51
|
Dual RNA-seq of Nontypeable Haemophilus influenzae and Host Cell Transcriptomes Reveals Novel Insights into Host-Pathogen Cross Talk. mBio 2015; 6:e01765-15. [PMID: 26578681 PMCID: PMC4659474 DOI: 10.1128/mbio.01765-15] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
UNLABELLED The ability to adhere and adapt to the human respiratory tract mucosa plays a pivotal role in the pathogenic lifestyle of nontypeable Haemophilus influenzae (NTHi). However, the temporal events associated with a successful colonization have not been fully characterized. In this study, by reconstituting the ciliated human bronchial epithelium in vitro, we monitored the global transcriptional changes in NTHi and infected mucosal epithelium simultaneously for up to 72 h by dual RNA sequencing. The initial stage of colonization was characterized by the binding of NTHi to ciliated cells. Temporal profiling of host mRNA signatures revealed significant dysregulation of the target cell cytoskeleton elicited by bacterial infection, with a profound effect on the intermediate filament network and junctional complexes. In response to environmental stimuli of the host epithelium, NTHi downregulated its central metabolism and increased the expression of transporters, indicating a change in the metabolic regime due to the availability of host substrates. Concurrently, the oxidative environment generated by infected cells instigated bacterial expression of stress-induced defense mechanisms, including the transport of exogenous glutathione and activation of the toxin-antitoxin system. The results of this analysis were validated by those of confocal microscopy, Western blotting, Bio-plex, and real-time quantitative reverse transcription-PCR (qRT-PCR). Notably, as part of our screening for novel signatures of infection, we identified a global profile of noncoding transcripts that are candidate small RNAs (sRNAs) regulated during human host infection in Haemophilus species. Our data, by providing a robust and comprehensive representation of the cross talk between the host and invading pathogen, provides important insights into NTHi pathogenesis and the development of efficacious preventive strategies. IMPORTANCE Simultaneous monitoring of infection-linked transcriptome alterations in an invading pathogen and its target host cells represents a key strategy for identifying regulatory responses that drive pathogenesis. In this study, we report the progressive events of NTHi colonization in a highly differentiated model of ciliated bronchial epithelium. Genome-wide transcriptome maps of NTHi during infection provided mechanistic insights into bacterial adaptive responses to the host niche, with modulation of the central metabolism as an important signature of the evolving milieu. Our data indicate that infected epithelia respond by substantial alteration of the cytoskeletal network and cytokine repertoire, revealing a dynamic cross talk that is responsible for the onset of inflammation. This work significantly enhances our understanding of the means by which NTHi promotes infection on human mucosae and reveals novel strategies exploited by this important pathogen to cause invasive disease.
Collapse
|
52
|
Lee IG, Lee SJ, Chae S, Lee KY, Kim JH, Lee BJ. Structural and functional studies of the Mycobacterium tuberculosis VapBC30 toxin-antitoxin system: implications for the design of novel antimicrobial peptides. Nucleic Acids Res 2015; 43:7624-37. [PMID: 26150422 PMCID: PMC4551927 DOI: 10.1093/nar/gkv689] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 06/24/2015] [Indexed: 12/21/2022] Open
Abstract
Toxin-antitoxin (TA) systems play important roles in bacterial physiology, such as multidrug tolerance, biofilm formation, and arrest of cellular growth under stress conditions. To develop novel antimicrobial agents against tuberculosis, we focused on VapBC systems, which encompass more than half of TA systems in Mycobacterium tuberculosis. Here, we report that theMycobacterium tuberculosis VapC30 toxin regulates cellular growth through both magnesium and manganese ion-dependent ribonuclease activity and is inhibited by the cognate VapB30 antitoxin. We also determined the 2.7-Å resolution crystal structure of the M. tuberculosis VapBC30 complex, which revealed a novel process of inactivation of the VapC30 toxin via swapped blocking by the VapB30 antitoxin. Our study on M. tuberculosis VapBC30 leads us to design two kinds of VapB30 and VapC30-based novel peptides which successfully disrupt the toxin-antitoxin complex and thus activate the ribonuclease activity of the VapC30 toxin. Our discovery herein possibly paves the way to treat tuberculosis for next generation.
