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Ji C, He T, Wu B, Cao X, Fan X, Liu X, Li X, Yang M, Wang J, Xu L, Hu S, Xia L, Sun Y. Identification and characterization of a novel type II toxin-antitoxin system in Aeromonas veronii. Arch Microbiol 2024; 206:381. [PMID: 39153128 DOI: 10.1007/s00203-024-04101-5] [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: 04/22/2024] [Accepted: 08/02/2024] [Indexed: 08/19/2024]
Abstract
The bacterial type II toxin-antitoxin (TA) system is a rich genetic element that participates in various physiological processes. Aeromonas veronii is the main bacterial pathogen threatening the freshwater aquaculture industry. However, the distribution of type II TA system in A. veronii was seldom documented and its roles in the life activities of A. veronii were still unexplored. In this study, a novel type II TA system AvtA-AvtT was predicted in a fish pathogen Aeromonas veronii biovar sobria with multi-drug resistance using TADB 2.0. Through an Escherichia coli host killing and rescue assay, we demonstrated that AvtA and AvtT worked as a genuine TA system, and the predicted toxin AvtT actually functioned as an antitoxin while the predicted antitoxin AvtA actually functioned as a toxin. The binding ability of AvtA with AvtT proteins were confirmed by dot blotting analysis and co-immunoprecipitation assay. Furthermore, we found that the toxin and antitoxin labelled with fluorescent proteins were co-localized. In addition, it was found that the transcription of AvtAT bicistronic operon was repressed by the AvtAT protein complex. Deletion of avtA gene and avtT gene had no obvious effect on the drug susceptibility. This study provides first characterization of type II TA system AvtA-AvtT in aquatic pathogen A. veronii.
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Affiliation(s)
- Caihong Ji
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, 410081, P. R. China
| | - Ting He
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, 410081, P. R. China
| | - Binbin Wu
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, 410081, P. R. China
| | - Xiaomei Cao
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, 410081, P. R. China
| | - Xiaping Fan
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, 410081, P. R. China
| | - Xia Liu
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, 410081, P. R. China
| | - Xiaodan Li
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, 410081, P. R. China
| | - Miao Yang
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, 410081, P. R. China
| | - Jihan Wang
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, 410081, P. R. China
| | - Ling Xu
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, 410081, P. R. China
| | - Shengbiao Hu
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, 410081, P. R. China
| | - Liqiu Xia
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, 410081, P. R. China
| | - Yunjun Sun
- State Key Laboratory of Developmental Biology of Freshwater Fish, College of Life Science, Hunan Normal University, Changsha, 410081, P. R. China.
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2
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Ruan S, Tu CH, Bourne CR. Friend or Foe: Protein Inhibitors of DNA Gyrase. BIOLOGY 2024; 13:84. [PMID: 38392303 PMCID: PMC10886550 DOI: 10.3390/biology13020084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2023] [Revised: 01/20/2024] [Accepted: 01/26/2024] [Indexed: 02/24/2024]
Abstract
DNA gyrase is essential for the successful replication of circular chromosomes, such as those found in most bacterial species, by relieving topological stressors associated with unwinding the double-stranded genetic material. This critical central role makes gyrase a valued target for antibacterial approaches, as exemplified by the highly successful fluoroquinolone class of antibiotics. It is reasonable that the activity of gyrase could be intrinsically regulated within cells, thereby helping to coordinate DNA replication with doubling times. Numerous proteins have been identified to exert inhibitory effects on DNA gyrase, although at lower doses, it can appear readily reversible and therefore may have regulatory value. Some of these, such as the small protein toxins found in plasmid-borne addiction modules, can promote cell death by inducing damage to DNA, resulting in an analogous outcome as quinolone antibiotics. Others, however, appear to transiently impact gyrase in a readily reversible and non-damaging mechanism, such as the plasmid-derived Qnr family of DNA-mimetic proteins. The current review examines the origins and known activities of protein inhibitors of gyrase and highlights opportunities to further exert control over bacterial growth by targeting this validated antibacterial target with novel molecular mechanisms. Furthermore, we are gaining new insights into fundamental regulatory strategies of gyrase that may prove important for understanding diverse growth strategies among different bacteria.
