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Pizzolato-Cezar LR, Spira B, Machini MT. Bacterial toxin-antitoxin systems: Novel insights on toxin activation across populations and experimental shortcomings. CURRENT RESEARCH IN MICROBIAL SCIENCES 2023; 5:100204. [PMID: 38024808 PMCID: PMC10643148 DOI: 10.1016/j.crmicr.2023.100204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2023] Open
Abstract
The alarming rise in hard-to-treat bacterial infections is of great concern to human health. Thus, the identification of molecular mechanisms that enable the survival and growth of pathogens is of utmost urgency for the development of more efficient antimicrobial therapies. In challenging environments, such as presence of antibiotics, or during host infection, metabolic adjustments are essential for microorganism survival and competitiveness. Toxin-antitoxin systems (TASs) consisting of a toxin with metabolic modulating activity and a cognate antitoxin that antagonizes that toxin are important elements in the arsenal of bacterial stress defense. However, the exact physiological function of TA systems is highly debatable and with the exception of stabilization of mobile genetic elements and phage inhibition, other proposed biological functions lack a broad consensus. This review aims at gaining new insights into the physiological effects of TASs in bacteria and exploring the experimental shortcomings that lead to discrepant results in TAS research. Distinct control mechanisms ensure that only subsets of cells within isogenic cultures transiently develop moderate levels of toxin activity. As a result, TASs cause phenotypic growth heterogeneity rather than cell stasis in the entire population. It is this feature that allows bacteria to thrive in diverse environments through the creation of subpopulations with different metabolic rates and stress tolerance programs.
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Affiliation(s)
- Luis R. Pizzolato-Cezar
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
| | - Beny Spira
- Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - M. Teresa Machini
- Department of Biochemistry, Institute of Chemistry, University of São Paulo, São Paulo, Brazil
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2
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Chan WT, Garcillán-Barcia MP, Yeo CC, Espinosa M. Type II bacterial toxin-antitoxins: hypotheses, facts, and the newfound plethora of the PezAT system. FEMS Microbiol Rev 2023; 47:fuad052. [PMID: 37715317 PMCID: PMC10532202 DOI: 10.1093/femsre/fuad052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 08/24/2023] [Accepted: 09/07/2023] [Indexed: 09/17/2023] Open
Abstract
Toxin-antitoxin (TA) systems are entities found in the prokaryotic genomes, with eight reported types. Type II, the best characterized, is comprised of two genes organized as an operon. Whereas toxins impair growth, the cognate antitoxin neutralizes its activity. TAs appeared to be involved in plasmid maintenance, persistence, virulence, and defence against bacteriophages. Most Type II toxins target the bacterial translational machinery. They seem to be antecessors of Higher Eukaryotes and Prokaryotes Nucleotide-binding (HEPN) RNases, minimal nucleotidyltransferase domains, or CRISPR-Cas systems. A total of four TAs encoded by Streptococcus pneumoniae, RelBE, YefMYoeB, Phd-Doc, and HicAB, belong to HEPN-RNases. The fifth is represented by PezAT/Epsilon-Zeta. PezT/Zeta toxins phosphorylate the peptidoglycan precursors, thereby blocking cell wall synthesis. We explore the body of knowledge (facts) and hypotheses procured for Type II TAs and analyse the data accumulated on the PezAT family. Bioinformatics analyses showed that homologues of PezT/Zeta toxin are abundantly distributed among 14 bacterial phyla mostly in Proteobacteria (48%), Firmicutes (27%), and Actinobacteria (18%), showing the widespread distribution of this TA. The pezAT locus was found to be mainly chromosomally encoded whereas its homologue, the tripartite omega-epsilon-zeta locus, was found mostly on plasmids. We found several orphan pezT/zeta toxins, unaccompanied by a cognate antitoxin.
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Affiliation(s)
- Wai Ting Chan
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, 9, 28040 Madrid, Spain
| | - Maria Pilar Garcillán-Barcia
- Instituto de Biomedicina y Biotecnología de Cantabria (IBBTEC), Universidad de Cantabria-Consejo Superior de Investigaciones Científicas, C/Albert Einstein 22, PCTCAN, 39011 Santander, Spain
| | - Chew Chieng Yeo
- Centre for Research in Infectious Diseases and Biotechnology (CeRIDB), Faculty of Medicine
, Universiti Sultan Zainal Abidin, Jalan Sultan Mahumd, 20400 Kuala Terengganu, Malaysia
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, 9, 28040 Madrid, Spain
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3
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Gu Q, He P, Wang D, Ma J, Zhong X, Zhu Y, Zhang Y, Bai Q, Pan Z, Yao H. An Auto-Regulating Type II Toxin-Antitoxin System Modulates Drug Resistance and Virulence in Streptococcus suis. Front Microbiol 2021; 12:671706. [PMID: 34475853 PMCID: PMC8406773 DOI: 10.3389/fmicb.2021.671706] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 05/26/2021] [Indexed: 11/13/2022] Open
Abstract
Toxin-antitoxin (TA) systems are ubiquitous genetic elements that play an essential role in multidrug tolerance and virulence of bacteria. So far, little is known about the TA systems in Streptococcus suis. In this study, the Xress-MNTss TA system, composed of the MNTss toxin in the periplasmic space and its interacting Xress antitoxin, was identified in S. suis. β-galactosidase activity and electrophoretic mobility shift assay (EMSA) revealed that Xress and the Xress-MNTss complex could bind directly to the Xress-MNTss promoter as well as downregulate streptomycin adenylyltransferase ZY05719_RS04610. Interestingly, the Xress deletion mutant was less pathogenic in vivo following a challenge in mice. Transmission electron microscopy and adhesion assays pointed to a significantly thinner capsule but greater biofilm-formation capacity in ΔXress than in the wild-type strain. These results indicate that Xress-MNTss, a new type II TA system, plays an important role in antibiotic resistance and pathogenicity in S. suis.