Collapse
Affiliation(s)
- In-Gyun Lee
- Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Sang Jae Lee
- Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Susanna Chae
- Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Ki-Young Lee
- Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Ji-Hun Kim
- Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| | - Bong-Jin Lee
- Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Seoul 151-742, Korea
| |
Collapse
|
53
|
Chan WT, Balsa D, Espinosa M. One cannot rule them all: Are bacterial toxins-antitoxins druggable? FEMS Microbiol Rev 2015; 39:522-40. [PMID: 25796610 PMCID: PMC4487406 DOI: 10.1093/femsre/fuv002] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/02/2015] [Indexed: 01/31/2023] Open
Abstract
Type II (proteic) toxin–antitoxin (TA) operons are widely spread in bacteria and archaea. They are organized as operons in which, usually, the antitoxin gene precedes the cognate toxin gene. The antitoxin generally acts as a transcriptional self-repressor, whereas the toxin acts as a co-repressor, both proteins constituting a harmless complex. When bacteria encounter a stressful environment, TAs are triggered. The antitoxin protein is unstable and will be degraded by host proteases, releasing the free toxin to halt essential processes. The result is a cessation of cell growth or even death. Because of their ubiquity and the essential processes targeted, TAs have been proposed as good candidates for development of novel antimicrobials. We discuss here the possible druggability of TAs as antivirals and antibacterials, with focus on the potentials and the challenges that their use may find in the ‘real’ world. We present strategies to develop TAs as antibacterials in view of novel technologies, such as the use of very small molecules (fragments) as inhibitors of protein–protein interactions. Appropriate fragments could disrupt the T:A interfaces leading to the release of the targeted TA pair. Possible ways of delivery and formulation of Tas are also discussed. We consider various approaches to develop the toxins of the type II family as possible candidates to drug discovery; druggability of toxins-antitoxins could be possible as antivirals. As antibacterials, they might be considered as druggable but delivery and formulation may not be simple so far.
Collapse
Affiliation(s)
- Wai Ting Chan
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, 9, 28006-Madrid, Spain
| | - Dolors Balsa
- Immunology & Vaccines, Laboratorios LETI, Gran Via de les Corts Catalanes 184. 08034-Barcelona, Spain
| | - Manuel Espinosa
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu, 9, 28006-Madrid, Spain
| |
Collapse
|
54
|
Distinct type I and type II toxin-antitoxin modules control Salmonella lifestyle inside eukaryotic cells. Sci Rep 2015; 5:9374. [PMID: 25792384 PMCID: PMC4366850 DOI: 10.1038/srep09374] [Citation(s) in RCA: 84] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2014] [Accepted: 03/02/2015] [Indexed: 02/02/2023] Open
Abstract
Toxin-antitoxin (TA) modules contribute to the generation of non-growing cells in response to stress. These modules abound in bacterial pathogens although the bases for this profusion remain largely unknown. Using the intracellular bacterial pathogen Salmonella enterica serovar Typhimurium as a model, here we show that a selected group of TA modules impact bacterial fitness inside eukaryotic cells. We characterized in this pathogen twenty-seven TA modules, including type I and type II TA modules encoding antisense RNA and proteinaceous antitoxins, respectively. Proteomic and gene expression analyses revealed that the pathogen produces numerous toxins of TA modules inside eukaryotic cells. Among these, the toxins HokST, LdrAST, and TisBST, encoded by type I TA modules and T4ST and VapC2ST, encoded by type II TA modules, promote bacterial survival inside fibroblasts. In contrast, only VapC2ST shows that positive effect in bacterial fitness when the pathogen infects epithelial cells. These results illustrate how S. Typhimurium uses distinct type I and type II TA modules to regulate its intracellular lifestyle in varied host cell types. This function specialization might explain why the number of TA modules increased in intracellular bacterial pathogens.
