Journal articles: 'TA SYSTEMS'

1

OuYang, Xuemei, Fucheng Yin, Jingxian Hu, Ye Liu, and Zhaohui Long. "Thermodynamic Modeling of B-Ta and B-C-Ta Systems." Journal of Phase Equilibria and Diffusion 38, no. 6 (November 3, 2017): 874–86. http://dx.doi.org/10.1007/s11669-017-0603-2.

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Li, Meng, Nannan Guo, Gaoyu Song, Yi Huang, Lecheng Wang, Yani Zhang, and Tietao Wang. "Type II Toxin–Antitoxin Systems in Pseudomonas aeruginosa." Toxins 15, no. 2 (February 17, 2023): 164. http://dx.doi.org/10.3390/toxins15020164.

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Toxin–antitoxin (TA) systems are typically composed of a stable toxin and a labile antitoxin; the latter counteracts the toxicity of the former under suitable conditions. TA systems are classified into eight types based on the nature and molecular modes of action of the antitoxin component so far. The 10 pairs of TA systems discovered and experimentally characterised in Pseudomonas aeruginosa are type II TA systems. Type II TA systems have various physiological functions, such as virulence and biofilm formation, protection host against antibiotics, persistence, plasmid maintenance, and prophage production. Here, we review the type II TA systems of P. aeruginosa, focusing on their biological functions and regulatory mechanisms, providing potential applications for the novel drug design.

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3

Massey, Robert F. "TA as a Family Systems Therapy." Transactional Analysis Journal 15, no. 2 (April 1985): 120–41. http://dx.doi.org/10.1177/036215378501500203.

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Habib, Gul, Qing Zhu, and Baolin Sun. "Bioinformatics and Functional Assessment of Toxin-Antitoxin Systems in Staphylococcus aureus." Toxins 10, no. 11 (November 14, 2018): 473. http://dx.doi.org/10.3390/toxins10110473.

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Staphylococcus aureus is a nosocomial pathogen that can cause chronic to persistent infections. Among different mediators of pathogenesis, toxin-antitoxin (TA) systems are emerging as the most prominent. These systems are frequently studied in Escherichia coli and Mycobacterial species but rarely explored in S. aureus. In the present study, we thoroughly analyzed the S. aureus genome and screened all possible TA systems using the Rasta bacteria and toxin-antitoxin database. We further searched E. coli and Mycobacterial TA homologs and selected 67 TA loci as putative TA systems in S. aureus. The host inhibition of growth (HigBA) TA family was predominantly detected in S. aureus. In addition, we detected seven pathogenicity islands in the S. aureus genome that are enriched with virulence genes and contain 26 out of 67 TA systems. We ectopically expressed multiple TA genes in E. coli and S. aureus that exhibited bacteriostatic and bactericidal effects on cell growth. The type I Fst toxin created holes in the cell wall while the TxpA toxin reduced cell size and induced cell wall septation. Besides, we identified a new TA system whose antitoxin functions as a transcriptional autoregulator while the toxin functions as an inhibitor of autoregulation. Altogether, this study provides a plethora of new as well as previously known TA systems that will revitalize the research on S. aureus TA systems.

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Xu, Jiali, Nian Zhang, Manman Cao, Sujing Ren, Ting Zeng, Minglu Qin, Xigong Zhao, Fangyan Yuan, Huanchun Chen, and Weicheng Bei. "Identification of Three Type II Toxin-Antitoxin Systems in Streptococcus suis Serotype 2." Toxins 10, no. 11 (November 13, 2018): 467. http://dx.doi.org/10.3390/toxins10110467.

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Type II toxin-antitoxin (TA) systems are highly prevalent in bacterial genomes and have been extensively studied. These modules involve in the formation of persistence cells, the biofilm formation, and stress resistance, which might play key roles in pathogen virulence. SezAT and yefM-yoeB TA modules in Streptococcus suis serotype 2 (S. suis 2) have been studied, although the other TA systems have not been identified. In this study, we investigated nine putative type II TA systems in the genome of S. suis 2 strain SC84 by bioinformatics analysis and identified three of them (two relBE loci and one parDE locus) that function as typical type II TA systems. Interestingly, we found that the introduction of the two RelBE TA systems into Escherichia coli or the induction of the ParE toxin led to cell filamentation. Promoter activity assays indicated that RelB1, RelB2, ParD, and ParDE negatively autoregulated the transcriptions of their respective TA operons, while RelBE2 positively autoregulated its TA operon transcription. Collectively, we identified three TA systems in S. suis 2, and our findings have laid an important foundation for further functional studies on these TA systems.

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Brantl, Sabine, and Peter Müller. "Toxin–Antitoxin Systems in Bacillus subtilis." Toxins 11, no. 5 (May 9, 2019): 262. http://dx.doi.org/10.3390/toxins11050262.

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Toxin–antitoxin (TA) systems were originally discovered as plasmid maintenance systems in a multitude of free-living bacteria, but were afterwards found to also be widespread in bacterial chromosomes. TA loci comprise two genes, one coding for a stable toxin whose overexpression kills the cell or causes growth stasis, and the other coding for an unstable antitoxin that counteracts toxin action. Of the currently known six types of TA systems, in Bacillus subtilis, so far only type I and type II TA systems were found, all encoded on the chromosome. Here, we review our present knowledge of these systems, the mechanisms of antitoxin and toxin action, and the regulation of their expression, and we discuss their evolution and possible physiological role.

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Kamruzzaman, Muhammad, Alma Y. Wu, and Jonathan R. Iredell. "Biological Functions of Type II Toxin-Antitoxin Systems in Bacteria." Microorganisms 9, no. 6 (June 11, 2021): 1276. http://dx.doi.org/10.3390/microorganisms9061276.

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After the first discovery in the 1980s in F-plasmids as a plasmid maintenance system, a myriad of toxin-antitoxin (TA) systems has been identified in bacterial chromosomes and mobile genetic elements (MGEs), including plasmids and bacteriophages. TA systems are small genetic modules that encode a toxin and its antidote and can be divided into seven types based on the nature of the antitoxin molecules and their mechanism of action to neutralise toxins. Among them, type II TA systems are widely distributed in chromosomes and plasmids and the best studied so far. Maintaining genetic material may be the major function of type II TA systems associated with MGEs, but the chromosomal TA systems contribute largely to functions associated with bacterial physiology, including the management of different stresses, virulence and pathogenesis. Due to growing interest in TA research, extensive work has been conducted in recent decades to better understand the physiological roles of these chromosomally encoded modules. However, there are still controversies about some of the functions associated with different TA systems. This review will discuss the most current findings and the bona fide functions of bacterial type II TA systems.

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Zhang, Enkuan, Xinpei Xu, Yun Chen, and Ying Tang. "Third-Generation Thermodynamic Descriptions for Ta-Cr and Ta-V Binary Systems." Materials 15, no. 6 (March 11, 2022): 2074. http://dx.doi.org/10.3390/ma15062074.

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The third-generation thermodynamic descriptions for Ta-Cr and Ta-V binary systems were performed to construct the reliable thermodynamic database for refractory high-entropy alloys (RHEAs) containing Laves phase. The third-generation Gibbs energy expressions of pure Cr and V in both solid and liquid phases were established, from which the thermodynamic properties and thermal vacancy can be well described. The thermodynamic descriptions of Ta-Cr and Ta-V over the whole composition and temperature regions were carried out based on the reviewed phase equilibria and thermodynamic data with the CALPHAD (CALculation of PHAse Diagrams) approach. Specifically, the thermodynamic parameters of C14 and C15 Laves phases were evaluated by combining the theoretically computed and experimentally measured thermodynamic properties as well as the semiempirical relations. The calculated phase diagrams and thermodynamic properties in Ta-Cr and Ta-V systems according to the present thermodynamic parameters had a nice agreement with the experimental data even down to 0 K, indicating the reliability of the present modeling.

