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Artykuły w czasopismach na temat "Toxin-antitoxin (TA) system"
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Wilbaux, Myriam, Natacha Mine, Anne-Marie Guérout, Didier Mazel i Laurence Van Melderen. "Functional Interactions between Coexisting Toxin-Antitoxin Systems of the ccd Family in Escherichia coli O157:H7". Journal of Bacteriology 189, nr 7 (26.01.2007): 2712–19. http://dx.doi.org/10.1128/jb.01679-06.
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ABSTRACT Toxin-antitoxin (TA) systems are widely represented on mobile genetic elements as well as in bacterial chromosomes. TA systems encode a toxin and an antitoxin neutralizing it. We have characterized a homolog of the ccd TA system of the F plasmid (ccd F) located in the chromosomal backbone of the pathogenic O157:H7 Escherichia coli strain (ccd O157). The ccd F and the ccd O157 systems coexist in O157:H7 isolates, as these pathogenic strains contain an F-related virulence plasmid carrying the ccd F system. We have shown that the chromosomal ccd O157 system encodes functional toxin and antitoxin proteins that share properties with their plasmidic homologs: the CcdBO157 toxin targets the DNA gyrase, and the CcdAO157 antitoxin is degraded by the Lon protease. The ccd O157 chromosomal system is expressed in its natural context, although promoter activity analyses revealed that its expression is weaker than that of ccd F. ccd O157 is unable to mediate postsegregational killing when cloned in an unstable plasmid, supporting the idea that chromosomal TA systems play a role(s) other than stabilization in bacterial physiology. Our cross-interaction experiments revealed that the chromosomal toxin is neutralized by the plasmidic antitoxin while the plasmidic toxin is not neutralized by the chromosomal antitoxin, whether expressed ectopically or from its natural context. Moreover, the ccd F system is able to mediate postsegregational killing in an E. coli strain harboring the ccd O157 system in its chromosome. This shows that the plasmidic ccd F system is functional in the presence of its chromosomal counterpart.
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Singletary, Larissa A., Janet L. Gibson, Elizabeth J. Tanner, Gregory J. McKenzie, Peter L. Lee, Caleb Gonzalez i Susan M. Rosenberg. "An SOS-Regulated Type 2 Toxin-Antitoxin System". Journal of Bacteriology 191, nr 24 (16.10.2009): 7456–65. http://dx.doi.org/10.1128/jb.00963-09.
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ABSTRACT The Escherichia coli chromosome encodes seven demonstrated type 2 toxin-antitoxin (TA) systems: cassettes of two or three cotranscribed genes, one encoding a stable toxin protein that can cause cell stasis or death, another encoding a labile antitoxin protein, and sometimes a third regulatory protein. We demonstrate that the yafNO genes constitute an additional chromosomal type 2 TA system that is upregulated during the SOS DNA damage response. The yafNOP genes are part of the dinB operon, of which dinB underlies stress-induced mutagenesis mechanisms. yafN was identified as a putative antitoxin by homology to known antitoxins, implicating yafO (and/or yafP) as a putative toxin. Using phage-mediated cotransduction assays for linkage disruption, we show first that yafN is an essential gene and second that it is essential only when yafO is present. Third, yafP is not a necessary part of either the toxin or the antitoxin. Fourth, although DinB is required, the yafNOP genes are not required for stress-induced mutagenesis in the E scherichia coli Lac assay. These results imply that yafN encodes an antitoxin that protects cells against a yafO-encoded toxin and show a protein-based TA system upregulated by the SOS response.
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Ni, Songwei, Baiyuan Li, Kaihao Tang, Jianyun Yao, Thomas K. Wood, Pengxia Wang i Xiaoxue Wang. "Conjugative plasmid-encoded toxin–antitoxin system PrpT/PrpA directly controls plasmid copy number". Proceedings of the National Academy of Sciences 118, nr 4 (22.01.2021): e2011577118. http://dx.doi.org/10.1073/pnas.2011577118.