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Affiliation(s)
- Qibing Gu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Peijuan He
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Dan Wang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Jiale Ma
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Xiaojun Zhong
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China.,College of Animal Science and Technology, College of Veterinary Medicine, Zhejiang A&F University, Hangzhou, China
| | - Yinchu Zhu
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China.,Institute of Animal Husbandry and Veterinary Sciences, Zhejiang Academy of Agricultural Sciences, Hangzhou, China
| | - Yue Zhang
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China.,College of Veterinary Medicine, Henan Agricultural University, Zhengzhou, China
| | - Qiankun Bai
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Zihao Pan
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
| | - Huochun Yao
- College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.,Key Laboratory of Animal Bacteriology, Ministry of Agriculture, Nanjing, China.,OIE Reference Laboratory for Swine Streptococcosis, Nanjing, China
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4
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Moreno-del Álamo M, Marchisone C, Alonso JC. Antitoxin ε Reverses Toxin ζ-Facilitated Ampicillin Dormants. Toxins (Basel) 2020; 12:toxins12120801. [PMID: 33333975 PMCID: PMC7765365 DOI: 10.3390/toxins12120801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Revised: 12/07/2020] [Accepted: 12/09/2020] [Indexed: 11/16/2022] Open
Abstract
Toxin-antitoxin (TA) modules are ubiquitous in bacteria, but their biological importance in stress adaptation remains a matter of debate. The inactive ζ-ε2-ζ TA complex is composed of one labile ε2 antitoxin dimer flanked by two stable ζ toxin monomers. Free toxin ζ reduces the ATP and GTP levels, increases the (p)ppGpp and c-di-AMP pool, inactivates a fraction of uridine diphosphate-N-acetylglucosamine, and induces reversible dormancy. A small subpopulation, however, survives toxin action. Here, employing a genetic orthogonal control of ζ and ε levels, the fate of bacteriophage SPP1 infection was analyzed. Toxin ζ induces an active slow-growth state that halts SPP1 amplification, but it re-starts after antitoxin expression rather than promoting abortive infection. Toxin ζ-induced and toxin-facilitated ampicillin (Amp) dormants have been revisited. Transient toxin ζ expression causes a metabolic heterogeneity that induces toxin and Amp dormancy over a long window of time rather than cell persistence. Antitoxin ε expression, by reversing ζ activities, facilitates the exit of Amp-induced dormancy both in rec+ and recA cells. Our findings argue that an unexploited target to fight against antibiotic persistence is to disrupt toxin-antitoxin interactions.
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Srivastava A, Garg S, Jain R, Ayana R, Kaushik H, Garg L, Pati S, Singh S. Identification and functional characterization of a bacterial homologue of Zeta toxin in Leishmania donovani. FEBS Lett 2019; 593:1223-1235. [PMID: 31074836 DOI: 10.1002/1873-3468.13429] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Revised: 03/05/2019] [Accepted: 03/11/2019] [Indexed: 02/04/2023]
Abstract
Zeta-toxin is a cognate toxin of epsilon antitoxin of prokaryotic Type II toxin-antitoxin system (TA) and play an important role in cell death. An orthologue of bacterial-zeta-toxin (BzT) was identified in Leishmania donovani with similar structural and functional features. Leishmania zeta-toxin (named Ld_ζ1) harboring similar UNAG and ATP-binding pockets showed UNAG kinase and ATP-binding activity. An active Ld_ζ1 was found to express in infective extracellular promastigotes stage of L. donovani and episomal overexpression of an active Ld_ζ1domain-triggered cell death. This study demonstrates the presence of prokaryotic-like-zeta-toxin in eukaryotic parasite Leishmania and its association with cell death. Conceivably, phosphorylated UNAG or analogues, the biochemical mimics of zeta-toxin function mediating cell death can act as a novel anti-leishmanial chemotherapeutics.
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Affiliation(s)
- Akriti Srivastava
- Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Greater Noida, India
| | - Swati Garg
- Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Greater Noida, India
| | - Ravi Jain
- Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Greater Noida, India
| | - Rajagopal Ayana
- Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Greater Noida, India
| | - Himani Kaushik
- Gene Regulation Laboratory, National Institute of Immunology, New Delhi, India
| | - Lalit Garg
- Gene Regulation Laboratory, National Institute of Immunology, New Delhi, India
| | - Soumya Pati
- Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Greater Noida, India
| | - Shailja Singh
- Department of Life Sciences, School of Natural Sciences, Shiv Nadar University, Greater Noida, India.,Special Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, India
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6
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In Silico Analysis of Genetic VapC Profiles from the Toxin-Antitoxin Type II VapBC Modules among Pathogenic, Intermediate, and Non-Pathogenic Leptospira. Microorganisms 2019; 7:microorganisms7020056. [PMID: 30791633 PMCID: PMC6406750 DOI: 10.3390/microorganisms7020056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Revised: 02/09/2019] [Accepted: 02/15/2019] [Indexed: 11/16/2022] Open
Abstract
Pathogenic Leptospira spp. is the etiological agent of leptospirosis. The high diversity among Leptospira species provides an array to look for important mediators involved in pathogenesis. Toxin-antitoxin (TA) systems represent an important survival mechanism on stress conditions. vapBC modules have been found in nearly one thousand genomes corresponding to about 40% of known TAs. In the present study, we investigated TA profiles of some strains of Leptospira using a TA database and compared them through protein alignment of VapC toxin sequences among Leptospira spp. genomes. Our analysis identified significant differences in the number of putative vapBC modules distributed in pathogenic, saprophytic, and intermediate strains: four in L. interrogans, three in L. borgpetersenii, eight in L. biflexa, and 15 in L. licerasiae. The VapC toxins show low identity among amino acid sequences within the species. Some VapC toxins appear to be exclusively conserved in unique species, others appear to be conserved among pathogenic or saprophytic strains, and some appear to be distributed randomly. The data shown here indicate that these modules evolved in a very complex manner, which highlights the strong need to identify and characterize new TAs as well as to understand their regulation networks and the possible roles of TA systems in pathogenic bacteria.
