration of genomic and phenotypic features provides insights into the evolution of V. anguillarum and can also be important for survey and diagnostic purposes. Vibrio anguillarum is a marine bacterium that can cause vibriosis in many fish and shellfish species, leading to high mortalities and economic losses in aquaculture. Although putative virulence factors have been identified, the mechanism of pathogenesis of V. anguillarum is not fully understood. Here, we analyzed whole-genome sequences of a collection of V. anguillarum strains and compared them to virulence of the strains as determined in larval challenge assays. Previously identified virulence factors were globally distributed among the strains, with some genetic diversity. However, the pan-genome revealed that six out of nine high-virulence strains possessed a unique accessory genome that was attributed to pathogenic genomic islands, prophage-like elements, virulence factors, and a new set of gene clusters involved in biosynthesis, modification, and transport of polysaccharides. In contrast, V. anguillarum strains that were medium to nonvirulent had a high degree of genomic homogeneity. Finally, we found that a phylogeny based on the core genomes clustered the strains with moderate to no virulence, while six out of nine high-virulence strains represented phylogenetically separate clusters. Hence, we suggest a link between genotype and virulence characteristics of Vibrio anguillarum, which can be used to unravel the molecular evolution of V. anguillarum and can also be important from survey and diagnostic perspectives. IMPORTANCE Comparative genome analysis of strains of a pathogenic bacterial species can be a powerful tool to discover acquisition of mobile genetic elements related to virulence. Here, we compared 28 V. anguillarum strains that differed in virulence in fish larval models. By pan-genome analyses, we found that six of nine highly virulent strains had a unique core and accessory genome. In contrast, V. anguillarum strains that were medium to nonvirulent had low genomic diversity. Integration of genomic and phenotypic features provides insights into the evolution of V. anguillarum and can also be important for survey and diagnostic purposes.
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Lee C, Kim J, Kwon M, Lee K, Min H, Kim SH, Kim D, Lee N, Kim J, Kim D, Ko C, Park C. Screening for Escherichia coli K-12 genes conferring glyoxal resistance or sensitivity by transposon insertions. FEMS Microbiol Lett 2016; 363:fnw199. [PMID: 27535647 DOI: 10.1093/femsle/fnw199] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/12/2016] [Indexed: 12/14/2022] Open
Abstract
Glyoxal (GO) belongs to the reactive electrophilic species generated in vivo in all organisms. In order to identify targets of GO and their response mechanisms, we attempted to screen for GO-sensitive mutants by random insertions of TnphoA-132. The genes responsible for GO susceptibility were functionally classified as the following: (i) tRNA modification; trmE, gidA and truA, (ii) DNA repair; recA and recC, (iii) toxin-antitoxin; mqsA and (iv) redox metabolism; yqhD and caiC In addition, an insertion in the crp gene, encoding the cAMP responsive transcription factor, exhibits a GO-resistant phenotype, which is consistent with the phenotype of adenylate cyclase (cya) mutant showing GO resistance. This suggests that global regulation involving cAMP is operated in a stress response to GO. To further characterize the CRP-regulated genes directly associated with GO resistance, we created double mutants deficient in both crp and one of the candidate genes including yqhD, gloA and sodB The results indicate that these genes are negatively regulated by CRP as confirmed by real-time RT-PCR. We propose that tRNA as well as DNA are the targets of GO and that toxin/antitoxin, antioxidant and cAMP are involved in cellular response to GO.
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Affiliation(s)
- Changhan Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Jihong Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Minsuk Kwon
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Kihyun Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Haeyoung Min
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Seong Hun Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Dongkyu Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Nayoung Lee
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Jiyeun Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Doyun Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Changmin Ko
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 305-701, Republic of Korea
| | - Chankyu Park
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Yuseong-gu, Daejeon 305-701, Republic of Korea
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Characterization of the Deep-Sea Streptomyces sp. SCSIO 02999 Derived VapC/VapB Toxin-Antitoxin System in Escherichia coli. Toxins (Basel) 2016; 8:toxins8070195. [PMID: 27376329 PMCID: PMC4963828 DOI: 10.3390/toxins8070195] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2016] [Revised: 06/13/2016] [Accepted: 06/20/2016] [Indexed: 11/16/2022] Open
Abstract
Toxin-antitoxin (TA) systems are small genetic elements that are ubiquitous in prokaryotes. Most studies on TA systems have focused on commensal and pathogenic bacteria; yet very few studies have focused on TAs in marine bacteria, especially those isolated from a deep sea environment. Here, we characterized a type II VapC/VapB TA system from the deep-sea derived Streptomyces sp. SCSIO 02999. The VapC (virulence-associated protein) protein belongs to the PIN (PilT N-terminal) superfamily. Overproduction of VapC strongly inhibited cell growth and resulted in a bleb-containing morphology in E. coli. The toxicity of VapC was neutralized through direct protein-protein interaction by a small protein antitoxin VapB encoded by a neighboring gene. Antitoxin VapB alone or the VapB/VapC complex negatively regulated the vapBC promoter activity. We further revealed that three conserved Asp residues in the PIN domain were essential for the toxic effect of VapC. Additionally, the VapC/VapB TA system stabilized plasmid in E. coli. Furthermore, VapC cross-activated transcription of several TA operons via a partially Lon-dependent mechanism in E. coli, and the activated toxins accumulated more preferentially than their antitoxin partners. Collectively, we identified and characterized a new deep sea TA system in the deep sea Streptomyces sp. and demonstrated that the VapC toxin in this system can cross-activate TA operons in E. coli.