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9

Rafaja, D., W. Lengauer, and H. Wiesenberger. "Non-metal diffusion coefficients for the Ta–C and Ta–N systems." Acta Materialia 46, no. 10 (June 1998): 3477–83. http://dx.doi.org/10.1016/s1359-6454(98)00036-6.

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10

Levante, Alessia, Camilla Lazzi, Giannis Vatsellas, Dimitris Chatzopoulos, Vasilis S. Dionellis, Periklis Makrythanasis, Erasmo Neviani, and Claudia Folli. "Genome Sequencing of five Lacticaseibacillus Strains and Analysis of Type I and II Toxin-Antitoxin System Distribution." Microorganisms 9, no. 3 (March 21, 2021): 648. http://dx.doi.org/10.3390/microorganisms9030648.

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The analysis of bacterial genomes is a potent tool to investigate the distribution of specific traits related to the ability of surviving in particular environments. Among the traits associated with the adaptation to hostile conditions, toxin–antitoxin (TA) systems have recently gained attention in lactic acid bacteria. In this work, genome sequences of Lacticaseibacillus strains of dairy origin were compared, focusing on the distribution of type I TA systems homologous to Lpt/RNAII and of the most common type II TA systems. A high number of TA systems have been identified spread in all the analyzed strains, with type I TA systems mainly located on plasmid DNA. The type II TA systems identified in these strains highlight the diversity of encoded toxins and antitoxins and their organization. This study opens future perspectives on the use of genomic data as a resource for the study of TA systems distribution and prevalence in microorganisms of industrial relevance.

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11

Hari Kumar, K. C., T. Van Rompaey, and P. Wollants. "Thermodynamic calculation of the phase diagram of the Co–Nb–Ta system." International Journal of Materials Research 93, no. 11 (November 1, 2002): 1146–53. http://dx.doi.org/10.1515/ijmr-2002-0196.

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Abstract A thermodynamic description of the ternary system Co–Nb–Ta is obtained by combining the descriptions of the lower-order systems according to the CALPHAD method. The thermodynamic data set for the binary Co–Nb system is taken from [1], where a new thermodynamic model for the μ-phase was introduced. The μ-phase appears in several transition metal systems, including Co–Ta. The model is applied to the Co–Ta system and extended to the ternary Co–Nb–Ta system. The thermodynamic descriptions of the systems Co–Ta, Nb–Ta and Co–Nb–Ta are reported in the present work.

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12

Soutourina, Olga. "Type I Toxin-Antitoxin Systems in Clostridia." Toxins 11, no. 5 (May 6, 2019): 253. http://dx.doi.org/10.3390/toxins11050253.

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Type I toxin-antitoxin (TA) modules are abundant in both bacterial plasmids and chromosomes and usually encode a small hydrophobic toxic protein and an antisense RNA acting as an antitoxin. The RNA antitoxin neutralizes toxin mRNA by inhibiting its translation and/or promoting its degradation. This review summarizes our current knowledge of the type I TA modules identified in Clostridia species focusing on the recent findings in the human pathogen Clostridium difficile. More than ten functional type I TA modules have been identified in the genome of this emerging enteropathogen that could potentially contribute to its fitness and success inside the host. Despite the absence of sequence homology, the comparison of these newly identified type I TA modules with previously studied systems in other Gram-positive bacteria, i.e., Bacillus subtilis and Staphylococcus aureus, revealed some important common traits. These include the conservation of characteristic sequence features for small hydrophobic toxic proteins, the localization of several type I TA within prophage or prophage-like regions and strong connections with stress response. Potential functions in the stabilization of genome regions, adaptations to stress conditions and interactions with CRISPR-Cas defence system, as well as promising applications of TA for genome-editing and antimicrobial developments are discussed.

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13

Kim, Younghoon, Xiaoxue Wang, Qun Ma, Xue-Song Zhang, and Thomas K. Wood. "Toxin-Antitoxin Systems in Escherichia coli Influence Biofilm Formation through YjgK (TabA) and Fimbriae." Journal of Bacteriology 191, no. 4 (December 5, 2008): 1258–67. http://dx.doi.org/10.1128/jb.01465-08.

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ABSTRACT The roles of toxin-antitoxin (TA) systems in bacteria have been debated. Here, the role of five TA systems in regard to biofilm development was investigated (listed as toxin/antitoxin: MazF/MazE, RelE/RelB, ChpB, YoeB/YefM, and YafQ/DinJ). Although these multiple TA systems were reported previously to not impact bacterial fitness, we found that deletion of the five TA systems decreased biofilm formation initially (8 h) on three different surfaces and then increased biofilm formation (24 h) by decreasing biofilm dispersal. Whole-transcriptome profiling revealed that the deletion of the five TA systems induced expression of a single gene, yjgK, which encodes an uncharacterized protein; quantitative real-time PCR (qRT-PCR) confirmed consistent induction of this gene (at 8, 15, and 24 h). Corroborating the complex phenotype seen upon deleting the TA systems, overexpression of YjgK decreased biofilm formation at 8 h and increased biofilm formation at 24 h; deletion of yjgK also affected biofilm formation in the expected manner by increasing biofilm formation after 8 h and decreasing biofilm formation after 24 h. In addition, YjgK significantly reduced biofilm dispersal. Whole-transcriptome profiling revealed YjgK represses fimbria genes at 8 h (corroborated by qRT-PCR and a yeast agglutination assay), which agrees with the decrease in biofilm formation upon deleting the five TA systems at 8 h, as well as that seen upon overexpressing YjgK. Sand column assays confirmed that deleting the five TA systems reduced cell attachment. Furthermore, deletion of each of the five toxins increased biofilm formation at 8 h, and overexpression of the five toxins repressed biofilm formation at 8 h, a result that is opposite that of deleting all five TA systems; this suggests that complex regulation occurs involving the antitoxins. Also, the ability of the global regulator Hha to reduce biofilm formation was dependent on the presence of these TA systems. Hence, we suggest that one role of TA systems is to influence biofilm formation.

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14

Tandon, Himani, Akhila Melarkode Vattekatte, Narayanaswamy Srinivasan, and Sankaran Sandhya. "Molecular and Structural Basis of Cross-Reactivity in M. tuberculosis Toxin–Antitoxin Systems." Toxins 12, no. 8 (July 29, 2020): 481. http://dx.doi.org/10.3390/toxins12080481.

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Mycobacterium tuberculosis genome encodes over 80 toxin–antitoxin (TA) systems. While each toxin interacts with its cognate antitoxin, the abundance of TA systems presents an opportunity for potential non-cognate interactions. TA systems mediate manifold interactions to manage pathogenicity and stress response network of the cell and non-cognate interactions may play vital roles as well. To address if non-cognate and heterologous interactions are feasible and to understand the structural basis of their interactions, we have performed comprehensive computational analyses on the available 3D structures and generated structural models of paralogous M. tuberculosis VapBC and MazEF TA systems. For a majority of the TA systems, we show that non-cognate toxin–antitoxin interactions are structurally incompatible except for complexes like VapBC15 and VapBC11, which show similar interfaces and potential for cross-reactivity. For TA systems which have been experimentally shown earlier to disfavor non-cognate interactions, we demonstrate that they are structurally and stereo-chemically incompatible. For selected TA systems, our detailed structural analysis identifies specificity conferring residues. Thus, our work improves the current understanding of TA interfaces and generates a hypothesis based on congenial binding site, geometric complementarity, and chemical nature of interfaces. Overall, our work offers a structure-based explanation for non-cognate toxin-antitoxin interactions in M. tuberculosis.