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Affiliation(s)
- Shengfeng Ruan
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019, USA
| | - Chih-Han Tu
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019, USA
| | - Christina R Bourne
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, OK 73019, USA
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Feng SY, Hauck Y, Morgene F, Mohammedi R, Mirouze N. The complex regulation of competence in Staphylococcus aureus under microaerobic conditions. Commun Biol 2023; 6:512. [PMID: 37173437 PMCID: PMC10182052 DOI: 10.1038/s42003-023-04892-1] [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: 07/19/2022] [Accepted: 04/28/2023] [Indexed: 05/15/2023] Open
Abstract
To perform natural transformation, one of the three main Horizontal Gene Transfer mechanisms, bacteria need to enter a physiological differentiated state called genetic competence. Interestingly, new bacteria displaying such aptitude are often discovered, and one of the latest is the human pathogen Staphylococcus aureus.Here, we show an optimized protocol, based on planktonic cells cultures, leading to a large percentage of the population activating the development of competence and a significant improvement of S. aureus natural transformation efficiencies. Taking advantage of these conditions, we perform transcriptomics analyses to characterize the regulon of each central competence regulator. SigH and ComK1 are both found essential for activating natural transformation genes but also important for activation or repression of peripheral functions. Even though ComK2 is not found important for the control of transformation genes, its regulon shows an important overlap with that of SigH and ComK1. Finally, we propose that microaerobic conditions, sensed by the SrrAB two-component system, are key to activate competence in S. aureus.
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Affiliation(s)
- Shi Yuan Feng
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-Sur-Yvette, France
| | - Yolande Hauck
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-Sur-Yvette, France
| | - Fedy Morgene
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-Sur-Yvette, France
| | - Roza Mohammedi
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-Sur-Yvette, France
| | - Nicolas Mirouze
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198, Gif-Sur-Yvette, France.
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4
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Kato F, Yamaguchi Y, Inouye K, Matsuo K, Ishida Y, Inouye M. A novel gyrase inhibitor from toxin-antitoxin system expressed by Staphylococcus aureus. FEBS J 2023; 290:1502-1518. [PMID: 36148483 DOI: 10.1111/febs.16634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 09/12/2022] [Accepted: 09/22/2022] [Indexed: 11/30/2022]
Abstract
Toxin-antitoxin (TA) systems consist of a toxin inhibiting essential cellular functions (such as DNA, RNA and protein synthesis), and its cognate antitoxin neutralizing the toxicity. Recently, we identified a TA system termed TsbA/TsbT in the Staphylococcus aureus genome. The induction of the tsbT gene in Escherichia coli halted both DNA and RNA synthesis, reduced supercoiled plasmid and resulted in increasingly relaxed DNA. These results suggested that DNA gyrase was the target of TsbT. In addition, TsbT inhibited both E. coli and S. aureus DNA gyrase activity and induced linearization of plasmid DNA in vitro. Taken together, these results demonstrate that the TsbT toxin targets DNA gyrase in vivo. Site-directed mutagenesis experiments showed that the E27 and D37 residues in TsbT are critical for toxicity. Secondary structure prediction combining the analysis of vacuum-ultraviolet circular-dichroism spectroscopy and neural network method demonstrated that the 22nd-32nd residues of TsbT form an α-helix structure, and that the E27 residue is located around the centre of the α-helix segment. These findings give new insights not only into S. aureus TA systems, but also into bacterial toxins targeting DNA topoisomerases.