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Merfa MV, Niza B, Takita MA, De Souza AA. The MqsRA Toxin-Antitoxin System from Xylella fastidiosa Plays a Key Role in Bacterial Fitness, Pathogenicity, and Persister Cell Formation. Front Microbiol 2016; 7:904. [PMID: 27375608 PMCID: PMC4901048 DOI: 10.3389/fmicb.2016.00904] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 05/26/2016] [Indexed: 01/01/2023] Open
Abstract
Through the formation of persister cells, bacteria exhibit tolerance to multidrug and other environmental stresses without undergoing genetic changes. The toxin-antitoxin (TA) systems are involved in the formation of persister cells because they are able to induce cell dormancy. Among the TA systems, the MqsRA system has been observed to be highly induced in persister cells of Xylella fastidiosa (causal agent of citrus variegated chlorosis-CVC) activated by copper stress, and has been described in Escherichia coli as related to the formation of persister cells and biofilms. Thus, we evaluated the role of this TA system in X. fastidiosa by overexpressing the MqsR toxin, and verified that the toxin positively regulated biofilm formation and negatively cell movement, resulting in reduced pathogenicity in citrus plants. The overexpression of MqsR also increased the formation of persister cells under copper stress. Analysis of the gene and protein expression showed that this system likely has an autoregulation mechanism to express the toxin and antitoxin in the most beneficial ratio for the cell to oppose stress. Our results suggest that this TA system plays a key role in the adaptation and survival of X. fastidiosa and reveal new insights into the physiology of phytopathogen-host interactions.
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Affiliation(s)
- Marcus V. Merfa
- Instituto Agronômico, Centro de Citricultura Sylvio MoreiraCordeirópolis, Brazil
- Departamento de Genética, Evolução e Bioagentes, Universidade Estadual de CampinasCampinas, Brazil
| | - Bárbara Niza
- Instituto Agronômico, Centro de Citricultura Sylvio MoreiraCordeirópolis, Brazil
- Departamento de Genética, Evolução e Bioagentes, Universidade Estadual de CampinasCampinas, Brazil
| | - Marco A. Takita
- Instituto Agronômico, Centro de Citricultura Sylvio MoreiraCordeirópolis, Brazil
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Chan WT, Espinosa M, Yeo CC. Keeping the Wolves at Bay: Antitoxins of Prokaryotic Type II Toxin-Antitoxin Systems. Front Mol Biosci 2016; 3:9. [PMID: 27047942 PMCID: PMC4803016 DOI: 10.3389/fmolb.2016.00009] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 03/04/2016] [Indexed: 12/21/2022] Open
Abstract
In their initial stages of discovery, prokaryotic toxin-antitoxin (TA) systems were confined to bacterial plasmids where they function to mediate the maintenance and stability of usually low- to medium-copy number plasmids through the post-segregational killing of any plasmid-free daughter cells that developed. Their eventual discovery as nearly ubiquitous and repetitive elements in bacterial chromosomes led to a wealth of knowledge and scientific debate as to their diversity and functionality in the prokaryotic lifestyle. Currently categorized into six different types designated types I–VI, type II TA systems are the best characterized. These generally comprised of two genes encoding a proteic toxin and its corresponding proteic antitoxin, respectively. Under normal growth conditions, the stable toxin is prevented from exerting its lethal effect through tight binding with the less stable antitoxin partner, forming a non-lethal TA protein complex. Besides binding with its cognate toxin, the antitoxin also plays a role in regulating the expression of the type II TA operon by binding to the operator site, thereby repressing transcription from the TA promoter. In most cases, full repression is observed in the presence of the TA complex as binding of the toxin enhances the DNA binding capability of the antitoxin. TA systems have been implicated in a gamut of prokaryotic cellular functions such as being mediators of programmed cell death as well as persistence or dormancy, biofilm formation, as defensive weapons against bacteriophage infections and as virulence factors in pathogenic bacteria. It is thus apparent that these antitoxins, as DNA-binding proteins, play an essential role in modulating the prokaryotic lifestyle whilst at the same time preventing the lethal action of the toxins under normal growth conditions, i.e., keeping the proverbial wolves at bay. In this review, we will cover the diversity and characteristics of various type II TA antitoxins. We shall also look into some interesting deviations from the canonical type II TA systems such as tripartite TA systems where the regulatory role is played by a third party protein and not the antitoxin, and a unique TA system encoding a single protein with both toxin as well as antitoxin domains.