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Norouzi, Masoumeh, Abbas Maleki, Elham Aboualigalehdari, and Sobhan Ghafourian. "Type II toxin- antitoxin systems in clinical isolates of antibiotic resistant Acinetobacter baumannii." Genetika 54, no. 2 (2022): 625–32. http://dx.doi.org/10.2298/gensr2202625n.

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The over use of antibiotics to treat infections in humans and animals made a phenomenon of the antibiotic-resistant bacteria. While studies focused to find on new antibiotics but, identification of novel antibacterial targets in bacteria is very important. By Toxin antitoxin systems this hypothesis could be done, whereas by the activation of a toxin or inactivation of an antitoxin, the raised toxin kills the bacterium. These systems are attractive target for antimicrobial therapy. However, the most important step for potency of TA system, as an antibacterial target, is to identify a TA system that is prevalent in all resistant clinical isolates. So, the prevalence of different TA systems among clinical isolates of Acinetobacter baumannii in Emam khomeini hospital, Ilam, Iran was evaluated to determine which TA system is prevalent in all antibiotic resistant A. baumannii. So, one hundred A. baumannii clinical isolates were identified during one-year period in Emam khomeini hospital, Ilam, Iran. A. baumannii clinical isolates were isolated from hospitalized patients in ICU and burn patients. All isolates were resistant to at least one antibiotic. Then, the isolates were subjected to evaluation to find mazEF and higBA TA genes by PCR. The results showed the frequency of mazEF and highBA TA genes in all isolates was 72% and 39%, respectively. mazEF or higBA TA systems are not presented in all isolates. So, the potency of these two TA systems are in challenged. Also, all isolates were not positive for one TA gene. So, more research in different geographical area should be done with functionality of TA genes.

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Hill, Virginia, Hatice Akarsu, Rubén Sánchez Barbarroja, Valentina L. Cippà, Peter Kuhnert, Martin Heller, Laurent Falquet, et al. "Minimalistic mycoplasmas harbor different functional toxin-antitoxin systems." PLOS Genetics 17, no. 10 (October 21, 2021): e1009365. http://dx.doi.org/10.1371/journal.pgen.1009365.

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Mycoplasmas are minute bacteria controlled by very small genomes ranging from 0.6 to 1.4 Mbp. They encompass several important medical and veterinary pathogens that are often associated with a wide range of chronic diseases. The long persistence of mycoplasma cells in their hosts can exacerbate the spread of antimicrobial resistance observed for many species. However, the nature of the virulence factors driving this phenomenon in mycoplasmas is still unclear. Toxin-antitoxin systems (TA systems) are genetic elements widespread in many bacteria that were historically associated with bacterial persistence. Their presence on mycoplasma genomes has never been carefully assessed, especially for pathogenic species. Here we investigated three candidate TA systems in M. mycoides subsp. capri encoding a (i) novel AAA-ATPase/subtilisin-like serine protease module, (ii) a putative AbiEii/AbiEi pair and (iii) a putative Fic/RelB pair. We sequence analyzed fourteen genomes of M. mycoides subsp. capri and confirmed the presence of at least one TA module in each of them. Interestingly, horizontal gene transfer signatures were also found in several genomic loci containing TA systems for several mycoplasma species. Transcriptomic and proteomic data confirmed differential expression profiles of these TA systems during mycoplasma growth in vitro. While the use of heterologous expression systems based on E. coli and B. subtilis showed clear limitations, the functionality and neutralization capacities of all three candidate TA systems were successfully confirmed using M. capricolum subsp. capricolum as a host. Additionally, M. capricolum subsp. capricolum was used to confirm the presence of functional TA system homologs in mycoplasmas of the Hominis and Pneumoniae phylogenetic groups. Finally, we showed that several of these M. mycoides subsp. capri toxins tested in this study, and particularly the subtilisin-like serine protease, could be used to establish a kill switch in mycoplasmas for industrial applications.

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Klimkaitė, Laurita, Julija Armalytė, Jūratė Skerniškytė, and Edita Sužiedėlienė. "The Toxin-Antitoxin Systems of the Opportunistic Pathogen Stenotrophomonas maltophilia of Environmental and Clinical Origin." Toxins 12, no. 10 (October 1, 2020): 635. http://dx.doi.org/10.3390/toxins12100635.

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Stenotrophomonas maltophilia is a ubiquitous environmental bacterium that has recently emerged as a multidrug-resistant opportunistic pathogen causing bloodstream, respiratory, and urinary tract infections. The connection between the commensal environmental S. maltophilia and the opportunistic pathogen strains is still under investigation. Bacterial toxin–antitoxin (TA) systems have been previously associated with pathogenic traits, such as biofilm formation and resistance to antibiotics, which are important in clinical settings. The same species of the bacterium can possess various sets of TAs, possibly influencing their overall stress response. While the TA systems of other important opportunistic pathogens have been researched, nothing is known about the TA systems of S. maltophilia. Here, we report the identification and characterization of S. maltophilia type II TA systems and their prevalence in the isolates of clinical and environmental origins. We found 49 putative TA systems by bioinformatic analysis in S. maltophilia genomes. Despite their even spread in sequenced S. maltophilia genomes, we observed that relBE, hicAB, and previously undescribed COG3832-ArsR operons were present solely in clinical S. maltophilia isolates collected in Lithuania, while hipBA was more frequent in the environmental ones. The kill-rescue experiments in Escherichia coli proved higBA, hicAB, and relBE systems to be functional TA modules. Together with different TA profiles, the clinical S. maltophilia isolates exhibited stronger biofilm formation, increased antibiotic, and serum resistance compared to environmental isolates. Such tendencies suggest that certain TA systems could be used as indicators of virulence traits.

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Horesh, Gal, Cinzia Fino, Alexander Harms, Matthew J. Dorman, Leopold Parts, Kenn Gerdes, Eva Heinz, and Nicholas R. Thomson. "Type II and type IV toxin–antitoxin systems show different evolutionary patterns in the global Klebsiella pneumoniae population." Nucleic Acids Research 48, no. 8 (March 31, 2020): 4357–70. http://dx.doi.org/10.1093/nar/gkaa198.

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Abstract The Klebsiella pneumoniae species complex includes important opportunistic pathogens which have become public health priorities linked to major hospital outbreaks and the recent emergence of multidrug-resistant hypervirulent strains. Bacterial virulence and the spread of multidrug resistance have previously been linked to toxin–antitoxin (TA) systems. TA systems encode a toxin that disrupts essential cellular processes, and a cognate antitoxin which counteracts this activity. Whilst associated with the maintenance of plasmids, they also act in bacterial immunity and antibiotic tolerance. However, the evolutionary dynamics and distribution of TA systems in clinical pathogens are not well understood. Here, we present a comprehensive survey and description of the diversity of TA systems in 259 clinically relevant genomes of K. pneumoniae. We show that TA systems are highly prevalent with a median of 20 loci per strain. Importantly, these toxins differ substantially in their distribution patterns and in their range of cognate antitoxins. Classification along these properties suggests different roles of TA systems and highlights the association and co-evolution of toxins and antitoxins.

