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Chen Y, Goh YX, Li P, Guan J, Chao Y, Qu H, Ou HY, Wang X. RES-Xre toxin-antitoxin locus knaAT maintains the stability of the virulence plasmid in Klebsiella pneumoniae. Emerg Microbes Infect 2024; 13:2316814. [PMID: 38323903 PMCID: PMC10896132 DOI: 10.1080/22221751.2024.2316814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Accepted: 02/06/2024] [Indexed: 02/08/2024]
Abstract
Hypervirulent Klebsiella pneumoniae isolates have been increasingly reported worldwide, especially hypervirulent drug-resistant variants owing to the acquisition of a mobilizable virulence plasmid by a carbapenem-resistant strain. This pLVPK-like mobilizable plasmid encodes various virulence factors; however, information about its genetic stability is lacking. This study aimed to investigate the type II toxin-antitoxin (TA) modules that facilitate the virulence plasmid to remain stable in K. pneumoniae. More than 3,000 TA loci in 2,000 K. pneumoniae plasmids were examined for their relationship with plasmid cargo genes. TA loci from the RES-Xre family were highly correlated with virulence plasmids of hypervirulent K. pneumoniae. Overexpression of the RES toxin KnaT, encoded by the virulence plasmid-carrying RES-Xre locus knaAT, halts the cell growth of K. pneumoniae and E. coli, whereas co-expression of the cognate Xre antitoxin KnaA neutralizes the toxicity of KnaT. knaA and knaT were co-transcribed, representing the characteristics of a type II TA module. The knaAT deletion mutation gradually lost its virulence plasmid in K. pneumoniae, whereas the stability of the plasmid in E. coli was enhanced by adding knaAT, which revealed that the knaAT operon maintained the genetic stability of the large virulence plasmid in K. pneumoniae. String tests and mouse lethality assays subsequently confirmed that a loss of the virulence plasmid resulted in reduced pathogenicity of K. pneumoniae. These findings provide important insights into the role of the RES-Xre TA pair in stabilizing virulence plasmids and disseminating virulence genes in K. pneumoniae.
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Affiliation(s)
- Yongkui Chen
- Department of Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People’s Republic of China
- State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Ying-Xian Goh
- State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Peifei Li
- State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Jiahao Guan
- State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Yanjie Chao
- The Center for Microbes, Development and Health (CMDH), CAS Key Laboratory of Molecular Virology and Immunology, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, Shanghai, People’s Republic of China
| | - Hongping Qu
- Department of Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People’s Republic of China
| | - Hong-Yu Ou
- State Key Laboratory of Microbial Metabolism, Joint International Laboratory on Metabolic & Developmental Sciences, School of Life Sciences & Biotechnology, Shanghai Jiao Tong University, Shanghai, People’s Republic of China
| | - Xiaoli Wang
- Department of Critical Care Medicine, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People’s Republic of China
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2
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Amini MS, Baseri Salehi M, Bahador N. Evaluating the antibacterial effect of meropenem-loaded chitosan/sodium tripolyphosphate (TPP) nanoparticles on Acinetobacter baumannii isolated from hospitalized patients. BMC Infect Dis 2024; 24:631. [PMID: 38914964 PMCID: PMC11197314 DOI: 10.1186/s12879-024-09522-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 06/17/2024] [Indexed: 06/26/2024] Open
Abstract
BACKGROUND Acinetobacter baumannii is a health threat due to its antibiotic resistance. Herein, antibiotic susceptibility and its association with the Toxin-antitoxin (TA) system genes in A. baumannii clinical isolates from Iran were investigated. Next, we prepared meropenem-loaded chitosan nanoparticles (MP-CS) and investigated their antibacterial effects against meropenem-susceptible bacterial isolates. METHODS Out of 240 clinical specimens, 60 A. baumannii isolates were assessed. Antibiotic resistance of the isolates against conventional antibiotics was determined alongside investigating the presence of three TA system genes (mazEF, relBE, and higBA). Chitosan nanoparticles were characterized in terms of size, zeta potential, encapsulation efficiency, and meropenem release activity. Their antibacterial effects were assessed using the well diffusion method, minimum inhibitory concentration (MIC), and colony-forming unit (CFU) counting. Their cytotoxic effects and biocompatibility index were determined via the MTT, LDH, and ROS formation assays. RESULTS Ampicillin, ceftazidime, and colistin were the least effective, and amikacin and tobramycin were the most effective antibiotics. Out of the 60 isolates, 10 (16.7%), 5 (8.3%), and 45 (75%) were multidrug-resistant (MDR), extensively drug-resistant (XDR), and pandrug-resistant (PDR), respectively. TA system genes had no significant effect on antibiotic resistance. MP-CS nanoparticles demonstrated an average size of 191.5 and zeta potential of 27.3 mV alongside a maximum encapsulation efficiency of 88.32% and release rate of 69.57%. MP-CS nanoparticles mediated similar antibacterial effects, as compared with free meropenem, against the A. baumannii isolates with significantly lower levels of meropenem. MP-CS nanoparticles remarkably prevented A549 and NCI-H292 cell infection by the A. baumannii isolates alongside demonstrating a favorable biocompatibility index. CONCLUSION Antibiotic-loaded nanoparticles should be further designed and investigated to increase their antibacterial effect against A. baumannii and assess their safety and applicability in vivo settings.
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Affiliation(s)
- Marziyeh Sadat Amini
- Department of Microbiology, Kazeroun Branch, Islamic Azad University, Kazeroun, Iran
| | - Majid Baseri Salehi
- Department of Microbiology, Kazeroun Branch, Islamic Azad University, Kazeroun, Iran.
| | - Nima Bahador
- Department of Microbiology, Shiraz Branch, Islamic Azad University, Shiraz, Iran
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3
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Ardissone S, Greub G. The Chlamydia-related Waddlia chondrophila encodes functional type II toxin-antitoxin systems. Appl Environ Microbiol 2024; 90:e0068123. [PMID: 38214519 PMCID: PMC10880633 DOI: 10.1128/aem.00681-23] [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: 04/25/2023] [Accepted: 11/13/2023] [Indexed: 01/13/2024] Open
Abstract
Bacterial toxin-antitoxin (TA) systems are widespread in chromosomes and plasmids of free-living microorganisms, but only a few have been identified in obligate intracellular species. We found seven putative type II TA modules in Waddlia chondrophila, a Chlamydia-related species that is able to infect a very broad series of eukaryotic hosts, ranging from protists to mammalian cells. The RNA levels of Waddlia TA systems are significantly upregulated by iron starvation and novobiocin, but they are not affected by antibiotics such as β-lactams and glycopeptides, which suggests different mechanisms underlying stress responses. Five of the identified TA modules, including HigBA1 and MazEF1, encoded on the Waddlia cryptic plasmid, proved to be functional when expressed in a heterologous host. TA systems have been associated with the maintenance of mobile genetic elements, bacterial defense against bacteriophages, and persistence upon exposure to adverse conditions. As their RNA levels are upregulated upon exposure to adverse conditions, Waddlia TA modules may be involved in survival to stress. Moreover, as Waddlia can infect a wide range of hosts including free-living amoebae, TA modules could also represent an innate immunity system to fight against bacteriophages and other microorganisms with which Waddlia has to share its replicative niche.IMPORTANCEThe response to adverse conditions, such as exposure to antibiotics, nutrient starvation and competition with other microorganisms, is essential for the survival of a bacterial population. TA systems are modules composed of two elements, a toxic protein and an antitoxin (protein or RNA) that counteracts the toxin. Although many aspects of TA biological functions still await to be elucidated, TAs have often been implicated in bacterial response to stress, including the response to nutrient starvation, antibiotic treatment and bacteriophage infection. TAs are ubiquitous in free-living bacteria but rare in obligate intracellular species such as chlamydiae. We identified functional TA systems in Waddlia chondrophila, a chlamydial species with a strikingly broad host range compared to other chlamydiae. Our work contributes to understand how obligate intracellular bacteria react to adverse conditions that might arise from competition with other viruses/bacteria for the same replicative niche and would threaten their ability to replicate.
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Affiliation(s)
- Silvia Ardissone
- Institute of Microbiology, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
| | - Gilbert Greub
- Institute of Microbiology, Lausanne University Hospital and Lausanne University, Lausanne, Switzerland
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Danov A, Segev O, Bograd A, Ben Eliyahu Y, Dotan N, Kaplan T, Levy A. Toxinome-the bacterial protein toxin database. mBio 2024; 15:e0191123. [PMID: 38117054 PMCID: PMC10790787 DOI: 10.1128/mbio.01911-23] [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: 08/08/2023] [Accepted: 11/14/2023] [Indexed: 12/21/2023] Open
Abstract
IMPORTANCE Microbes use protein toxins as important tools to attack neighboring cells, microbial or eukaryotic, and for self-killing when attacked by viruses. These toxins work through different mechanisms to inhibit cell growth or kill cells. Microbes also use antitoxin proteins to neutralize the toxin activities. Here, we developed a comprehensive database called Toxinome of nearly two million toxins and antitoxins that are encoded in 59,475 bacterial genomes. We described the distribution of bacterial toxins and identified that they are depleted by bacteria that live in hot and cold temperatures. We found 5,161 cases in which toxins and antitoxins are densely clustered in bacterial genomes and termed these areas "Toxin Islands." The Toxinome database is a useful resource for anyone interested in toxin biology and evolution, and it can guide the discovery of new toxins.
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Affiliation(s)
- Aleks Danov
- Department of Plant Pathology and Microbiology, Institute of Environmental Science, The Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Ofir Segev
- Department of Plant Pathology and Microbiology, Institute of Environmental Science, The Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Avi Bograd
- Department of Plant Pathology and Microbiology, Institute of Environmental Science, The Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
| | - Yedidya Ben Eliyahu
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Noam Dotan
- Department of Brain Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Tommy Kaplan
- School of Computer Science and Engineering, The Hebrew University of Jerusalem, Jerusalem, Israel
- Department of Developmental Biology and Cancer Research, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Asaf Levy
- Department of Plant Pathology and Microbiology, Institute of Environmental Science, The Faculty of Agriculture, Food, and Environment, The Hebrew University of Jerusalem, Rehovot, Israel
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5
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Garcia-Rodriguez G, Girardin Y, Kumar Singh R, Volkov AN, Van Dyck J, Muruganandam G, Sobott F, Charlier D, Loris R. Toxin:antitoxin ratio sensing autoregulation of the Vibrio cholerae parDE2 module. SCIENCE ADVANCES 2024; 10:eadj2403. [PMID: 38181072 PMCID: PMC10776004 DOI: 10.1126/sciadv.adj2403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 12/04/2023] [Indexed: 01/07/2024]
Abstract
The parDE family of toxin-antitoxin (TA) operons is ubiquitous in bacterial genomes and, in Vibrio cholerae, is an essential component to maintain the presence of chromosome II. Here, we show that transcription of the V. cholerae parDE2 (VcparDE) operon is regulated in a toxin:antitoxin ratio-dependent manner using a molecular mechanism distinct from other type II TA systems. The repressor of the operon is identified as an assembly with a 6:2 stoichiometry with three interacting ParD2 dimers bridged by two ParE2 monomers. This assembly docks to a three-site operator containing 5'- GGTA-3' motifs. Saturation of this TA complex with ParE2 toxin results in disruption of the interface between ParD2 dimers and the formation of a TA complex of 2:2 stoichiometry. The latter is operator binding-incompetent as it is incompatible with the required spacing of the ParD2 dimers on the operator.
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Affiliation(s)
- Gabriela Garcia-Rodriguez
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
- Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, Pleinlaan 2, B-1050 Brussel, Belgium
| | - Yana Girardin
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
- Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, Pleinlaan 2, B-1050 Brussel, Belgium
| | - Ranjan Kumar Singh
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
- Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, Pleinlaan 2, B-1050 Brussel, Belgium
| | - Alexander N. Volkov
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
- Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, Pleinlaan 2, B-1050 Brussel, Belgium
- Jean Jeener NMR Centre, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
| | - Jeroen Van Dyck
- Department of Chemistry, Universiteit Antwerpen, Groenenborgerlaan 171, Antwerpen 2020, Belgium
| | - Gopinath Muruganandam
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
- Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, Pleinlaan 2, B-1050 Brussel, Belgium
| | - Frank Sobott
- Astbury Centre for Structural Molecular Biology and School of Molecular and Cellular Biology, University of Leeds, Leeds LS2 9JT, UK
| | - Daniel Charlier
- Research Group of Microbiology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
| | - Remy Loris
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
- Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, Pleinlaan 2, B-1050 Brussel, Belgium
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6
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Wang X, Kan Y, Bai K, Xu X, Chen X, Yu C, Shi J, Jiang N, Li J, Luo L. A novel double-ribonuclease toxin-antitoxin system linked to the stress response and survival of Acidovorax citrulli. Microbiol Spectr 2023; 11:e0216923. [PMID: 37819152 PMCID: PMC10714953 DOI: 10.1128/spectrum.02169-23] [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: 05/25/2023] [Accepted: 08/30/2023] [Indexed: 10/13/2023] Open
Abstract
IMPORTANCE Bacterial fruit blotch (BFB), which is caused by the seed-borne bacterium Acidovorax citrulli, is a devastating disease affecting cucurbit crops throughout the world. Although seed fermentation and treatment with disinfectants can provide effective management of BFB, they cannot completely guarantee pathogen-free seedstock, which suggests that A. citrulli is a highly stress-resistant pathogen. Toxin-antitoxin (TA) systems are common among a diverse range of bacteria and have been reported to play a role in bacterial stress response. However, there is currently much debate about the relationship between TA systems and stress response in bacteria. The current study characterized a novel TA system (Aave_1720-Aave_1719) from A. citrulli that affects both biofilm formation and survival in response to sodium hypochlorite stress. The mechanism of neutralization differed from typical TA systems as two separate mechanisms were associated with the antitoxin, which exhibited characteristics of both type II and type V TA systems. The Aave_1720-Aave_1719 system described here also constitutes the first known report of a double-ribonuclease TA system in bacteria, which expands our understanding of the range of regulatory mechanisms utilized by bacterial TA systems, providing new insight into the survival of A. citrulli in response to stress.