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Affiliation(s)
- Wai Ting Chan
- Molecular Microbiology and Infection Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - Manuel Espinosa
- Molecular Microbiology and Infection Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - Chew Chieng Yeo
- Faculty of Medicine, Biomedical Research Centre, Universiti Sultan Zainal Abidin Kuala Terengganu, Malaysia
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Luo P, He X, Liu Q, Hu C. Developing Universal Genetic Tools for Rapid and Efficient Deletion Mutation in Vibrio Species Based on Suicide T-Vectors Carrying a Novel Counterselectable Marker, vmi480. PLoS One 2015; 10:e0144465. [PMID: 26641275 PMCID: PMC4671572 DOI: 10.1371/journal.pone.0144465] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Accepted: 11/18/2015] [Indexed: 01/06/2023] Open
Abstract
Despite that Vibrio spp. have a significant impact on the health of humans and aquatic animals, the molecular basis of their pathogenesis is little known, mainly due to the limited genetic tools for the functional research of genes in Vibrio. In some cases, deletion of target DNAs in Vibrio can be achieved through the use of suicide vectors. However, these strategies are time-consuming and lack universality, and the widely used counterselectable gene sacB does not work well in Vibrio cells. In this study, we developed universal genetic tools for rapid and efficient deletion mutations in Vibrio species based on suicide T-Vectors carrying a novel counterselectable marker, vmi480. We explored two uncharacterized genes, vmi480 and vmi470, in a genomic island from Vibrio mimicus VM573 and confirmed that vmi480 and vmi470 constitute a two-component toxin-antitoxin system through deletion and expression of vmi480 and vmi470. The product of vmi480 exhibited strong toxicity to Escherichia coli cells. Based on vmi480 and the PBAD or PTAC promoter system, we constructed two suicide T-vectors, pLP11 and pLP12, and each of these vectors contained a multiple cloning region with two AhdI sites. Both vectors linearized by AhdI digestion could be stored and directly ligated with purified PCR products without a digestion step. By using pLP11 and pLP12 coupled with a highly efficient conjugation system provided by E. coli β2163, six genes from four representative Vibrio species were easily deleted. By using the counterselective marker vmi480, we obtained 3–12 positive colonies (deletion mutants) among no more than 20 colonies randomly selected on counterselection plates. The strategy does not require the digestion of PCR products and suicide vectors every time, and it avoids large-scale screening colonies on counterselective plates. These results demonstrate that we successfully developed universal genetic tools for rapid and efficient gene deletion in Vibrio species.
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Affiliation(s)
- Peng Luo
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Key Laboratory of Applied Marine Biology, Chinese Academy of Sciences, Guangzhou, China
- South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Guangzhou, China
| | - Xiangyan He
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Qiuting Liu
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Chaoqun Hu
- Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Guangdong Key Laboratory of Applied Marine Biology, Chinese Academy of Sciences, Guangzhou, China
- South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Guangzhou, China
- * E-mail: (CQH)
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33
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Gil F, Pizarro-Guajardo M, Álvarez R, Garavaglia M, Paredes-Sabja D. Clostridium difficile recurrent infection: possible implication of TA systems. Future Microbiol 2015; 10:1649-57. [DOI: 10.2217/fmb.15.94] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Clostridium difficile is an important nosocomial pathogen associated with antibiotic treatments. C. difficile's ability to survive antimicrobial therapy and transition from inert colonization to active infection is one of the most perplexing aspects of C. difficile infections and suggests that additional mechanisms are involved in persistence. In this regard, novel mechanisms linked with pathogenesis and persistence of C. difficile such as toxin–antitoxin systems might significantly contribute to biofilm formation and persistent infection. This review will focus on advances of toxin–antitoxin systems in C. difficile and their putative roles will be discussed.
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Affiliation(s)
- Fernando Gil
- Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andres Bello, República 217, Santiago, Chile
| | - Marjorie Pizarro-Guajardo
- Gut Microbiota & Clostridia Research Group, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andres Bello, República 217, Santiago, Chile
| | - Ricardo Álvarez
- Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andres Bello, República 217, Santiago, Chile
| | - Marco Garavaglia
- Centre for Biomolecular Sciences, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Daniel Paredes-Sabja
- Gut Microbiota & Clostridia Research Group, Departamento de Ciencias Biológicas, Facultad de Ciencias Biológicas, Universidad Andres Bello, República 217, Santiago, Chile
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Uppal S, Jawali N. The cyclic AMP receptor protein (CRP) regulates mqsRA, coding for the bacterial toxin-antitoxin gene pair, in Escherichia coli. Res Microbiol 2015; 167:58-62. [PMID: 26408451 DOI: 10.1016/j.resmic.2015.09.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 09/03/2015] [Accepted: 09/11/2015] [Indexed: 11/29/2022]
Abstract
Bacterial persisters represent a small number of slow-growing antibiotic-tolerant cells among populations of rapidly growing cells, and are the main cause of frequent recurrent infections. MqsR-MqsA, the toxin-antitoxin (TA) pair, is the most frequently induced TA system associated with antibiotic persistence in Escherichia coli. In this study, we show that the cyclic AMP receptor protein (CRP) indirectly upregulates mqsRA transcription. We also show that CRP plays an important role in antibiotic persistence, which seems to be partially mediated through MqsRA. Overall, this study highlights the role of CRP as an important regulator of antibiotic persistence in E. coli.