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7
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Moreno-Del Álamo M, Tabone M, Muñoz-Martínez J, Valverde JR, Alonso JC. Toxin ζ Reduces the ATP and Modulates the Uridine Diphosphate-N-acetylglucosamine Pool. Toxins (Basel) 2019; 11:E29. [PMID: 30634431 PMCID: PMC6356619 DOI: 10.3390/toxins11010029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 12/21/2018] [Accepted: 01/04/2019] [Indexed: 11/20/2022] Open
Abstract
Toxin ζ expression triggers a reversible state of dormancy, diminishes the pool of purine nucleotides, promotes (p)ppGpp synthesis, phosphorylates a fraction of the peptidoglycan precursor uridine diphosphate-N-acetylglucosamine (UNAG), leading to unreactive UNAG-P, induces persistence in a reduced subpopulation, and sensitizes cells to different antibiotics. Here, we combined computational analyses with biochemical experiments to examine the mechanism of toxin ζ action. Free ζ toxin showed low affinity for UNAG. Toxin ζ bound to UNAG hydrolyzed ATP·Mg2+, with the accumulation of ADP, Pi, and produced low levels of phosphorylated UNAG (UNAG-P). Toxin ζ, which has a large ATP binding pocket, may temporally favor ATP binding in a position that is distant from UNAG, hindering UNAG phosphorylation upon ATP hydrolysis. The residues D67, E116, R158 and R171, involved in the interaction with metal, ATP, and UNAG, were essential for the toxic and ATPase activities of toxin ζ; whereas the E100 and T128 residues were partially dispensable. The results indicate that ζ bound to UNAG reduces the ATP concentration, which indirectly induces a reversible dormant state, and modulates the pool of UNAG.
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Affiliation(s)
- María Moreno-Del Álamo
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin Str., 28049 Madrid, Spain.
| | - Mariangela Tabone
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin Str., 28049 Madrid, Spain.
| | - Juan Muñoz-Martínez
- Scientific Computing Service, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin Str., 28049 Madrid, Spain.
| | - José R Valverde
- Scientific Computing Service, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin Str., 28049 Madrid, Spain.
| | - Juan C Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin Str., 28049 Madrid, Spain.
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8
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Abstract
Site-directed mutagenesis is a key tool in the analysis of biological mechanisms. We have established an efficient and systematic gene targeting strategy for Bacillus subtilis based on the Golden Gate cloning methodology. Our approach permits the introduction of single or multiple point mutations or of heavily engineered alleles into the endogenous gene locus in a single step using a 96-well microtiter plate format. We have successfully applied this system for high-throughput functional screening of resized variants of the Structural Maintenance of Chromosome (Smc) protein and for exhaustive cysteine cross-linking mutagenesis. Here we describe, in detail, the experimental setup for high-throughput introduction of modifications into the B. subtilis chromosome. With minor modifications, the approach should be applicable to other bacteria and yeast.
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9
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Chan WT, Domenech M, Moreno-Córdoba I, Navarro-Martínez V, Nieto C, Moscoso M, García E, Espinosa M. The Streptococcus pneumoniaeyefM-yoeB and relBE Toxin-Antitoxin Operons Participate in Oxidative Stress and Biofilm Formation. Toxins (Basel) 2018; 10:toxins10090378. [PMID: 30231554 PMCID: PMC6162744 DOI: 10.3390/toxins10090378] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Revised: 09/03/2018] [Accepted: 09/13/2018] [Indexed: 12/20/2022] Open
Abstract
Type II (proteic) toxin-antitoxin systems (TAs) are widely distributed among bacteria and archaea. They are generally organized as operons integrated by two genes, the first encoding the antitoxin that binds to its cognate toxin to generate a harmless protein–protein complex. Under stress conditions, the unstable antitoxin is degraded by host proteases, releasing the toxin to achieve its toxic effect. In the Gram-positive pathogen Streptococcus pneumoniae we have characterized four TAs: pezAT, relBE, yefM-yoeB, and phD-doc, although the latter is missing in strain R6. We have assessed the role of the two yefM-yoeB and relBE systems encoded by S. pneumoniae R6 by construction of isogenic strains lacking one or two of the operons, and by complementation assays. We have analyzed the phenotypes of the wild type and mutants in terms of cell growth, response to environmental stress, and ability to generate biofilms. Compared to the wild-type, the mutants exhibited lower resistance to oxidative stress. Further, strains deleted in yefM-yoeB and the double mutant lacking yefM-yoeB and relBE exhibited a significant reduction in their ability for biofilm formation. Complementation assays showed that defective phenotypes were restored to wild type levels. We conclude that these two loci may play a relevant role in these aspects of the S. pneumoniae lifestyle and contribute to the bacterial colonization of new niches.
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Affiliation(s)
- Wai Ting Chan
- i-DNA Biotechnology (M) Sdn Bhd. A-1-6 Pusat Perdagangan Kuchai, No. 2, Jalan 1/127, Kuchai Entrepreneurs Park, Kuala Lumpur 58200, Malaysia.
| | - Mirian Domenech
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
- CIBER de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III, 28040 Madrid, Spain.
| | - Inmaculada Moreno-Córdoba
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
| | - Verónica Navarro-Martínez
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
| | - Concha Nieto
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
| | - Miriam Moscoso
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
| | - Ernesto García
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
- CIBER de Enfermedades Respiratorias (CIBERES), Instituto de Salud Carlos III, 28040 Madrid, Spain.
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain.
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Jaén-Luchoro D, Aliaga-Lozano F, Gomila RM, Gomila M, Salvà-Serra F, Lalucat J, Bennasar-Figueras A. First insights into a type II toxin-antitoxin system from the clinical isolate Mycobacterium sp. MHSD3, similar to epsilon/zeta systems. PLoS One 2017; 12:e0189459. [PMID: 29236773 PMCID: PMC5728571 DOI: 10.1371/journal.pone.0189459] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Accepted: 11/28/2017] [Indexed: 01/21/2023] Open
Abstract
A putative type II toxin-antitoxin (TA) system was found in the clinical isolate Mycobacterium sp. MHSD3, a strain closely related to Mycobacterium chelonae. Further analyses of the protein sequences of the two genes revealed the presence of domains related to a TA system. BLAST analyses indicated the presence of closely related proteins in the genomes of other recently published M. chelonae strains. The functionality of both elements of the TA system was demonstrated when expressed in Escherichia coli cells, and the predicted structure of the toxin is very similar to those of well-known zeta-toxins, leading to the definition of a type II TA system similar to epsilon/zeta TA systems in strains that are closely related to M. chelonae.