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Affiliation(s)
- Xudong Wang
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China
- Key Laboratory of Surveillance and Management for Plant Quarantine Pests, Ministry of Agriculture and Rural Affairs, Beijing, China
- Beijing Key Laboratory of Seed Disease Testing and Control, Beijing, China
| | - Yumin Kan
- Department of Biochemistry and Cell Biology, State University of New York, Stony Brook, New York, USA
| | - Kaihong Bai
- School of Life Sciences, Zhengzhou University, Zhengzhou, Henan, China
| | - Xiaoli Xu
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China
- Key Laboratory of Surveillance and Management for Plant Quarantine Pests, Ministry of Agriculture and Rural Affairs, Beijing, China
- Beijing Key Laboratory of Seed Disease Testing and Control, Beijing, China
| | - Xing Chen
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China
- Key Laboratory of Surveillance and Management for Plant Quarantine Pests, Ministry of Agriculture and Rural Affairs, Beijing, China
- Beijing Key Laboratory of Seed Disease Testing and Control, Beijing, China
| | - Chengxuan Yu
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China
- Key Laboratory of Surveillance and Management for Plant Quarantine Pests, Ministry of Agriculture and Rural Affairs, Beijing, China
- Beijing Key Laboratory of Seed Disease Testing and Control, Beijing, China
| | - Jia Shi
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China
- Key Laboratory of Surveillance and Management for Plant Quarantine Pests, Ministry of Agriculture and Rural Affairs, Beijing, China
- Beijing Key Laboratory of Seed Disease Testing and Control, Beijing, China
| | - Na Jiang
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China
- Beijing Key Laboratory of Seed Disease Testing and Control, Beijing, China
| | - Jianqiang Li
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China
- Key Laboratory of Surveillance and Management for Plant Quarantine Pests, Ministry of Agriculture and Rural Affairs, Beijing, China
- Beijing Key Laboratory of Seed Disease Testing and Control, Beijing, China
| | - Laixin Luo
- Department of Plant Pathology, College of Plant Protection, China Agricultural University, Beijing, China
- Key Laboratory of Surveillance and Management for Plant Quarantine Pests, Ministry of Agriculture and Rural Affairs, Beijing, China
- Beijing Key Laboratory of Seed Disease Testing and Control, Beijing, China
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Alvarez Narvaez S, Sanchez S. Exploring the Accessory Genome of Multidrug-Resistant Rhodococcus equi Clone 2287. Antibiotics (Basel) 2023; 12:1631. [PMID: 37998833 PMCID: PMC10669575 DOI: 10.3390/antibiotics12111631] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/15/2023] [Accepted: 11/16/2023] [Indexed: 11/25/2023] Open
Abstract
Decades of antimicrobial overuse to treat respiratory disease in foals have promoted the emergence and spread of zoonotic multidrug-resistant (MDR) Rhodococcus equi worldwide. Three main R. equi MDR clonal populations-2287, G2106, and G2017-have been identified so far. However, only clones 2287 and G2016 have been isolated from sick animals, with clone 2287 being the main MDR R. equi recovered. The genetic mechanisms that make this MDR clone superior to the others at infecting foals are still unknown. Here, we performed a deep genetic characterization of the accessory genomes of 207 R. equi isolates, and we describe IME2287, a novel genetic element in the accessory genome of clone 2287, potentially involved in the maintenance and spread of this MDR population over time. IME2287 is a putative self-replicative integrative mobilizable element (IME) carrying a DNA replication and partitioning operon and genes encoding its excision and integration from the R. equi genome via a serine recombinase. Additionally, IME2287 encodes a protein containing a Toll/interleukin-1 receptor (TIR) domain that may inhibit TLR-mediated NF-kB signaling in the host and a toxin-antitoxin (TA) system, whose orthologs have been associated with antibiotic resistance/tolerance, virulence, pathogenicity islands, bacterial persistence, and pathogen trafficking. This new set of genes may explain the success of clone 2287 over the other MDR R. equi clones.
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Affiliation(s)
- Sonsiray Alvarez Narvaez
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
| | - Susan Sanchez
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602, USA
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8
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Lin JD, Stogios PJ, Abe KT, Wang A, MacPherson J, Skarina T, Gingras AC, Savchenko A, Ensminger AW. Functional diversification despite structural congruence in the HipBST toxin-antitoxin system of Legionella pneumophila. mBio 2023; 14:e0151023. [PMID: 37819088 PMCID: PMC10653801 DOI: 10.1128/mbio.01510-23] [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: 06/16/2023] [Accepted: 08/29/2023] [Indexed: 10/13/2023] Open
Abstract
IMPORTANCE Toxin-antitoxin (TA) systems are parasitic genetic elements found in almost all bacterial genomes. They are exchanged horizontally between cells and are typically poorly conserved across closely related strains and species. Here, we report the characterization of a tripartite TA system in the bacterial pathogen Legionella pneumophila that is highly conserved across Legionella species genomes. This system (denoted HipBSTLp) is a distant homolog of the recently discovered split-HipA system in Escherichia coli (HipBSTEc). We present bioinformatic, molecular, and structural analyses of the divergence between these two systems and the functionality of this newly described TA system family. Furthermore, we provide evidence to refute previous claims that the toxin in this system (HipTLp) possesses bifunctionality as an L. pneumophila virulence protein. Overall, this work expands our understanding of the split-HipA system architecture and illustrates the potential for undiscovered biology in these abundant genetic elements.
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Affiliation(s)
- Jordan D. Lin
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Peter J. Stogios
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Kento T. Abe
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- Lunenfeld-Tanenbaum Research Institute, Sinai Health, Toronto, Ontario, Canada
| | - Avril Wang
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - John MacPherson
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
| | - Tatiana Skarina
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Anne-Claude Gingras
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- Lunenfeld-Tanenbaum Research Institute, Sinai Health, Toronto, Ontario, Canada
| | - Alexei Savchenko
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
- Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta, Canada
- Center for Structural Genomics of Infectious Diseases (CSGID), University of Calgary, Calgary, Alberta, Canada
| | - Alexander W. Ensminger
- Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
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9
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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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10
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Shen Z, Yang XY, Xia S, Huang W, Taylor DJ, Nakanishi K, Fu TM. Oligomerization-mediated activation of a short prokaryotic Argonaute. Nature 2023; 621:154-161. [PMID: 37494956 DOI: 10.1038/s41586-023-06456-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 07/19/2023] [Indexed: 07/28/2023]
Abstract
Although eukaryotic and long prokaryotic Argonaute proteins (pAgos) cleave nucleic acids, some short pAgos lack nuclease activity and hydrolyse NAD(P)+ to induce bacterial cell death1. Here we present a hierarchical activation pathway for SPARTA, a short pAgo consisting of an Argonaute (Ago) protein and TIR-APAZ, an associated protein2. SPARTA progresses through distinct oligomeric forms, including a monomeric apo state, a monomeric RNA-DNA-bound state, two dimeric RNA-DNA-bound states and a tetrameric RNA-DNA-bound active state. These snapshots together identify oligomerization as a mechanistic principle of SPARTA activation. The RNA-DNA-binding channel of apo inactive SPARTA is occupied by an auto-inhibitory motif in TIR-APAZ. After the binding of RNA-DNA, SPARTA transitions from a monomer to a symmetric dimer and then an asymmetric dimer, in which two TIR domains interact through charge and shape complementarity. Next, two dimers assemble into a tetramer with a central TIR cluster responsible for hydrolysing NAD(P)+. In addition, we observe unique features of interactions between SPARTA and RNA-DNA, including competition between the DNA 3' end and the auto-inhibitory motif, interactions between the RNA G2 nucleotide and Ago, and splaying of the RNA-DNA duplex by two loops exclusive to short pAgos. Together, our findings provide a mechanistic basis for the activation of short pAgos, a large section of the Ago superfamily.
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Affiliation(s)
- Zhangfei Shen
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, USA
- Comprehensive Cancer Center and Center for Cancer Metabolism, The Ohio State University, Columbus, OH, USA
| | - Xiao-Yuan Yang
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, USA
- Comprehensive Cancer Center and Center for Cancer Metabolism, The Ohio State University, Columbus, OH, USA
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, USA
| | - Shiyu Xia
- Divison of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Wei Huang
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Derek J Taylor
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH, USA
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Kotaro Nakanishi
- Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH, USA
| | - Tian-Min Fu
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, OH, USA.
- Comprehensive Cancer Center and Center for Cancer Metabolism, The Ohio State University, Columbus, OH, USA.
- The Ohio State Biochemistry Program, The Ohio State University, Columbus, OH, USA.
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11
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Ernits K, Saha CK, Brodiazhenko T, Chouhan B, Shenoy A, Buttress JA, Duque-Pedraza JJ, Bojar V, Nakamoto JA, Kurata T, Egorov AA, Shyrokova L, Johansson MJO, Mets T, Rustamova A, Džigurski J, Tenson T, Garcia-Pino A, Strahl H, Elofsson A, Hauryliuk V, Atkinson GC. The structural basis of hyperpromiscuity in a core combinatorial network of type II toxin-antitoxin and related phage defense systems. Proc Natl Acad Sci U S A 2023; 120:e2305393120. [PMID: 37556498 PMCID: PMC10440598 DOI: 10.1073/pnas.2305393120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Accepted: 07/11/2023] [Indexed: 08/11/2023] Open
Abstract
Toxin-antitoxin (TA) systems are a large group of small genetic modules found in prokaryotes and their mobile genetic elements. Type II TAs are encoded as bicistronic (two-gene) operons that encode two proteins: a toxin and a neutralizing antitoxin. Using our tool NetFlax (standing for Network-FlaGs for toxins and antitoxins), we have performed a large-scale bioinformatic analysis of proteinaceous TAs, revealing interconnected clusters constituting a core network of TA-like gene pairs. To understand the structural basis of toxin neutralization by antitoxins, we have predicted the structures of 3,419 complexes with AlphaFold2. Together with mutagenesis and functional assays, our structural predictions provide insights into the neutralizing mechanism of the hyperpromiscuous Panacea antitoxin domain. In antitoxins composed of standalone Panacea, the domain mediates direct toxin neutralization, while in multidomain antitoxins the neutralization is mediated by other domains, such as PAD1, Phd-C, and ZFD. We hypothesize that Panacea acts as a sensor that regulates TA activation. We have experimentally validated 16 NetFlax TA systems and used domain annotations and metabolic labeling assays to predict their potential mechanisms of toxicity (such as membrane disruption, and inhibition of cell division or protein synthesis) as well as biological functions (such as antiphage defense). We have validated the antiphage activity of a RosmerTA system encoded by Gordonia phage Kita, and used fluorescence microscopy to confirm its predicted membrane-depolarizing activity. The interactive version of the NetFlax TA network that includes structural predictions can be accessed at http://netflax.webflags.se/.
