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Hernández-Ramírez KC, Valle-Maldonado MI, Patiño-Medina JA, Calo S, Jácome-Galarza IE, Garre V, Meza-Carmen V, Ramírez-Díaz MI. Role of PumB antitoxin as a transcriptional regulator of the PumAB type-II toxin-antitoxin system and its endoribonuclease activity on the PumA (toxin) transcript. Mol Genet Genomics 2023; 298:455-472. [PMID: 36604348 DOI: 10.1007/s00438-022-01988-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 12/20/2022] [Indexed: 01/07/2023]
Abstract
The PumAB type-II toxin-antitoxin (TA) system is encoded by pumAB genes that are organized into an operon. This system is encoded by the pUM505 plasmid, isolated from a Pseudomonas aeruginosa clinical strain. The pumA gene encodes a putative RelE toxin protein (toxic component), whereas the pumB gene encodes a putative HTH antitoxin protein. The expression of the PumAB system in Escherichia coli confers plasmid stability. In addition, PumA toxin overexpression in P. aeruginosa possesses the capability to increase bacterial virulence, an effect that is neutralized by the PumB antitoxin. The aim of this study was to establish the mechanism of regulation of the PumAB toxin-antitoxin system from pUM505. By an in silico analysis of the putative regulatory elements, we identified two putative internal promoters, PpumB and PpumB-AlgU (in addition to the already reported PpumAB), located upstream of pumB. By RT-qPCR assays, we determined that the pumAB genes are transcribed differentially, in that the mRNA of pumB is more abundant than the pumA transcript. We also observed that pumB could be expressed individually and that its mRNA levels decreased under oxidative stress, during individual expression as well as co-expression of pumAB. However, under stressful conditions, the pumA mRNA levels were not affected. This suggests the negative regulation of pumB by stressful conditions. The PumB purified protein was found to bind to a DNA region located between the PpumAB and the pumA coding region, and PumA participates in PumB binding, suggesting that a PumA-PumB complex co-regulates the transcription of the pumAB operon. Interestingly, the pumA mRNA levels decreased after incubation in vitro with PumB protein. This effect was repressed by ribonuclease inhibitors, suggesting that PumB could function as an RNAse toward the mRNA of the toxin. Taken together, we conclude that the PumAB TA system possesses multiple mechanisms to regulate its expression, as well as that the PumB antitoxin generates a decrease in the mRNA toxin levels, suggesting an RNase function. Our analysis provides new insights into the understanding of the control of TA systems from mobile plasmid-encoded genes from a human pathogen.
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Affiliation(s)
- K C Hernández-Ramírez
- Laboratorio de Microbiología, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio B-3, Ciudad Universitaria, 58030, Morelia, Michoacán, Mexico
| | - M I Valle-Maldonado
- Laboratorio de Diferenciación Celular, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, 58030, Morelia, Michoacán, Mexico.,Laboratorio Estatal de Salud Pública, Secretaría de Salud Michoacán, Morelia, Mexico
| | - J A Patiño-Medina
- Laboratorio de Diferenciación Celular, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, 58030, Morelia, Michoacán, Mexico
| | - S Calo
- School of Natural and Exact Sciences, Pontificia Universidad Católica Madre y Maestra, 51033, Santiago de los Caballeros, Dominican Republic
| | - I E Jácome-Galarza
- Laboratorio Estatal de Salud Pública, Secretaría de Salud Michoacán, Morelia, Mexico
| | - V Garre
- Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, 30100, Murcia, Spain
| | - V Meza-Carmen
- Laboratorio de Diferenciación Celular, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Ciudad Universitaria, 58030, Morelia, Michoacán, Mexico
| | - M I Ramírez-Díaz
- Laboratorio de Microbiología, Instituto de Investigaciones Químico-Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Edificio B-3, Ciudad Universitaria, 58030, Morelia, Michoacán, Mexico.
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2
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Bakre AA, Duffy C, Abdullah H, Cosby SL, Tripp RA. Small Non-coding RNA Expression Following Respiratory Syncytial Virus or Measles Virus Infection of Neuronal Cells. Front Microbiol 2021; 12:671852. [PMID: 34539595 PMCID: PMC8446675 DOI: 10.3389/fmicb.2021.671852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 08/03/2021] [Indexed: 11/24/2022] Open
Abstract
Respiratory syncytial virus (RSV) or measles virus (MeV) infection modifies host responses through small non-coding RNA (sncRNA) expression. We show that RSV or MeV infection of neuronal cells induces sncRNAs including various microRNAs and transfer RNA fragments (tRFs). We show that these tRFs originate from select tRNAs (GCC and CAC for glycine, CTT and AAC for Valine, and CCC and TTT for Lysine). Some of the tRNAs are rarely used by RSV or MeV as indicated by relative synonymous codon usage indices suggesting selective cleavage of the tRNAs occurs in infected neuronal cells. The data implies that differentially expressed sncRNAs may regulate host gene expression via multiple mechanisms in neuronal cells.