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Affiliation(s)
- Fuminori Kato
- Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan
| | - Yoshihiro Yamaguchi
- Department of Biology and Geosciences, Graduate School of Sciences, Osaka City University, Japan
| | - Keiko Inouye
- Department of Biochemistry and Molecular Biology, Center for Advanced Biotechnology and Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, USA
| | - Koichi Matsuo
- Hiroshima Synchrotron Radiation Center, Hiroshima University, Higashi-Hiroshima, Japan
| | - Yojiro Ishida
- Department of Biochemistry and Molecular Biology, Center for Advanced Biotechnology and Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, USA
| | - Masayori Inouye
- Department of Biochemistry and Molecular Biology, Center for Advanced Biotechnology and Medicine, Rutgers-Robert Wood Johnson Medical School, Piscataway, NJ, USA
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Choi E, Huh A, Oh C, Oh JI, Kang HY, Hwang J. Functional characterization of HigBA toxin-antitoxin system in an Arctic bacterium, Bosea sp. PAMC 26642. J Microbiol 2022; 60:192-206. [PMID: 35102526 DOI: 10.1007/s12275-022-1619-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/15/2021] [Accepted: 12/20/2021] [Indexed: 01/02/2023]
Abstract
Toxin-antitoxin (TA) systems are growth-controlling genetic elements consisting of an intracellular toxin protein and its cognate antitoxin. TA systems have been spread among microbial genomes through horizontal gene transfer and are now prevalent in most bacterial and archaeal genomes. Under normal growth conditions, antitoxins tightly counteract the activity of the toxins. Upon stresses, antitoxins are inactivated, releasing activated toxins, which induce growth arrest or cell death. In this study, among nine functional TA modules in Bosea sp. PAMC 26642 living in Arctic lichen, we investigated the functionality of BoHigBA2. BohigBA2 is located close to a genomic island and adjacent to flagellar gene clusters. The expression of BohigB2 induced the inhibition of E. coli growth at 37°C, which was more manifest at 18°C, and this growth defect was reversed when BohigA2 was co-expressed, suggesting that this BoHigBA2 module might be an active TA module in Bosea sp. PAMC 26642. Live/dead staining and viable count analyses revealed that the BoHigB2 toxin had a bactericidal effect, causing cell death. Furthermore, we demonstrated that BoHigB2 possessed mRNA-specific ribonuclease activity on various mRNAs and cleaved only mRNAs being translated, which might impede overall translation and consequently lead to cell death. Our study provides the insight to understand the cold adaptation of Bosea sp. PAMC 26642 living in the Arctic.
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Affiliation(s)
- Eunsil Choi
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea.,Microbiological Resource Research Institute, Pusan National University, Busan, 46241, Republic of Korea
| | - Ahhyun Huh
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea
| | - Changmin Oh
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea
| | - Jeong-Il Oh
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea.,Microbiological Resource Research Institute, Pusan National University, Busan, 46241, Republic of Korea
| | - Ho Young Kang
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea.,Microbiological Resource Research Institute, Pusan National University, Busan, 46241, Republic of Korea
| | - Jihwan Hwang
- Department of Microbiology, Pusan National University, Busan, 46241, Republic of Korea. .,Microbiological Resource Research Institute, Pusan National University, Busan, 46241, Republic of Korea.
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Jeon H, Choi E, Hwang J. Identification and characterization of VapBC toxin-antitoxin system in Bosea sp. PAMC 26642 isolated from Arctic lichens. RNA (NEW YORK, N.Y.) 2021; 27:1374-1389. [PMID: 34429367 PMCID: PMC8522696 DOI: 10.1261/rna.078786.121] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 08/19/2021] [Indexed: 06/13/2023]
Abstract
Toxin-antitoxin (TA) systems are genetic modules composed of a toxin interfering with cellular processes and its cognate antitoxin, which counteracts the activity of the toxin. TA modules are widespread in bacterial and archaeal genomes. It has been suggested that TA modules participate in the adaptation of prokaryotes to unfavorable conditions. The Bosea sp. PAMC 26642 used in this study was isolated from the Arctic lichen Stereocaulon sp. There are 12 putative type II TA loci in the genome of Bosea sp. PAMC 26642. Of these, nine functional TA systems have been shown to be toxic in Escherichia coli The toxin inhibits growth, but this inhibition is reversed when the cognate antitoxin genes are coexpressed, indicating that these putative TA loci were bona fide TA modules. Only the BoVapC1 (AXW83_01405) toxin, a homolog of VapC, showed growth inhibition specific to low temperatures, which was recovered by the coexpression of BoVapB1 (AXW83_01400). Microscopic observation and growth monitoring revealed that the BoVapC1 toxin had bacteriostatic effects on the growth of E. coli and induced morphological changes. Quantitative real time polymerase chain reaction and northern blotting analyses showed that the BoVapC1 toxin had a ribonuclease activity on the initiator tRNAfMet, implying that degradation of tRNAfMet might trigger growth arrest in E. coli Furthermore, the BoVapBC1 system was found to contribute to survival against prolonged exposure at 4°C. This is the first study to identify the function of TA systems in cold adaptation.