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Affiliation(s)
- Karin Ernits
- Department of Experimental Medicine, Lund University, Lund221 84, Sweden
| | - Chayan Kumar Saha
- Department of Experimental Medicine, Lund University, Lund221 84, Sweden
| | | | - Bhanu Chouhan
- Department of Experimental Medicine, Lund University, Lund221 84, Sweden
- Department of Molecular Biology, Umeå University, Umeå901 87, Sweden
| | - Aditi Shenoy
- Department of Biochemistry and Biophysics and Science for Life Laboratory, Stockholm University, Solna171 21, Sweden
| | - Jessica A. Buttress
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon TyneNE2 4AX, United Kingdom
| | | | - Veda Bojar
- Department of Experimental Medicine, Lund University, Lund221 84, Sweden
| | - Jose A. Nakamoto
- Department of Experimental Medicine, Lund University, Lund221 84, Sweden
| | - Tatsuaki Kurata
- Department of Experimental Medicine, Lund University, Lund221 84, Sweden
| | - Artyom A. Egorov
- Department of Experimental Medicine, Lund University, Lund221 84, Sweden
| | - Lena Shyrokova
- Department of Experimental Medicine, Lund University, Lund221 84, Sweden
| | | | - Toomas Mets
- Department of Experimental Medicine, Lund University, Lund221 84, Sweden
- Institute of Technology, University of Tartu, Tartu50411, Estonia
| | - Aytan Rustamova
- Institute of Technology, University of Tartu, Tartu50411, Estonia
| | | | - Tanel Tenson
- Institute of Technology, University of Tartu, Tartu50411, Estonia
| | - Abel Garcia-Pino
- Cellular and Molecular Microbiology, Faculté des Sciences, Université libre de Bruxelles, Brussels1050, Belgium
| | - Henrik Strahl
- Centre for Bacterial Cell Biology, Biosciences Institute, Newcastle University, Newcastle upon TyneNE2 4AX, United Kingdom
| | - Arne Elofsson
- Department of Biochemistry and Biophysics and Science for Life Laboratory, Stockholm University, Solna171 21, Sweden
| | - Vasili Hauryliuk
- Department of Experimental Medicine, Lund University, Lund221 84, Sweden
- Institute of Technology, University of Tartu, Tartu50411, Estonia
- Science for Life Laboratory, Lund221 84, Sweden
- Lund University Virus Centre, Lund221 84, Sweden
| | - Gemma C. Atkinson
- Department of Experimental Medicine, Lund University, Lund221 84, Sweden
- Lund University Virus Centre, Lund221 84, Sweden
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12
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Riascos C, Martínez-Carrasco A, Díaz M, Santamaría RI. Role of fourteen XRE-DUF397 pairs from Streptomyces coelicolor as regulators of antibiotic production and differentiation. New players in a complex regulatory network. Front Microbiol 2023; 14:1217350. [PMID: 37492264 PMCID: PMC10364602 DOI: 10.3389/fmicb.2023.1217350] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Accepted: 06/19/2023] [Indexed: 07/27/2023] Open
Abstract
Bacteria of the genus Streptomyces have a plethora of transcriptional regulators, among which the xenobiotic response element (XRE) plays an important role. In this organism, XRE regulators are often followed downstream by small proteins of unknown function containing a DUF397 domain. It has been proposed that XRE/DUF397 pairs constitute type II toxin-antitoxin (TA) systems. However, previous work carried out by our group has shown that one of these systems is a strong activator of antibiotic production in S. coelicolor and other Streptomyces species. In this work, we have studied the overexpression of fourteen XRE/DUF397 pairs present in the S. coelicolor genome and found that none behave as a type II TA system. Instead, they act as pleiotropic regulators affecting, in a dependent manner, antibiotic production and morphological differentiation on different culture media. After deleting, individually, six XRE/DUF397 pairs (those systems producing more notable phenotypic changes when overexpressed: SCO2246/45, SCO2253/52, SCO4176/77, SCO4678/79, SCO6236/35, and SCO7615/16), the pair SCO7615/16 was identified as producing the most dramatic differences as compared to the wild-type strain. The SCO7615/16 mutant had a different phenotype on each of the media tested (R2YE, LB, NMMP, YEPD, and MSA). In particular, on R2YE and YEPD media, a bald phenotype was observed even after 7 days, with little or no actinorhodin (ACT) production. Lower ACT production was also observed on LB medium, but the bacteria were able to produce aerial mycelium. On NMMP medium, the mutant produced a larger amount of ACT as compared with the wild-type strain.
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13
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Boss L, Kędzierska B. Bacterial Toxin-Antitoxin Systems' Cross-Interactions-Implications for Practical Use in Medicine and Biotechnology. Toxins (Basel) 2023; 15:380. [PMID: 37368681 DOI: 10.3390/toxins15060380] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2023] [Revised: 05/30/2023] [Accepted: 06/02/2023] [Indexed: 06/29/2023] Open
Abstract
Toxin-antitoxin (TA) systems are widely present in bacterial genomes. They consist of stable toxins and unstable antitoxins that are classified into distinct groups based on their structure and biological activity. TA systems are mostly related to mobile genetic elements and can be easily acquired through horizontal gene transfer. The ubiquity of different homologous and non-homologous TA systems within a single bacterial genome raises questions about their potential cross-interactions. Unspecific cross-talk between toxins and antitoxins of non-cognate modules may unbalance the ratio of the interacting partners and cause an increase in the free toxin level, which can be deleterious to the cell. Moreover, TA systems can be involved in broadly understood molecular networks as transcriptional regulators of other genes' expression or modulators of cellular mRNA stability. In nature, multiple copies of highly similar or identical TA systems are rather infrequent and probably represent a transition stage during evolution to complete insulation or decay of one of them. Nevertheless, several types of cross-interactions have been described in the literature to date. This implies a question of the possibility and consequences of the TA system cross-interactions, especially in the context of the practical application of the TA-based biotechnological and medical strategies, in which such TAs will be used outside their natural context, will be artificially introduced and induced in the new hosts. Thus, in this review, we discuss the prospective challenges of system cross-talks in the safety and effectiveness of TA system usage.
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Affiliation(s)
- Lidia Boss
- Department of Bacterial Molecular Genetics, Faculty of Biology, University of Gdańsk, 80-309 Gdańsk, Poland
| | - Barbara Kędzierska
- Department of Bacterial Molecular Genetics, Faculty of Biology, University of Gdańsk, 80-309 Gdańsk, Poland
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14
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Pisani F, Pisani V, Arcangeli F, Harding A, Singhrao SK. Treponema denticola Has the Potential to Cause Neurodegeneration in the Midbrain via the Periodontal Route of Infection-Narrative Review. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2023; 20:6049. [PMID: 37297653 PMCID: PMC10252855 DOI: 10.3390/ijerph20116049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2023] [Revised: 03/30/2023] [Accepted: 05/29/2023] [Indexed: 06/12/2023]
Abstract
Alzheimer's disease (AD) is a neurodegenerative disease and the most common example of dementia. The neuropathological features of AD are the abnormal deposition of extracellular amyloid-β (Aβ) and intraneuronal neurofibrillary tangles with hyperphosphorylated tau protein. It is recognized that AD starts in the frontal cerebral cortex, and then it progresses to the entorhinal cortex, the hippocampus, and the rest of the brain. However, some studies on animals suggest that AD could also progress in the reverse order starting from the midbrain and then spreading to the frontal cortex. Spirochetes are neurotrophic: From a peripheral route of infection, they can reach the brain via the midbrain. Their direct and indirect effect via the interaction of their virulence factors and the microglia potentially leads to the host peripheral nerve, the midbrain (especially the locus coeruleus), and cortical damage. On this basis, this review aims to discuss the hypothesis of the ability of Treponema denticola to damage the peripheral axons in the periodontal ligament, to evade the complemental pathway and microglial immune response, to determine the cytoskeletal impairment and therefore causing the axonal transport disruption, an altered mitochondrial migration and the consequent neuronal apoptosis. Further insights about the central neurodegeneration mechanism and Treponema denticola's resistance to the immune response when aggregated in biofilm and its quorum sensing are suggested as a pathogenetic model for the advanced stages of AD.
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Affiliation(s)
- Flavio Pisani
- Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston PR1 2HE, UK
| | - Valerio Pisani
- IRCCS, “Santa Lucia” Foundation, Neurology and Neurorehabilitation Unit, Via Ardeatina, 306, 00179 Rome, Italy
| | - Francesca Arcangeli
- Azienda Sanitaria Locale ASLRM1, Nuovo Regina Margherita Hospital, Geriatric Department, Advanced Centre for Dementia and Cognitive Disorders, Via Emilio Morosini, 30, 00153 Rome, Italy
| | - Alice Harding
- Dementia and Neurodegenerative Disease Research Group, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston PR1 2HE, UK
| | - Simarjit Kaur Singhrao
- Dementia and Neurodegenerative Disease Research Group, Faculty of Clinical and Biomedical Sciences, School of Dentistry, University of Central Lancashire, Preston PR1 2HE, UK
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15
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Zhang Y, Song X, Chen C, Liu L, Xu Y, Zhang N, Huang W, Zheng J, Yuan W, Tang L, Lin Z. Structural insights of the toxin-antitoxin system VPA0770-VPA0769 in Vibrio parahaemolyticus. Int J Biol Macromol 2023:124755. [PMID: 37164131 DOI: 10.1016/j.ijbiomac.2023.124755] [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: 02/24/2023] [Revised: 04/13/2023] [Accepted: 05/02/2023] [Indexed: 05/12/2023]
Abstract
Toxin-antitoxin (TA) systems are involved in both normal bacterial physiology and pathogenicity, including gene regulation, antibiotic resistance, and bacteria persistence under stressful environments. In pathogenic Vibrio parahaemolyticus, however, TA interaction and assembly remain largely unknown. In this work, we identified a new RES-Xre type II TA module, encoded by gene cluster vpa0770-vpa0769 on chromosome II of V. parahaemolyticus. Ectopic expression of the VPA0770 toxin rapidly arrests the growth of E. coli cells, which can be neutralized by co-expression of the VPA0769 antitoxin. To decipher the action mechanism, we determined the crystal structure of the VPA0770-VPA0769 TA complex. VPA0770 and VPA0769 proteins can assemble into two types of large complexes, a W-shaped hetero-hexamer and a donut-like hetero-dodecamer, in a concentration-dependent manner in solution. Disruption of the TA interface results in a loss of the antitoxic phenotype. The toxicity of the VPA0770 toxin, which harbors a NAD+-binding pocket, may be largely ascribed to its highly effective capability to degrade intracellular NAD+. Our study provides a structural basis for a better understanding of diverse molecular mechanisms employed by human pathogens.
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Affiliation(s)
- Yan Zhang
- School of Life Sciences, Tianjin University, Tianjin 300073, China
| | - Xiaojie Song
- School of Life Sciences, Tianjin University, Tianjin 300073, China
| | - Cheng Chen
- School of Life Sciences, Tianjin University, Tianjin 300073, China
| | - Lin Liu
- Guangdong Provincial Key Laboratory of Infectious Diseases and Molecular Immunopathology, Shantou University Medical College, Shantou 515041, China
| | - Yangyang Xu
- School of Life Sciences, Tianjin University, Tianjin 300073, China
| | - Ning Zhang
- School of Life Sciences, Tianjin University, Tianjin 300073, China
| | - Weidong Huang
- Department of Biochemistry and Molecular Biology, School of Basic Medicine, Ningxia Medical University, 750004, China
| | - Jun Zheng
- Faculty of Health Sciences, University of Macau, Macao
| | - Wensu Yuan
- School of Life Sciences, Tianjin University, Tianjin 300073, China.
| | - Le Tang
- Guangdong Provincial Key Laboratory of Infectious Diseases and Molecular Immunopathology, Shantou University Medical College, Shantou 515041, China.
| | - Zhi Lin
- School of Life Sciences, Tianjin University, Tianjin 300073, China.
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16
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Chen Y, Li W, Shi K, Fang Z, Yang Y, Zhang R. Isolation and characterization of a novel phage belonging to a new genus against Vibrio parahaemolyticus. Virol J 2023; 20:81. [PMID: 37127579 PMCID: PMC10152775 DOI: 10.1186/s12985-023-02036-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2022] [Accepted: 04/11/2023] [Indexed: 05/03/2023] Open
Abstract
BACKGROUND Vibrio parahaemolyticus is a major foodborne pathogen that contaminates aquatic products and causes great economic losses to aquaculture. Because of the emergence of multidrug-resistant V. parahaemolyticus strains, bacteriophages are considered promising agents for their biocontrol as an alternative or supplement to antibiotics. In this study, a lytic vibriophage, vB_VpaM_R16F (R16F), infecting V. parahaemolyticus 1.1997T was isolated, characterized and evaluated for its biocontrol potential. METHODS A vibriophage R16F was isolated from sewage from a seafood market with the double-layer agar method. R16F was studied by transmission electron microscopy, host range, sensitivity of phage particles to chloroform, one-step growth curve and lytic activity. The phage genome was sequenced and in-depth characterized, including phylogenetic and taxonomic analysis. RESULTS R16F belongs to the myovirus morphotype and infects V. parahaemolyticus, but not nine other Vibrio spp. As characterized by determining its host range, one-step growth curve, and lytic activity, phage R16F was found to highly effective in lysing host cells with a short latent period (< 10 min) and a small burst size (13 plaque-forming units). R16F has a linear double-stranded DNA with genome size 139,011 bp and a G + C content of 35.21%. Phylogenetic and intergenomic nucleotide sequence similarity analysis revealed that R16F is distinct from currently known vibriophages and belongs to a novel genus. Several genes (e.g., encoding ultraviolet damage endonuclease and endolysin) that may enhance environmental competitiveness were found in the genome of R16F, while no antibiotic resistance- or virulence factor-related gene was detected. CONCLUSIONS In consideration of its biological and genetic properties, this newly discovered phage R16F belongs to a novel genus and may be a potential alternate biocontrol agent.