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Toxin–antitoxin (TA) loci were initially identified on conjugative plasmids, and one function of plasmid-encoded TA systems is to stabilize plasmids or increase plasmid competition via postsegregational killing. Here, we discovered that the type II TA system, Pseudoalteromonas rubra plasmid toxin–antitoxin PrpT/PrpA, on a low-copy-number conjugative plasmid, directly controls plasmid replication. Toxin PrpT resembles ParE of plasmid RK2 while antitoxin PrpA (PF03693) shares no similarity with previously characterized antitoxins. Surprisingly, deleting this prpA-prpT operon from the plasmid does not result in plasmid segregational loss, but greatly increases plasmid copy number. Mechanistically, the antitoxin PrpA functions as a negative regulator of plasmid replication, by binding to the iterons in the plasmid origin that inhibits the binding of the replication initiator to the iterons. We also demonstrated that PrpA is produced at a higher level than PrpT to prevent the plasmid from overreplicating, while partial or complete degradation of labile PrpA derepresses plasmid replication. Importantly, the PrpT/PrpA TA system is conserved and is widespread on many conjugative plasmids. Altogether, we discovered a function of a plasmid-encoded TA system that provides new insights into the physiological significance of TA systems.
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Rathore, Jitendra Singh, i Lalit Kumar Gautam. "Expression, Purification, and Functional Analysis of Novel RelE Operon fromX. nematophila". Scientific World Journal 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/428159.
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Bacterial toxin-antitoxin (TA) complexes induce programmed cell death and also function to relieve cell from stress by various response mechanisms.Escherichia coliRelB-RelE TA complex consists of a RelE toxin functionally counteracted by RelB antitoxin. In the present study, a novel homolog of RelE toxin designated as Xn-relE toxin fromXenorhabdus nematophilapossessing its own antitoxin designated as Xn-relEAT has been identified. Expression and purification of recombinant proteins under native conditions with GST and Ni-NTA chromatography prove the existence of novel TA module. The expression of recombinant Xn-relE under tightly regulated ara promoter inE. coliTop 10 cells confirms its toxic nature in endogenous toxicity assay. The neutralization activity in endogenous toxicity assay by Xn-relEAT antitoxin confirms its antidote nature when studying the whole TA operon under ara regulated promoter. This study promotes newly discovered TA module to be regarded as important as other proteins of type II toxin-antitoxin system.
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Piscotta, Frank J., Philip D. Jeffrey i A. James Link. "ParST is a widespread toxin–antitoxin module that targets nucleotide metabolism". Proceedings of the National Academy of Sciences 116, nr 3 (31.12.2018): 826–34. http://dx.doi.org/10.1073/pnas.1814633116.
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Toxin–antitoxin (TA) systems interfere with essential cellular processes and are implicated in bacterial lifestyle adaptations such as persistence and the biofilm formation. Here, we present structural, biochemical, and functional data on an uncharacterized TA system, the COG5654–COG5642 pair. Bioinformatic analysis showed that this TA pair is found in 2,942 of the 16,286 distinct bacterial species in the RefSeq database. We solved a structure of the toxin bound to a fragment of the antitoxin to 1.50 Å. This structure suggested that the toxin is a mono-ADP-ribosyltransferase (mART). The toxin specifically modifies phosphoribosyl pyrophosphate synthetase (Prs), an essential enzyme in nucleotide biosynthesis conserved in all organisms. We propose renaming the toxin ParT for Prs ADP-ribosylating toxin and ParS for the cognate antitoxin. ParT is a unique example of an intracellular protein mART in bacteria and is the smallest known mART. This work demonstrates that TA systems can induce bacteriostasis through interference with nucleotide biosynthesis.