Collapse
|
55
|
Haemophilus influenzae: recent advances in the understanding of molecular pathogenesis and polymicrobial infections. Curr Opin Infect Dis 2015; 27:268-74. [PMID: 24699388 DOI: 10.1097/qco.0000000000000056] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
PURPOSE OF REVIEW Non-typeable Haemophilus influenzae (NTHi) is a human-specific mucosal pathogen and one of the most common causes of bacterial infections in children and patients with chronic obstructive pulmonary disease. It is also frequently found in polymicrobial superinfections. Great strides have recently been made in the understanding of the molecular mechanisms underlying NTHi pathogenesis. RECENT FINDINGS By using new methodology, such as experimental human colonization models and whole-genome approaches, investigators have shed light upon the various strategies of NTHi that are involved in pathogenesis. These include the escape of the mucociliary elevator, evasion of host immunity, survival in environments with scarce nutrients, and finally participation in polymicrobial infections. Lipooligosaccharide branching, proteinous adhesins, metabolic adaption to nutrient availability and many scavenging systems are implicated in these processes. Interestingly, genome-based studies comparing virulent and commensal strains have identified many hypothetical proteins as virulence determinants, suggesting that much regarding the molecular pathogenesis of NTHi remains to be solved. SUMMARY NTHi is an opportunistic pathogen and highly specialized colonizer of the human respiratory tract that has developed intricate mechanisms to establish growth and survival in the human host. Continued research is needed to further elucidate NTHi host-pathogen and pathogen-pathogen interactions.
Collapse
|
56
|
MazF ribonucleases promote Mycobacterium tuberculosis drug tolerance and virulence in guinea pigs. Nat Commun 2015; 6:6059. [PMID: 25608501 DOI: 10.1038/ncomms7059] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2014] [Accepted: 12/05/2014] [Indexed: 11/08/2022] Open
Abstract
Toxin-antitoxin (TA) systems are highly conserved in members of the Mycobacterium tuberculosis (Mtb) complex and have been proposed to play an important role in physiology and virulence. Nine of these TA systems belong to the mazEF family, encoding the intracellular MazF toxin and its antitoxin, MazE. By overexpressing each of the nine putative MazF homologues in Mycobacterium bovis BCG, here we show that Rv1102c (MazF3), Rv1991c (MazF6) and Rv2801c (MazF9) induce bacteriostasis. The construction of various single-, double- and triple-mutant Mtb strains reveals that these MazF ribonucleases contribute synergistically to the ability of Mtb to adapt to conditions such as oxidative stress, nutrient depletion and drug exposure. Moreover, guinea pigs infected with the triple-mutant strain exhibits significantly reduced bacterial loads and pathological damage in infected tissues in comparison with parental strain-infected guinea pigs. The present study highlights the importance of MazF ribonucleases in Mtb stress adaptation, drug tolerance and virulence.
Collapse
|
57
|
Chan WT, Yeo CC, Sadowy E, Espinosa M. Functional validation of putative toxin-antitoxin genes from the Gram-positive pathogen Streptococcus pneumoniae: phd-doc is the fourth bona-fide operon. Front Microbiol 2014; 5:677. [PMID: 25538695 PMCID: PMC4257102 DOI: 10.3389/fmicb.2014.00677] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 11/19/2014] [Indexed: 11/13/2022] Open
Abstract
Bacterial toxin-antitoxin (TAs) loci usually consist of two genes organized as an operon, where their products are bound together and inert under normal conditions. However, under stressful circumstances the antitoxin, which is more labile, will be degraded more rapidly, thereby unleashing its cognate toxin to act on the cell. This, in turn, causes cell stasis or cell death, depending on the type of TAs and/or time of toxin exposure. Previously based on in silico analyses, we proposed that Streptococcus pneumoniae, a pathogenic Gram-positive bacterium, may harbor between 4 and 10 putative TA loci depending on the strains. Here we have chosen the pneumococcal strain Hungary(19A)-6 which contains all possible 10 TA loci. In addition to the three well-characterized operons, namely relBE2, yefM-yoeB, and pezAT, we show here the functionality of a fourth operon that encodes the pneumococcal equivalent of the phd-doc TA. Transcriptional fusions with gene encoding Green Fluorescent Protein showed that the promoter was slightly repressed by the Phd antitoxin, and exhibited almost background values when both Phd-Doc were expressed together. These findings demonstrate that phd-doc shows the negative self-regulatory features typical for an authentic TA. Further, we also show that the previously proposed TAs XreA-Ant and Bro-XreB, although they exhibit a genetic organization resembling those of typical TAs, did not appear to confer a functional behavior corresponding to bona fide TAs. In addition, we have also discovered new interesting bioinformatics results for the known pneumococcal TAs RelBE2 and PezAT. A global analysis of the four identified toxins-antitoxins in the pneumococcal genomes (PezAT, RelBE2, YefM-YoeB, and Phd-Doc) showed that RelBE2 and Phd-Doc are the most conserved ones. Further, there was good correlation among TA types, clonal complexes and sequence types in the 48 pneumococcal strains analyzed.