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Affiliation(s)
- Hyerin Jeon
- Department of Microbiology, Pusan National University, Busan 46241, Republic of Korea
| | - Eunsil Choi
- Department of Microbiology, Pusan National University, Busan 46241, Republic of Korea
- Microbiological Resource Research Institute, Pusan National University, Busan 46241, Republic of Korea
| | - Jihwan Hwang
- Department of Microbiology, Pusan National University, Busan 46241, Republic of Korea
- Microbiological Resource Research Institute, Pusan National University, Busan 46241, Republic of Korea
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Identification of Three Type II Toxin-Antitoxin Systems in Model Bacterial Plant Pathogen Dickeya dadantii 3937. Int J Mol Sci 2021; 22:ijms22115932. [PMID: 34073004 PMCID: PMC8198452 DOI: 10.3390/ijms22115932] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 05/28/2021] [Accepted: 05/28/2021] [Indexed: 11/17/2022] Open
Abstract
Type II toxin-antitoxin (TA) systems are genetic elements usually encoding two proteins: a stable toxin and an antitoxin, which binds the toxin and neutralizes its toxic effect. The disturbance in the intracellular toxin and antitoxin ratio typically leads to inhibition of bacterial growth or bacterial cell death. Despite the fact that TA modules are widespread in bacteria and archaea, the biological role of these systems is ambiguous. Nevertheless, a number of studies suggests that the TA modules are engaged in such important processes as biofilm formation, stress response or virulence and maintenance of mobile genetic elements. The Dickeya dadantii 3937 strain serves as a model for pathogens causing the soft-rot disease in a wide range of angiosperm plants. Until now, several chromosome-encoded type II TA systems were identified in silico in the genome of this economically important bacterium, however so far only one of them was experimentally validated. In this study, we investigated three putative type II TA systems in D. dadantii 3937: ccdAB2Dda, phd-docDda and dhiTA, which represents a novel toxin/antitoxin superfamily. We provide an experimental proof for their functionality in vivo both in D. dadantii and Escherichia coli. Finally, we examined the prevalence of those systems across the Pectobacteriaceae family by a phylogenetic analysis.
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Levante A, Lazzi C, Vatsellas G, Chatzopoulos D, Dionellis VS, Makrythanasis P, Neviani E, Folli C. Genome Sequencing of five Lacticaseibacillus Strains and Analysis of Type I and II Toxin-Antitoxin System Distribution. Microorganisms 2021; 9:microorganisms9030648. [PMID: 33800997 PMCID: PMC8003834 DOI: 10.3390/microorganisms9030648] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/10/2021] [Accepted: 03/18/2021] [Indexed: 11/16/2022] Open
Abstract
The analysis of bacterial genomes is a potent tool to investigate the distribution of specific traits related to the ability of surviving in particular environments. Among the traits associated with the adaptation to hostile conditions, toxin–antitoxin (TA) systems have recently gained attention in lactic acid bacteria. In this work, genome sequences of Lacticaseibacillus strains of dairy origin were compared, focusing on the distribution of type I TA systems homologous to Lpt/RNAII and of the most common type II TA systems. A high number of TA systems have been identified spread in all the analyzed strains, with type I TA systems mainly located on plasmid DNA. The type II TA systems identified in these strains highlight the diversity of encoded toxins and antitoxins and their organization. This study opens future perspectives on the use of genomic data as a resource for the study of TA systems distribution and prevalence in microorganisms of industrial relevance.
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Affiliation(s)
- Alessia Levante
- Department of Food and Drug, University of Parma, 43124 Parma, Italy; (C.L.); (E.N.)