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Affiliation(s)
- Yubing Chen
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, Fujian, China
- China-ASEAN College of Marine Sciences, Xiamen University Malaysia, Sepang, 43900, Selangor, Malaysia
| | - Wenqing Li
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, Fujian, China
- College of Ocean and Earth Sciences, Fujian Key Laboratory of Marine Carbon Sequestration, Xiamen University, Xiamen, 361102, Fujian, China
| | - Keming Shi
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, Fujian, China
- College of Ocean and Earth Sciences, Fujian Key Laboratory of Marine Carbon Sequestration, Xiamen University, Xiamen, 361102, Fujian, China
| | - Zheng Fang
- China-ASEAN College of Marine Sciences, Xiamen University Malaysia, Sepang, 43900, Selangor, Malaysia
| | - Yunlan Yang
- State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361102, Fujian, China.
- College of Ocean and Earth Sciences, Fujian Key Laboratory of Marine Carbon Sequestration, Xiamen University, Xiamen, 361102, Fujian, China.
| | - Rui Zhang
- Institute for Advanced Study, Shenzhen University, Shenzhen, 518061, Guangdong, China.
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17
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Lewis AM, Willard DJ, H. Manesh MJ, Sivabalasarma S, Albers SV, Kelly RM. Stay or Go: Sulfolobales Biofilm Dispersal Is Dependent on a Bifunctional VapB Antitoxin. mBio 2023; 14:e0005323. [PMID: 37036347 PMCID: PMC10127717 DOI: 10.1128/mbio.00053-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Accepted: 03/14/2023] [Indexed: 04/11/2023] Open
Abstract
A type II VapB14 antitoxin regulates biofilm dispersal in the archaeal thermoacidophile Sulfolobus acidocaldarius through traditional toxin neutralization but also through noncanonical transcriptional regulation. Type II VapC toxins are ribonucleases that are neutralized by their proteinaceous cognate type II VapB antitoxin. VapB antitoxins have a flexible tail at their C terminus that covers the toxin's active site, neutralizing its activity. VapB antitoxins also have a DNA-binding domain at their N terminus that allows them to autorepress not only their own promoters but also distal targets. VapB14 antitoxin gene deletion in S. acidocaldarius stunted biofilm and planktonic growth and increased motility structures (archaella). Conversely, planktonic cells were devoid of archaella in the ΔvapC14 cognate toxin mutant. VapB14 is highly conserved at both the nucleotide and amino acid levels across the Sulfolobales, extremely unusual for type II antitoxins, which are typically acquired through horizontal gene transfer. Furthermore, homologs of VapB14 are found across the Crenarchaeota, in some Euryarchaeota, and even bacteria. S. acidocaldarius vapB14 and its homolog in the thermoacidophile Metallosphaera sedula (Msed_0871) were both upregulated in biofilm cells, supporting the role of the antitoxin in biofilm regulation. In several Sulfolobales species, including M. sedula, homologs of vapB14 and vapC14 are not colocalized. Strikingly, Sulfuracidifex tepidarius has an unpaired VapB14 homolog and lacks a cognate VapC14, illustrating the toxin-independent conservation of the VapB14 antitoxin. The findings here suggest that a stand-alone VapB-type antitoxin was the product of selective evolutionary pressure to influence biofilm formation in these archaea, a vital microbial community behavior. IMPORTANCE Biofilms allow microbes to resist a multitude of stresses and stay proximate to vital nutrients. The mechanisms of entering and leaving a biofilm are highly regulated to ensure microbial survival, but are not yet well described in archaea. Here, a VapBC type II toxin-antitoxin system in the thermoacidophilic archaeon Sulfolobus acidocaldarius was shown to control biofilm dispersal through a multifaceted regulation of the archaeal motility structure, the archaellum. The VapC14 toxin degrades an RNA that causes an increase in archaella and swimming. The VapB14 antitoxin decreases archaella and biofilm dispersal by binding the VapC14 toxin and neutralizing its activity, while also repressing the archaellum genes. VapB14-like antitoxins are highly conserved across the Sulfolobales and respond similarly to biofilm growth. In fact, VapB14-like antitoxins are also found in other archaea, and even in bacteria, indicating an evolutionary pressure to maintain this protein and its role in biofilm formation.
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Affiliation(s)
- April M. Lewis
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
| | - Daniel J. Willard
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
| | - Mohamad J. H. Manesh
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
| | - Shamphavi Sivabalasarma
- Institute for Biology, Molecular Biology of Archaea, University of Freiburg, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
| | - Sonja-Verena Albers
- Institute for Biology, Molecular Biology of Archaea, University of Freiburg, Freiburg, Germany
- Spemann Graduate School of Biology and Medicine, University of Freiburg, Freiburg, Germany
- Signalling Research Centres BIOSS and CIBBS, Faculty of Biology, University of Freiburg, Freiburg, Germany
| | - Robert M. Kelly
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina, USA
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18
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Choi W, Maharjan A, Im HG, Park JY, Park JT, Park JH. Identification and Characterization of HEPN-MNT Type II TA System from Methanothermobacter thermautotrophicus ΔH. J Microbiol 2023; 61:411-421. [PMID: 37071293 DOI: 10.1007/s12275-023-00041-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 03/02/2023] [Accepted: 03/06/2023] [Indexed: 04/19/2023]
Abstract
Toxin-antitoxin (TA) systems are widespread in bacteria and archaea plasmids and genomes to regulate DNA replication, gene transcription, or protein translation. Higher eukaryotic and prokaryotic nucleotide-binding (HEPN) and minimal nucleotidyltransferase (MNT) domains are prevalent in prokaryotic genomes and constitute TA pairs. However, three gene pairs (MTH304/305, 408/409, and 463/464) of Methanothermobacter thermautotropicus ΔH HEPN-MNT family have not been studied as TA systems. Among these candidates, our study characterizes the MTH463/MTH464 TA system. MTH463 expression inhibited Escherichia coli growth, whereas MTH464 did not and blocked MTH463 instead. Using site-directed MTH463 mutagenesis, we determined that amino acids R99G, H104A, and Y106A from the R[ɸX]4-6H motif are involved with MTH463 cell toxicity. Furthermore, we established that purified MTH463 could degrade MS2 phage RNA, whereas purified MTH464 neutralized MTH463 activity in vitro. Our results indicate that the endonuclease toxin MTH463 (encoding a HEPN domain) and its cognate antitoxin MTH464 (encoding the MNT domain) may act as a type II TA system in M. thermautotropicus ΔH. This study provides initial and essential information studying TA system functions, primarily archaea HEPN-MNT family.
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Affiliation(s)
- Wonho Choi
- Bio-Evaluation Center, Korea Research Institute of Bioscience and Biotechnology, Cheongju, 28116, Republic of Korea
- 4D Convergence Technology Institute (National Key Technology Institute in University), Korea National University of Transportation, Jungpyeong, 27909, Republic of Korea
| | - Anoth Maharjan
- Bio-Evaluation Center, Korea Research Institute of Bioscience and Biotechnology, Cheongju, 28116, Republic of Korea
| | - Hae Gang Im
- BIORCHESTRA Co., LTD., Daejeon, 34013, Republic of Korea
| | - Ji-Young Park
- Bio-Evaluation Center, Korea Research Institute of Bioscience and Biotechnology, Cheongju, 28116, Republic of Korea
| | - Jong-Tae Park
- Department of Food Science and Technology, Chungnam National University, Daejeon, 34134, Republic of Korea.
| | - Jung-Ho Park
- Bio-Evaluation Center, Korea Research Institute of Bioscience and Biotechnology, Cheongju, 28116, Republic of Korea.
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19
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Sather LM, Zamani M, Muhammed Z, Kearsley JVS, Fisher GT, Jones KM, Finan TM. A broadly distributed predicted helicase/nuclease confers phage resistance via abortive infection. Cell Host Microbe 2023; 31:343-355.e5. [PMID: 36893733 DOI: 10.1016/j.chom.2023.01.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 11/16/2022] [Accepted: 01/11/2023] [Indexed: 03/11/2023]
Abstract
There is strong selection for the evolution of systems that protect bacterial populations from viral attack. We report a single phage defense protein, Hna, that provides protection against diverse phages in Sinorhizobium meliloti, a nitrogen-fixing alpha-proteobacterium. Homologs of Hna are distributed widely across bacterial lineages, and a homologous protein from Escherichia coli also confers phage defense. Hna contains superfamily II helicase motifs at its N terminus and a nuclease motif at its C terminus, with mutagenesis of these motifs inactivating viral defense. Hna variably impacts phage DNA replication but consistently triggers an abortive infection response in which infected cells carrying the system die but do not release phage progeny. A similar host cell response is triggered in cells containing Hna upon expression of a phage-encoded single-stranded DNA binding protein (SSB), independent of phage infection. Thus, we conclude that Hna limits phage spread by initiating abortive infection in response to a phage protein.
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Affiliation(s)
- Leah M Sather
- Department of Biology, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
| | - Maryam Zamani
- Department of Biology, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
| | - Zahed Muhammed
- Department of Biology, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
| | - Jason V S Kearsley
- Department of Biology, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada
| | - Gabrielle T Fisher
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Kathryn M Jones
- Department of Biological Science, Florida State University, Tallahassee, FL 32306, USA
| | - Turlough M Finan
- Department of Biology, McMaster University, 1280 Main St. W., Hamilton, ON L8S 4K1, Canada.
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20
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Vassallo CN, Doering CR, Littlehale ML, Teodoro GIC, Laub MT. A functional selection reveals previously undetected anti-phage defence systems in the E. coli pangenome. Nat Microbiol 2022; 7:1568-1579. [PMID: 36123438 PMCID: PMC9519451 DOI: 10.1038/s41564-022-01219-4] [Citation(s) in RCA: 93] [Impact Index Per Article: 46.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2022] [Accepted: 07/28/2022] [Indexed: 11/09/2022]
Abstract
The ancient, ongoing coevolutionary battle between bacteria and their viruses, bacteriophages, has given rise to sophisticated immune systems including restriction-modification and CRISPR-Cas. Many additional anti-phage systems have been identified using computational approaches based on genomic co-location within defence islands, but these screens may not be exhaustive. Here we developed an experimental selection scheme agnostic to genomic context to identify defence systems in 71 diverse E. coli strains. Our results unveil 21 conserved defence systems, none of which were previously detected as enriched in defence islands. Additionally, our work indicates that intact prophages and mobile genetic elements are primary reservoirs and distributors of defence systems in E. coli, with defence systems typically carried in specific locations or hotspots. These hotspots encode dozens of additional uncharacterized defence system candidates. Our findings reveal an extended landscape of antiviral immunity in E. coli and provide an approach for mapping defence systems in other species.
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Affiliation(s)
| | | | - Megan L Littlehale
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - Michael T Laub
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA.
- Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA, USA.
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21
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Karamycheva S, Wolf YI, Persi E, Koonin EV, Makarova KS. Analysis of lineage-specific protein family variability in prokaryotes combined with evolutionary reconstructions. Biol Direct 2022; 17:22. [PMID: 36042479 PMCID: PMC9425974 DOI: 10.1186/s13062-022-00337-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 08/13/2022] [Indexed: 12/24/2022] Open
Abstract
Background Evolutionary rate is a key characteristic of gene families that is linked to the functional importance of the respective genes as well as specific biological functions of the proteins they encode. Accurate estimation of evolutionary rates is a challenging task that requires precise phylogenetic analysis. Here we present an easy to estimate protein family level measure of sequence variability based on alignment column homogeneity in multiple alignments of protein sequences from Clade-Specific Clusters of Orthologous Genes (csCOGs). Results We report genome-wide estimates of variability for 8 diverse groups of bacteria and archaea and investigate the connection between variability and various genomic and biological features. The variability estimates are based on homogeneity distributions across amino acid sequence alignments and can be obtained for multiple groups of genomes at minimal computational expense. About half of the variance in variability values can be explained by the analyzed features, with the greatest contribution coming from the extent of gene paralogy in the given csCOG. The correlation between variability and paralogy appears to originate, primarily, not from gene duplication, but from acquisition of distant paralogs and xenologs, introducing sequence variants that are more divergent than those that could have evolved in situ during the lifetime of the given group of organisms. Both high-variability and low-variability csCOGs were identified in all functional categories, but as expected, proteins encoded by integrated mobile elements as well as proteins involved in defense functions and cell motility are, on average, more variable than proteins with housekeeping functions. Additionally, using linear discriminant analysis, we found that variability and fraction of genomes carrying a given gene are the two variables that provide the best prediction of gene essentiality as compared to the results of transposon mutagenesis in Sulfolobus islandicus. Conclusions Variability, a measure of sequence diversity within an alignment relative to the overall diversity within a group of organisms, offers a convenient proxy for evolutionary rate estimates and is informative with respect to prediction of functional properties of proteins. In particular, variability is a strong predictor of gene essentiality for the respective organisms and indicative of sub- or neofunctionalization of paralogs. Supplementary Information The online version contains supplementary material available at 10.1186/s13062-022-00337-7.
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Affiliation(s)
- Svetlana Karamycheva
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, 20894, USA
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, 20894, USA
| | - Erez Persi
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, 20894, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, 20894, USA
| | - Kira S Makarova
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD, 20894, USA.