Collapse
Affiliation(s)
- Wai Ting Chan
- Molecular Microbiology and Infection Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas Madrid, Spain
| | - Chew Chieng Yeo
- Faculty of Medicine and Health Sciences, Universiti Sultan Zainal Abidin, Kuala Terengganu Terengganu, Malaysia
| | - Ewa Sadowy
- Department of Molecular Microbiology, National Medicines Institute Warsaw, Poland
| | - Manuel Espinosa
- Molecular Microbiology and Infection Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas Madrid, Spain
| |
Collapse
|
58
|
Wieteska Ł, Skulimowski A, Cybula M, Szemraj J. Toxins vapC and pasB from prokaryotic TA modules remain active in mammalian cancer cells. Toxins (Basel) 2014; 6:2948-61. [PMID: 25271785 PMCID: PMC4210878 DOI: 10.3390/toxins6102948] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Revised: 09/23/2014] [Accepted: 09/24/2014] [Indexed: 11/17/2022] Open
Abstract
Among the great number of addictive modules which have been discovered, only a few have been characterized. However, research concerning the adoption of toxins from these systems shows their great potential as a tool for molecular biology and medicine. In our study, we tested two different toxins derived from class II addictive modules, pasAB from plasmid pTF-FC2 (Thiobacillus ferrooxidans) and vapBC 2829Rv (Mycobacterium tuberculosis), in terms of their usefulness as growth inhibitors of human cancer cell lines, namely KYSE 30, MCF-7 and HCT 116. Transfection of the pasB and vapC genes into the cells was conducted with the use of two different expression systems. Cellular effects, such as apoptosis, necrosis and changes in the cell cycle, were tested by applying flow cytometry with immunofluorescence staining. Our findings demonstrated that toxins VapC and PasB demonstrate proapoptotic activity in the human cancer cells, regardless of the expression system used. As for the toxin PasB, observed changes were more subtle than for the VapC. The level of expression for both the genes was monitored by QPCR and did not reveal statistically significant differences within the same cell line.
Collapse
Affiliation(s)
- Łukasz Wieteska
- Department of Medical Biochemistry, Medical University of Lodz, ul. Mazowiecka 6/8, 92-215 Lodz, Poland.
| | - Aleksander Skulimowski
- Department of Medical Biochemistry, Medical University of Lodz, ul. Mazowiecka 6/8, 92-215 Lodz, Poland.
| | - Magdalena Cybula
- Department of Medical Biochemistry, Medical University of Lodz, ul. Mazowiecka 6/8, 92-215 Lodz, Poland.
| | - Janusz Szemraj
- Department of Medical Biochemistry, Medical University of Lodz, ul. Mazowiecka 6/8, 92-215 Lodz, Poland.