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Affiliation(s)
- Sheetal Uppal
- Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India.
| | - Narendra Jawali
- Molecular Biology Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
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35
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Yao J, Guo Y, Zeng Z, Liu X, Shi F, Wang X. Identification and characterization of a HEPN-MNT family type II toxin-antitoxin in Shewanella oneidensis. Microb Biotechnol 2015; 8:961-73. [PMID: 26112399 PMCID: PMC4621449 DOI: 10.1111/1751-7915.12294] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 04/20/2015] [Accepted: 05/02/2015] [Indexed: 11/30/2022] Open
Abstract
Toxin-antitoxin (TA) systems are prevalent in bacteria and archaea. However, related studies in the ecologically and bioelectrochemically important strain Shewanella oneidensis are limited. Here, we show that SO_3166, a member of the higher eukaryotes and prokaryotes nucleotide-binding (HEPN) superfamily, strongly inhibited cell growth in S. oneidensis and Escherichia coli. SO_3165, a putative minimal nucleotidyltransferase (MNT), neutralized the toxicity of SO_3166. Gene SO_3165 lies upstream of SO_3166, and they are co-transcribed. Moreover, the SO_3165 and SO_3166 proteins interact with each other directly in vivo, and antitoxin SO_3165 bound to the promoter of the TA operon and repressed its activity. Finally, the conserved Rx4-6H domain in HEPN family was identified in SO_3166. Mutating either the R or H abolished SO_3166 toxicity, confirming that Rx4-6H domain is critical for SO_3166 activity. Taken together, these results demonstrate that SO_3166 and SO_3165 in S. oneidensis form a typical type II TA pair. This TA pair plays a critical role in regulating bacterial functions because its disruption led to impaired cell motility in S. oneidensis. Thus, we demonstrated for the first time that HEPN-MNT can function as a TA system, thereby providing important insights into the understanding of the function and regulation of HEPNs and MNTs in prokaryotes.
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Affiliation(s)
- Jianyun Yao
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Yunxue Guo
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
| | - Zhenshun Zeng
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China.,University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Xiaoxiao Liu
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
| | - Fei Shi
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
| | - Xiaoxue Wang
- Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, 510301, China
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36
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Rocker A, Meinhart A. A
cis
‐acting antitoxin domain within the chromosomal toxin–antitoxin module
EzeT
of
E
scherichia coli
quenches toxin activity. Mol Microbiol 2015; 97:589-604. [DOI: 10.1111/mmi.13051] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Andrea Rocker
- Department of Biomolecular Mechanisms Max Planck Institute for Medical Research Jahnstrasse 29 Heidelberg 69120 Germany
| | - Anton Meinhart
- Department of Biomolecular Mechanisms Max Planck Institute for Medical Research Jahnstrasse 29 Heidelberg 69120 Germany
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Transcriptional responses to sucrose mimic the plant-associated life style of the plant growth promoting endophyte Enterobacter sp. 638. PLoS One 2015; 10:e0115455. [PMID: 25607953 PMCID: PMC4301647 DOI: 10.1371/journal.pone.0115455] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Accepted: 11/24/2014] [Indexed: 11/19/2022] Open
Abstract
Growth in sucrose medium was previously found to trigger the expression of functions involved in the plant associated life style of the endophytic bacterium Enterobacter sp. 638. Therefore, comparative transcriptome analysis between cultures grown in sucrose or lactate medium was used to gain insights in the expression levels of bacterial functions involved in the endophytic life style of strain 638. Growth on sucrose as a carbon source resulted in major changes in cell physiology, including a shift from a planktonic life style to the formation of bacterial aggregates. This shift was accompanied by a decrease in transcription of genes involved in motility (e.g. flagella biosynthesis) and an increase in the transcription of genes involved in colonization, adhesion and biofilm formation. The transcription levels of functions previously suggested as being involved in endophytic behavior and functions responsible for plant growth promoting properties, including the synthesis of indole-acetic acid, acetoin and 2,3-butanediol, also increased significantly for cultures grown in sucrose medium. Interestingly, despite an abundance of essential nutrients transcription levels of functions related to uptake and processing of nitrogen and iron became increased for cultures grown on sucrose as sole carbon source. Transcriptome data were also used to analyze putative regulatory relationships. In addition to the small RNA csrABCD regulon, which seems to play a role in the physiological adaptation and possibly the shift between free-living and plant-associated endophytic life style of Enterobacter sp. 638, our results also pointed to the involvement of rcsAB in controlling responses by Enterobacter sp. 638 to a plant-associated life style. Targeted mutagenesis was used to confirm this role and showed that compared to wild-type Enterobacter sp. 638 a ΔrcsB mutant was affected in its plant growth promoting ability.
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Karimi S, Ghafourian S, Taheri Kalani M, Azizi Jalilian F, Hemati S, Sadeghifard N. Association between toxin-antitoxin systems and biofilm formation. Jundishapur J Microbiol 2014; 8:e14540. [PMID: 25789127 PMCID: PMC4350053 DOI: 10.5812/jjm.14540] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Revised: 04/03/2014] [Accepted: 04/09/2014] [Indexed: 11/16/2022] Open
Abstract
Background: Toxin-antitoxin (TA) systems are found on the chromosomes and plasmids of many Bacteria such as Escherichia coli. The roles of TA systems in bacteria are enigmatic. Multiple biological functions of TA systems are proposed including growth modulation, persistence, and biofilm formation. Biofilms of E. coli are cause of urinary tract infections, as well as bacteraemia. Objectives: The current study aimed to find the association between biofilm formation and toxin-antitoxin systems in clinical isolates of E. coli. Materials and Methods: A total of 150 E. coli isolates were evaluated for biofilm formation by Congo red agar medium (CRA) and microtiter plate assay and the presence of different TA systems including MazEF, RelBE, hipBA, ccdAB and MqsRA. Results: The results of the analysis revealed that 107 E. coli isolates were potent for biofilm formation by CRA. The findings by microtiter plates showed that 102 E. coli isolates were biofilm producers. The results indicated that 80%, 85%, 70%, 91% and 82% of the isolates possessed MazEF, RelBE, hipBA, ccdAB and MqsRA TA loci, respectively. Conclusions: The analysis recommended that TA genes are prevalent in clinical isolates of E. coli strains. The analysis revealed that hipBA TA system is associated with biofilm formation.