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22
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Merlin TS, Umar M, Puthiyedathu ST. Genomic insights into symbiosis and host adaptation of an ascidian-associated bacterium Bacillus aryabhattai MCCB 387. Symbiosis 2022. [DOI: 10.1007/s13199-022-00860-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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23
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Borreliella burgdorferi Antimicrobial-Tolerant Persistence in Lyme Disease and Posttreatment Lyme Disease Syndromes. mBio 2022; 13:e0344021. [PMID: 35467428 PMCID: PMC9239140 DOI: 10.1128/mbio.03440-21] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The annual incidence of Lyme disease, caused by tick-transmitted Borreliella burgdorferi, is estimated to be at least 476,000 cases in the United States and many more worldwide. Ten to 20% of antimicrobial-treated Lyme disease patients display posttreatment Lyme disease syndrome (PTLDS), a clinical complication whose etiology and pathogenesis remain uncertain. Autoimmunity, cross-reactivity, molecular mimicry, coinfections, and borrelial tolerance to antimicrobials/persistence have been hypothesized and studied as potential causes of PTLDS. Studies of borrelial tolerance/persistence in vitro in response to antimicrobials and experimental studies in mice and nonhuman primates, taken together with clinical reports, have revealed that B. burgdorferi becomes tolerant to antimicrobials and may sometimes persist in animals and humans after the currently recommended antimicrobial treatment. Moreover, B. burgdorferi is pleomorphic and can generate viable-but-nonculturable bacteria, states also involved in antimicrobial tolerance. The multiple regulatory pathways and structural genes involved in mediating this tolerance to antimicrobials and environmental stressors by persistence might include the stringent (rel and dksA) and host adaptation (rpoS) responses, sugar metabolism (glpD), and polypeptide transporters (opp). Application of this recently reported knowledge to clinical studies can be expected to clarify the potential role of bacterial antibacterial tolerance/persistence in Lyme disease and PTLDS.
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24
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Comparative Analysis of Diverse Acetyltransferase-Type Toxin-Antitoxin Loci in Klebsiella pneumoniae. Microbiol Spectr 2022; 10:e0032022. [PMID: 35703555 PMCID: PMC9431474 DOI: 10.1128/spectrum.00320-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Toxin-antitoxin (TA) modules containing a Gcn5-related N-acetyltransferase (GNAT) toxin domain regulate bacterial physiology under adverse environmental stresses. Multiple GNAT-ribbon-helix-helix domain (RHH) TA loci have been identified in single bacterial genomes. However, their diversity and interactions are still obscure. Our previous analysis showed that the GNAT toxin of Klebsiella pneumoniae, KacT, introduces antibiotic tolerance and the toxicity of GNAT is neutralized by KacA, an RHH antitoxin. We here present a phylogenetic analysis of GNAT toxins of more than 1,000 GNAT-RHH pairs detected in completely sequenced K. pneumoniae genomes, revealing that the GNAT toxins are diverse and grouped into four distinct clades. Overexpression of GNAT toxins representative of each of the four clades halts the cell growth of K. pneumoniae, while the coexpression of the cognate RHH antitoxin neutralizes GNAT toxicity. We also identify point mutations that inactivate the GNAT toxins. Moreover, we observe a cross-interaction between GNAT-RHH pairs encoded by different replicons, where a chromosomal toxin (KacT2) can be neutralized by its cognate RHH antitoxin (KacA2 on a chromosome) and another antitoxin (KacA3 on a plasmid). Finally, statistical analysis of the distribution of GNAT-RHH loci in K. pneumoniae strains shows pronounced deviation from random distribution within the same clades. Moreover, we also obtain statistically significant correlations between different clades, which we discuss in terms of the experimental results. IMPORTANCE Elucidating the roles of multifaceted GNAT-RHH TA loci is essential for understanding how these TAs interact among themselves. Recently, the reaction mechanisms and structures of several GNAT-RHH pairs have been reported. While bacterial strains can carry multiple GNAT-RHH loci with diverse origins, studies on the possible cross-interactions of these TA pairs are still limited. Here, we find that 1,000 predicted GNAT toxins of K. pneumoniae can be grouped into four distinct clades. The distributions of TA loci within these clades in K. pneumoniae strains are highly nonrandom, with the presence of a single locus of each clade per strain being highly overrepresented. Moreover, the toxicity of a GNAT toxin encoded by a chromosome was alleviated by a noncognate RHH antitoxin on a plasmid. These results might yield a profound understanding of the widespread GNAT-RHH TA pairs and the cross-interactions between noncognate TA pairs located on different replicons.
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25
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Bikmetov D, Hall AMJ, Livenskyi A, Gollan B, Ovchinnikov S, Gilep K, Kim J, Larrouy-Maumus G, Zgoda V, Borukhov S, Severinov K, Helaine S, Dubiley S. GNAT toxins evolve toward narrow tRNA target specificities. Nucleic Acids Res 2022; 50:5807-5817. [PMID: 35609997 PMCID: PMC9177977 DOI: 10.1093/nar/gkac356] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Revised: 04/10/2022] [Accepted: 05/05/2022] [Indexed: 12/16/2022] Open
Abstract
Type II toxin–antitoxin (TA) systems are two-gene modules widely distributed among prokaryotes. GNAT toxins associated with the DUF1778 antitoxins represent a large family of type II TAs. GNAT toxins inhibit cell growth by disrupting translation via acetylation of aminoacyl-tRNAs. In this work, we explored the evolutionary trajectory of GNAT toxins. Using LC/MS detection of acetylated aminoacyl-tRNAs combined with ribosome profiling, we systematically investigated the in vivo substrate specificity of an array of diverse GNAT toxins. Our functional data show that the majority of GNAT toxins are specific to Gly-tRNA isoacceptors. However, the phylogenetic analysis shows that the ancestor of GNAT toxins was likely a relaxed specificity enzyme capable of acetylating multiple elongator tRNAs. Together, our data provide a remarkable snapshot of the evolution of substrate specificity.
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Affiliation(s)
| | | | - Alexei Livenskyi
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, Moscow 119334, Russia
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119992, Russia
| | - Bridget Gollan
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Stepan Ovchinnikov
- Center for Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia
| | - Konstantin Gilep
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, Moscow 119334, Russia
| | - Jenny Y Kim
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Gerald Larrouy-Maumus
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London SW7 2AZ, UK
| | - Viktor Zgoda
- Institute of Biomedical Chemistry, Moscow 119435, Russia
| | - Sergei Borukhov
- Department of Cell Biology and Neuroscience, Rowan University School of Osteopathic Medicine, Stratford, NJ 08084-1489, USA
| | | | | | - Svetlana Dubiley
- To whom correspondence should be addressed. Tel: +7 499 135 6089;
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26
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Chattopadhyay G, Bhasin M, Ahmed S, Gosain TP, Ganesan S, Das S, Thakur C, Chandra N, Singh R, Varadarajan R. Functional and Biochemical Characterization of the MazEF6 Toxin-Antitoxin System of Mycobacterium tuberculosis. J Bacteriol 2022; 204:e0005822. [PMID: 35357163 PMCID: PMC9053165 DOI: 10.1128/jb.00058-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 03/07/2022] [Indexed: 12/15/2022] Open
Abstract
The Mycobacterium tuberculosis genome harbors nine toxin-antitoxin (TA) systems that are members of the mazEF family, unlike other prokaryotes, which have only one or two. Although the overall tertiary folds of MazF toxins are predicted to be similar, it is unclear how they recognize structurally different RNAs and antitoxins with divergent sequence specificity. Here, we have expressed and purified the individual components and complex of the MazEF6 TA system from M. tuberculosis. Size exclusion chromatography-multiangle light scattering (SEC-MALS) was performed to determine the oligomerization status of the toxin, antitoxin, and the complex in different stoichiometric ratios. The relative stabilities of the proteins were determined by nano-differential scanning fluorimetry (nano-DSF). Microscale thermophoresis (MST) and yeast surface display (YSD) were performed to measure the relative affinities between the cognate toxin-antitoxin partners. The interaction between MazEF6 complexes and cognate promoter DNA was also studied using MST. Analysis of paired-end RNA sequencing data revealed that the overexpression of MazF6 resulted in differential expression of 323 transcripts in M. tuberculosis. Network analysis was performed to identify the nodes from the top-response network. The analysis of mRNA protection ratios resulted in identification of putative MazF6 cleavage site in its native host, M. tuberculosis. IMPORTANCE M. tuberculosis harbors a large number of type II toxin-antitoxin (TA) systems, the exact roles for most of which are unclear. Prior studies have reported that overexpression of several of these type II toxins inhibits bacterial growth and contributes to the formation of drug-tolerant populations in vitro. To obtain insights into M. tuberculosis MazEF6 type II TA system function, we determined stability, oligomeric states, and binding affinities of cognate partners with each other and with their promoter operator DNA. Using RNA-seq data obtained from M. tuberculosis overexpression strains, we have identified putative MazF6 cleavage sites and targets in its native, cellular context.
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Affiliation(s)
| | - Munmun Bhasin
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | - Shahbaz Ahmed
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
| | - Tannu Priya Gosain
- Tuberculosis Research Laboratory, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana, India
| | - Srivarshini Ganesan
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, Tamil Nadu, India
| | - Sayan Das
- Tuberculosis Research Laboratory, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana, India
| | - Chandrani Thakur
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | - Nagasuma Chandra
- Department of Biochemistry, Indian Institute of Science, Bangalore, Karnataka, India
| | - Ramandeep Singh
- Tuberculosis Research Laboratory, Translational Health Science and Technology Institute, NCR Biotech Science Cluster, Faridabad, Haryana, India
| | - Raghavan Varadarajan
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, Karnataka, India
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27
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Abstract
Toxin-antitoxin (TA) systems are ubiquitous genetic elements in bacteria that consist of a growth-inhibiting toxin and its cognate antitoxin. These systems are prevalent in bacterial chromosomes, plasmids, and phage genomes, but individual systems are not highly conserved, even among closely related strains. The biological functions of TA systems have been controversial and enigmatic, although a handful of these systems have been shown to defend bacteria against their viral predators, bacteriophages. Additionally, their patterns of conservation-ubiquitous, but rapidly acquired and lost from genomes-as well as the co-occurrence of some TA systems with known phage defense elements are suggestive of a broader role in mediating phage defense. Here, we review the existing evidence for phage defense mediated by TA systems, highlighting how toxins are activated by phage infection and how toxins disrupt phage replication. We also discuss phage-encoded systems that counteract TA systems, underscoring the ongoing coevolutionary battle between bacteria and phage. We anticipate that TA systems will continue to emerge as central players in the innate immunity of bacteria against phage. Expected final online publication date for the Annual Review of Microbiology, Volume 76 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Michele LeRoux
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA;
| | - Michael T Laub
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA; .,Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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28
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Benler S, Koonin EV. Recruitment of Mobile Genetic Elements for Diverse Cellular Functions in Prokaryotes. Front Mol Biosci 2022; 9:821197. [PMID: 35402511 PMCID: PMC8987985 DOI: 10.3389/fmolb.2022.821197] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 02/08/2022] [Indexed: 12/15/2022] Open
Abstract
Prokaryotic genomes are replete with mobile genetic elements (MGE) that span a continuum of replication autonomy. On numerous occasions during microbial evolution, diverse MGE lose their autonomy altogether but, rather than being quickly purged from the host genome, assume a new function that benefits the host, rendering the immobilized MGE subject to purifying selection, and resulting in its vertical inheritance. This mini-review highlights the diversity of the repurposed (exapted) MGE as well as the plethora of cellular functions that they perform. The principal contribution of the exaptation of MGE and their components is to the prokaryotic functional systems involved in biological conflicts, and in particular, defense against viruses and other MGE. This evolutionary entanglement between MGE and defense systems appears to stem both from mechanistic similarities and from similar evolutionary predicaments whereby both MGEs and defense systems tend to incur fitness costs to the hosts and thereby evolve mechanisms for survival including horizontal mobility, causing host addiction, and exaptation for functions beneficial to the host. The examples discussed demonstrate that the identity of an MGE, overall mobility and relationship with the host cell (mutualistic, symbiotic, commensal, or parasitic) are all factors that affect exaptation.
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29
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Cao H, Xu D, Zhang T, Ren Q, Xiang L, Ning C, Zhang Y, Gao R. Comprehensive and functional analyses reveal the genomic diversity and potential toxicity of Microcystis. HARMFUL ALGAE 2022; 113:102186. [PMID: 35287927 DOI: 10.1016/j.hal.2022.102186] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Revised: 01/11/2022] [Accepted: 01/12/2022] [Indexed: 06/14/2023]
Abstract
Microcystis is a cyanobacteria that is widely distributed across the world. It has attracted great attention because it produces the hepatotoxin microcystin (MC) that can inhibit eukaryotic protein phosphatases and pose a great risk to animal and human health. Due to the high diversity of morphospecies and genomes, it is still difficult to classify Microcystis species. In this study, we investigated the pangenome of 23 Microcystis strains to detect the genetic diversity and evolutionary dynamics. Microcystis revealed an open pangenome containing 22,009 gene families and exhibited different functional constraints. The core-genome phylogenetic analysis accurately differentiated the toxic and nontoxic strains and could be used as a taxonomic standard at the genetic level. We also investigated the functions of HGT events, of which were mostly conferred from cyanobacteria and closely related species. In order to detect the potential toxicity of Microcystis, we searched and characterized MC biosynthetic gene clusters and other secondary metabolite gene clusters. Our work provides insights into the genetic diversity, evolutionary dynamics, and potential toxicity of Microcystis, which could benefit the species classification and development of new methods for drinking water quality control and management of bloom formation in the future.