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Affiliation(s)
- Abhijeet A Bakre
- Department of Infectious Diseases, University of Georgia, Athens, GA, United States
| | - Catherine Duffy
- Virology Branch, Veterinary Sciences Division, Agri-Food and Biosciences Institute, Belfast, United Kingdom
| | - Hani'ah Abdullah
- Wellcome Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, United Kingdom
| | - S Louise Cosby
- Virology Branch, Veterinary Sciences Division, Agri-Food and Biosciences Institute, Belfast, United Kingdom.,Wellcome Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, United Kingdom
| | - Ralph A Tripp
- Department of Infectious Diseases, University of Georgia, Athens, GA, United States
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3
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Ovchinnikov SV, Bikmetov D, Livenskyi A, Serebryakova M, Wilcox B, Mangano K, Shiriaev DI, Osterman IA, Sergiev PV, Borukhov S, Vazquez-Laslop N, Mankin AS, Severinov K, Dubiley S. Mechanism of translation inhibition by type II GNAT toxin AtaT2. Nucleic Acids Res 2020; 48:8617-8625. [PMID: 32597957 PMCID: PMC7470980 DOI: 10.1093/nar/gkaa551] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 06/05/2020] [Accepted: 06/17/2020] [Indexed: 12/25/2022] Open
Abstract
Type II toxin–antitoxins systems are widespread in prokaryotic genomes. Typically, they comprise two proteins, a toxin, and an antitoxin, encoded by adjacent genes and forming a complex in which the enzymatic activity of the toxin is inhibited. Under stress conditions, the antitoxin is degraded liberating the active toxin. Though thousands of various toxin–antitoxins pairs have been predicted bioinformatically, only a handful has been thoroughly characterized. Here, we describe the AtaT2 toxin from a toxin–antitoxin system from Escherichia coli O157:H7. We show that AtaT2 is the first GNAT (Gcn5-related N-acetyltransferase) toxin that specifically targets charged glycyl tRNA. In vivo, the AtaT2 activity induces ribosome stalling at all four glycyl codons but does not evoke a stringent response. In vitro, AtaT2 acetylates the aminoacyl moiety of isoaccepting glycyl tRNAs, thus precluding their participation in translation. Our study broadens the known target specificity of GNAT toxins beyond the earlier described isoleucine and formyl methionine tRNAs, and suggest that various GNAT toxins may have evolved to specificaly target other if not all individual aminoacyl tRNAs.
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Affiliation(s)
- Stepan V Ovchinnikov
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia
| | - Dmitry Bikmetov
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia.,Institute of Gene Biology, Russian Academy of Science, 119334 Moscow, Russia
| | - Alexei Livenskyi
- Institute of Gene Biology, Russian Academy of Science, 119334 Moscow, Russia.,Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow 119992, Russia
| | - Marina Serebryakova
- Institute of Gene Biology, Russian Academy of Science, 119334 Moscow, Russia.,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia
| | - Brendan Wilcox
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia
| | - Kyle Mangano
- Center for Biomolecular Sciences, University of Illinois, Chicago, IL 60607, USA.,Department of Pharmaceutical Sciences, University of Illinois, Chicago, IL 60607, USA
| | - Dmitrii I Shiriaev
- Department of Chemistry, Lomonosov Moscow State University, Moscow 119992, Russia
| | - Ilya A Osterman
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia.,Department of Chemistry, Lomonosov Moscow State University, Moscow 119992, Russia
| | - Petr V Sergiev
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia.,Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow 119992, Russia
| | - Sergei Borukhov
- Department of Cell Biology and Neuroscience, Rowan University School of Osteopathic Medicine, Stratford, NJ 08084-1489, USA
| | - Nora Vazquez-Laslop
- Center for Biomolecular Sciences, University of Illinois, Chicago, IL 60607, USA.,Department of Pharmaceutical Sciences, University of Illinois, Chicago, IL 60607, USA
| | - Alexander S Mankin
- Center for Biomolecular Sciences, University of Illinois, Chicago, IL 60607, USA.,Department of Pharmaceutical Sciences, University of Illinois, Chicago, IL 60607, USA
| | - Konstantin Severinov
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia.,Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, 119334 Moscow, Russia.,Waksman Institute for Microbiology, Piscataway, NJ 08854-8020, USA
| | - Svetlana Dubiley