| |
Collapse
|
59
|
Sterckx YGJ, Haesaerts S, Van Melderen L, Loris R. Crystallization and preliminary X-ray analysis of two variants of the Escherichia coli O157 ParE2-PaaA2 toxin-antitoxin complex. Acta Crystallogr F Struct Biol Commun 2014; 70:1284-91. [PMID: 25195911 PMCID: PMC4157438 DOI: 10.1107/s2053230x1401749x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 07/30/2014] [Indexed: 11/11/2022] Open
Abstract
The paaR2-paaA2-parE2 operon is a three-component toxin-antitoxin module encoded in the genome of the human pathogen Escherichia coli O157. The toxin (ParE2) and antitoxin (PaaA2) interact to form a nontoxic toxin-antitoxin complex. In this paper, the crystallization and preliminary characterization of two variants of the ParE2-PaaA2 toxin-antitoxin complex are described. Selenomethionine-derivative crystals of the full-length ParE2-PaaA2 toxin-antitoxin complex diffracted to 2.8 Å resolution and belonged to space group P41212 (or P43212), with unit-cell parameters a = b = 90.5, c = 412.3 Å. It was previously reported that the full-length ParE2-PaaA2 toxin-antitoxin complex forms a higher-order oligomer. In contrast, ParE2 and PaaA213-63, a truncated form of PaaA2 in which the first 12 N-terminal residues of the antitoxin have been deleted, form a heterodimer as shown by analytical gel filtration, dynamic light scattering and small-angle X-ray scattering. Crystals of the PaaA213-63-ParE2 complex diffracted to 2.7 Å resolution and belonged to space group P6122 (or P6522), with unit-cell parameters a = b = 91.6, c = 185.6 Å.
Collapse
Affiliation(s)
- Yann G. J. Sterckx
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
- Structural Biology Research Center, VIB, Pleinlaan 2, B-1050 Brussel, Belgium
| | - Sarah Haesaerts
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
- Structural Biology Research Center, VIB, Pleinlaan 2, B-1050 Brussel, Belgium
| | - Laurence Van Melderen
- Génétique et Physiologie Bactérienne, IBMM, Université Libre de Bruxelles (ULB), 12 Rue des Professeurs Jeener et Brachet, B-6041 Gosselies, Belgium
| | - Remy Loris
- Structural Biology Brussels, Department of Biotechnology, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussel, Belgium
- Structural Biology Research Center, VIB, Pleinlaan 2, B-1050 Brussel, Belgium
| |
Collapse
|
60
|
Functional and structural analysis of HicA3-HicB3, a novel toxin-antitoxin system of Yersinia pestis. J Bacteriol 2014; 196:3712-23. [PMID: 25112480 DOI: 10.1128/jb.01932-14] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The mechanisms involved in the virulence of Yersinia pestis, the plague pathogen, are not fully understood. In previous research, we found that a Y. pestis mutant lacking the HicB3 (YPO3369) putative orphan antitoxin was attenuated for virulence in a murine model of bubonic plague. Toxin-antitoxin systems (TASs) are widespread in prokaryotes. Most bacterial species possess many TASs of several types. In type II TASs, the toxin protein is bound and neutralized by its cognate antitoxin protein in the cytoplasm. Here we identify the hicA3 gene encoding the toxin neutralized by HicB3 and show that HicA3-HicB3 constitutes a new functional type II TAS in Y. pestis. Using biochemical and mutagenesis-based approaches, we demonstrate that the HicA3 toxin is an RNase with a catalytic histidine residue. HicB3 has two functions: it sequesters and neutralizes HicA3 by blocking its active site, and it represses transcription of the hicA3B3 operon. Gel shift assays and reporter fusion experiments indicate that the HicB3 antitoxin binds to two operators in the hicA3B3 promoter region. We solved the X-ray structures of HicB3 and the HicA3-HicB3 complex; thus, we present the first crystal structure of a TA complex from the HicAB family. HicB3 forms a tetramer that can bind two HicA3 toxin molecules. HicA3 is monomeric and folds as a double-stranded-RNA-binding domain. The HicB3 N-terminal domain occludes the HicA3 active site, whereas its C-terminal domain folds as a ribbon-helix-helix DNA-binding motif.