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Affiliation(s)
- Sajedeh Karimi
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, IR Iran
| | - Sobhan Ghafourian
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, IR Iran
| | - Morovat Taheri Kalani
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, IR Iran
| | - Farid Azizi Jalilian
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, IR Iran
| | - Saeed Hemati
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, IR Iran
| | - Nourkhoda Sadeghifard
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, IR Iran
- Corresponding author: Nourkhoda Sadeghifard, Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, IR Iran. Tel: +98-8412227101, Fax: +98-8412227136, E-mail:
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Martínez LC, Vadyvaloo V. Mechanisms of post-transcriptional gene regulation in bacterial biofilms. Front Cell Infect Microbiol 2014; 4:38. [PMID: 24724055 PMCID: PMC3971182 DOI: 10.3389/fcimb.2014.00038] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2014] [Accepted: 03/08/2014] [Indexed: 12/19/2022] Open
Abstract
Biofilms are characterized by a dense multicellular community of microorganisms that can be formed by the attachment of bacteria to an inert surface and to each other. The development of biofilm involves the initial attachment of planktonic bacteria to a surface, followed by replication, cell-to-cell adhesion to form microcolonies, maturation, and detachment. Mature biofilms are embedded in a self-produced extracellular polymeric matrix composed primarily of bacterial-derived exopolysaccharides, specialized proteins, adhesins, and occasionally DNA. Because the synthesis and assembly of biofilm matrix components is an exceptionally complex process, the transition between its different phases requires the coordinate expression and simultaneous regulation of many genes by complex genetic networks involving all levels of gene regulation. The finely controlled intracellular level of the chemical second messenger molecule, cyclic-di-GMP is central to the post-transcriptional mechanisms governing the switch between the motile planktonic lifestyle and the sessile biofilm forming state in many bacteria. Several other post-transcriptional regulatory mechanisms are known to dictate biofilm development and assembly and these include RNA-binding proteins, small non-coding RNAs, toxin-antitoxin systems, riboswitches, and RNases. Post-transcriptional regulation is therefore a powerful molecular mechanism employed by bacteria to rapidly adjust to the changing environment and to fine tune gene expression to the developmental needs of the cell. In this review, we discuss post-transcriptional mechanisms that influence the biofilm developmental cycle in a variety of pathogenic bacteria.
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Affiliation(s)
| | - Viveka Vadyvaloo
- Paul G. Allen School for Global Animal Health, Washington State UniversityPullman, WA, USA
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Wen Y, Behiels E, Devreese B. Toxin-Antitoxin systems: their role in persistence, biofilm formation, and pathogenicity. Pathog Dis 2014; 70:240-9. [DOI: 10.1111/2049-632x.12145] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 01/15/2014] [Accepted: 01/15/2014] [Indexed: 11/29/2022] Open
Affiliation(s)
- Yurong Wen
- Unit for Biological Mass Spectrometry and Proteomics; Laboratory for Protein Biochemistry and Biomolecular Engineering (L-ProBE); Ghent University; Ghent Belgium
| | - Ester Behiels
- Unit for Biological Mass Spectrometry and Proteomics; Laboratory for Protein Biochemistry and Biomolecular Engineering (L-ProBE); Ghent University; Ghent Belgium
| | - Bart Devreese
- Unit for Biological Mass Spectrometry and Proteomics; Laboratory for Protein Biochemistry and Biomolecular Engineering (L-ProBE); Ghent University; Ghent Belgium
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Hadži S, Garcia-Pino A, Martinez-Rodriguez S, Verschueren K, Christensen-Dalsgaard M, Gerdes K, Lah J, Loris R. Crystallization of the HigBA2 toxin-antitoxin complex from Vibrio cholerae. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:1052-9. [PMID: 23989162 PMCID: PMC3758162 DOI: 10.1107/s1744309113021490] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Accepted: 08/01/2013] [Indexed: 02/06/2023]
Abstract
The genome of Vibrio cholerae encodes two higBA toxin-antitoxin (TA) modules that are activated by amino-acid starvation. Here, the TA complex of the second module, higBA2, as well as the C-terminal domain of the corresponding HigA2 antitoxin, have been purified and crystallized. The HigBA2 complex crystallized in two crystal forms. Crystals of form I belonged to space group P2(1)2(1)2, with unit-cell parameters a = 129.0, b = 119.8, c = 33.4 Å, and diffracted to 3.0 Å resolution. The asymmetric unit is likely to contain a single complex consisting of two toxin monomers and one antitoxin dimer. The second crystal form crystallized in space group P3(2)21, with unit-cell parameters a = 134.5, c = 55.4 Å. These crystals diffracted to 2.2 Å resolution and probably contain a complex with a different stoichiometry. Crystals of the C-terminal domain of HigA2 belonged to space group C2, with unit-cell parameters a = 115.4, b = 61.2, c = 73.8 Å, β = 106.7°, and diffracted to 1.8 Å resolution.