- Centre for Life Sciences, Skolkovo Institute of Science and Technology, Skolkovo 143025, Russia.,Institute of Gene Biology, Russian Academy of Science, 119334 Moscow, Russia
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4
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Structure of Schlafen13 reveals a new class of tRNA/rRNA- targeting RNase engaged in translational control. Nat Commun 2018; 9:1165. [PMID: 29563550 PMCID: PMC5862951 DOI: 10.1038/s41467-018-03544-x] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 02/20/2018] [Indexed: 01/07/2023] Open
Abstract
Cleavage of transfer (t)RNA and ribosomal (r)RNA are critical and conserved steps of translational control for cells to overcome varied environmental stresses. However, enzymes that are responsible for this event have not been fully identified in high eukaryotes. Here, we report a mammalian tRNA/rRNA-targeting endoribonuclease: SLFN13, a member of the Schlafen family. Structural study reveals a unique pseudo-dimeric U-pillow-shaped architecture of the SLFN13 N'-domain that may clamp base-paired RNAs. SLFN13 is able to digest tRNAs and rRNAs in vitro, and the endonucleolytic cleavage dissevers 11 nucleotides from the 3'-terminus of tRNA at the acceptor stem. The cytoplasmically localised SLFN13 inhibits protein synthesis in 293T cells. Moreover, SLFN13 restricts HIV replication in a nucleolytic activity-dependent manner. According to these observations, we term SLFN13 RNase S13. Our study provides insights into the modulation of translational machinery in high eukaryotes, and sheds light on the functional mechanisms of the Schlafen family.
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5
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Belasco JG. Death by translation: ribosome-assisted degradation of mRNA by endonuclease toxins. FEBS Lett 2017. [PMID: 28649728 DOI: 10.1002/1873-3468.12715] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Joel G Belasco
- Kimmel Center for Biology and Medicine at the Skirball Institute, New York University School of Medicine, New York, NY, USA.,Department of Microbiology, New York University School of Medicine, NY, USA
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6
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Physical and Functional Interplay between MazF 1Bif and Its Noncognate Antitoxins from Bifidobacterium longum. Appl Environ Microbiol 2017; 83:AEM.03232-16. [PMID: 28213540 DOI: 10.1128/aem.03232-16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 02/09/2017] [Indexed: 11/20/2022] Open
Abstract
Bifidobacterium longum strain JDM301, a widely used commercial strain in China, encodes at least two MazEF-like modules and one RelBE-like toxin-antitoxin (TA) system in its chromosome, designated MazE1F1Bif, MazE2F2Bif, and RelBEBif, respectively. Bacterial TA systems play an important role in several stress responses, but the relationship between these TA systems is largely unknown. In this study, the interactions between MazF1Bif and MazE2Bif or RelBBif were assessed in B. longum strain JDM301. MazF1Bif caused the degradation of tufABif mRNA, and its toxicity was inhibited by forming a protein complex with its cognate antitoxin, MazE1Bif Notably, MazF1Bif toxicity was also partially neutralized when jointly expressed with noncognate antitoxin MazE2Bif or RelBBif Our results show that the two noncognate antitoxins also inhibited mRNA degradation caused by MazF1Bif toxin. Furthermore, the physical interplay between MazF1Bif and its noncognate antitoxins was confirmed by immunoprecipitation. These results suggest that MazF1Bif can arrest cell growth and that MazF1Bif toxicity can be neutralized by its cognate and noncognate antitoxins. These results imply that JDM301 uses a sophisticated toxin-antitoxin interaction network to alter its physiology when coping with environmental stress.IMPORTANCE Although toxin-antitoxin (TA) systems play an important role in several stress responses, the regulatory mechanisms of multiple TA system homologs in the bacterial genome remain largely unclear. In this study, the relationships between MazE1F1Bif and the other two TA systems of Bifidobacterium longum strain JDM301 were explored, and the interactions between MazF1Bif and MazE2Bif or RelBBif were characterized. In addition, the mRNA degradation activity of MazF1Bif was demonstrated. In particular, the interaction of the toxin with noncognate antitoxins was shown, even between different TA families (MazF1Bif toxin and RelBBif antitoxin) in JDM301. This work provides insight into the regulatory mechanisms of TA systems implicated in the stress responses of bifidobacteria.