- Correspondence: (A.L.); (C.F.); Tel.: +39-0521-906524 (A.L.); +39-0521-905174 (C.F.)
| | - Camilla Lazzi
- Department of Food and Drug, University of Parma, 43124 Parma, Italy; (C.L.); (E.N.)
| | - Giannis Vatsellas
- Biomedical Research Foundation of the Academy of Athens (BRFAA), 115 27 Athens, Greece; (G.V.); (D.C.); (V.S.D.); (P.M.)
| | - Dimitris Chatzopoulos
- Biomedical Research Foundation of the Academy of Athens (BRFAA), 115 27 Athens, Greece; (G.V.); (D.C.); (V.S.D.); (P.M.)
| | - Vasilis S. Dionellis
- Biomedical Research Foundation of the Academy of Athens (BRFAA), 115 27 Athens, Greece; (G.V.); (D.C.); (V.S.D.); (P.M.)
- Department of Molecular Biology, University of Geneva, 1211 Geneva, Switzerland
| | - Periklis Makrythanasis
- Biomedical Research Foundation of the Academy of Athens (BRFAA), 115 27 Athens, Greece; (G.V.); (D.C.); (V.S.D.); (P.M.)
| | - Erasmo Neviani
- Department of Food and Drug, University of Parma, 43124 Parma, Italy; (C.L.); (E.N.)
| | - Claudia Folli
- Department of Food and Drug, University of Parma, 43124 Parma, Italy; (C.L.); (E.N.)
- Correspondence: (A.L.); (C.F.); Tel.: +39-0521-906524 (A.L.); +39-0521-905174 (C.F.)
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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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Janczak M, Hyz K, Bukowski M, Lyzen R, Hydzik M, Wegrzyn G, Szalewska-Palasz A, Grudnik P, Dubin G, Wladyka B. Chromosomal localization of PemIK toxin-antitoxin system results in the loss of toxicity - Characterization of pemIK Sa1-Sp from Staphylococcus pseudintermedius. Microbiol Res 2020; 240:126529. [PMID: 32622987 DOI: 10.1016/j.micres.2020.126529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 06/11/2020] [Accepted: 06/12/2020] [Indexed: 11/20/2022]
Abstract
Toxin-antitoxin (TA) systems are ubiquitous in bacteria and on numerous occasions have been postulated to play a role in virulence of pathogens. Some Staphylococcus aureus strains carry a plasmid, which encodes the highly toxic PemIKSa TA system involved in maintenance of the plasmid but also implicated in modulation of gene expression. Here we showed that pemIKSa1-Sp TA system, homologous to the plasmid-encoded PemIKSa, is present in virtually each chromosome of S. pseudintermedius strain, however exhibits sequence heterogeneity. This results in two length variants of the PemKSa1-Sp toxin. The shorter (96 aa), C-terminally truncated toxin is enzymatically inactive, whereas the full length (112 aa) variant is an RNase, though nontoxic to the host cells. The lack of toxicity of the active PemKSa-Sp2 toxin is explained by increased substrate specificity. The pemISa1-Sp antitoxin gene seems pseudogenized, however, the whole pemIKSa1-Sp system is transcriptionally active. When production of N-terminally truncated antitoxins using alternative start codons is assumed, there are five possible length variants. Here we showed that even substantially truncated antitoxins are able to interact with PemKSa-Sp2 toxin and inhibit its RNase activity. Moreover, the antitoxins can rescue bacterial cells from toxic effects of overexpression of plasmid-encoded PemKSa toxin. Collectively, our data indicates that, contrary to the toxic plasmid-encoded PemIKSa TA system, location of pemIKSa1-Sp in the chromosome of S. pseudintermedius results in the loss of its toxicity. Interestingly, the retained RNase activity of PemKSa1-Sp2 toxin and functionality of the putative, N-terminally truncated antitoxins suggest the existence of evolutionary pressure for alleviation/mitigation of the toxin's toxicity and retention of the inhibitory activity of the antitoxin, respectively.
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Affiliation(s)
- Monika Janczak
- Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Karolina Hyz
- Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Michal Bukowski
- Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Robert Lyzen
- Intercollegiate Faculty of Biotechnology UG&MUG, University of Gdansk, Gdansk, Poland
| | - Marcin Hydzik
- Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Grzegorz Wegrzyn
- Department of Molecular Biology, Faculty of Biology, University of Gdansk, Gdansk, Poland
| | | | - Przemyslaw Grudnik
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland
| | - Grzegorz Dubin
- Malopolska Centre of Biotechnology, Jagiellonian University, Krakow, Poland
| | - Benedykt Wladyka
- Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland.
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