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Affiliation(s)
- Hengchun Cao
- School of Mathematics and Statistics, Shandong University, Weihai, 264209, Shandong, China
| | - Da Xu
- School of Mathematics and Statistics, Shandong University, Weihai, 264209, Shandong, China
| | - Tiantian Zhang
- School of Mathematics and Statistics, Shandong University, Weihai, 264209, Shandong, China
| | - Qiufang Ren
- School of Mathematics and Statistics, Shandong University, Weihai, 264209, Shandong, China
| | - Li Xiang
- School of Mathematics and Statistics, Shandong University, Weihai, 264209, Shandong, China
| | - Chunhui Ning
- School of Mathematics and Statistics, Shandong University, Weihai, 264209, Shandong, China
| | - Yusen Zhang
- School of Mathematics and Statistics, Shandong University, Weihai, 264209, Shandong, China.
| | - Rui Gao
- School of Control Science and Engineering, Shandong University, Jinan 250061, Shandong, China.
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30
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Johansen J, Plichta DR, Nissen JN, Jespersen ML, Shah SA, Deng L, Stokholm J, Bisgaard H, Nielsen DS, Sørensen SJ, Rasmussen S. Genome binning of viral entities from bulk metagenomics data. Nat Commun 2022; 13:965. [PMID: 35181661 PMCID: PMC8857322 DOI: 10.1038/s41467-022-28581-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2021] [Accepted: 01/28/2022] [Indexed: 12/26/2022] Open
Abstract
Despite the accelerating number of uncultivated virus sequences discovered in metagenomics and their apparent importance for health and disease, the human gut virome and its interactions with bacteria in the gastrointestinal tract are not well understood. This is partly due to a paucity of whole-virome datasets and limitations in current approaches for identifying viral sequences in metagenomics data. Here, combining a deep-learning based metagenomics binning algorithm with paired metagenome and metavirome datasets, we develop Phages from Metagenomics Binning (PHAMB), an approach that allows the binning of thousands of viral genomes directly from bulk metagenomics data, while simultaneously enabling clustering of viral genomes into accurate taxonomic viral populations. When applied on the Human Microbiome Project 2 (HMP2) dataset, PHAMB recovered 6,077 high-quality genomes from 1,024 viral populations, and identified viral-microbial host interactions. PHAMB can be advantageously applied to existing and future metagenomes to illuminate viral ecological dynamics with other microbiome constituents.
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Affiliation(s)
- Joachim Johansen
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Damian R Plichta
- Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Jakob Nybo Nissen
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Statens Serum Institut, Viral & Microbial Special diagnostics, Copenhagen, Denmark
| | - Marie Louise Jespersen
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,National Food Institute, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Shiraz A Shah
- Copenhagen Prospective Studies on Asthma in Childhood (COPSAC), Herlev and Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Ling Deng
- Section of Food Microbiology and Fermentation, Department of Food Science, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Jakob Stokholm
- Copenhagen Prospective Studies on Asthma in Childhood (COPSAC), Herlev and Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark.,Section of Food Microbiology and Fermentation, Department of Food Science, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Hans Bisgaard
- Copenhagen Prospective Studies on Asthma in Childhood (COPSAC), Herlev and Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark
| | - Dennis Sandris Nielsen
- Section of Food Microbiology and Fermentation, Department of Food Science, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Søren J Sørensen
- Section of Microbiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Simon Rasmussen
- Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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31
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A hyperpromiscuous antitoxin protein domain for the neutralization of diverse toxin domains. Proc Natl Acad Sci U S A 2022; 119:2102212119. [PMID: 35121656 PMCID: PMC8832971 DOI: 10.1073/pnas.2102212119] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/02/2021] [Indexed: 12/20/2022] Open
Abstract
Toxin–antitoxin systems are enigmatic and diverse elements of bacterial and bacteriophage genomes. We have uncovered remarkable versatility in an antitoxin protein domain that has evolved to neutralize dozens of different toxin domains. We find that antitoxins carrying this domain—Panacea—form complexes with their cognate toxins, indicating a direct neutralization mechanism, and that Panacea can be evolved to neutralize a noncognate and nonhomologous toxin with just two amino acid substitutions. This raises the possibility that this domain could be an adaptable universal or semi-universal protein neutralizer with significant biotechnological and medical potential. Toxin–antitoxin (TA) gene pairs are ubiquitous in microbial chromosomal genomes and plasmids as well as temperate bacteriophages. They act as regulatory switches, with the toxin limiting the growth of bacteria and archaea by compromising diverse essential cellular targets and the antitoxin counteracting the toxic effect. To uncover previously uncharted TA diversity across microbes and bacteriophages, we analyzed the conservation of genomic neighborhoods using our computational tool FlaGs (for flanking genes), which allows high-throughput detection of TA-like operons. Focusing on the widespread but poorly experimentally characterized antitoxin domain DUF4065, our in silico analyses indicated that DUF4065-containing proteins serve as broadly distributed antitoxin components in putative TA-like operons with dozens of different toxic domains with multiple different folds. Given the versatility of DUF4065, we have named the domain Panacea (and proteins containing the domain, PanA) after the Greek goddess of universal remedy. We have experimentally validated nine PanA-neutralized TA pairs. While the majority of validated PanA-neutralized toxins act as translation inhibitors or membrane disruptors, a putative nucleotide cyclase toxin from a Burkholderia prophage compromises transcription and translation as well as inducing RelA-dependent accumulation of the nucleotide alarmone (p)ppGpp. We find that Panacea-containing antitoxins form a complex with their diverse cognate toxins, characteristic of the direct neutralization mechanisms employed by Type II TA systems. Finally, through directed evolution, we have selected PanA variants that can neutralize noncognate TA toxins, thus experimentally demonstrating the evolutionary plasticity of this hyperpromiscuous antitoxin domain.
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32
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Marzhoseyni Z, Shojaie L, Tabatabaei SA, Movahedpour A, Safari M, Esmaeili D, Mahjoubin-Tehran M, Jalili A, Morshedi K, Khan H, Okhravi R, Hamblin MR, Mirzaei H. Streptococcal bacterial components in cancer therapy. Cancer Gene Ther 2022; 29:141-155. [PMID: 33753868 DOI: 10.1038/s41417-021-00308-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Revised: 01/25/2021] [Accepted: 02/05/2021] [Indexed: 02/01/2023]
Abstract
The incidence rate of cancer is steadily increasing all around the world, and there is an urgent need to develop novel and more effective treatment strategies. Recently, bacterial therapy has been investigated as a new approach to target cancer, and is becoming a serious option. Streptococcus strains are among the most common and well-studied virulent bacteria that cause a variety of human infections. Everyone has experienced a sore throat during their lifetime, or has been asymptomatically colonized by streptococci. The ability of Streptococcus bacteria to fight cancer was discovered more than 100 years ago, and over the years has undergone clinical trials, but the mechanism is not yet completely understood. Recently, several animal models and human clinical trials have been reported. Streptococcal strains can have an intrinsic anti-tumor activity, or can activate the host immune system to fight the tumor. Bacteria can selectively accumulate and proliferate in the hypoxic regions of solid tumors. Moreover, the bacteria can be genetically engineered to secrete toxins or enzymes that can specifically attack the tumors.
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Affiliation(s)
- Zeynab Marzhoseyni
- Department of Microbiology and Immunology, Faculty of Medicine, Kashan University of Medical Sciences, Kashan, Iran
| | - Layla Shojaie
- Research Center for Liver Diseases, Keck School of Medicine, Department of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Seyed Alireza Tabatabaei
- Department of Internal Medicine, School of Medicine, Shahid Beheshti University of Medical Science, Tehran, Iran
| | - Ahmad Movahedpour
- Department of Medical Biotechnology, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mahmood Safari
- Department of Microbiology and Immunology, Faculty of Medicine, Kashan University of Medical Sciences, Kashan, Iran
| | - Davoud Esmaeili
- Department of Microbiology and Applied Microbiology Research Center, Systems Biology and Poisonings Institute and Department of Microbiology, Baqiyatallah University of Medical Sciences, Tehran, Iran
| | - Maryam Mahjoubin-Tehran
- Department of Medical Biotechnology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Amin Jalili
- Department of Medical Biotechnology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Korosh Morshedi
- School of Medicine, Kashan University of Medical Sciences, Kashan, Iran
| | - Haroon Khan
- Department of Pharmacy, Abdul Wali Khan University Mardan, Mardan, 23200, Pakistan
| | - Ranaa Okhravi
- Department of Medical Sciences, Shahrood Branch, Islamic Azad University, Shahrood, Iran.
| | - Michael R Hamblin
- Laser Research Centre, Faculty of Health Science, University of Johannesburg, Doornfontein, 2028, South Africa.
| | - Hamed Mirzaei
- Research Center for Biochemistry and Nutrition in Metabolic Diseases, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran.
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Abstract
Toxin-antitoxin systems are widespread in bacterial genomes. They are usually composed of two elements: a toxin that inhibits an essential cellular process and an antitoxin that counteracts its cognate toxin. In the past decade, a number of new toxin-antitoxin systems have been described, bringing new growth inhibition mechanisms to light as well as novel modes of antitoxicity. However, recent advances in the field profoundly questioned the role of these systems in bacterial physiology, stress response and antimicrobial persistence. This shifted the paradigm of the functions of toxin-antitoxin systems to roles related to interactions between hosts and their mobile genetic elements, such as viral defence or plasmid stability. In this Review, we summarize the recent progress in understanding the biology and evolution of these small genetic elements, and discuss how genomic conflicts could shape the diversification of toxin-antitoxin systems.
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Cargo Genes of Tn 7-Like Transposons Comprise an Enormous Diversity of Defense Systems, Mobile Genetic Elements, and Antibiotic Resistance Genes. mBio 2021; 12:e0293821. [PMID: 34872347 PMCID: PMC8649781 DOI: 10.1128/mbio.02938-21] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Transposition is a major mechanism of horizontal gene mobility in prokaryotes. However, exploration of the genes mobilized by transposons (cargo) is hampered by the difficulty in delineating integrated transposons from their surrounding genetic context. Here, we present a computational approach that allowed us to identify the boundaries of 6,549 Tn7-like transposons. We found that 96% of these transposons carry at least one cargo gene. Delineation of distinct communities in a gene-sharing network demonstrates how transposons function as a conduit of genes between phylogenetically distant hosts. Comparative analysis of the cargo genes reveals significant enrichment of mobile genetic elements (MGEs) nested within Tn7-like transposons, such as insertion sequences and toxin-antitoxin modules, and of genes involved in recombination, anti-MGE defense, and antibiotic resistance. More unexpectedly, cargo also includes genes encoding central carbon metabolism enzymes. Twenty-two Tn7-like transposons carry both an anti-MGE defense system and antibiotic resistance genes, illustrating how bacteria can overcome these combined pressures upon acquisition of a single transposon. This work substantially expands the distribution of Tn7-like transposons, defines their evolutionary relationships, and provides a large-scale functional classification of prokaryotic genes mobilized by transposition.
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Minigene as a Novel Regulatory Element in Toxin-Antitoxin Systems. Int J Mol Sci 2021; 22:ijms222413389. [PMID: 34948189 PMCID: PMC8708949 DOI: 10.3390/ijms222413389] [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: 11/16/2021] [Revised: 12/08/2021] [Accepted: 12/09/2021] [Indexed: 12/05/2022] Open
Abstract
The axe-txe type II toxin-antitoxin (TA) system is characterized by a complex and multilayered mode of gene expression regulation. Precise and tight control of this process is crucial to keep the toxin in an appropriate balance with the cognate antitoxin until its activation is needed for the cell. In this report, we provide evidence that a minigene encoded within the axe-txe operon influences translation of the Txe toxin. This is the first example to date of such a regulatory mechanism identified in the TA modules. Here, in a series of genetic studies, we employed translational reporter gene fusions to establish the molecular basis of this phenomenon. Our results show that translation of the two-codon mini-ORF displays an in cis mode of action, and positively affects the expression of txe, possibly by increasing its mRNA stability through protection from an endonuclease attack. Moreover, we established that the reading frame in which the two cistrons are encoded, as well as the distance between them, are critical parameters that affect the level of such regulation. In addition, by searching for two-codon ORFs we found sequences of several potential minigenes in the leader sequences of several other toxins belonging to the type II TA family. These findings suggest that this type of gene regulation may not only apply for the axe-txe cassette, but could be more widespread among other TA systems.