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7
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Hall AMJ, Gollan B, Helaine S. Toxin–antitoxin systems: reversible toxicity. Curr Opin Microbiol 2017; 36:102-110. [DOI: 10.1016/j.mib.2017.02.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 01/06/2017] [Accepted: 02/04/2017] [Indexed: 10/20/2022]
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8
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Goeders N, Chai R, Chen B, Day A, Salmond GPC. Structure, Evolution, and Functions of Bacterial Type III Toxin-Antitoxin Systems. Toxins (Basel) 2016; 8:toxins8100282. [PMID: 27690100 PMCID: PMC5086642 DOI: 10.3390/toxins8100282] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 09/14/2016] [Accepted: 09/19/2016] [Indexed: 01/21/2023] Open
Abstract
Toxin-antitoxin (TA) systems are small genetic modules that encode a toxin (that targets an essential cellular process) and an antitoxin that neutralises or suppresses the deleterious effect of the toxin. Based on the molecular nature of the toxin and antitoxin components, TA systems are categorised into different types. Type III TA systems, the focus of this review, are composed of a toxic endoribonuclease neutralised by a non-coding RNA antitoxin in a pseudoknotted configuration. Bioinformatic analysis shows that the Type III systems can be classified into subtypes. These TA systems were originally discovered through a phage resistance phenotype arising due to a process akin to an altruistic suicide; the phenomenon of abortive infection. Some Type III TA systems are bifunctional and can stabilise plasmids during vegetative growth and sporulation. Features particular to Type III systems are explored here, emphasising some of the characteristics of the RNA antitoxin and how these may affect the co-evolutionary relationship between toxins and cognate antitoxins in their quaternary structures. Finally, an updated analysis of the distribution and diversity of these systems are presented and discussed.
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Affiliation(s)
- Nathalie Goeders
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK.
| | - Ray Chai
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK.
| | - Bihe Chen
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK.
| | - Andrew Day
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK.
| | - George P C Salmond
- Department of Biochemistry, University of Cambridge, Cambridge CB2 1QW, UK.
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9
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Schureck MA, Repack A, Miles SJ, Marquez J, Dunham CM. Mechanism of endonuclease cleavage by the HigB toxin. Nucleic Acids Res 2016; 44:7944-53. [PMID: 27378776 PMCID: PMC5027501 DOI: 10.1093/nar/gkw598] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 06/17/2016] [Accepted: 06/22/2016] [Indexed: 01/11/2023] Open
Abstract
Bacteria encode multiple type II toxin-antitoxin modules that cleave ribosome-bound mRNAs in response to stress. All ribosome-dependent toxin family members structurally characterized to date adopt similar microbial RNase architectures despite possessing low sequence identities. Therefore, determining which residues are catalytically important in this specialized RNase family has been a challenge in the field. Structural studies of RelE and YoeB toxins bound to the ribosome provided significant insights but biochemical experiments with RelE were required to clearly demonstrate which residues are critical for acid-base catalysis of mRNA cleavage. Here, we solved an X-ray crystal structure of the wild-type, ribosome-dependent toxin HigB bound to the ribosome revealing potential catalytic residues proximal to the mRNA substrate. Using cell-based and biochemical assays, we further determined that HigB residues His54, Asp90, Tyr91 and His92 are critical for activity in vivo, while HigB H54A and Y91A variants have the largest effect on mRNA cleavage in vitro Comparison of X-ray crystal structures of two catalytically inactive HigB variants with 70S-HigB bound structures reveal that HigB active site residues undergo conformational rearrangements likely required for recognition of its mRNA substrate. These data support the emerging concept that ribosome-dependent toxins have diverse modes of mRNA recognition.