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Affiliation(s)
- San Hadži
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
- Molecular Recognition Unit, Department of Structural Biology, VIB, Pleinlaan 2, B-1050 Brussel, Belgium
- Department of Physical Chemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Abel Garcia-Pino
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
- Molecular Recognition Unit, Department of Structural Biology, VIB, Pleinlaan 2, B-1050 Brussel, Belgium
| | - Sergio Martinez-Rodriguez
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
- Molecular Recognition Unit, Department of Structural Biology, VIB, Pleinlaan 2, B-1050 Brussel, Belgium
- Departamento de Quimica y Fisica, Universidad de Almeria, Almeria, Spain
| | - Koen Verschueren
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
- Molecular Recognition Unit, Department of Structural Biology, VIB, Pleinlaan 2, B-1050 Brussel, Belgium
| | - Mikkel Christensen-Dalsgaard
- Center for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, England
| | - Kenn Gerdes
- Center for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, England
| | - Jurij Lah
- Department of Physical Chemistry, Faculty of Chemistry and Chemical Technology, University of Ljubljana, 1000 Ljubljana, Slovenia
| | - Remy Loris
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
- Molecular Recognition Unit, Department of Structural Biology, VIB, Pleinlaan 2, B-1050 Brussel, Belgium
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Unterholzner SJ, Poppenberger B, Rozhon W. Toxin-antitoxin systems: Biology, identification, and application. Mob Genet Elements 2013; 3:e26219. [PMID: 24251069 PMCID: PMC3827094 DOI: 10.4161/mge.26219] [Citation(s) in RCA: 230] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 08/16/2013] [Accepted: 08/19/2013] [Indexed: 02/07/2023] Open
Abstract
Toxin–antitoxin (TA) systems are small genetic elements composed of a toxin gene and its cognate antitoxin. The toxins of all known TA systems are proteins while the antitoxins are either proteins or non-coding RNAs. Based on the molecular nature of the antitoxin and its mode of interaction with the toxin the TA modules are currently grouped into five classes. In general, the toxin is more stable than the antitoxin but the latter is expressed to a higher level. If supply of the antitoxin stops, for instance under special growth conditions or by plasmid loss in case of plasmid encoded TA systems, the antitoxin is rapidly degraded and can no longer counteract the toxin. Consequently, the toxin becomes activated and can act on its cellular targets. Typically, TA toxins act on crucial cellular processes including translation, replication, cytoskeleton formation, membrane integrity, and cell wall biosynthesis. TA systems and their components are also versatile tools for a multitude of purposes in basic research and biotechnology. Currently, TA systems are frequently used for selection in cloning and for single protein expression in living bacterial cells. Since several TA toxins exhibit activity in yeast and mammalian cells they may be useful for applications in eukaryotic systems. TA modules are also considered as promising targets for the development of antibacterial drugs and their potential to combat viral infection may aid in controlling infectious diseases.
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Affiliation(s)
- Simon J Unterholzner
- 1 Biotechnology of Horticultural Crops; Technische Universität München; Freising, Germany
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Zhao J, Wang Q, Li M, Heijstra BD, Wang S, Liang Q, Qi Q. Escherichia coli toxin gene hipA affects biofilm formation and DNA release. Microbiology (Reading) 2013; 159:633-640. [DOI: 10.1099/mic.0.063784-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Affiliation(s)
- Junqiao Zhao
- State Key Laboratory of Microbial Technology, National Glycoengineering Research Center, Shandong University, Jinan 250100, PR China
| | - Qian Wang
- National Glycoengineering Research Center, Shandong University, Jinan 250100, PR China
| | - Mingji Li
- State Key Laboratory of Microbial Technology, National Glycoengineering Research Center, Shandong University, Jinan 250100, PR China
| | - Björn D. Heijstra
- School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, New Zealand
| | - Shengjun Wang
- State Key Laboratory of Microbial Technology, National Glycoengineering Research Center, Shandong University, Jinan 250100, PR China
| | - Quanfeng Liang
- National Glycoengineering Research Center, Shandong University, Jinan 250100, PR China
- State Key Laboratory of Microbial Technology, National Glycoengineering Research Center, Shandong University, Jinan 250100, PR China
| | - Qingsheng Qi
- National Glycoengineering Research Center, Shandong University, Jinan 250100, PR China
- State Key Laboratory of Microbial Technology, National Glycoengineering Research Center, Shandong University, Jinan 250100, PR China
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Kasari V, Mets T, Tenson T, Kaldalu N. Transcriptional cross-activation between toxin-antitoxin systems of Escherichia coli. BMC Microbiol 2013; 13:45. [PMID: 23432955 PMCID: PMC3598666 DOI: 10.1186/1471-2180-13-45] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 02/18/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Bacterial toxin-antitoxin (TA) systems are formed by potent regulatory or suicide factors (toxins) and their short-lived inhibitors (antitoxins). Antitoxins are DNA-binding proteins and auto-repress transcription of TA operons. Transcription of multiple TA operons is activated in temporarily non-growing persister cells that can resist killing by antibiotics. Consequently, the antitoxin levels of persisters must have been dropped and toxins are released of inhibition. RESULTS Here, we describe transcriptional cross-activation between different TA systems of Escherichia coli. We find that the chromosomal relBEF operon is activated in response to production of the toxins MazF, MqsR, HicA, and HipA. Expression of the RelE toxin in turn induces transcription of several TA operons. We show that induction of mazEF during amino acid starvation depends on relBE and does not occur in a relBEF deletion mutant. Induction of TA operons has been previously shown to depend on Lon protease which is activated by polyphospate accumulation. We show that transcriptional cross-activation occurs also in strains deficient for Lon, ClpP, and HslV proteases and polyphosphate kinase. Furthermore, we find that toxins cleave the TA mRNA in vivo, which is followed by degradation of the antitoxin-encoding fragments and selective accumulation of the toxin-encoding regions. We show that these accumulating fragments can be translated to produce more toxin. CONCLUSION Transcriptional activation followed by cleavage of the mRNA and disproportionate production of the toxin constitutes a possible positive feedback loop, which can fire other TA systems and cause bistable growth heterogeneity. Cross-interacting TA systems have a potential to form a complex network of mutually activating regulators in bacteria.