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Kang, Sung-Min, Do-Hee Kim, Chenglong Jin, and Bong-Jin Lee. "A Systematic Overview of Type II and III Toxin-Antitoxin Systems with a Focus on Druggability." Toxins 10, no. 12 (December 4, 2018): 515. http://dx.doi.org/10.3390/toxins10120515.

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Toxin-antitoxin (TA) systems are known to play various roles in physiological processes, such as gene regulation, growth arrest and survival, in bacteria exposed to environmental stress. Type II TA systems comprise natural complexes consisting of protein toxins and antitoxins. Each toxin and antitoxin participates in distinct regulatory mechanisms depending on the type of TA system. Recently, peptides designed by mimicking the interfaces between TA complexes showed its potential to activate the activity of toxin by competing its binding counterparts. Type II TA systems occur more often in pathogenic bacteria than in their nonpathogenic kin. Therefore, they can be possible drug targets, because of their high abundance in some pathogenic bacteria, such as Mycobacterium tuberculosis. In addition, recent bioinformatic analyses have shown that type III TA systems are highly abundant in the intestinal microbiota, and recent clinical studies have shown that the intestinal microbiota is linked to inflammatory diseases, obesity and even several types of cancer. We therefore focused on exploring the putative relationship between intestinal microbiota-related human diseases and type III TA systems. In this paper, we review and discuss the development of possible druggable materials based on the mechanism of type II and type III TA system.

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Zhan, Waner, Jianyun Yao, Kaihao Tang, Yangmei Li, Yunxue Guo, and Xiaoxue Wang. "Characterization of Two Toxin-Antitoxin Systems in Deep-Sea Streptomyces sp. SCSIO 02999." Marine Drugs 17, no. 4 (April 4, 2019): 211. http://dx.doi.org/10.3390/md17040211.

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Toxin-antitoxin (TA) systems are ubiquitous and abundant genetic elements in bacteria and archaea. Most previous TA studies have focused on commensal and pathogenic bacteria, but have rarely focused on marine bacteria, especially those isolated from the deep sea. Here, we identified and characterized three putative TA pairs in the deep-sea-derived Streptomyces sp. strain SCSIO 02999. Our results showed that Orf5461/Orf5462 and Orf2769/Orf2770 are bona fide TA pairs. We provide several lines of evidence to demonstrate that Orf5461 and Orf5462 constitute a type-II TA pair that are homologous to the YoeB/YefM TA pair from Escherichia coli. Although YoeB from SCSIO 02999 was toxic to an E. coli host, the homologous YefM antitoxin from SCSIO 02999 did not neutralize the toxic effect of YoeB from E. coli. For the Orf2769/Orf2770 TA pair, Orf2769 overexpression caused significant cell elongation and could lead to cell death in E. coli, and the neighboring Orf2770 could neutralize the toxic effect of Orf2769. However, no homologous toxin or antitoxin was found for this pair, and no direct interaction was found between Orf2769 and Orf2770. These results suggest that Orf2769 and Orf2770 may constitute a novel TA pair. Thus, deep-sea bacteria harbor typical and novel TA pairs. The biochemical and physiological functions of different TAs in deep-sea bacteria warrant further investigation.

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Syed, Mohammad Adnan, and Céline M. Lévesque. "Chromosomal bacterial type II toxin–antitoxin systems." Canadian Journal of Microbiology 58, no. 5 (May 2012): 553–62. http://dx.doi.org/10.1139/w2012-025.

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Most prokaryotic chromosomes contain a number of toxin–antitoxin (TA) modules consisting of a pair of genes that encode 2 components, a stable toxin and its cognate labile antitoxin. TA systems are also known as addiction modules, since the cells become “addicted” to the short-lived antitoxin product (the unstable antitoxin is degraded faster than the more stable toxin) because its de novo synthesis is essential for their survival. While toxins are always proteins, antitoxins are either RNAs (type I, type III) or proteins (type II). Type II TA systems are widely distributed throughout the chromosomes of almost all free-living bacteria and archaea. The vast majority of type II toxins are mRNA-specific endonucleases arresting cell growth through the mechanism of RNA cleavage, thus preventing the translation process. The physiological role of chromosomal type II TA systems still remains the subject of debate. This review describes the currently known type II toxins and their characteristics. The different hypotheses that have been proposed to explain their role in bacterial physiology are also discussed.

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Wadie, Bishoy, Mohamed A. Abdel-Fattah, Alshymaa Yousef, Shaimaa F. Mouftah, Mohamed Elhadidy, and Tamer Z. Salem. "In Silico Characterization of Toxin-Antitoxin Systems in Campylobacter Isolates Recovered from Food Sources and Sporadic Human Illness." Genes 12, no. 1 (January 7, 2021): 72. http://dx.doi.org/10.3390/genes12010072.

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Campylobacter spp. represents the most common cause of gastroenteritis worldwide with the potential to cause serious sequelae. The ability of Campylobacter to survive stressful environmental conditions has been directly linked with food-borne illness. Toxin-antitoxin (TA) modules play an important role as defense systems against antimicrobial agents and are considered an invaluable strategy harnessed by bacterial pathogens to survive in stressful environments. Although TA modules have been extensively studied in model organisms such as Escherichia coli K12, the TA landscape in Campylobacter remains largely unexplored. Therefore, in this study, a comprehensive in silico screen of 111 Campylobacter (90 C.jejuni and 21 C.coli) isolates recovered from different food and clinical sources was performed. We identified 10 type II TA systems belonging to four TA families predicted in Campylobacter genomes. Furthermore, there was a significant association between the clonal population structure and distribution of TA modules; more specifically, most (12/13) of the Campylobacter isolates belonging to ST-21 isolates possess HicB-HicA TA modules. Finally, we observed a high degree of shared synteny among isolates bearing certain TA systems or even coexisting pairs of TA systems. Collectively, these findings provide useful insights about the distribution of TA modules in a heterogeneous pool of Campylobacter isolates from different sources, thus developing a better understanding regarding the mechanisms by which these pathogens survive stressful environmental conditions, which will further aid in the future designing of more targeted antimicrobials.

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Wadie, Bishoy, Mohamed A. Abdel-Fattah, Alshymaa Yousef, Shaimaa F. Mouftah, Mohamed Elhadidy, and Tamer Z. Salem. "In Silico Characterization of Toxin-Antitoxin Systems in Campylobacter Isolates Recovered from Food Sources and Sporadic Human Illness." Genes 12, no. 1 (January 7, 2021): 72. http://dx.doi.org/10.3390/genes12010072.

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Campylobacter spp. represents the most common cause of gastroenteritis worldwide with the potential to cause serious sequelae. The ability of Campylobacter to survive stressful environmental conditions has been directly linked with food-borne illness. Toxin-antitoxin (TA) modules play an important role as defense systems against antimicrobial agents and are considered an invaluable strategy harnessed by bacterial pathogens to survive in stressful environments. Although TA modules have been extensively studied in model organisms such as Escherichia coli K12, the TA landscape in Campylobacter remains largely unexplored. Therefore, in this study, a comprehensive in silico screen of 111 Campylobacter (90 C.jejuni and 21 C.coli) isolates recovered from different food and clinical sources was performed. We identified 10 type II TA systems belonging to four TA families predicted in Campylobacter genomes. Furthermore, there was a significant association between the clonal population structure and distribution of TA modules; more specifically, most (12/13) of the Campylobacter isolates belonging to ST-21 isolates possess HicB-HicA TA modules. Finally, we observed a high degree of shared synteny among isolates bearing certain TA systems or even coexisting pairs of TA systems. Collectively, these findings provide useful insights about the distribution of TA modules in a heterogeneous pool of Campylobacter isolates from different sources, thus developing a better understanding regarding the mechanisms by which these pathogens survive stressful environmental conditions, which will further aid in the future designing of more targeted antimicrobials.