Collapse
|
61
|
Soo VWC, Cheng HY, Kwan BW, Wood TK. de novo synthesis of a bacterial toxin/antitoxin system. Sci Rep 2014; 4:4807. [PMID: 24797297 PMCID: PMC4010927 DOI: 10.1038/srep04807] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2014] [Accepted: 04/10/2014] [Indexed: 12/14/2022] Open
Abstract
The prevalence of toxin/antitoxin (TA) systems in almost all genomes suggests they evolve rapidly. Here we show that an antitoxin from a type V system (GhoS, an endoribonuclease specific for the mRNA of the toxin GhoT) can be converted into a novel toxin (ArT) simply by adding two mutations. In contrast to GhoS, which increases growth, the new toxin ArT decreases growth dramatically in Escherichia coli. Transmission electron microscopy analysis revealed that the nucleoid in ArT-producing cells is concentrated and appears hollow. Whole-transcriptome profiling revealed ArT cleaves 50 additional transcripts, which shows that the endoribonuclease activity of GhoS has been broadened as it was converted to ArT. Furthermore, we evolved an antitoxin for the new toxin ArT from two unrelated antitoxin templates, the protein-based antitoxin MqsA and RNA-based antitoxin ToxI, and showed that the evolved MqsA and ToxI variants are able to counteract the toxicity of ArT. In addition, the de novo TA system was found to increase persistence, a phenotype commonly associated with TA systems. Therefore, toxins and antitoxins from disparate systems can be interconverted.
Collapse
Affiliation(s)
- Valerie W. C. Soo
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Hsin-Yao Cheng
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Brian W. Kwan
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| | - Thomas K. Wood
- Department of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania, 16802, USA
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, 16802, USA
| |
Collapse
|
62
|
The ToxAvapA toxin-antitoxin locus contributes to the survival of nontypeable Haemophilus influenzae during infection. PLoS One 2014; 9:e91523. [PMID: 24621787 PMCID: PMC3951411 DOI: 10.1371/journal.pone.0091523] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Accepted: 02/13/2014] [Indexed: 12/02/2022] Open
Abstract
Nontypeable Haemophilus influenzae (NTHi) is an opportunistic pathogen that is a common cause of acute and recurrent mucosal infections. One uncharacterized NTHi toxin-antitoxin (TA) module, NTHI1912-1913, is a host inhibition of growth (higBA) homologue. We hypothesized that this locus, which we designated toxAvapA, contributed to NTHi survival during infection. We deleted toxAvapA and determined that growth of the mutant in defined media was not different from the parent strain. We tested the mutant for persistence during long-term in vitro co-culture with primary human respiratory tissues, which revealed that the ΔtoxAvapA mutant was attenuated for survival. We then performed challenge studies using the chinchilla model of otitis media and determined that mutant survival was also reduced in vivo. Following purification, the toxin exhibited ribonuclease activity on RNA in vitro, while the antitoxin did not. A microarray comparison of the transcriptome revealed that the tryptophan biosynthetic regulon was significantly repressed in the mutant compared to the parent strain. HPLC studies of conditioned medium confirmed that there was no significant difference in the concentration of tryptophan remaining in the supernatant, indicating that the uptake of tryptophan by the mutant was not affected. We conclude that the role of the NTHi toxAvapA TA module in persistence following stress is multifactorial and includes effects on essential metabolic pathways.
Collapse
|
63
|
Wen Y, Behiels E, Devreese B. Toxin-Antitoxin systems: their role in persistence, biofilm formation, and pathogenicity. Pathog Dis 2014; 70:240-9. [DOI: 10.1111/2049-632x.12145] [Citation(s) in RCA: 143] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2013] [Revised: 01/15/2014] [Accepted: 01/15/2014] [Indexed: 11/29/2022] Open
Affiliation(s)
- Yurong Wen
- Unit for Biological Mass Spectrometry and Proteomics; Laboratory for Protein Biochemistry and Biomolecular Engineering (L-ProBE); Ghent University; Ghent Belgium
| | - Ester Behiels
- Unit for Biological Mass Spectrometry and Proteomics; Laboratory for Protein Biochemistry and Biomolecular Engineering (L-ProBE); Ghent University; Ghent Belgium
| | - Bart Devreese
- Unit for Biological Mass Spectrometry and Proteomics; Laboratory for Protein Biochemistry and Biomolecular Engineering (L-ProBE); Ghent University; Ghent Belgium
| |
Collapse
|