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https://www.readbyqxmd.com/read/28098783/the-influence-of-the-toxin-antitoxin-mazef-on-growth-and-survival-of-listeria-monocytogenes-under-stress
#1
Thomas D Curtis, Ippei Takeuchi, Lone Gram, Gitte M Knudsen
A major factor in the resilience of Listeria monocytogenes is the alternative sigma factor B (σ(B)). Type II Toxin/Antitoxin (TA) systems are also known to have a role in the bacterial stress response upon activation via the ClpP or Lon proteases. Directly upstream of the σ(B) operon in L. monocytogenes is the TA system mazEF, which can cleave mRNA at UACMU sites. In this study, we showed that the mazEF TA locus does not affect the level of persister formation during treatment with antibiotics in lethal doses, but exerts different effects according to the sub-inhibitory stress added...
January 13, 2017: Toxins
https://www.readbyqxmd.com/read/28094982/bacterial-genome-editing-via-a-designed-toxin-antitoxin-cassette
#2
Jie Wu, Aihua Deng, Qinyun Sun, Hua Bai, Zhaopeng Sun, Xiuling Shang, Yun Zhang, Qian Liu, Yong Liang, Shuwen Liu, Yongsheng Che, Tingyi Wen
Manipulating the bacterial genomes in an efficient manner is essential to biological and biotechnological research. Despite usage of various modules for genomic editing with counter-selectable markers including the toxin genes, an easy-to-use and highly designable toxin-antitoxin (TA) cassette without causing any leakages is urgently needed for efficient genome editing of the Gram-positive bacteria. Here, we reprogramed the bacterial TA systems as a toxin counter-selectable cassette regulated by an antitoxin switch (TCCRAS) for genetic modifications in the extensively studied and utilized Gram-positive bacteria, B...
January 17, 2017: ACS Synthetic Biology
https://www.readbyqxmd.com/read/28089288/the-role-of-reactive-oxygen-species-in-antibiotic-mediated-killing-of-bacteria
#3
REVIEW
Heleen Van Acker, Tom Coenye
Recently, it was proposed that there is a common mechanism behind the activity of bactericidal antibiotics, involving the production of reactive oxygen species (ROS). However, the involvement of ROS in antibiotic-mediated killing has become the subject of much debate. In the present review, we provide an overview of the data supporting the ROS hypothesis; we also present data that explain the contradictory results often obtained when studying antibiotic-induced ROS production. For this latter aspect we will focus on the importance of taking the experimental setup into consideration and on the importance of some technical aspects of the assays typically used...
January 12, 2017: Trends in Microbiology
https://www.readbyqxmd.com/read/28077560/mechanistic-insights-into-type-i-toxin-antitoxin-systems-in-helicobacter-pylori-the-importance-of-mrna-folding-in-controlling-toxin-expression
#4
Hélène Arnion, Dursun Nizam Korkut, Sara Masachis Gelo, Sandrine Chabas, Jérémy Reignier, Isabelle Iost, Fabien Darfeuille
Type I toxin-antitoxin (TA) systems have been identified in a wide range of bacterial genomes. Here, we report the characterization of a new type I TA system present on the chromosome of the major human gastric pathogen, Helicobacter pylori We show that the aapA1 gene encodes a 30 amino acid peptide whose artificial expression in H. pylori induces cell death. The synthesis of this toxin is prevented by the transcription of an antitoxin RNA, named IsoA1, expressed on the opposite strand of the toxin gene. We further reveal additional layers of post-transcriptional regulation that control toxin expression: (i) transcription of the aapA1 gene generates a full-length transcript whose folding impedes translation (ii) a 3' end processing of this message generates a shorter transcript that, after a structural rearrangement, becomes translatable (iii) but this rearrangement also leads to the formation of two stem-loop structures allowing formation of an extended duplex with IsoA1 via kissing-loop interactions...
January 10, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28074222/regulation-of-membrane-fixation-and-energy-production-conversion-for-adaptation-and-recovery-of-zno-nanoparticle-impacted-nitrosomonas-europaea
#5
Junkang Wu, Huijie Lu, Guangcan Zhu, Lianghui Chen, Yan Chang, Ran Yu
The ZnO nanoparticle (NP) effects on typical ammonia-oxidizing bacteria, Nitrosomonas europaea in a chemostat bioreactor, and the cells' toxicity adaptation and recovery potentials were explored. Hardly any inhibition was observed when the NP concentration was high up to 10 mg/L. The cells exposed to 50 mg/L ZnO NPs displayed time-dependent impairment and recovery potentials in terms of cell density, membrane integrity, nitrite production rate, and ammonia monooxygenase activity. The 6-h NP stress impaired cells were nearly completely restored during a 12-h recovery incubation, while the longer exposure time would cause irretrievable cell damage...