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Hansen, Sanni, Kasper Klintoe, Martin Austevoll, Keith E. Baptiste, and Julie Fjeldborg. "Equine airway inflammation in loose-housing management compared with pasture and conventional stabling." Veterinary Record 184, no. 19 (March 9, 2019): 590. http://dx.doi.org/10.1136/vr.104580.

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Icelandic horses are often stabled in loose-housing systems, and to date this type of stabling has not been evaluated with regard to its potential impact on respiratory health. The objective was to assess if differences in management systems (eg, conventional stable, loose housing and pasture only) affect the degree of airway inflammation, evaluated by cytology of tracheal aspirate (TA) and bronchoalveolar lavage (BAL) fluid. In total, 84 Icelandic horses (aged 8.1±4.6 years) housed under three different management systems (conventional stables [n=29], loose-house systems [n=29] and pasture [n=26]) were included. Endoscopy including mucus scoring, TA and BAL was performed. TA and BAL cytologies were evaluated by performing both the total cell count (TCC) and the differential cell count (DCC). Significantly higher BAL neutrophil DCC (P=0.032, P=0.040) and TA TCC (P=0.007, P=0.028) were found for each of the two groups of horses with indoor access (conventional stable and loose housing) compared with the pasture group. Regardless of stabling environment, weak positive correlations were found between TA and BAL TCC (r=0.37, P<0.001), between TA TCC and TA neutrophil ratio (r=0.33, P=0.002), as well as between TA and BAL neutrophil ratio (r=0.39, P=<0.001). A larger proportion of horses with indoor access showed evidence of subclinical airway inflammation characterised by an increase in TA and BAL neutrophil ratios.

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Sala, Ambre Julie, Patricia Bordes, Sara Ayala, Nawel Slama, Samuel Tranier, Michèle Coddeville, Anne-Marie Cirinesi, Marie-Pierre Castanié-Cornet, Lionel Mourey, and Pierre Genevaux. "Directed evolution of SecB chaperones toward toxin-antitoxin systems." Proceedings of the National Academy of Sciences 114, no. 47 (November 7, 2017): 12584–89. http://dx.doi.org/10.1073/pnas.1710456114.

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SecB chaperones assist protein export in bacteria. However, certain SecB family members have diverged to become specialized toward the control of toxin-antitoxin (TA) systems known to promote bacterial adaptation to stress and persistence. In such tripartite TA-chaperone (TAC) systems, the chaperone was shown to assist folding and to prevent degradation of its cognate antitoxin, thus facilitating inhibition of the toxin. Here, we used both the export chaperone SecB ofEscherichia coliand the tripartite TAC system ofMycobacterium tuberculosisas a model to investigate how generic chaperones can specialize toward the control of TA systems. Through directed evolution of SecB, we have identified and characterized mutations that specifically improve the ability of SecB to control our model TA system without affecting its function in protein export. Such a remarkable plasticity of SecB chaperone function suggests that its substrate binding surface can be readily remodeled to accommodate specific clients.

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Tsilibaris, Virginie, Geneviève Maenhaut-Michel, Natacha Mine, and Laurence Van Melderen. "What Is the Benefit to Escherichia coli of Having Multiple Toxin-Antitoxin Systems in Its Genome?" Journal of Bacteriology 189, no. 17 (May 18, 2007): 6101–8. http://dx.doi.org/10.1128/jb.00527-07.

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ABSTRACT The Escherichia coli K-12 chromosome encodes at least five proteic toxin-antitoxin (TA) systems. The mazEF and relBE systems have been extensively characterized and were proposed to be general stress response modules. On one hand, mazEF was proposed to act as a programmed cell death system that is triggered by a variety of stresses. On the other hand, relBE and mazEF were proposed to serve as growth modulators that induce a dormancy state during amino acid starvation. These conflicting hypotheses led us to test a possible synergetic effect of the five characterized E. coli TA systems on stress response. We compared the behavior of a wild-type strain and its derivative devoid of the five TA systems under various stress conditions. We were unable to detect TA-dependent programmed cell death under any of these conditions, even under conditions previously reported to induce it. Thus, our results rule out the programmed-cell-death hypothesis. Moreover, the presence of the five TA systems advantaged neither recovery from the different stresses nor cell growth under nutrient-limited conditions in competition experiments. This casts a doubt on whether TA systems significantly influence bacterial fitness and competitiveness during non-steady-state growth conditions.

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Boss, Lidia, and Barbara Kędzierska. "Bacterial Toxin-Antitoxin Systems’ Cross-Interactions—Implications for Practical Use in Medicine and Biotechnology." Toxins 15, no. 6 (June 4, 2023): 380. http://dx.doi.org/10.3390/toxins15060380.

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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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Hosseini, Mandana, Jamileh Nowroozi, and Nour Amirmozafari. "The effect of type II toxin-antitoxin systems on methicillinresistant Staphylococcus aureus persister cell formation and antibiotic tolerance." Acta Biologica Szegediensis 65, no. 1 (August 23, 2021): 113–17. http://dx.doi.org/10.14232/abs.2021.1.113-117.

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Persister cells are defi ned as a subpopulation of bacteria in a dormant state with the ability to reduce bacterial metabolism and they are involved in antibiotic tolerance. Toxin-antitoxin (TA) systems have been previously suggested as important players in persistence. Therefore, this study aimed to study the involvement of TA systems in persister cell formation in methicillin-resistant Staphylococcus aureus following antibiotic exposure. Using TADB and RASTA database, two type II TA systems including MazF/MazE and RelE/RelB were predicted in S. aureus. The presence of these TA genes was determined in 5 methicillin-resistant S. aureus isolates and the standard strain S. aureus subsp. aureus N315 using PCR method. To induce persistence, isolates were exposed to lethal doses of ciprofl oxacin and the expression of the studied TA system genes was measured after 5 h using Real-Time PCR. According to our results, all the studied isolates harbored the TA system genes. S. aureus was highly capable of persister cell formation following exposure to sub-MIC of ciprofl oxacin and RT-qPCR showed a signifi cant increase in the expression of the MazEF and RelBE loci, indicating their potential role in antibiotic tolerance. Considering the importance of antibiotic tolerance, further studies on persister cell formation and TA systems involved in this phenomenon are required to effi ciently target these systems.

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Sezer, Esma, and İpek Öztürk. "Mild steel protection with tannic and polyaspartic acid in cooling systems." Anti-Corrosion Methods and Materials 66, no. 5 (September 2, 2019): 583–94. http://dx.doi.org/10.1108/acmm-04-2019-2105.