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Affiliation(s)
- Marc A Schureck
- Emory University School of Medicine, Department of Biochemistry, 1510 Clifton Road NE, Atlanta, GA 30322, USA
| | - Adrienne Repack
- Emory University School of Medicine, Department of Biochemistry, 1510 Clifton Road NE, Atlanta, GA 30322, USA
| | - Stacey J Miles
- Emory University School of Medicine, Department of Biochemistry, 1510 Clifton Road NE, Atlanta, GA 30322, USA
| | - Jhomar Marquez
- Emory University School of Medicine, Department of Biochemistry, 1510 Clifton Road NE, Atlanta, GA 30322, USA
| | - Christine M Dunham
- Emory University School of Medicine, Department of Biochemistry, 1510 Clifton Road NE, Atlanta, GA 30322, USA
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10
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Hartman CE, Samuels DJ, Karls AC. Modulating Salmonella Typhimurium's Response to a Changing Environment through Bacterial Enhancer-Binding Proteins and the RpoN Regulon. Front Mol Biosci 2016; 3:41. [PMID: 27583250 PMCID: PMC4987338 DOI: 10.3389/fmolb.2016.00041] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 07/28/2016] [Indexed: 12/25/2022] Open
Abstract
Transcription sigma factors direct the selective binding of RNA polymerase holoenzyme (Eσ) to specific promoters. Two families of sigma factors determine promoter specificity, the σ(70) (RpoD) family and the σ(54) (RpoN) family. In transcription controlled by σ(54), the Eσ(54)-promoter closed complex requires ATP hydrolysis by an associated bacterial enhancer-binding protein (bEBP) for the transition to open complex and transcription initiation. Given the wide host range of Salmonella enterica serovar Typhimurium, it is an excellent model system for investigating the roles of RpoN and its bEBPs in modulating the lifestyle of bacteria. The genome of S. Typhimurium encodes 13 known or predicted bEBPs, each responding to a unique intracellular or extracellular signal. While the regulons of most alternative sigma factors respond to a specific environmental or developmental signal, the RpoN regulon is very diverse, controlling genes for response to nitrogen limitation, nitric oxide stress, availability of alternative carbon sources, phage shock/envelope stress, toxic levels of zinc, nucleic acid damage, and other stressors. This review explores how bEBPs respond to environmental changes encountered by S. Typhimurium during transmission/infection and influence adaptation through control of transcription of different components of the S. Typhimurium RpoN regulon.
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Affiliation(s)
| | - David J Samuels
- Department of Microbiology, University of Georgia Athens, GA, USA
| | - Anna C Karls
- Department of Microbiology, University of Georgia Athens, GA, USA
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11
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Abstract
The expression of a gene is a tightly regulated process and is exerted by a myriad of different mechanisms. Recently, RNA modifications located in coding sequences of mRNAs, have been identified as potential regulators of gene expression. N6-methyladenosine (m6A), 5-methylcytosine (m5C), pseudouridine (Ψ) and N1-methyladenosine (m1A) have been found within open reading frames of mRNAs. The presence of these mRNA modifications has been implicated to modulate the fate of an mRNA, ranging from maturation to its translation and even degradation. However, many aspects concerning the biological functions of mRNA modifications remain elusive. Recently, systematic in vitro studies allowed a first glimpse of the direct interplay of mRNA modifications and the efficiency and fidelity of ribosomal translation. It thereby became evident that the effects of mRNA modifications were, astonishingly versatile, depending on the type, position or sequence context. The incorporation of a single modification could either prematurely terminate protein synthesis, reduce the peptide yield or alter the amino acid sequence identity. These results implicate that mRNA modifications are a powerful mechanism to post-transcriptionally regulate gene expression.
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Affiliation(s)
- Thomas Philipp Hoernes
- a Division of Genomics and RNomics, Biocenter, Medical University of Innsbruck , Innsbruck , Austria
| | - Alexander Hüttenhofer
- a Division of Genomics and RNomics, Biocenter, Medical University of Innsbruck , Innsbruck , Austria
| | - Matthias David Erlacher
- a Division of Genomics and RNomics, Biocenter, Medical University of Innsbruck , Innsbruck , Austria
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12
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Emerging Roles of Toxin-Antitoxin Modules in Bacterial Pathogenesis. Molecules 2016; 21:molecules21060790. [PMID: 27322231 PMCID: PMC6273597 DOI: 10.3390/molecules21060790] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 06/06/2016] [Accepted: 06/13/2016] [Indexed: 11/17/2022] Open
Abstract
Toxin-antitoxin (TA) cassettes are encoded widely by bacteria. The modules typically comprise a protein toxin and protein or RNA antitoxin that sequesters the toxin factor. Toxin activation in response to environmental cues or other stresses promotes a dampening of metabolism, most notably protein translation, which permits survival until conditions improve. Emerging evidence also implicates TAs in bacterial pathogenicity. Bacterial persistence involves entry into a transient semi-dormant state in which cells survive unfavorable conditions including killing by antibiotics, which is a significant clinical problem. TA complexes play a fundamental role in inducing persistence by downregulating cellular metabolism. Bacterial biofilms are important in numerous chronic inflammatory and infectious diseases and cause serious therapeutic problems due to their multidrug tolerance and resistance to host immune system actions. Multiple TAs influence biofilm formation through a network of interactions with other factors that mediate biofilm production and maintenance. Moreover, in view of their emerging contributions to bacterial virulence, TAs are potential targets for novel prophylactic and therapeutic approaches that are required urgently in an era of expanding antibiotic resistance. This review summarizes the emerging evidence that implicates TAs in the virulence profiles of a diverse range of key bacterial pathogens that trigger serious human disease.
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