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Affiliation(s)
- Daniel Jaén-Luchoro
- Microbiologia, Departament de Biologia, Universitat de les Illes Balears, Palma de Mallorca, Spain
- Department of Infectious Diseases, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Centre for Antibiotic Resistance Research (CARe) at University of Gothenburg, Gothenburg, Sweden
- * E-mail:
| | - Francisco Aliaga-Lozano
- Microbiologia, Departament de Biologia, Universitat de les Illes Balears, Palma de Mallorca, Spain
- Laboratorio de Biología Molecular, Clínica Rotger, Palma de Mallorca, Spain
| | - Rosa Maria Gomila
- Serveis Cientifico-Tècnics, Universitat de les Illes Balears, Palma de Mallorca, Spain
| | - Margarita Gomila
- Microbiologia, Departament de Biologia, Universitat de les Illes Balears, Palma de Mallorca, Spain
| | - Francisco Salvà-Serra
- Microbiologia, Departament de Biologia, Universitat de les Illes Balears, Palma de Mallorca, Spain
- Department of Infectious Diseases, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Centre for Antibiotic Resistance Research (CARe) at University of Gothenburg, Gothenburg, Sweden
| | - Jorge Lalucat
- Microbiologia, Departament de Biologia, Universitat de les Illes Balears, Palma de Mallorca, Spain
- Institut Mediterrani d’Estudis Avançats (IMEDEA, CSIC-UIB), Esporles, Spain
| | - Antoni Bennasar-Figueras
- Microbiologia, Departament de Biologia, Universitat de les Illes Balears, Palma de Mallorca, Spain
- Area de Enfermedades Infecciosas, Instituto Universitario de Investigaciones en Ciencias de la Salud (IUNICS-UIB), Universitat de les Illes Balears, Palma de Mallorca, Spain
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11
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Moreno-Del Álamo M, Tabone M, Lioy VS, Alonso JC. Toxin ζ Triggers a Survival Response to Cope with Stress and Persistence. Front Microbiol 2017; 8:1130. [PMID: 28690594 PMCID: PMC5481361 DOI: 10.3389/fmicb.2017.01130] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 06/02/2017] [Indexed: 12/20/2022] Open
Abstract
Bacteria have evolved complex regulatory controls in response to various environmental stresses. Protein toxins of the ζ superfamily, found in prominent human pathogens, are broadly distributed in nature. We show that ζ is a uridine diphosphate-N-acetylglucosamine (UNAG)-dependent ATPase whose activity is inhibited in vitro by stoichiometric concentrations of ε2 antitoxin. In vivo, transient ζ expression promotes a reversible multi-level response by altering the pool of signaling purine nucleotides, which leads to growth arrest (dormancy), although a small cell subpopulation persists rather than tolerating toxin action. High c-di-AMP levels (absence of phosphodiesterase GdpP) decrease, and low c-di-AMP levels (absence of diadenylate cyclase DisA) increase the rate of ζ persistence. The absence of CodY, a transition regulator from exponential to stationary phase, sensitizes cells to toxin action, and suppresses persisters formed in the ΔdisA context. These changes, which do not affect the levels of stochastic ampicillin (Amp) persistence, sensitize cells to toxin and Amp action. Our findings provide an explanation for the connection between ζ-mediated growth arrest (with alterations in the GTP and c-di-AMP pools) and persistence formation.
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Affiliation(s)
- María Moreno-Del Álamo
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología (CSIC)Madrid, Spain
| | - Mariangela Tabone
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología (CSIC)Madrid, Spain
| | - Virginia S Lioy
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología (CSIC)Madrid, Spain
| | - Juan C Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología (CSIC)Madrid, Spain
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12
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Van Melderen L, Wood TK. Commentary: What Is the Link between Stringent Response, Endoribonuclease Encoding Type II Toxin-Antitoxin Systems and Persistence? Front Microbiol 2017; 8:191. [PMID: 28261163 PMCID: PMC5306293 DOI: 10.3389/fmicb.2017.00191] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Accepted: 01/26/2017] [Indexed: 11/13/2022] Open
Affiliation(s)
- Laurence Van Melderen
- Laboratoire de Génétique et Physiologie Bactérienne, Faculté des Sciences, Université Libre de Bruxelles (ULB) Gosselies, Belgium
| | - Thomas K Wood
- Department of Chemical Engineering, Pennsylvania State University State College, PA, USA
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13
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Demidenok OI, Shumkov MS, Goncharenko AV. VapC toxin inhibition as a method for prevention of the formation of resting forms of mycobacteria. APPL BIOCHEM MICRO+ 2016. [DOI: 10.1134/s0003683816060041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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14
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Kaldalu N, Jõers A, Ingelman H, Tenson T. A General Method for Measuring Persister Levels in Escherichia coli Cultures. Methods Mol Biol 2016; 1333:29-42. [PMID: 26468097 DOI: 10.1007/978-1-4939-2854-5_3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Genetically homogeneous bacterial cultures contain persisters, cells that are not killed by bactericidal antibiotics. These cells are suggested to be involved in the establishment of chronic infections. Persister levels depend on growth conditions. Here, we discuss the parameters that have to be considered when measuring persister levels and provide a sample protocol to do it.
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Affiliation(s)
- Niilo Kaldalu
- Institute of Technology, University of Tartu, Nooruse 1, Tartu, 50411, Estonia
| | - Arvi Jõers
- Institute of Technology, University of Tartu, Nooruse 1, Tartu, 50411, Estonia
| | - Henri Ingelman
- Institute of Technology, University of Tartu, Nooruse 1, Tartu, 50411, Estonia
| | - Tanel Tenson
- Institute of Technology, University of Tartu, Nooruse 1, Tartu, 50411, Estonia.
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15
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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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16
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The Interplay between Different Stability Systems Contributes to Faithful Segregation: Streptococcus pyogenes pSM19035 as a Model. Microbiol Spectr 2016; 2:PLAS-0007-2013. [PMID: 26104212 DOI: 10.1128/microbiolspec.plas-0007-2013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The Streptococcus pyogenes pSM19035 low-copy-number θ-replicating plasmid encodes five segregation (seg) loci that contribute to plasmid maintenance. These loci map outside of the minimal replicon. The segA locus comprises β2 recombinase and two six sites, and segC includes segA and also the γ topoisomerase and two ssiA sites. Recombinase β2 plays a role both in maximizing random segregation by resolving plasmid dimers (segA) and in catalyzing inversion between two inversely oriented six sites. segA, in concert with segC, facilitates replication fork pausing at ssiA sites and overcomes the accumulation of "toxic" replication intermediates. The segB1 locus encodes ω, ε, and ζ genes. The short-lived ε2 antitoxin and the long-lived ζ toxin form an inactive ζε2ζ complex. Free ζ toxin halts cell proliferation upon decay of the ε2 antitoxin and enhances survival. If ε2 expression is not recovered, by loss of the plasmid, the toxin raises lethality. The segB2 locus comprises δ and ω genes and six parS sites. Proteins δ2 and ω2, by forming complexes with parS and chromosomal DNA, pair the plasmid copies at the nucleoid, leading to the formation of a dynamic δ2 gradient that separates the plasmids to ensure roughly equal distribution to daughter cells at cell division. The segD locus, which comprises ω2 (or ω2 plus ω22) and parS sites, coordinates expression of genes that control copy number, better-than-random segregation, faithful partition, and antibiotic resistance. The interplay of the seg loci and with the rep locus facilitates almost absolute plasmid stability.