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Affiliation(s)
- Villu Kasari
- Institute of Technology, University of Tartu, Nooruse 1, 50411, Tartu, Estonia
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Solution structure and biophysical properties of MqsA, a Zn-containing antitoxin from Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1824:1401-8. [DOI: 10.1016/j.bbapap.2012.06.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 06/28/2012] [Accepted: 06/29/2012] [Indexed: 11/23/2022]
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New-found fundamentals of bacterial persistence. Trends Microbiol 2012; 20:577-85. [DOI: 10.1016/j.tim.2012.08.009] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Revised: 08/10/2012] [Accepted: 08/17/2012] [Indexed: 12/26/2022]
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Norton JP, Mulvey MA. Toxin-antitoxin systems are important for niche-specific colonization and stress resistance of uropathogenic Escherichia coli. PLoS Pathog 2012; 8:e1002954. [PMID: 23055930 PMCID: PMC3464220 DOI: 10.1371/journal.ppat.1002954] [Citation(s) in RCA: 141] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2012] [Accepted: 08/16/2012] [Indexed: 01/04/2023] Open
Abstract
Toxin-antitoxin (TA) systems are prevalent in many bacterial genomes and have been implicated in biofilm and persister cell formation, but the contribution of individual chromosomally encoded TA systems during bacterial pathogenesis is not well understood. Of the known TA systems encoded by Escherichia coli, only a subset is associated with strains of extraintestinal pathogenic E. coli (ExPEC). These pathogens colonize diverse niches and are a major cause of sepsis, meningitis, and urinary tract infections. Using a murine infection model, we show that two TA systems (YefM-YoeB and YbaJ-Hha) independently promote colonization of the bladder by the reference uropathogenic ExPEC isolate CFT073, while a third TA system comprised of the toxin PasT and the antitoxin PasI is critical to ExPEC survival within the kidneys. The PasTI TA system also enhances ExPEC persister cell formation in the presence of antibiotics and markedly increases pathogen resistance to nutrient limitation as well as oxidative and nitrosative stresses. On its own, low-level expression of PasT protects ExPEC from these stresses, whereas overexpression of PasT is toxic and causes bacterial stasis. PasT-induced stasis can be rescued by overexpression of PasI, indicating that PasTI is a bona fide TA system. By mutagenesis, we find that the stress resistance and toxic effects of PasT can be uncoupled and mapped to distinct domains. Toxicity was specifically linked to sequences within the N-terminus of PasT, a region that also promotes the development of persister cells. These results indicate discrete, multipurpose functions for a TA-associated toxin and demonstrate that individual TA systems can provide bacteria with pronounced fitness advantages dependent on toxin expression levels and the specific environmental niche occupied. Toxin-antitoxin (TA) systems are widespread among prokaryotes, including many important human pathogens. It has long been hypothesized that TA systems contribute to bacterial pathogenesis, but clear-cut phenotypes associated with any individual TA system have not been described. Using bioinformatics, we demonstrate that distinct subsets of TA systems are linked with a major group of bacterial pathogens known as Extraintestinal Pathogenic E. coli (ExPEC). These bacteria are responsible for the majority of urinary tract infections worldwide, and are major causes of sepsis and meningitis. Using murine infection models with a reference uropathogenic ExPEC isolate, we found that three of the ExPEC-associated TA systems act independently to promote bacterial survival and persistence within the host urinary tract. Furthermore, we show that the toxin protein associated with one of these TA systems increases ExPEC stress resistance and persistence in the face of antibiotics. This work demonstrates the functional importance of specific TA systems to ExPEC pathogenesis, highlighting their potential as therapeutic targets.