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Purpose Tannic acid (TA) is one of the green corrosion inhibitors for mild steel; its anti-corrosive performance in alkaline water on mild steel when it is used together with polyaspartic acid (PASA) still has not been investigated. The purpose of this study is to develop an effective, biodegradable and environment-friendly novel corrosion inhibitor based on TA and PASA as an alternative to the conventional inorganic inhibitors for mild steel in decarbonised water, which is common in cooling systems. Design/methodology/approach Corrosion inhibition mechanism is investigated by electrochemical techniques such as polarisation measurements and electrochemical impedance spectroscopy, and results were evaluated to determine the optimum inhibitor concentration for industrial applications. Additionally, practice-like conditions are carried out in pilot plant studies to simulate the conditions in cooling systems. Thus, the efficiencies of the inhibitors are evaluated through both weight loss and linear polarisation resistance measurements. Moreover, the corrosion product is characterised by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) and Fourier-transform infrared spectroscopy (FTIR) analysis. Findings TA shows high inhibition efficiency especially towards pitting corrosion for mild steel in decarbonised water. PASA addition in the cooling systems improves the inhibition efficiency of TA, and at lower concentrations of TA + PASA, it is possible to obtained better inhibition efficiency than TA alone at higher inhibitor amounts, which is essential in economic and environmental aspect. Originality/value A blended inhibitor program including TA and PASA with suggested concentrations in this work can be used as an environmental friendly treatment concept for the mild steel corrosion inhibition at cooling systems.

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Alkhalili, Rawana, Joel Wallenius, and Björn Canbäck. "Towards Exploring Toxin-Antitoxin Systems in Geobacillus: A Screen for Type II Toxin-Antitoxin System Families in a Thermophilic Genus." International Journal of Molecular Sciences 20, no. 23 (November 22, 2019): 5869. http://dx.doi.org/10.3390/ijms20235869.

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The toxin-antitoxin (TA) systems have been attracting attention due to their role in regulating stress responses in prokaryotes and their biotechnological potential. Much recognition has been given to type II TA system of mesophiles, while thermophiles have received merely limited attention. Here, we are presenting the putative type II TA families encoded on the genomes of four Geobacillus strains. We employed the TA finder tool to mine for TA-coding genes and manually curated the results using protein domain analysis tools. We also used the NCBI BLAST, Operon Mapper, ProOpDB, and sequence alignment tools to reveal the geobacilli TA features. We identified 28 putative TA pairs, distributed over eight TA families. Among the identified TAs, 15 represent putative novel toxins and antitoxins, belonging to the MazEF, MNT-HEPN, ParDE, RelBE, and XRE-COG2856 TA families. We also identified a potentially new TA composite, AbrB-ParE. Furthermore, we are suggesting the Geobacillus acetyltransferase TA (GacTA) family, which potentially represents one of the unique TA families with a reverse gene order. Moreover, we are proposing a hypothesis on the xre-cog2856 gene expression regulation, which seems to involve the c-di-AMP. This study aims for highlighting the significance of studying TAs in Geobacillus and facilitating future experimental research.

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Dijkink, Suzan, Charlie J. Nederpelt, Pieta Krijnen, George C. Velmahos, and Inger B. Schipper. "Trauma systems around the world." Journal of Trauma and Acute Care Surgery 83, no. 5 (November 2017): 917–25. http://dx.doi.org/10.1097/ta.0000000000001633.

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Saavedra De Bast, Manuel, Natacha Mine, and Laurence Van Melderen. "Chromosomal Toxin-Antitoxin Systems May Act as Antiaddiction Modules." Journal of Bacteriology 190, no. 13 (April 25, 2008): 4603–9. http://dx.doi.org/10.1128/jb.00357-08.

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ABSTRACT Toxin-antitoxin (TA) systems are widespread among bacterial chromosomes and mobile genetic elements. Although in plasmids TA systems have a clear role in their vertical inheritance by selectively killing plasmid-free daughter cells (postsegregational killing or addiction phenomenon), the physiological role of chromosomally encoded ones remains under debate. The assumption that chromosomally encoded TA systems are part of stress response networks and/or programmed cell death machinery has been called into question recently by the observation that none of the five canonical chromosomally encoded TA systems in the Escherichia coli chromosome seem to confer any selective advantage under stressful conditions (V. Tsilibaris, G. Maenhaut-Michel, N. Mine, and L. Van Melderen, J. Bacteriol. 189:6101-6108, 2007). Their prevalence in bacterial chromosomes indicates that they might have been acquired through horizontal gene transfer. Once integrated in chromosomes, they might in turn interfere with their homologues encoded by mobile genetic elements. In this work, we show that the chromosomally encoded Erwinia chrysanthemi ccd (control of cell death) (ccdEch ) system indeed protects the cell against postsegregational killing mediated by its F-plasmid ccd (ccd F) homologue. Moreover, competition experiments have shown that this system confers a fitness advantage under postsegregational conditions mediated by the ccd F system. We propose that ccdEch acts as an antiaddiction module and, more generally, that the integration of TA systems in bacterial chromosomes could drive the evolution of plasmid-encoded ones and select toxins that are no longer recognized by the antiaddiction module.

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Massey, Robert F. "Integrating Systems Theory and TA in Couples Therapy." Transactional Analysis Journal 19, no. 3 (July 1989): 128–36. http://dx.doi.org/10.1177/036215378901900303.

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Gil, Fernando, Marjorie Pizarro-Guajardo, Ricardo Álvarez, Marco Garavaglia, and Daniel Paredes-Sabja. "Clostridium difficilerecurrent infection: possible implication of TA systems." Future Microbiology 10, no. 10 (October 2015): 1649–57. http://dx.doi.org/10.2217/fmb.15.94.

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De Sousa, V. C., M. M. Oliveira, M. Orlandi, E. R. Leite, and E. Longo. "(Ta, Cr)-doped {T}{i}O2 electroceramic systems." Journal of Materials Science: Materials in Electronics 17, no. 1 (January 2006): 79–84. http://dx.doi.org/10.1007/s10854-005-5145-4.

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Wang, Xiaoxue, and Thomas K. Wood. "Toxin-Antitoxin Systems Influence Biofilm and Persister Cell Formation and the General Stress Response." Applied and Environmental Microbiology 77, no. 16 (June 17, 2011): 5577–83. http://dx.doi.org/10.1128/aem.05068-11.

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ABSTRACTIn many genomes, toxin-antitoxin (TA) systems have been identified; however, their role in cell physiology has been unclear. Here we examine the evidence that TA systems are involved in biofilm formation and persister cell formation and that these systems may be important regulators of the switch from the planktonic to the biofilm lifestyle as a stress response by their control of secondary messenger 3′,5′-cyclic diguanylic acid. Specifically, upon stress, the sequence-specific mRNA interferases MqsR and MazF mediate cell survival. In addition, we propose that TA systems are not redundant, as they may have developed to respond to specific stresses.

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Równicki, Marcin, Robert Lasek, Joanna Trylska, and Dariusz Bartosik. "Targeting Type II Toxin–Antitoxin Systems as Antibacterial Strategies." Toxins 12, no. 9 (September 4, 2020): 568. http://dx.doi.org/10.3390/toxins12090568.

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The identification of novel targets for antimicrobial agents is crucial for combating infectious diseases caused by evolving bacterial pathogens. Components of bacterial toxin–antitoxin (TA) systems have been recognized as promising therapeutic targets. These widespread genetic modules are usually composed of two genes that encode a toxic protein targeting an essential cellular process and an antitoxin that counteracts the activity of the toxin. Uncontrolled toxin expression may elicit a bactericidal effect, so they may be considered “intracellular molecular bombs” that can lead to elimination of their host cells. Based on the molecular nature of antitoxins and their mode of interaction with toxins, TA systems have been classified into six groups. The most prevalent are type II TA systems. Due to their ubiquity among clinical isolates of pathogenic bacteria and the essential processes targeted, they are promising candidates for the development of novel antimicrobial strategies. In this review, we describe the distribution of type II TA systems in clinically relevant human pathogens, examine how these systems could be developed as the targets for novel antibacterials, and discuss possible undesirable effects of such therapeutic intervention, such as the induction of persister cells, biofilm formation and toxicity to eukaryotic cells.