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17
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Abstract
Active containment systems are a major tool for reducing the uncertainty associated with the introduction of monocultures, genetically engineered or not, into target habitats for a large number of biotechnological applications (e.g., bioremediation, bioleaching, biopesticides, biofuels, biotransformations, live vaccines, etc.). While biological containment reduces the survival of the introduced organism outside the target habitat and/or upon completion of the projected task, gene containment strategies reduce the lateral spread of the key genetic determinants to indigenous microorganisms. In fundamental research, suicide circuits become relevant tools to address the role of gene transfer, mainly plasmid transfer, in evolution and how this transfer contributes to genome plasticity and to the rapid adaptation of microbial communities to environmental changes. Many lethal functions and regulatory circuits have been used and combined to design efficient containment systems. As many new genomes are being sequenced, novel lethal genes and regulatory elements are available, e.g., new toxin-antitoxin modules, and they could be used to increase further the current containment efficiencies and to expand containment to other organisms. Although the current containment systems can increase the predictability of genetically modified organisms in the environment, containment will never be absolute, due to the existence of mutations that lead to the appearance of surviving subpopulations. In this sense, orthogonal systems (xenobiology) appear to be the solution for setting a functional genetic firewall that will allow absolute containment of recombinant organisms.
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18
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Volante A, Carrasco B, Tabone M, Alonso JC. The interaction of ω2 with the RNA polymerase β' subunit functions as an activation to repression switch. Nucleic Acids Res 2015; 43:9249-61. [PMID: 26243774 PMCID: PMC4627068 DOI: 10.1093/nar/gkv788] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Accepted: 07/23/2015] [Indexed: 12/03/2022] Open
Abstract
The ω gene is encoded in broad-host range and low-copy plasmids. It is genetically linked to antibiotic resistance genes of the major human pathogens of phylum Firmicutes. The homodimeric forms of ω (ω2) coordinate the plasmid copy number control, faithful partition (ω2 and δ2) and better-than-random segregation (ζϵ2ζ) systems. The promoter (P) of the ωϵζ operon (Pω) transiently interacts with ω2. Adding δ2 facilitates the formation of stable ω2·Pω complexes. Here we show that limiting ω2 interacts with the N-terminal domain of the β’ subunit of the Bacillus subtilis RNA polymerase (RNAP-σA) vegetative holoenzyme. In this way ω2 recruits RNAP-σA onto Pω DNA. Partial Pω occupancy by ω2 increases the rate at which RNAP-σA complex shifts from its closed (RPC) to open (RPO) form. This shift increases transcription activation. Adding δ2 further increases the rate of Pω transcription initiation, perhaps by stabilizing the ω2·Pω complex. In contrast, full operator occupancy by ω2 facilitates RPC formation, but it blocks RPO isomerization and represses Pω utilization. The stimulation and inhibition of RPO formation is the mechanism whereby ω2 mediates copy number fluctuation and stable plasmid segregation. By this mechanism, ω2 also indirectly influences the acquisition of antibiotic resistance genes.
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Affiliation(s)
- Andrea Volante
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3, Darwin Street, 28049 Madrid, Spain
| | - Begoña Carrasco
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3, Darwin Street, 28049 Madrid, Spain
| | - Mariangela Tabone
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3, Darwin Street, 28049 Madrid, Spain
| | - Juan C Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3, Darwin Street, 28049 Madrid, Spain
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19
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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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20
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Carrasco B, Yadav T, Serrano E, Alonso JC. Bacillus subtilis RecO and SsbA are crucial for RecA-mediated recombinational DNA repair. Nucleic Acids Res 2015; 43:5984-97. [PMID: 26001966 PMCID: PMC4499154 DOI: 10.1093/nar/gkv545] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 05/12/2015] [Indexed: 11/13/2022] Open
Abstract
Genetic data have revealed that the absence of Bacillus subtilis RecO and one of the end-processing avenues (AddAB or RecJ) renders cells as sensitive to DNA damaging agents as the null recA, suggesting that both end-resection pathways require RecO for recombination. RecA, in the rATP·Mg(2+) bound form (RecA·ATP), is inactive to catalyze DNA recombination between linear double-stranded (ds) DNA and naked complementary circular single-stranded (ss) DNA. We showed that RecA·ATP could not nucleate and/or polymerize on SsbA·ssDNA or SsbB·ssDNA complexes. RecA·ATP nucleates and polymerizes on RecO·ssDNA·SsbA complexes more efficiently than on RecO·ssDNA·SsbB complexes. Limiting SsbA concentrations were sufficient to stimulate RecA·ATP assembly on the RecO·ssDNA·SsbB complexes. RecO and SsbA are necessary and sufficient to 'activate' RecA·ATP to catalyze DNA strand exchange, whereas the AddAB complex, RecO alone or in concert with SsbB was not sufficient. In presence of AddAB, RecO and SsbA are still necessary for efficient RecA·ATP-mediated three-strand exchange recombination. Based on genetic and biochemical data, we proposed that SsbA and RecO (or SsbA, RecO and RecR in vivo) are crucial for RecA activation for both, AddAB and RecJ-RecQ (RecS) recombinational repair pathways.