January 10, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28069396/multi-level-evaluation-of-escherichia-coli-polyphosphate-related-mutants-using-global-transcriptomic-proteomic-and-phenomic-analyses
#6
Macarena Varas, Camilo Valdivieso, Cecilia Mauriaca, Javiera Ortíz-Severín, Alberto Paradela, Ignacio Poblete-Castro, Ricardo Cabrera, Francisco P Chávez
BACKGROUND: Polyphosphate (polyP) is a linear biopolymer found in all living cells. In bacteria, mutants lacking polyphosphate kinase 1 (PPK1), the enzyme responsible for synthesis of most polyP, have many structural and functional defects. However, little is known about the causes of these pleiotropic alterations. The link between ppk1 deletion and those numerous phenotypes observed can be the result of complex molecular interactions that can be elucidated via a systems biology approach...
January 6, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28067598/why-so-narrow-distribution-of-anti-sense-regulated-type-i-toxin-antitoxin-systems-compared-to-type-ii-and-type-iii-systems
#7
Dorien S Coray, Nicole E Wheeler, Jack A Heinemann, Paul P Gardner
Toxin-antitoxin (TA) systems are gene modules that appear to be horizontally mobile across a wide range of prokaryotes. It has been proposed that type I TA systems, with an antisense RNA-antitoxin, are less mobile than other TAs that rely on direct toxin-antitoxin binding but no direct comparisons have been made. We searched for type I, II and III toxin families using iterative searches with profile hidden Markov models across phyla and replicons. The distribution of type I toxin families were comparatively narrow, but these patterns weakened with recently discovered families...
January 9, 2017: RNA Biology
https://www.readbyqxmd.com/read/28062294/assessment-of-biofilm-formation-in-pseudomonas-aeruginosa-by-antisense-maze-pna
#8
Hassan Valadbeigi, Nourkhoda Sadeghifard, Majid Baseri Salehi
The hallmark patogenicity in Pseudomonas aeruginosa (P. aeruginosa) is biofilm formation that is not easy to eradicate, because it has variety mechanisms for antibiotic resistance. In addition, toxin-antitoxin (TA) system may play role in biofilm formation. The current study aimed to evaluate the role of TA loci in biofilm formation. Therefore, 18 P. aeruginosa clinical isolates were collected and evaluated for specific biofilm and TA genes. The analysis by RT-qPCR demonstrated that expression of mazE antitoxin in biofilm formation was increase...
January 3, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28056815/comparative-genomics-of-host-adaptive-traits-in-xanthomonas-translucens-pv-graminis
#9
Lena Hersemann, Daniel Wibberg, Jochen Blom, Alexander Goesmann, Franco Widmer, Frank-Jörg Vorhölter, Roland Kölliker
BACKGROUND: Xanthomonas translucens pathovars differ in their individual host ranges among Poaceae. As the causal agent of bacterial wilt in Italian ryegrass (Lolium multiflorum Lam.), X. translucens pv. graminis (Xtg) is one of the most important bacterial pathogens in temperate grassland regions. The genomes of six Xtg strains from Switzerland, Norway, and New Zealand were sequenced in order to gain insight into conserved genomic traits from organisms covering a wide geographical range...
January 5, 2017: BMC Genomics
https://www.readbyqxmd.com/read/28032302/the-1925-diphtheria-antitoxin-run-to-nome-alaska-a-public-health-illustration-of-human-animal-collaboration
#10
Basil H Aboul-Enein, William C Puddy, Jacquelyn E Bowser
Diphtheria is an acute toxin-mediated superficial infection of the respiratory tract or skin caused by the aerobic gram-positive bacillus Corynebacterium diphtheriae. The epidemiology of infection and clinical manifestations of the disease vary in different parts of the world. Historical accounts of diphtheria epidemics have been described in many parts of the world since antiquity. Developed in the late 19th century, the diphtheria antitoxin (DAT) played a pivotal role in the history of public health and vaccinology prior to the advent of the diphtheria-tetanus toxoids and acellular pertussis (DTaP) vaccine...