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Tamiya-Ishitsuka H, Tsuruga M, Noda N, Yokota A. Conserved Amino Acid Moieties of Candidatus Desulforudis audaxviator MazF Determine Ribonuclease Activity and Specificity. Front Microbiol 2021; 12:748619. [PMID: 34867867 PMCID: PMC8634880 DOI: 10.3389/fmicb.2021.748619] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 10/21/2021] [Indexed: 11/17/2022] Open
Abstract
The toxin-antitoxin (TA) system, inherent to various prokaryotes, plays a critical role in survival and adaptation to diverse environmental stresses. The toxin MazF, belonging to the type II TA system, functions as a sequence-specific ribonuclease that recognizes 3 to 7 bases. In recent studies, crystallographic analysis of MazFs from several species have suggested the presence of amino acid sites important for MazF substrate RNA binding and for its catalytic activity. Herein, we characterized MazF obtained from Candidatus Desulforudis audaxviator (MazF-Da) and identified the amino acid residues necessary for its catalytic function. MazF-Da, expressed using a cell-free protein synthesis system, is a six-base-recognition-specific ribonuclease that preferentially cleaves UACAAA sequences and weakly cleaves UACGAA and UACUAA sequences. We found that MazF-Da exhibited the highest activity at around 60°C. Analysis using mutants with a single mutation at an amino acid residue site that is well conserved across various MazF toxins showed that G18, E20, R25, and P26 were important for the ribonuclease activity of MazF-Da. The recognition sequence of the N36A mutant differed from that of the wild type. This mutant cleaved UACAAG sequences in addition to UACAAA sequences, but did not cleave UACGAA or UACUAA sequences, suggesting that Asn36 affects the loosening and narrowing of MazF-Da cleavage sequence recognition. Our study posits UACAAA as the recognition sequence of MazF-Da and provides insight into the amino acid sites that are key to its unique enzymatic properties.
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Affiliation(s)
- Hiroko Tamiya-Ishitsuka
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Masako Tsuruga
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Naohiro Noda
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Akiko Yokota
- Biomedical Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
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Takashima A, Kawano H, Ueda T, Suzuki-Minakuchi C, Okada K, Nojiri H. A toxin-antitoxin system confers stability to the IncP-7 plasmid pCAR1. Gene 2021; 812:146068. [PMID: 34838639 DOI: 10.1016/j.gene.2021.146068] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 10/01/2021] [Accepted: 11/16/2021] [Indexed: 11/28/2022]
Abstract
Toxin-antitoxin (TA) systems were initially discovered as plasmid addiction systems. Previously, our studies implied that the high stability of the IncP-7 plasmid pCAR1 in different Pseudomonas spp. hosts was due to the presence of a TA system on the plasmid. Bioinformatics approaches suggested that ORF174 and ORF175 could constitute a type II TA system, a member of the RES-Xre family, and that these two open reading frames (ORFs) constitute a single operon. As expected, the ORF175 product is a toxin, which decreases the viability of the host, P. resinovorans, while the ORF174 product functions as an antitoxin that counteracts the effect of ORF175 on cell growth. Based on these findings, we renamed ORF174 and ORF175 as prcA (antitoxin gene) and prcT (toxin gene), respectively. The prcA and prcT genes were cloned into the unstable plasmid vector pSEVA644. The recombinant vector was stably maintained in P. resinovorans and Escherichia coli cells under nonselective conditions following 6 days of daily subculturing. The empty vector (without the prcA and prcT genes) could not be maintained, which suggested that the PrcA/T system can be used as a tool to improve the stability of otherwise unstable plasmids in P. resinovorans and E. coli strains.
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Affiliation(s)
- Aya Takashima
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Hibiki Kawano
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Tomomi Ueda
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Chiho Suzuki-Minakuchi
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Kazunori Okada
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Hideaki Nojiri
- Agro-Biotechnology Research Center, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
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38
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Douglas GM, Shapiro BJ. Genic Selection Within Prokaryotic Pangenomes. Genome Biol Evol 2021; 13:6402011. [PMID: 34665261 PMCID: PMC8598171 DOI: 10.1093/gbe/evab234] [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] [Accepted: 10/14/2021] [Indexed: 11/13/2022] Open
Abstract
Understanding the evolutionary forces shaping prokaryotic pangenome structure is a major goal of microbial evolution research. Recent work has highlighted that a substantial proportion of accessory genes appear to confer niche-specific adaptations. This work has primarily focused on selection acting at the level of individual cells. Herein, we discuss a lower level of selection that also contributes to pangenome variation: genic selection. This refers to cases where genetic elements, rather than individual cells, are the entities under selection. The clearest examples of this form of selection are selfish mobile genetic elements, which are those that have either a neutral or a deleterious effect on host fitness. We review the major classes of these and other mobile elements and discuss the characteristic features of such elements that could be under genic selection. We also discuss how genetic elements that are beneficial to hosts can also be under genic selection, a scenario that may be more prevalent but not widely appreciated, because disentangling the effects of selection at different levels (i.e., organisms vs. genes) is challenging. Nonetheless, an appreciation for the potential action and implications of genic selection is important to better understand the evolution of prokaryotic pangenomes.
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Affiliation(s)
- Gavin M Douglas
- Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada
| | - B Jesse Shapiro
- Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada
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Identification of Type II Toxin-Antitoxin Loci in Levilactobacillus brevis. Interdiscip Sci 2021; 14:80-88. [PMID: 34664198 DOI: 10.1007/s12539-021-00486-9] [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: 07/13/2021] [Revised: 09/30/2021] [Accepted: 10/05/2021] [Indexed: 10/20/2022]
Abstract
Levilactobacillus brevis are present in various environments, such as beer, fermented foods, silage, and animal host. Like other lactic acid bacteria, L. brevis might adopt the viable but nonculturable (VBNC) state under unfavorable conditions. The toxin-antitoxin (TA) system, known to regulate cell growth in response to environmental stresses, is found to control the dynamic of the VBNC state. Here, we investigate the type II TA locus prevalence and compare the TA diversity in L. brevis genomes. Using the TAfinder software, we identified a total of 273 putative type II TA loci in 110 replicons of 21 completely sequenced genomes. Genome size does not appear to correlate with the amount of putative type II TA in L. brevis. Besides, type II TA loci are distributed differently among the chromosomes and plasmids. The most prevalent toxin domain is MazF-like in the chromosomes, and RelE/RelE-like in the plasmids; while for antitoxin, Xre-like and Phd-like domains are the most common in the chromosomes and plasmids, respectively. We also observed a unique GNAT-like/ArsR-like TA pair that presents only in the L. brevis chromosome. Detection of 273 putative type II TA loci in 21 complete genomes of Levilactobacillus brevis.
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40
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Moradkasani S, Kouhsari E, Jazi FM, Kalani BS, Pakzad I. Evaluation of Putative Toxin-antitoxins Systems in Clinical Brucella melitensis in Iran. Infect Disord Drug Targets 2021; 21:38-42. [PMID: 31957618 DOI: 10.2174/1871526520666200117113420] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 12/02/2019] [Accepted: 12/26/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND Toxin-antitoxin systems (TAs) are two-component elements, which are extensive in the bacterial genome and have a regulatory role in many cellular activities including, growth arrest, survival, biofilm formation, and bacterial persistence. OBJECTIVE TAs have not well studied in Brucella spp. METHODS We evaluated the presence of different toxin-antitoxin systems, including relE- rhhlike, Fic- Phd, Cog- Rhh, and cogT- cogAT in 40 clinical Brucella melitensis isolates using PCRbased sequencing assay. RESULTS Our results showed the high presence of relE-rhh-like, Fic-Phd, Cog-rhh, and cogTcogAT s TAs genes in B. melitensis isolates that were 96.25%, 92.5%, 96.25%, and 95%, respectively. CONCLUSION A high presence of TAs genes in clinical B. melitensis isolates revealed that the TA system could be an antibacterial target in B. melitensis but more investigation is necessitated to elucidate the exact roles of these genes.
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Affiliation(s)
- Safoura Moradkasani
- Department of Medical Microbiology, Faculty of Medicine, Ilam University of Medical Sciences, Ilam, Iran
| | - Ebrahim Kouhsari
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran
| | - Faramarz Masjedian Jazi
- Department of Microbiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | | | - Iraj Pakzad
- Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran
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41
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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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42
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Vaid RK, Thakur Z, Anand T, Kumar S, Tripathi BN. Comparative genome analysis of Salmonella enterica serovar Gallinarum biovars Pullorum and Gallinarum decodes strain specific genes. PLoS One 2021; 16:e0255612. [PMID: 34411120 PMCID: PMC8375982 DOI: 10.1371/journal.pone.0255612] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 07/19/2021] [Indexed: 12/27/2022] Open
Abstract
Salmonella enterica serovar Gallinarum biovar Pullorum (bvP) and biovar Gallinarum (bvG) are the etiological agents of pullorum disease (PD) and fowl typhoid (FT) respectively, which cause huge economic losses to poultry industry especially in developing countries including India. Vaccination and biosecurity measures are currently being employed to control and reduce the S. Gallinarum infections. High endemicity, poor implementation of hygiene and lack of effective vaccines pose challenges in prevention and control of disease in intensively maintained poultry flocks. Comparative genome analysis unravels similarities and dissimilarities thus facilitating identification of genomic features that aids in pathogenesis, niche adaptation and in tracing of evolutionary history. The present investigation was carried out to assess the genotypic differences amongst S.enterica serovar Gallinarum strains including Indian strain S. Gallinarum Sal40 VTCCBAA614. The comparative genome analysis revealed an open pan-genome consisting of 5091 coding sequence (CDS) with 3270 CDS belonging to core-genome, 1254 CDS to dispensable genome and strain specific genes i.e. singletons ranging from 3 to 102 amongst the analyzed strains. Moreover, the investigated strains exhibited diversity in genomic features such as virulence factors, genomic islands, prophage regions, toxin-antitoxin cassettes, and acquired antimicrobial resistance genes. Core genome identified in the study can give important leads in the direction of design of rapid and reliable diagnostics, and vaccine design for effective infection control as well as eradication. Additionally, the identified genetic differences among the S. enterica serovar Gallinarum strains could be used for bacterial typing, structure based inhibitor development by future experimental investigations on the data generated.
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Affiliation(s)
- Rajesh Kumar Vaid
- Bacteriology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana, India
| | - Zoozeal Thakur
- Bacteriology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana, India
| | - Taruna Anand
- Bacteriology Laboratory, National Centre for Veterinary Type Cultures, ICAR-National Research Centre on Equines, Hisar, Haryana, India
| | - Sanjay Kumar
- Bacteriology Laboratory, ICAR-National Research Centre on Equines, Hisar, Haryana, India
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43
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Garcia-Rodriguez G, Charlier D, Wilmaerts D, Michiels J, Loris R. Alternative dimerization is required for activity and inhibition of the HEPN ribonuclease RnlA. Nucleic Acids Res 2021; 49:7164-7178. [PMID: 34139012 PMCID: PMC8266594 DOI: 10.1093/nar/gkab513] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 05/09/2021] [Accepted: 06/03/2021] [Indexed: 11/14/2022] Open
Abstract
The rnlAB toxin-antitoxin operon from Escherichia coli functions as an anti-phage defense system. RnlA was identified as a member of the HEPN (Higher Eukaryotes and Prokaryotes Nucleotide-binding domain) superfamily of ribonucleases. The activity of the toxin RnlA requires tight regulation by the antitoxin RnlB, the mechanism of which remains unknown. Here we show that RnlA exists in an equilibrium between two different homodimer states: an inactive resting state and an active canonical HEPN dimer. Mutants interfering with the transition between states show that canonical HEPN dimerization via the highly conserved RX4-6H motif is required for activity. The antitoxin RnlB binds the canonical HEPN dimer conformation, inhibiting RnlA by blocking access to its active site. Single-alanine substitutions mutants of the highly conserved R255, E258, R318 and H323 show that these residues are involved in catalysis and substrate binding and locate the catalytic site near the dimer interface of the canonical HEPN dimer rather than in a groove located between the HEPN domain and the preceding TBP-like domain. Overall, these findings elucidate the structural basis of the activity and inhibition of RnlA and highlight the crucial role of conformational heterogeneity in protein function.