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Affiliation(s)
- Begoña Carrasco
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin Street, 28049 Madrid, Spain
| | - Tribhuwan Yadav
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin Street, 28049 Madrid, Spain
| | - Ester Serrano
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin Street, 28049 Madrid, Spain
| | - Juan C Alonso
- Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CNB-CSIC, 3 Darwin Street, 28049 Madrid, Spain
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21
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Toxin ζ reversible induces dormancy and reduces the UDP-N-acetylglucosamine pool as one of the protective responses to cope with stress. Toxins (Basel) 2014; 6:2787-803. [PMID: 25238046 PMCID: PMC4179160 DOI: 10.3390/toxins6092787] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2014] [Revised: 08/14/2014] [Accepted: 09/09/2014] [Indexed: 12/21/2022] Open
Abstract
Toxins of the ζ/PezT family, found in the genome of major human pathogens, phosphorylate the peptidoglycan precursor uridine diphosphate-N-acetylglucosamine (UNAG) leading to unreactive UNAG-3P. Transient over-expression of a PezT variant impairs cell wall biosynthesis and triggers autolysis in Escherichia coli. Conversely, physiological levels of ζ reversibly induce dormancy produce a sub-fraction of membrane-compromised cells, and a minor subpopulation of Bacillus subtilis cells become tolerant of toxin action. We report here that purified ζ is a strong UNAG-dependent ATPase, being GTP a lower competitor. In vitro, ζ toxin phosphorylates a fraction of UNAG. In vivo, ζ-mediated inactivation of UNAG by phosphorylation does not deplete the active UNAG pool, because expression of the toxin enhances the efficacy of genuine cell wall inhibitors (fosfomycin, vancomycin or ampicillin). Transient ζ expression together with fosfomycin treatment halt cell proliferation, but ε2 antitoxin expression facilitates the exit of ζ-induced dormancy, suggesting that there is sufficient UNAG for growth. We propose that ζ induces diverse cellular responses to cope with stress, being the reduction of the UNAG pool one among them. If the action of ζ is not inhibited, e.g., by de novo ε2 antitoxin synthesis, the toxin markedly enhances the efficacy of antimicrobial treatment without massive autolysis in Firmicutes.
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22
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Yadav T, Carrasco B, Serrano E, Alonso JC. Roles of Bacillus subtilis DprA and SsbA in RecA-mediated genetic recombination. J Biol Chem 2014; 289:27640-52. [PMID: 25138221 DOI: 10.1074/jbc.m114.577924] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Bacillus subtilis competence-induced RecA, SsbA, SsbB, and DprA are required to internalize and to recombine single-stranded (ss) DNA with homologous resident duplex. RecA, in the ATP · Mg(2+)-bound form (RecA · ATP), can nucleate and form filament onto ssDNA but is inactive to catalyze DNA recombination. We report that SsbA or SsbB bound to ssDNA blocks the RecA filament formation and fails to activate recombination. DprA facilitates RecA filamentation; however, the filaments cannot engage in DNA recombination. When ssDNA was preincubated with SsbA, but not SsbB, DprA was able to activate DNA strand exchange dependent on RecA · ATP. This work demonstrates that RecA · ATP, in concert with SsbA and DprA, catalyzes DNA strand exchange, and SsbB is an accessory factor in the reaction. In contrast, RecA · dATP efficiently catalyzes strand exchange even in the absence of single-stranded binding proteins or DprA, and addition of the accessory factors marginally improved it. We proposed that the RecA-bound nucleotide (ATP and to a lesser extent dATP) might dictate the requirement for accessory factors.
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Affiliation(s)
- Tribhuwan Yadav
- From the Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CSIC, 28049 Madrid, Spain
| | - Begoña Carrasco
- From the Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CSIC, 28049 Madrid, Spain
| | - Ester Serrano
- From the Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CSIC, 28049 Madrid, Spain
| | - Juan C Alonso
- From the Department of Microbial Biotechnology, Centro Nacional de Biotecnología, CSIC, 28049 Madrid, Spain
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23
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Liu CC, Kuo HY, Tang CY, Chang KC, Liou ML. Prevalence and mapping of a plasmid encoding a type IV secretion system in Acinetobacter baumannii. Genomics 2014; 104:215-23. [PMID: 25072866 DOI: 10.1016/j.ygeno.2014.07.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 06/21/2014] [Accepted: 07/18/2014] [Indexed: 11/16/2022]
Abstract
We investigated the prevalence of a type IV secretion system (T4SS)-bearing plasmid among clinical isolates of carbapenem-resistant Acinetobacter baumannii (CRAB) using plasmid replicon typing. The complete sequence of a T4SS-bearing plasmid, pAB_CC, isolated from A. baumannii TYTH-1 was determined, and a comparative analysis of the T4SS gene modules was performed. Of the 129 isolates studied, GR6 (repAci6) was the most common (45 of 96 isolates) and was strongly linked with the T4SS. A comparative analysis of the T4SS locus in seven plasmid genomes, including pAB_CC, pACICU2, pABKp1, pABTJ1, p1BJAB0714, p2BJAB0868, and p2ABTCDC0715, indicated that fourteen genes on these plasmids were highly conserved compared to those of the F plasmid. Additionally, the chromosomes in the seven representative isolates may be evolutionarily distinct from their intrinsic T4SS-bearing plasmids, suggesting that the two T4SS lineages emerged long before the appearance of EC II. These two lineages are now widespread in A. baumannii strains.
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Affiliation(s)
- Chih-Chin Liu
- Department of Bioinformatics, Chung Hua University, Hsin-Chu City, Taiwan; Department of Computer Science and Information Engineering, Providence University, Taichung County, Taiwan
| | - Han-Yueh Kuo
- Department of Medicine, National Taiwan University Hospital Hsin-Chu Branch, Hsin-Chu City, Taiwan; School of Medicine, National Taiwan University, Taipei City, Taiwan
| | - Chuan Yi Tang
- Department of Computer Science and Information Engineering, Providence University, Taichung County, Taiwan; Department of Computer Science, National Tsing Hua University, Hsin-Chu City, Taiwan
| | - Kai-Chih Chang
- Department of Laboratory Medicine and Biotechnology, Tzu Chi University, Hualien City, Taiwan
| | - Ming-Li Liou
- Department of Computer Science and Information Engineering, Providence University, Taichung County, Taiwan; Department of Medical Laboratory Science and Biotechnology, Yuanpei University, Hsin-Chu City, Taiwan.