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Alkhalili, Rawana, Joel Wallenius i 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, nr 23 (22.11.2019): 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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Tu, Chih-Han, Michelle Holt, Shengfeng Ruan i Christina Bourne. "Evaluating the Potential for Cross-Interactions of Antitoxins in Type II TA Systems". Toxins 12, nr 6 (26.06.2020): 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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Habib, Gul, Qing Zhu i Baolin Sun. "Bioinformatics and Functional Assessment of Toxin-Antitoxin Systems in Staphylococcus aureus". Toxins 10, nr 11 (14.11.2018): 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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Pathak, Chinar, Hookang Im, Sun-bok Jang, Yeon-Jin Yang, Hye-Jin Yoon, Hong-Man Kim, Ae-Ran Kwon i Bong-Jin Lee. "Toxins from TA system of Helicobacter pylori and insight into mRNase activity". Acta Crystallographica Section A Foundations and Advances 70, a1 (5.08.2014): C828. http://dx.doi.org/10.1107/s2053273314091712.
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The toxin-antitoxin (TA) systems widely spread among bacteria and archaea are important for antibiotic resistance and virulence. The bacterial kingdom uses TA systems to adjust the global level of gene expression and translation through RNA degradation. The HP0892-HP0893 and HP0894-HP0895 toxin-antitoxin systems are the only two known TA systems belonging to Helicobacter pylori. In both of these TA systems, the antitoxin binds and inhibits the toxin and regulates the transcription of the TA operon. However, the precise molecular basis for interaction with substrate or antitoxin and the mechanism of mRNA cleavage remains unclear. Therefore, here an attempt was made to shed some light on the mechanism behind the TA system of HP0892-HP0893 and HP0894-HP0895. Here, we present the crystal structures of apo- and copper-bound HP0894 at 1.28 Å and 1.89 Å, respectively, and the crystal structure of the zinc-bound HP0892 toxin at 1.8 Å resolution. Reorientation of residues involving the mRNase active site was shown. Through the combined approach of structural analysis along with isothermal calorimetry studies and structural homology search, the amino acids involved in mRNase active site were monitored. In the mRNase active site of HP0894 toxin, His84 acts as a catalytic residue and reorients itself acting as a general acid in an acid-base catalysis reaction, while His47 and His60 stabilize the transition state. Glu58 acts as a general base, and substrate reorientation is caused by Phe88. In the mRNase active site of HP0892 toxin, the most catalytically important residue, His86, reorients itself to exhibit RNase activity while Glu58 acts as a general base. His47 and His60 are considered to be involved in enzymatic activity. Glu58 and Asp64 are involved in substrate binding and specific sequence recognition. The mutational constructs were used for isothermal calorimetric studies to analyze the effect of catalytic residues.
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Choi, Wonho, Yoshihiro Yamaguchi, Ji-Young Park, Sang-Hyun Park, Hyeok-Won Lee, Byung-Kwan Lim, Michael Otto, Masayori Inouye, Min-Ho Yoon i Jung-Ho Park. "Functional Characterization of the mazEF Toxin-Antitoxin System in the Pathogenic Bacterium Agrobacterium tumefaciens". Microorganisms 9, nr 5 (20.05.2021): 1107. http://dx.doi.org/10.3390/microorganisms9051107.
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Agrobacterium tumefaciens is a pathogen of various plants which transfers its own DNA (T-DNA) to the host plants. It is used for producing genetically modified plants with this ability. To control T-DNA transfer to the right place, toxin-antitoxin (TA) systems of A. tumefaciens were used to control the target site of transfer without any unintentional targeting. Here, we describe a toxin-antitoxin system, Atu0939 (mazE-at) and Atu0940 (mazF-at), in the chromosome of Agrobacterium tumefaciens. The toxin in the TA system has 33.3% identity and 45.5% similarity with MazF in Escherichia coli. The expression of MazF-at caused cell growth inhibition, while cells with MazF-at co-expressed with MazE-at grew normally. In vivo and in vitro assays revealed that MazF-at inhibited protein synthesis by decreasing the cellular mRNA stability. Moreover, the catalytic residue of MazF-at was determined to be the 24th glutamic acid using site-directed mutagenesis. From the results, we concluded that MazF-at is a type II toxin-antitoxin system and a ribosome-independent endoribonuclease. Here, we characterized a TA system in A. tumefaciens whose understanding might help to find its physiological function and to develop further applications.