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Affiliation(s)
| | - Matthew A. Mulvey
- Division of Microbiology and Immunology, Pathology Department, University of Utah School of Medicine, Salt Lake City, Utah, United States of America
- * E-mail:
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Muranaka LS, Takita MA, Olivato JC, Kishi LT, de Souza AA. Global expression profile of biofilm resistance to antimicrobial compounds in the plant-pathogenic bacterium Xylella fastidiosa reveals evidence of persister cells. J Bacteriol 2012; 194:4561-9. [PMID: 22730126 PMCID: PMC3415493 DOI: 10.1128/jb.00436-12] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 06/14/2012] [Indexed: 01/05/2023] Open
Abstract
Investigations of biofilm resistance response rarely focus on plant-pathogenic bacteria. Since Xylella fastidiosa is a multihost plant-pathogenic bacterium that forms biofilm in the xylem, the behavior of its biofilm in response to antimicrobial compounds needs to be better investigated. We analyzed here the transcriptional profile of X. fastidiosa subsp. pauca in response to inhibitory and subinhibitory concentrations of copper and tetracycline. Copper-based products are routinely used to control citrus diseases in the field, while antibiotics are more widely used for bacterial control in mammals. The use of antimicrobial compounds triggers specific responses to each compound, such as biofilm formation and phage activity for copper. Common changes in expression responses comprise the repression of genes associated with metabolic functions and movement and the induction of toxin-antitoxin systems, which have been associated with the formation of persister cells. Our results also show that these cells were found in the population at a ca. 0.05% density under inhibitory conditions for both antimicrobial compounds and that pretreatment with subinhibitory concentration of copper increases this number. No previous report has detected the presence of these cells in X. fastidiosa population, suggesting that this could lead to a multidrug tolerance response in the biofilm under a stressed environment. This is a mechanism that has recently become the focus of studies on resistance of human-pathogenic bacteria to antibiotics and, based on our data, it seems to be more broadly applicable.
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Affiliation(s)
- Lígia S. Muranaka
- Centro APTA Citros Sylvio Moreira/IAC, Cordeirópolis, São Paulo, Brazil
- Universidade Estadual de Campinas/UNICAMP, Centro de Biologia Molecular e Engenharia Genética, Departamento de Genética e Evolução, Instituto de Biologia, Campinas, São Paulo, Brazil
| | - Marco A. Takita
- Centro APTA Citros Sylvio Moreira/IAC, Cordeirópolis, São Paulo, Brazil
| | | | - Luciano T. Kishi
- Centro APTA Citros Sylvio Moreira/IAC, Cordeirópolis, São Paulo, Brazil
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Rezzonico F, Smits THM, Duffy B. Detection of AI-2 receptors in genomes of Enterobacteriaceae suggests a role of type-2 quorum sensing in closed ecosystems. SENSORS 2012; 12:6645-65. [PMID: 22778662 PMCID: PMC3386761 DOI: 10.3390/s120506645] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2012] [Revised: 05/11/2012] [Accepted: 05/16/2012] [Indexed: 01/04/2023]
Abstract
The LuxS enzyme, an S-ribosyl-homocysteine lyase, catalyzes the production of the signal precursor for autoinducer-2 mediated quorum sensing (QS-2) in Vibrio. Its widespread occurrence among bacteria is often considered the evidence for a universal language for interspecies communication. Presence of the luxS gene and production of the autoinducer-2 (AI-2) signal have repeatedly been the only evidences presented to assign a functional QS-2 to the most diverse species. In fact, LuxS has a primary metabolic role as part of the activated methyl cycle. In this review we have analyzed the distribution of QS-2 related genes in Enterobacteriaceae by moving the focus of the investigation from AI-2 production to the detection of potential AI-2 receptors. The latter are common in pathogens or endosymbionts of animals, but were also found in a limited number of Enterobacteriaceae of the genera Enterobacter, Klebsiella, and Pantoea that live in close association with plants or fungi. Although a precise function of QS-2 in these species has not been identified, they all show an endophytic or endosymbiontic lifestyle that suggests a role of type-2 quorum sensing in the adaptation to closed ecosystems.
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Affiliation(s)
- Fabio Rezzonico
- Plant Protection Division, Agroscope Changins-Wädenswil ACW, Schloss 1, Wädenswil CH-8820, Switzerland.
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Abstract
Almost all bacteria and many archaea contain genes whose expression inhibits cell growth and may lead to cell death when overproduced, reminiscent of apoptotic genes in higher systems. The cellular targets of these toxins are quite diverse and include DNA replication, mRNA stability, protein synthesis, cell-wall biosynthesis, and ATP synthesis. These toxins are co-expressed and neutralized with their cognate antitoxins from a TA (toxin-antitoxin) operon in normally growing cells. Antitoxins are more labile than toxins and are readily degraded under stress conditions, allowing the toxins to exert their toxic effect. Presence of at least 33 TA systems in Escherichia coli and more than 60 TA systems in Mycobacterium tuberculosis suggests that the TA systems are involved not only in normal bacterial physiology but also in pathogenicity of bacteria. The elucidation of their cellular function and regulation is thus crucial for our understanding of bacterial physiology under various stress conditions.
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Affiliation(s)
- Yoshihiro Yamaguchi
- Department of Biochemistry, Center for Advanced Biotechnology and Medicine, Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
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