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Tigane, Samir, Fayçal Guerrouf, Nadia Hamani, Laid Kahloul, Mohamed Khalgui, and Masood Ashraf Ali. "Dynamic Timed Automata for Reconfigurable System Modeling and Verification." Axioms 12, no. 3 (February 22, 2023): 230. http://dx.doi.org/10.3390/axioms12030230.

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Modern discrete-event systems (DESs) are often characterized by their dynamic structures enabling highly flexible behaviors that can respond in real time to volatile environments. On the other hand, timed automata (TA) are powerful tools used to design various DESs. However, they lack the ability to naturally describe dynamic-structure reconfigurable systems. Indeed, TA are characterized by their rigid structures, which cannot handle the complexity of dynamic structures. To overcome this limitation, we propose an extension to TA, called dynamic timed automata (DTA), enabling the modeling and verification of reconfigurable systems. Additionally, we present a new algorithm that transforms DTA into semantic-equivalent TA while preserving their behavior. We demonstrate the usefulness and applicability of this new modeling and verification technique using an illustrative example.

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Mohamadizadeh, Maryam, Seyed Hossein Mojtahedzadeh, and Farimah Ayati. "Ga-(Nb+Ta)-(Nb/Ta)(Zr/Hf) Ternary Diagram: An Excellent Tool for Discriminating Barren and Ta-Hosting Granite-Pegmatite Systems." Journal of Earth Science 31, no. 3 (June 2020): 551–58. http://dx.doi.org/10.1007/s12583-020-1302-1.

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Дьяченко, Ф. А., Л. Л. Мейснер, А. Р. Шугуров, А. А. Нейман, В. О. Семин, and А. А. Атовуллаева. "Механические свойства поверхностных Ti-Ni-Ta- и Ti-Ni-Ta-Si-сплавов, синтезированных на подложках из никелида титана." Журнал технической физики 91, no. 1 (2021): 51. http://dx.doi.org/10.21883/jtf.2021.01.50272.176-20.

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The physical-mechanical properties of Ti-Ni-Ta and Ti-Ni-Ta-Si-based surface alloys of ~1 μm thickness synthesized on the NiTi substrates by the additive thin-film electron beam method were investigated. The effect of these surface alloys on the functional properties of the composite systems [Ti-Ni-Ta surface alloy/TiNi substrate] and [Ti-Ni-Ta-Si surface alloy/TiNi substrate] was explored. It was established that Ti-Ni-Ta-Si based surface alloy with an amorphous structure is characterized by higher gradients of hardness and Young’s modulus in comparison with Ti-Ni-Ta based surface alloy, and has an increased by ~10% and ~2 times greater plasticity compared to the initial NiTi substrate and the Ti-Ni-Ta based surface alloy, respectively. Evaluation of the shape memory effect and superelasticity of the composite systems [Ti-Ni-Ta surface alloy/TiNi substrate] and [Ti-Ni-Ta-Si surface alloy/TiNi substrate] has shown that synthesis of the surface alloy with an amorphous structure results in an almost 2-fold increase in the martensitic shear stress and a significant decrease in the stress hysteresis width compared with the untreated TiNi samples.

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Hameed, Syed Morad, Nadine Schuurman, Tarek Razek, Darrell Boone, Rardi Van Heest, Tracey Taulu, Nasira Lakha, et al. "Access to Trauma Systems in Canada." Journal of Trauma: Injury, Infection, and Critical Care 69, no. 6 (December 2010): 1350–61. http://dx.doi.org/10.1097/ta.0b013e3181e751f7.

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Boss, Lidia, Marcin Górniak, Alicja Lewańczyk, Joanna Morcinek-Orłowska, Sylwia Barańska, and Agnieszka Szalewska-Pałasz. "Identification of Three Type II Toxin-Antitoxin Systems in Model Bacterial Plant Pathogen Dickeya dadantii 3937." International Journal of Molecular Sciences 22, no. 11 (May 31, 2021): 5932. http://dx.doi.org/10.3390/ijms22115932.

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Type II toxin-antitoxin (TA) systems are genetic elements usually encoding two proteins: a stable toxin and an antitoxin, which binds the toxin and neutralizes its toxic effect. The disturbance in the intracellular toxin and antitoxin ratio typically leads to inhibition of bacterial growth or bacterial cell death. Despite the fact that TA modules are widespread in bacteria and archaea, the biological role of these systems is ambiguous. Nevertheless, a number of studies suggests that the TA modules are engaged in such important processes as biofilm formation, stress response or virulence and maintenance of mobile genetic elements. The Dickeya dadantii 3937 strain serves as a model for pathogens causing the soft-rot disease in a wide range of angiosperm plants. Until now, several chromosome-encoded type II TA systems were identified in silico in the genome of this economically important bacterium, however so far only one of them was experimentally validated. In this study, we investigated three putative type II TA systems in D. dadantii 3937: ccdAB2Dda, phd-docDda and dhiTA, which represents a novel toxin/antitoxin superfamily. We provide an experimental proof for their functionality in vivo both in D. dadantii and Escherichia coli. Finally, we examined the prevalence of those systems across the Pectobacteriaceae family by a phylogenetic analysis.

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Shidore, Teja, Quan Zeng, and Lindsay Triplett. "Survey of Toxin–Antitoxin Systems in Erwinia amylovora Reveals Insights into Diversity and Functional Specificity." Toxins 11, no. 4 (April 6, 2019): 206. http://dx.doi.org/10.3390/toxins11040206.

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Toxin–antitoxin (TA) systems are diverse genetic modules with demonstrated roles in plasmid stability, stress management, biofilm formation and antibiotic persistence. However, relatively little is known about their functional significance in plant pathogens. In this study we characterize type II and IV TA systems in the economically important plant pathogen Erwinia amylovora. Hidden Markov Model (HMM) and BLAST-based programs were used to predict the identity and distribution of putative TA systems among sequenced genomes of E. amylovora and other plant-associated Erwinia spp. Of six conserved TA systems tested for function from E. amylovora, three (CbtA/CbeA, ParE/RHH and Doc/PhD) were validated as functional. CbtA was toxic to E. amylovora, but not to Escherichia coli. While the E. coli homolog of CbtA elicits the formation of lemon-shaped cells upon overexpression and targets cytoskeletal proteins FtsZ and MreB, E. amylovora CbtA led to cell elongation and did not interact with these cytoskeletal proteins. Phylogenetic analysis revealed that E. amylovora CbtA belongs to a distinct clade from the CbtA of pathogenic E. coli. This study expands the repertoire of experimentally validated TA systems in plant pathogenic bacteria, and suggests that the E. amylovora homolog of CbtA is functionally distinct from that of E. coli.

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van der Kolk, G. J. "Crystallization temperatures of 5d–5d alloys." Journal of Materials Research 3, no. 2 (April 1988): 209–11. http://dx.doi.org/10.1557/jmr.1988.0209.

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Binary alloys of Re–Ta, Os–Ta, Ir–Ta, Os–W, and Ir–W were vapor deposited. A wide amorphous formation range was found for all systems, except Ir–W. The crystallization temperatures were generally very high—between 800 and 1000 K.