December 29, 2016: Journal of Medical Humanities
https://www.readbyqxmd.com/read/28017694/pitfalls-to-avoid-when-using-phage-display-for-snake-toxins
#11
Andreas Hougaard Laustsen, Line Præst Lauridsen, Bruno Lomonte, Mikael Rørdam Andersen, Brian Lohse
Antivenoms against bites and stings from snakes, spiders, and scorpions are associated with immunological side effects and high cost of production, since these therapies are still derived from the serum of hyper-immunized production animals. Biotechnological innovations within envenoming therapies are thus warranted, and phage display technology may be a promising avenue for bringing antivenoms into the modern era of biologics. Although phage display technology represents a robust and high-throughput approach for the discovery of antibody-based antitoxins, several pitfalls may present themselves when animal toxins are used as targets for phage display selection...
December 23, 2016: Toxicon: Official Journal of the International Society on Toxinology
https://www.readbyqxmd.com/read/28017433/passive-antibodies-derived-from-intramuscularly-immunized-toxoid-fusion-3xstan12s-dmlt-protect-against-sta-enterotoxigenic-escherichia-coli-etec-diarrhea-in-a-pig-model
#12
Rahul M Nandre, Qiangde Duan, Yin Wang, Weiping Zhang
Enterotoxigenic Escherichia coli (ETEC) strains are among the most common causes of children's diarrhea and travelers' diarrhea. Developing effective vaccines against ETEC associated diarrhea becomes a top priority. ETEC heat-labile toxin (LT) and heat-stable toxin (STa) toxoid fusion 3xSTaN12S-dmLT was demonstrated recently to induce neutralizing antitoxin antibodies in intraperitoneally or subcutaneously immunized mice. However, whether antibodies derived from this toxoid fusion are protective against ETEC diarrhea has not been examined...
December 22, 2016: Vaccine
https://www.readbyqxmd.com/read/28000508/proteomic-insight-into-the-primycin-fermentation-process-of-saccharomonospora-azurea
#13
Andrea Valasek, Írisz Éva Kiss, István Fodor, Márk Kovács, Péter Urbán, Éva Jámbor, Csaba Fekete, Ildikó Kerepesi
Saccharomonospora azurea SZMC 14600 is a member of the family Pseudonocardiaceae exclusively used for industrial scale production of primycin a large 36-membered non-polyene macrolide lactone antibiotic belonging to the polyketide class of natural products. Even though maximum antibiotic yield has been achieved by empirically optimized two-step fermentation process, little is known about the molecular components and mechanisms underlying the efficient antibiotic production. In order to identify differentially expressed proteins (DEPs) between the pre- and main-fermentation stages of primycin, comparative 2D-PAGE experiments were performed...
December 2016: Acta Biologica Hungarica
https://www.readbyqxmd.com/read/27999163/single-cell-analysis-of-the-plasmablast-response-to-vibrio-cholerae-demonstrates-expansion-of-cross-reactive-memory-b-cells
#14
Robert C Kauffman, Taufiqur R Bhuiyan, Rie Nakajima, Leslie M Mayo-Smith, Rasheduzzaman Rashu, Mohammad Rubel Hoq, Fahima Chowdhury, Ashraful Islam Khan, Atiqur Rahman, Siddhartha K Bhaumik, Levelle Harris, Justin T O'Neal, Jessica F Trost, Nur Haq Alam, Algis Jasinskas, Emmanuel Dotsey, Meagan Kelly, Richelle C Charles, Peng Xu, Pavol Kováč, Stephen B Calderwood, Edward T Ryan, Phillip L Felgner, Firdausi Qadri, Jens Wrammert, Jason B Harris
: We characterized the acute B cell response in adults with cholera by analyzing the repertoire, specificity, and functional characteristics of 138 monoclonal antibodies (MAbs) generated from single-cell-sorted plasmablasts. We found that the cholera-induced responses were characterized by high levels of somatic hypermutation and large clonal expansions. A majority of the expansions targeted cholera toxin (CT) or lipopolysaccharide (LPS). Using a novel proteomics approach, we were able to identify sialidase as another major antigen targeted by the antibody response to Vibrio cholerae infection...
December 20, 2016: MBio
https://www.readbyqxmd.com/read/27998932/toxin-inhibition-in-c-crescentus-vapbc1-is-mediated-by-a-flexible-pseudo-palindromic-protein-motif-and-modulated-by-dna-binding
#15
Kirstine L Bendtsen, Kehan Xu, Majbritt Luckmann, Kristoffer S Winther, Shiraz A Shah, Christian N S Pedersen, Ditlev E Brodersen
Expression of bacterial type II toxin-antitoxin (TA) systems is regulated at the transcriptional level through direct binding of the antitoxin to pseudo-palindromic sequences on operator DNA. In this context, the toxin functions as a co-repressor by stimulating DNA binding through direct interaction with the antitoxin. Here, we determine crystal structures of the complete 90 kDa heterooctameric VapBC1 complex from Caulobacter crescentus CB15 both in isolation and bound to its cognate DNA operator sequence at 1...