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24
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Lopes APY, Lopes LM, Fraga TR, Chura-Chambi RM, Sanson AL, Cheng E, Nakajima E, Morganti L, Martins EAL. VapC from the leptospiral VapBC toxin-antitoxin module displays ribonuclease activity on the initiator tRNA. PLoS One 2014; 9:e101678. [PMID: 25047537 PMCID: PMC4105405 DOI: 10.1371/journal.pone.0101678] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Accepted: 06/10/2014] [Indexed: 11/30/2022] Open
Abstract
The prokaryotic ubiquitous Toxin-Antitoxin (TA) operons encode a stable toxin and an unstable antitoxin. The most accepted hypothesis of the physiological function of the TA system is the reversible cessation of cellular growth under stress conditions. The major TA family, VapBC is present in the spirochaete Leptospira interrogans. VapBC modules are classified based on the presence of a predicted ribonucleasic PIN domain in the VapC toxin. The expression of the leptospiral VapC in E. coli promotes a strong bacterial growth arrestment, making it difficult to express the recombinant protein. Nevertheless, we showed that long term induction of expression in E. coli enabled the recovery of VapC in inclusion bodies. The recombinant protein was successfully refolded by high hydrostatic pressure, providing a new method to obtain the toxin in a soluble and active form. The structural integrity of the recombinant VapB and VapC proteins was assessed by circular dichroism spectroscopy. Physical interaction between the VapC toxin and the VapB antitoxin was demonstrated in vivo and in vitro by pull down and ligand affinity blotting assays, respectively, thereby indicating the ultimate mechanism by which the activity of the toxin is regulated in bacteria. The predicted model of the leptospiral VapC structure closely matches the Shigella's VapC X-ray structure. In agreement, the ribonuclease activity of the leptospiral VapC was similar to the activity described for Shigella's VapC, as demonstrated by the cleavage of tRNAfMet and by the absence of unspecific activity towards E. coli rRNA. This finding suggests that the cleavage of the initiator transfer RNA may represent a common mechanism to a larger group of bacteria and potentially configures a mechanism of post-transcriptional regulation leading to the inhibition of global translation.
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Affiliation(s)
| | - Luana M. Lopes
- Centro de Biotecnologia, Instituto Butantan, São Paulo, São Paulo, Brazil
| | - Tatiana R. Fraga
- Centro de Biotecnologia, Instituto Butantan, São Paulo, São Paulo, Brazil
| | - Rosa M. Chura-Chambi
- Centro de Biotecnologia, Instituto de Pesquisas Energéticas e Nucleares, Comissão Nacional de Energia Nuclear, São Paulo, São Paulo, Brazil
| | - André L. Sanson
- Centro de Biotecnologia, Instituto Butantan, São Paulo, São Paulo, Brazil
| | - Elisabeth Cheng
- Centro de Biotecnologia, Instituto Butantan, São Paulo, São Paulo, Brazil
| | - Erika Nakajima
- Centro de Biotecnologia, Instituto Butantan, São Paulo, São Paulo, Brazil
| | - Ligia Morganti
- Centro de Biotecnologia, Instituto de Pesquisas Energéticas e Nucleares, Comissão Nacional de Energia Nuclear, São Paulo, São Paulo, Brazil
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25
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Demidenok OI, Kaprelyants AS, Goncharenko AV. Toxin-antitoxinvapBClocus participates in formation of the dormant state inMycobacterium smegmatis. FEMS Microbiol Lett 2014; 352:69-77. [DOI: 10.1111/1574-6968.12380] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2013] [Revised: 12/31/2013] [Accepted: 12/31/2013] [Indexed: 01/01/2023] Open
Affiliation(s)
- Oksana I. Demidenok
- Laboratory of Biochemistry of Stresses in Microorganisms; A.N. Bach Institute of Biochemistry Russian Academy of Sciences; Moscow Russia
| | - Arseny S. Kaprelyants
- Laboratory of Biochemistry of Stresses in Microorganisms; A.N. Bach Institute of Biochemistry Russian Academy of Sciences; Moscow Russia
| | - Anna V. Goncharenko
- Laboratory of Biochemistry of Stresses in Microorganisms; A.N. Bach Institute of Biochemistry Russian Academy of Sciences; Moscow Russia
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26
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Tabone M, Lioy VS, Ayora S, Machón C, Alonso JC. Role of toxin ζ and starvation responses in the sensitivity to antimicrobials. PLoS One 2014; 9:e86615. [PMID: 24489751 PMCID: PMC3906061 DOI: 10.1371/journal.pone.0086615] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 12/13/2013] [Indexed: 11/23/2022] Open
Abstract
A fraction of otherwise antimicrobial-sensitive Bacillus subtilis cells, called persisters, are phenotypically tolerant of antimicrobial treatment. We report that, independently of B. subtilis' growth phase, transient ζ toxin expression induces a dormant state and alters cellular responses so that cells are more sensitive to antimicrobials with different modes of action. This outcome is modulated by fine tuning (p)ppGpp and GTP levels: i) in the presence of low “dysregulated” (p)ppGpp levels (as in relA− cells) hyper-tolerance to both toxin and antimicrobials was observed; ii) physiological or low (p)ppGpp levels (as in the wild-type, sasA−, sasB− and relA−sasA− context) show a normal toxin and antimicrobial tolerance; and iii) lower levels (in relA−sasB−) or absence of (p)ppGpp (in the relA−sasA−sasB− context), in concert with elevated GTP levels, potentiate the efficacy of both toxin and antimicrobial action, rendering tolerance vulnerable to eradication.
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Affiliation(s)
- Mariangela Tabone
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, (CNB-CSIC), Madrid, Spain
| | - Virginia S. Lioy
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, (CNB-CSIC), Madrid, Spain
| | - Silvia Ayora
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, (CNB-CSIC), Madrid, Spain
| | - Cristina Machón
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, (CNB-CSIC), Madrid, Spain
| | - Juan C. Alonso
- Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, (CNB-CSIC), Madrid, Spain
- * E-mail:
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27
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The presence of conjugative plasmid pLS20 affects global transcription of Its Bacillus subtilis host and confers beneficial stress resistance to cells. Appl Environ Microbiol 2013; 80:1349-58. [PMID: 24334659 DOI: 10.1128/aem.03154-13] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Conjugation activity of plasmid pLS20 from Bacillus subtilis subsp. natto is induced when cells are diluted into fresh medium and diminishes as cells enter into stationary-phase growth. Transcriptional profiling shows that during mid-exponential growth, more than 5% of the host genes are affected in the presence of the plasmid, in contrast to the minor changes seen in freshly diluted and stationary-phase cells. Changes occurred in many metabolic pathways, although pLS20 does not confer any detectable burden on its host cell, as well as in membrane and cell wall-associated processes, in the large motility operon, and in several other cellular processes. In agreement with these changes, we found considerable alterations in motility and enzyme activity and increased resistance against several different forms of stress in cells containing the plasmid, revealing that the presence of pLS20 has a broad impact on the physiology of its host cell and increases its stress resistance in multiple aspects. Additionally, we found that the lack of chromosomal gene yueB, known to encode a phage receptor protein, which is upregulated in cells containing pLS20, strongly reduced conjugation efficiency, revealing that pLS20 not only increases fitness of its host but also employs host proteins for efficient transfer into a new cell.