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Manikandan, Parthasarathy, Sankaran Sandhya, Kavyashree Nadig, Souradip Paul, Narayanaswamy Srinivasan, Ulli Rothweiler, and Mahavir Singh. "Identification, functional characterization, assembly and structure of ToxIN type III toxin–antitoxin complex from E. coli." Nucleic Acids Research 50, no. 3 (January 8, 2022): 1687–700. http://dx.doi.org/10.1093/nar/gkab1264.

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Abstract Toxin–antitoxin (TA) systems are proposed to play crucial roles in bacterial growth under stress conditions such as phage infection. The type III TA systems consist of a protein toxin whose activity is inhibited by a noncoding RNA antitoxin. The toxin is an endoribonuclease, while the antitoxin consists of multiple repeats of RNA. The toxin assembles with the individual antitoxin repeats into a cyclic complex in which the antitoxin forms a pseudoknot structure. While structure and functions of some type III TA systems are characterized, the complex assembly process is not well understood. Using bioinformatics analysis, we have identified type III TA systems belonging to the ToxIN family across different Escherichia coli strains and found them to be clustered into at least five distinct clusters. Furthermore, we report a 2.097 Å resolution crystal structure of the first E. coli ToxIN complex that revealed the overall assembly of the protein-RNA complex. Isothermal titration calorimetry experiments showed that toxin forms a high-affinity complex with antitoxin RNA resulting from two independent (5′ and 3′ sides of RNA) RNA binding sites on the protein. These results further our understanding of the assembly of type III TA complexes in bacteria.

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Tu, Chih-Han, Michelle Holt, Shengfeng Ruan, and Christina Bourne. "Evaluating the Potential for Cross-Interactions of Antitoxins in Type II TA Systems." Toxins 12, no. 6 (June 26, 2020): 422. http://dx.doi.org/10.3390/toxins12060422.

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The diversity of Type-II toxin–antitoxin (TA) systems in bacterial genomes requires tightly controlled interaction specificity to ensure protection of the cell, and potentially to limit cross-talk between toxin–antitoxin pairs of the same family of TA systems. Further, there is a redundant use of toxin folds for different cellular targets and complexation with different classes of antitoxins, increasing the apparent requirement for the insulation of interactions. The presence of Type II TA systems has remained enigmatic with respect to potential benefits imparted to the host cells. In some cases, they play clear roles in survival associated with unfavorable growth conditions. More generally, they can also serve as a “cure” against acquisition of highly similar TA systems such as those found on plasmids or invading genetic elements that frequently carry virulence and resistance genes. The latter model is predicated on the ability of these highly specific cognate antitoxin–toxin interactions to form cross-reactions between chromosomal antitoxins and invading toxins. This review summarizes advances in the Type II TA system models with an emphasis on antitoxin cross-reactivity, including with invading genetic elements and cases where toxin proteins share a common fold yet interact with different families of antitoxins.

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Shi, Liyin, Qianwei Liang, Qikai Zang, Ze Lv, Xiaohan Meng, and Jianguo Feng. "Construction of Prochloraz-Loaded Hollow Mesoporous Silica Nanoparticles Coated with Metal–Phenolic Networks for Precise Release and Improved Biosafety of Pesticides." Nanomaterials 12, no. 16 (August 22, 2022): 2885. http://dx.doi.org/10.3390/nano12162885.

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Currently, environmental-responsive pesticide delivery systems have become an essential way to improve the effective utilization of pesticides. In this paper, by using hollow mesoporous silica (HMS) as a nanocarrier and TA-Cu metal–phenolic networks as a capping agent, a pH-responsive controlled release nano-formulation loaded with prochloraz (Pro@HMS-TA-Cu) was constructed. The structure and properties of Pro@HMS-TA-Cu were adequately characterised and analysed. The results showed that the loading content of Pro@HMS-TA-Cu nanoparticles was about 17.7% and the Pro@HMS-TA-Cu nanoparticles exhibited significant pH-responsive properties. After a coating of the TA-Cu metal–phenolic network, the contact angle and adhesion work of Pro@HMS-TA-Cu nanoparticles on the surface of oilseed rape leaves after 360 s were 59.6° and 107.2 mJ·m−2, respectively, indicating that the prepared nanoparticles possessed excellent adhesion. In addition, the Pro@HMS-TA-Cu nanoparticles demonstrated better antifungal activity against Sclerotinia sclerotiorum and lower toxicity to zebrafish compared to prochloraz technical. Hence, the pH-responsive nanoparticles prepared with a TA-Cu metal–phenolic network as a capping agent are highly efficient and environmentally friendly, providing a new approach for the development of new pesticide delivery systems.

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Birch, Phil D. J., and Amy E. Whitehead. "Investigating the Comparative Suitability of Traditional and Task-Specific Think Aloud Training." Perceptual and Motor Skills 127, no. 1 (October 15, 2019): 202–24. http://dx.doi.org/10.1177/0031512519882274.

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The think aloud (TA) protocol is used to capture conscious cognition for wide ranging applications. However, the methods used to train the TA technique have been inconsistent, involving a mixture of both traditional guidelines and task-specific examples. This study aimed to examine how best to train the TA process. We recruited 20 competitive golfers as research participants, and we randomly assigned them to equal sized groups of traditional TA training as described by Ericsson and Simon and task-specific training in which participants were familiarized with TA via task-specific examples. Following training, all participants performed a golf task and were asked to TA. We transcribed audiotapes of their verbatim TA content and analyzed them using a deductive framework. We also collected various social validation self-report measures to assess participant perceptions of TA training. Overall, we found no significant differences in the frequency or type of TA verbalizations when comparing traditional and task-specific TA training groups. However, participants in the task-specific training group reported more favorable perceptions of training and found training significantly clearer than did participants in the traditional training group. We suggest that these findings support traditional TA training following Ericsson and Simon’s training guidelines, but adding task-specific examples seems to increase the familiarity of TA use and facilitate more reliable and accurate cognition data for research use.

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Zheng, Jianqing (Frank), and Sirkka L. Jarvenpaa. "Thinking Technology as Human: Affordances, Technology Features, and Egocentric Biases in Technology Anthropomorphism." Journal of the Association for Information Systems 22, no. 5 (2021): 1429–53. http://dx.doi.org/10.17705/1jais.00698.

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Advanced information technologies (ITs) are increasingly assuming tasks that have previously required human capabilities, such as learning and judgment. What drives this technology anthropomorphism (TA), or the attribution of humanlike characteristics to IT? What is it about users, IT, and their interactions that influences the extent to which people think of technology as humanlike? While TA can have positive effects, such as increasing user trust in technology, what are the negative consequences of TA? To provide a framework for addressing these questions, we advance a theory of TA that integrates the general three-factor anthropomorphism theory in social and cognitive psychology with the needs-affordances-features perspective from the information systems (IS) literature. The theory we construct helps to explain and predict which technological features and affordances are likely: (1) to satisfy users’ psychological needs, and (2) to lead to TA. More importantly, we problematize some negative consequences of TA. Technology features and affordances contributing to TA can intensify users’ anchoring with their elicited agent knowledge and psychological needs and also can weaken the adjustment process in TA under cognitive load. The intensified anchoring and weakened adjustment processes increase egocentric biases that lead to negative consequences. Finally, we propose a research agenda for TA and egocentric biases.

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Pauldine, Ronald, George Beck, Jose Salinas, and David W. Kaczka. "Closed-Loop Strategies for Patient Care Systems." Journal of Trauma: Injury, Infection, and Critical Care 64, Supplement (April 2008): S289—S294. http://dx.doi.org/10.1097/ta.0b013e31816bce43.

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Journal articles on the topic 'TA SYSTEMS'

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