December 19, 2016: Nucleic Acids Research
https://www.readbyqxmd.com/read/27997707/two-regulatory-rna-elements-affect-tisb-dependent-depolarization-and-persister-formation
#16
Bork A Berghoff, Mirthe Hoekzema, Lena Aulbach, E Gerhart H Wagner
Bacterial survival strategies involve phenotypic diversity which is generated by regulatory factors and noisy expression of effector proteins. The question of how bacteria exploit regulatory RNAs to make decisions between phenotypes is central to a general understanding of these universal regulators. We investigated the TisB/IstR-1 toxin-antitoxin system of Escherichia coli to appreciate the role of the RNA antitoxin IstR-1 in TisB-dependent depolarization of the inner membrane and persister formation. Persisters are phenotypic variants that have become transiently drug-tolerant by arresting growth...
December 20, 2016: Molecular Microbiology
https://www.readbyqxmd.com/read/27984742/back-to-the-roots-deep-view-into-the-evolutionary-history-of-adp-ribosylation-opened-by-the-dna-targeting-toxin-antitoxin-module-dartg
#17
Alexander Harms, Kenn Gerdes
In this issue of Molecular Cell, Jankevicius et al. (2016) characterize the DarTG toxin-antitoxin module in which the DarT toxin ADP-ribosylates single-stranded DNA and the DarG antitoxin counteracts DarT by direct binding and by enzymatic removal of the ADP-ribosylation.
December 15, 2016: Molecular Cell
https://www.readbyqxmd.com/read/27980159/mechanisms-of-bacterial-persistence-during-stress-and-antibiotic-exposure
#18
REVIEW
Alexander Harms, Etienne Maisonneuve, Kenn Gerdes
Bacterial persister cells avoid antibiotic-induced death by entering a physiologically dormant state and are considered a major cause of antibiotic treatment failure and relapsing infections. Such dormant cells form stochastically, but also in response to environmental cues, by various pathways that are usually controlled by the second messenger (p)ppGpp. For example, toxin-antitoxin modules have been shown to play a major role in persister formation in many model systems. More generally, the diversity of molecular mechanisms driving persister formation is increasingly recognized as the cause of physiological heterogeneity that underlies collective multistress and multidrug tolerance of persister subpopulations...
December 16, 2016: Science
https://www.readbyqxmd.com/read/27965650/an-integrative-genomic-island-affects-the-adaptations-of-the-piezophilic-hyperthermophilic-archaeon-pyrococcus-yayanosii-to-high-temperature-and-high-hydrostatic-pressure
#19
Zhen Li, Xuegong Li, Xiang Xiao, Jun Xu
Deep-sea hydrothermal vent environments are characterized by high hydrostatic pressure and sharp temperature and chemical gradients. Horizontal gene transfer is thought to play an important role in the microbial adaptation to such an extreme environment. In this study, a 21.4-kb DNA fragment was identified as a genomic island, designated PYG1, in the genomic sequence of the piezophilic hyperthermophile Pyrococcus yayanosii. According to the sequence alignment and functional annotation, the genes in PYG1 could tentatively be divided into five modules, with functions related to mobility, DNA repair, metabolic processes and the toxin-antitoxin system...
2016: Frontiers in Microbiology
https://www.readbyqxmd.com/read/27940461/comparative-analysis-of-mazef-and-hicab-toxin-antitoxin-systems-of-the-cyanobacterium-anabaena-sp-pcc7120
#20
Akhilesh A Potnis, Prashanth S Raghavan, Ashwini Shelke, T D Nikam, Hema Rajaram
Anabaena PCC7120 has two annotated toxin-antitoxin systems: MazEF and HicAB. Overexpression of either of the toxins severely inhibited the growth of Escherichia coli BL21(plysS)(DE3). Of the two Anabaena toxins, MazF exhibited higher toxicity than HicA as evidenced by (i) 100-fold lower viability upon overexpression of MazF compared to HicA; (ii) complete loss of cell viability within 1 h of induction of MazF expression, as against >10(3) colony forming units mL(-1) in case of HicA; (iii) inability to maintain the MazF overexpressing plasmid in E...
January 2017: FEMS Microbiology Letters
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