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28
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Unterholzner SJ, Hailer B, Poppenberger B, Rozhon W. Characterisation of the stbD/E toxin-antitoxin system of pEP36, a plasmid of the plant pathogen Erwinia pyrifoliae. Plasmid 2013; 70:216-25. [PMID: 23632277 DOI: 10.1016/j.plasmid.2013.04.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Revised: 04/15/2013] [Accepted: 04/17/2013] [Indexed: 11/29/2022]
Abstract
pEP36 is a plasmid ubiquitously present in Erwinia pyrifoliae, a pathogen which causes black stem blight of Asian pear. pEP36 is highly stable in its host, even in the absence of selective pressure. The plasmid is closely related to pEA29, which is widespread in E. amylovora, the causative agent of fire blight of apple and pear trees. Here we report that pEP36 possesses a functional hybrid toxin-antitoxin module, stbD/E(pEP36), with the toxin showing homology to the RelE/ParE proteins and the antidote belonging to the Phd/YefM antitoxin family. Bacteria expressing the StbE(pEP36) toxin arrest cell growth and enter a viable but non-culturable stage. However, they maintain their typical cell length and do not show filamentation. Pulse-chase experiments revealed that StbE(pEP36) acts as a global inhibitor of protein synthesis while it does not interfere with DNA and RNA synthesis. The StbD(pEP36) antitoxin is capable of neutralising StbE(pEP36) toxicity. Additional experiments show that the stbD/E(pEP36) module can stabilise plasmids at least 20-fold. Thus the toxin-antitoxin system may contribute to the remarkable stability of pEP36.
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Affiliation(s)
- Simon J Unterholzner
- Biotechnology of Horticultural Crops, Technische Universität München, Liesel-Beckmann-Straße 1, 85354 Freising, Germany.
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Bullman S, Lucid A, Corcoran D, Sleator RD, Lucey B. Genomic investigation into strain heterogeneity and pathogenic potential of the emerging gastrointestinal pathogen Campylobacter ureolyticus. PLoS One 2013; 8:e71515. [PMID: 24023611 PMCID: PMC3758288 DOI: 10.1371/journal.pone.0071515] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Accepted: 07/01/2013] [Indexed: 12/29/2022] Open
Abstract
The recent detection and isolation of C. ureolyticus from patients with diarrhoeal illness and inflammatory bowel diseases warrants further investigation into its role as an emerging pathogen of the human gastrointestinal tract. Regarding the pathogenic mechanisms employed by this species we provide the first whole genome analysis of two C. ureolyticus isolates including the type strain. Comparative analysis, subtractive hybridisation and gene ontology searches against other Campylobacter species identifies the high degree of heterogenicity between C. ureolyticus isolates, in addition to the identification of 106 putative virulence associated factors, 52 of which are predicted to be secreted. Such factors encompass each of the known virulence tactics of pathogenic Campylobacter spp. including adhesion and colonisation (CadF, PEB1, IcmF and FlpA), invasion (ciaB and 16 virB-virD4 genes) and toxin production (S-layer RTX and ZOT). Herein, we provide the first virulence catalogue for C. ureolyticus, the components of which theoretically provide this emerging species with sufficient arsenal to establish pathology.
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Affiliation(s)
- Susan Bullman
- Department of Biological Sciences, Cork Institute of Technology, Cork, Ireland
| | - Alan Lucid
- Department of Biological Sciences, Cork Institute of Technology, Cork, Ireland
| | - Daniel Corcoran
- Department of Medical Microbiology, Cork University Hospital, Cork, Ireland
| | - Roy D. Sleator
- Department of Biological Sciences, Cork Institute of Technology, Cork, Ireland
- * E-mail:
| | - Brigid Lucey
- Department of Biological Sciences, Cork Institute of Technology, Cork, Ireland
- Department of Medical Microbiology, Cork University Hospital, Cork, Ireland
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Mruk I, Kobayashi I. To be or not to be: regulation of restriction-modification systems and other toxin-antitoxin systems. Nucleic Acids Res 2013; 42:70-86. [PMID: 23945938 PMCID: PMC3874152 DOI: 10.1093/nar/gkt711] [Citation(s) in RCA: 164] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
One of the simplest classes of genes involved in programmed death is that containing the toxin–antitoxin (TA) systems of prokaryotes. These systems are composed of an intracellular toxin and an antitoxin that neutralizes its effect. These systems, now classified into five types, were initially discovered because some of them allow the stable maintenance of mobile genetic elements in a microbial population through postsegregational killing or the death of cells that have lost these systems. Here, we demonstrate parallels between some TA systems and restriction–modification systems (RM systems). RM systems are composed of a restriction enzyme (toxin) and a modification enzyme (antitoxin) and limit the genetic flux between lineages with different epigenetic identities, as defined by sequence-specific DNA methylation. The similarities between these systems include their postsegregational killing and their effects on global gene expression. Both require the finely regulated expression of a toxin and antitoxin. The antitoxin (modification enzyme) or linked protein may act as a transcriptional regulator. A regulatory antisense RNA recently identified in an RM system can be compared with those RNAs in TA systems. This review is intended to generalize the concept of TA systems in studies of stress responses, programmed death, genetic conflict and epigenetics.
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Affiliation(s)
- Iwona Mruk
- Department of Microbiology, University of Gdansk, Wita Stwosza 59, Gdansk, 80-308, Poland, Department of Medical Genome Sciences, Graduate School of Frontier Sciences, University of Tokyo, Tokyo 108-8639, Japan and Institute of Medical Science, University of Tokyo, Tokyo 108-8639, Japan
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