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Affiliation(s)
- Gabriela Garcia-Rodriguez
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, B-1050 Brussel, Belgium
- Molecular Recognition Unit, Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, B-1050 Brussel, Belgium
| | - Daniel Charlier
- Research Group of Microbiology, Department of Bioengineering Sciences, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
| | - Dorien Wilmaerts
- Center of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20, Box 2460, 3001 Leuven, Belgium
- Center for Microbiology, Vlaams Instituut voor Biotechnologie, Leuven, Belgium
| | - Jan Michiels
- Center of Microbial and Plant Genetics, KU Leuven, Kasteelpark Arenberg 20, Box 2460, 3001 Leuven, Belgium
- Center for Microbiology, Vlaams Instituut voor Biotechnologie, Leuven, Belgium
| | - Remy Loris
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, B-1050 Brussel, Belgium
- Molecular Recognition Unit, Structural Biology Research Center, Vlaams Instituut voor Biotechnologie, B-1050 Brussel, Belgium
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44
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Geller AM, Pollin I, Zlotkin D, Danov A, Nachmias N, Andreopoulos WB, Shemesh K, Levy A. The extracellular contractile injection system is enriched in environmental microbes and associates with numerous toxins. Nat Commun 2021; 12:3743. [PMID: 34145238 PMCID: PMC8213781 DOI: 10.1038/s41467-021-23777-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 05/14/2021] [Indexed: 12/26/2022] Open
Abstract
The extracellular Contractile Injection System (eCIS) is a toxin-delivery particle that evolved from a bacteriophage tail. Four eCISs have previously been shown to mediate interactions between bacteria and their invertebrate hosts. Here, we identify eCIS loci in 1,249 bacterial and archaeal genomes and reveal an enrichment of these loci in environmental microbes and their apparent absence from mammalian pathogens. We show that 13 eCIS-associated toxin genes from diverse microbes can inhibit the growth of bacteria and/or yeast. We identify immunity genes that protect bacteria from self-intoxication, further supporting an antibacterial role for some eCISs. We also identify previously undescribed eCIS core genes, including a conserved eCIS transcriptional regulator. Finally, we present our data through an extensive eCIS repository, termed eCIStem. Our findings support eCIS as a toxin-delivery system that is widespread among environmental prokaryotes and likely mediates antagonistic interactions with eukaryotes and other prokaryotes.
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Affiliation(s)
- Alexander Martin Geller
- Department of Plant Pathology and Microbiology, the Robert H. Smith Faculty of Food and Environment, the Hebrew University of Jerusalem, Rehovot, Israel
| | - Inbal Pollin
- Department of Plant Pathology and Microbiology, the Robert H. Smith Faculty of Food and Environment, the Hebrew University of Jerusalem, Rehovot, Israel
| | - David Zlotkin
- Department of Plant Pathology and Microbiology, the Robert H. Smith Faculty of Food and Environment, the Hebrew University of Jerusalem, Rehovot, Israel
| | - Aleks Danov
- Department of Plant Pathology and Microbiology, the Robert H. Smith Faculty of Food and Environment, the Hebrew University of Jerusalem, Rehovot, Israel
| | - Nimrod Nachmias
- Department of Plant Pathology and Microbiology, the Robert H. Smith Faculty of Food and Environment, the Hebrew University of Jerusalem, Rehovot, Israel
| | | | - Keren Shemesh
- Department of Plant Pathology and Microbiology, the Robert H. Smith Faculty of Food and Environment, the Hebrew University of Jerusalem, Rehovot, Israel
| | - Asaf Levy
- Department of Plant Pathology and Microbiology, the Robert H. Smith Faculty of Food and Environment, the Hebrew University of Jerusalem, Rehovot, Israel.
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Ely B. Evolutionary history of Caulobacter toxin-antitoxin systems. Curr Microbiol 2021; 78:2899-2904. [PMID: 34047829 DOI: 10.1007/s00284-021-02549-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 05/21/2021] [Indexed: 11/29/2022]
Abstract
Toxin-antitoxin (TA) systems have been studied in many bacterial genera, but a clear understanding of the evolutionary trajectory of TA operons has not emerged. To address this issue, I identified 42 distinct TA operons in three genomes that represent the three branches of the Caulobacter phylogenetic tree. The location of each operon was then examined to determine if the operon was present in eight additional Caulobacter genomes. Most of the 42 TA operons were present at the same chromosomal location in genomes that represent at least two different branches of the Caulobacter phylogenetic tree. This result indicates that the chromosomal location of TA operons is conserved over evolutionary time scales. One the other hand, there were 177 instances where a TA operon was not present at an expected chromosomal location and four instances where only the antitoxin gene was present. Thus, the variable number of TA operons found in each genome appears to be due primarily to the loss of TA operons, and the addition of new TA operons to a genome was relatively rare. An additional feature of the TA operons was that they seemed to accumulate mutations faster than the adjacent genes.
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Affiliation(s)
- Bert Ely
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA.
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Elucidating the Regulatory Elements for Transcription Termination and Posttranscriptional Processing in the Streptomyces clavuligerus Genome. mSystems 2021; 6:6/3/e01013-20. [PMID: 33947798 PMCID: PMC8269248 DOI: 10.1128/msystems.01013-20] [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] [Indexed: 11/20/2022] Open
Abstract
Identification of transcriptional regulatory elements in the GC-rich Streptomyces genome is essential for the production of novel biochemicals from secondary metabolite biosynthetic gene clusters (smBGCs). Despite many efforts to understand the regulation of transcription initiation in smBGCs, information on the regulation of transcription termination and posttranscriptional processing remains scarce. In this study, we identified the transcriptional regulatory elements in β-lactam antibiotic-producing Streptomyces clavuligerus ATCC 27064 by determining a total of 1,427 transcript 3'-end positions (TEPs) using the term-seq method. Termination of transcription was governed by three classes of TEPs, of which each displayed unique sequence features. The data integration with transcription start sites and transcriptome data generated 1,648 transcription units (TUs) and 610 transcription unit clusters (TUCs). TU architecture showed that the transcript abundance in TU isoforms of a TUC was potentially affected by the sequence context of their TEPs, suggesting that the regulatory elements of TEPs could control the transcription level in additional layers. We also identified TU features of a xenobiotic response element (XRE) family regulator and DUF397 domain-containing protein, particularly showing the abundance of bidirectional TEPs. Finally, we found that 189 noncoding TUs contained potential cis- and trans-regulatory elements that played a major role in regulating the 5' and 3' UTR. These findings highlight the role of transcriptional regulatory elements in transcription termination and posttranscriptional processing in Streptomyces sp.IMPORTANCE Streptomyces sp. is a great source of bioactive secondary metabolites, including antibiotics, antifungal agents, antiparasitic agents, immunosuppressant compounds, and other drugs. Secondary metabolites are synthesized via multistep conversions of the precursor molecules from primary metabolism, governed by multicomplex enzymes from secondary metabolite biosynthetic gene clusters. As their production is closely related with the growth phase and dynamic cellular status in response to various intra- and extracellular signals, complex regulatory systems tightly control the gene expressions related to secondary metabolism. In this study, we determined genome-wide transcript 3'-end positions and transcription units in the β-lactam antibiotic producer Streptomyces clavuligerus ATCC 27064 to elucidate the transcriptional regulatory elements in transcription termination and posttranscriptional processing by integration of multiomics data. These unique features, such as transcript 3'-end sequence, potential riboregulators, and potential 3'-untranslated region (UTR) cis-regulatory elements, can be potentially used to design engineering tools that can regulate the transcript abundance of genes for enhancing secondary metabolite production.
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Zhang Q, Zhou Y, Li Y, Ali B, Zhu Z. Functional characterization of Kid-Kis and MazF-MazE in Sf9 cells and Mythimna separata embryos. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2021; 174:104814. [PMID: 33838714 DOI: 10.1016/j.pestbp.2021.104814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 01/10/2021] [Accepted: 02/28/2021] [Indexed: 06/12/2023]
Abstract
Toxin-antitoxin (TA) systems are comprised of a toxin and its antidote antitoxin and are widely present in bacterial and in eukaryotic systems. However, no work regarding TA systems has been reported in insects. We characterized the Kid-Kis and MazF-MazE TA systems in Spodoptera frugiperda cells and Mythimna separata embryos and observed that the Kid and MazF toxins were highly toxic. In Sf9 cells transfected with Kid plasmid and MazF alone, the apoptosis rate was 24.37% and 29.47%, respectively. Whereas the toxicity of their cognate antitoxins were limited. Both apoptosis and necrosis were induced by the two toxins. Both the Kis and MazE antitoxins partly neutralized toxicity in a dose-dependent manner, with MazE accomplishing almost full neutralization at a 1:4 toxin:antitoxin ratio, the cell survival rate was 81% and 97%, respectively. Our results indicate that MazF-MazE is a good candidate module for application in insects, such as in developing new sterile insect technique (SIT).
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Affiliation(s)
- Qiuyuan Zhang
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Yicheng Zhou
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Yunfei Li
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Bahar Ali
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Zhihui Zhu
- Hubei Insect Resources Utilization and Sustainable Pest Management Key Laboratory, College of Plant Science & Technology, Huazhong Agricultural University, Wuhan, Hubei, China.
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Coexistence of SOS-Dependent and SOS-Independent Regulation of DNA Repair Genes in Radiation-Resistant Deinococcus Bacteria. Cells 2021; 10:cells10040924. [PMID: 33923690 PMCID: PMC8072749 DOI: 10.3390/cells10040924] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/13/2021] [Accepted: 04/14/2021] [Indexed: 11/28/2022] Open
Abstract
Deinococcus bacteria are extremely resistant to radiation and able to repair a shattered genome in an essentially error-free manner after exposure to high doses of radiation or prolonged desiccation. An efficient, SOS-independent response mechanism to induce various DNA repair genes such as recA is essential for radiation resistance. This pathway, called radiation/desiccation response, is controlled by metallopeptidase IrrE and repressor DdrO that are highly conserved in Deinococcus. Among various Deinococcus species, Deinococcus radiodurans has been studied most extensively. Its genome encodes classical DNA repair proteins for error-free repair but no error-prone translesion DNA polymerases, which may suggest that absence of mutagenic lesion bypass is crucial for error-free repair of massive DNA damage. However, many other radiation-resistant Deinococcus species do possess translesion polymerases, and radiation-induced mutagenesis has been demonstrated. At least dozens of Deinococcus species contain a mutagenesis cassette, and some even two cassettes, encoding error-prone translesion polymerase DnaE2 and two other proteins, ImuY and ImuB-C, that are probable accessory factors required for DnaE2 activity. Expression of this mutagenesis cassette is under control of the SOS regulators RecA and LexA. In this paper, we review both the RecA/LexA-controlled mutagenesis and the IrrE/DdrO-controlled radiation/desiccation response in Deinococcus.
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Redox signaling through zinc activates the radiation response in Deinococcus bacteria. Sci Rep 2021; 11:4528. [PMID: 33633226 PMCID: PMC7907104 DOI: 10.1038/s41598-021-84026-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 02/11/2021] [Indexed: 02/06/2023] Open
Abstract
Deinococcus bacteria are extremely resistant to radiation and other DNA damage- and oxidative stress-generating conditions. An efficient SOS-independent response mechanism inducing expression of several DNA repair genes is essential for this resistance, and is controlled by metalloprotease IrrE that cleaves and inactivates transcriptional repressor DdrO. Here, we identify the molecular signaling mechanism that triggers DdrO cleavage. We show that reactive oxygen species (ROS) stimulate the zinc-dependent metalloprotease activity of IrrE in Deinococcus. Sudden exposure of Deinococcus to zinc excess also rapidly induces DdrO cleavage, but is not accompanied by ROS production and DNA damage. Further, oxidative treatment leads to an increase of intracellular free zinc, indicating that IrrE activity is very likely stimulated directly by elevated levels of available zinc ions. We conclude that radiation and oxidative stress induce changes in redox homeostasis that result in IrrE activation by zinc in Deinococcus. We propose that a part of the zinc pool coordinated with cysteine thiolates is released due to their oxidation. Predicted regulation systems involving IrrE- and DdrO-like proteins are present in many bacteria, including pathogens, suggesting that such a redox signaling pathway including zinc as a second messenger is widespread and participates in various stress responses.
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The Disordered C-Terminus of the Chaperone DnaK Increases the Competitive Fitness of Pseudomonas putida and Facilitates the Toxicity of GraT. Microorganisms 2021; 9:microorganisms9020375. [PMID: 33668424 PMCID: PMC7918210 DOI: 10.3390/microorganisms9020375] [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: 01/14/2021] [Revised: 02/10/2021] [Accepted: 02/11/2021] [Indexed: 11/23/2022] Open
Abstract
Chaperone proteins are crucial for proper protein folding and quality control, especially when cells encounter stress caused by non-optimal temperatures. DnaK is one of such essential chaperones in bacteria. Although DnaK has been well characterized, the function of its intrinsically disordered C-terminus has remained enigmatic as the deletion of this region has been shown to either enhance or reduce its protein folding ability. We have shown previously that DnaK interacts with toxin GraT of the GraTA toxin-antitoxin system in Pseudomonas putida. Interestingly, the C-terminal truncation of DnaK was shown to alleviate GraT-caused growth defects. Here, we aim to clarify the importance of DnaK in GraT activity. We show that DnaK increases GraT toxicity, and particularly important is the negatively charged motif in the DnaK C-terminus. Given that GraT has an intrinsically disordered N-terminus, the assistance of DnaK is probably needed for re-modelling the toxin structure. We also demonstrate that the DnaK C-terminal negatively charged motif contributes to the competitive fitness of P. putida at both high and optimal growth temperatures. Thus, our data suggest that the disordered C-terminal end of DnaK enhances the chaperone functionality.
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