Rozprawy doktorskie na temat "Toxin-antitoxin (TA) system"
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Bare, Harriet Leah. "Mutagenesis and functional characterisation of toxin HicA from the HicBA TA system in Burkholderia pseudomallei". Thesis, University of Exeter, 2016. http://hdl.handle.net/10871/26797.
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Four type II toxin-antitoxin (TA) systems were previously identified in Burkholderia pseudomallei K96243. Type II TA toxins are able to induce cell growth arrest or death by interfering with key processes within the organism. BPSS0390-0391 is one of the TA systems previously identified and has homology to hicBA system in Acinetobacter baumannii. B. pseudomallei HicA is able to cause a reduction in the number of culturable cells after expression in E. coli. This study aimed to characterise B. pseudomallei HicA in three ways: by inducing expression of HicA in bacterial species other than E. coli, by identifying amino acids in HicA involved in toxicity and neutralisation by the antitoxin HicB and by examining the interaction of HicA with other TA antitoxins identified within B. pseudomallei genome. A broad host range plasmid encoding BPSS0390 was transformed into a range of Gram negative bacteria including Yersinia pseudotuberculosis IP32953, Vibrio vulnificus E64MW, Salmonella enterica serovar Typhimurium SL1344 and Burkholderia thailandensis E264. Expression of BPSS0390 was toxic in all bacterial species tested, despite the presence of antitoxin BPSS0391 homologues in some species. Unregulated expression in E. coli resulted in the appearance of escape mutants encoding non-toxic variants of HicA. An alanine scanning mutagenesis study of HicA identified 20 mutants where toxicity was abolished despite high levels of expression, but identified no mutants that affected TA complex formation. Finally an existing co-expression assay was modified to examine interactions between HicA and other type II TA antitoxins in B. pseudomallei. The assay revealed no interaction between HicA and non-cognate antitoxins and clarified the role of IPTG as an inhibitor of PBAD promoter on the arabinose operon.
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Butt, Aaron Trevor. "Identification and characterisation of toxin-antitoxin systems (TA) in Burkholderia pseudomallei". Thesis, University of Exeter, 2013. http://hdl.handle.net/10871/9303.
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The aim of this study was to identify and characterise type II toxin-antitoxin (TA) systems in Burkholderia pseudomallei, the causative agent of the human disease melioidosis. 8 putative TA systems were identified within the genome of B. pseudomallei K96243. 5 of these were located witihn genome islands. Of the candidate toxins, BPSL0175 (RelE1) or BPSS1060 (RelE2) caused growth to cease when expressed in Escherichia coli, whereas expression of BPSS0390 (HicA) or BPSS1584 (HipA) (in an E. coli ΔhipBA background) caused a reduction in the number of culturable bacteria. HicA also caused growth arrest in B. pseudomallei K96243 ΔhicAB. These toxin induced phenotypes were enhanced by an <3kDa extracellular factor that accumulated in the spent medium during growth. Expression of the cognate antitoxins could restore growth and culturability of cells. Expression of hicA in E. coli gave an increased number of persister cells in response to ciprofloxacin or ceftazidime. Site directed mutagenesis studies identified two key residues within the HicA toxin that were essential for both the reduced culturability and increased persistence phenotypes. Deletion of hicAB from B. pseudomallei K96243 did not affect persister cell or survival frequencies compared to the wild type following treatment with a variety of stress conditions. Deletion of the ΔhipBA locus from B. pseudomallei K96243 also had no affect on bacterial persistence or survival under the conditions tested.
Części książek na temat "Toxin-antitoxin (TA) system"
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Kumar, Ashutosh, Anwar Alam, Pranami Bharadwaj, Sharmistha Tapadar, Mamta Rani i Seyed E. Hasnain. "Toxin-Antitoxin (TA) Systems in Stress Survival and Pathogenesis". W Mycobacterium Tuberculosis: Molecular Infection Biology, Pathogenesis, Diagnostics and New Interventions, 257–74. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-32-9413-4_15.
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