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toxin antitoxin

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https://www.readbyqxmd.com/read/27910884/the-hha-tomb-toxin-antitoxin-system-shows-conditional-toxicity-and-promotes-persister-cell-formation-by-inhibiting-apoptosis-like-death-in-s-typhimurium
#1
Sangeeta Jaiswal, Prajita Paul, Chandrashekhar Padhi, Shilpa Ray, Daniel Ryan, Shantoshini Dash, Mrutyunjay Suar
Toxin-antitoxin (TA) modules are two component "addictive" genetic elements found on either plasmid or bacterial chromosome, sometimes on both. TA systems perform a wide range of functions like biofilm formation, persistence, programmed cell death, phage abortive infection etc. Salmonella has been reported to contain several such TA systems. However, the hemolysin expression modulating protein (Hha) and its adjacent uncharacterized hypothetical protein TomB (previously known as YbaJ), have not been listed as a TA module in Salmonella...
December 2, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27903909/the-5-utr-of-the-type-i-toxin-zoro-can-both-inhibit-and-enhance-translation
#2
Jia Wen, John R Harp, Elizabeth M Fozo
Many bacterial type I toxin mRNAs possess a long 5' untranslated region (UTR) that serves as the target site of the corresponding antitoxin sRNA. This is the case for the zorO-orzO type I system where the OrzO antitoxin base pairs to the 174-nucleotide zorO 5' UTR. Here, we demonstrate that the full-length 5' UTR of the zorO type I toxin hinders its own translation independent of the sRNA whereas a processed 5' UTR (zorO Δ28) promotes translation. The full-length zorO 5' UTR folds into an extensive secondary structure sequestering the ribosome binding site (RBS)...
November 29, 2016: Nucleic Acids Research
https://www.readbyqxmd.com/read/27902906/generalized-tetanus-in-a-gyrfalcon-falco-rusticolus-with-pododermatitis
#3
Hugues Beaufrère, Delphine Laniesse, Paul Stickings, Robert Tierney, Thea Sesardic, Durda Slavic, Nicole Compo, Dale A Smith
A 2-yr-old male gyrfalcon ( Falco rusticolus ) was presented for severe and generalized muscle spasticity and pododermatitis. The falcon had been treated for pododermatitis over the previous 4 mo. Muscle rigidity and spasms involved the entire bird but were more severe on the right leg. The bird was also tachypneic and hyperthermic at 45 C. While the plantar pododermatitis lesions had healed, there was still a small abscess on the lateral aspect of the right foot. Clinical signs were consistent with tetanus...
December 2016: Avian Diseases
https://www.readbyqxmd.com/read/27902436/exploring-the-parameters-of-post-segregation-killing-using-heterologous-expression-of-secreted-toxin-barnase-and-antitoxin-barstar-in-an-e-coli-case-study
#4
Dorien S Coray, Brigitta Kurenbach, Jack A Heinemann
Post-segregational killing (PSK) is a phenotype determined by plasmids using a toxin and an antitoxin (TA) gene pair. Loss of the genes depletes the cell's reserve of antitoxin and allows the toxin to act upon the cell. PSK benefits mobile elements when it increases reproductive success relative to other mobile competitors. A side effect of PSK is that plasmids become refractory to displacement from the cell during growth as a monoculture. Most PSK systems use a cytoplasmic toxin, but the external toxins of bacteriocins also have a PSK-like effect...
November 16, 2016: Microbiology
https://www.readbyqxmd.com/read/27902432/self-replicating-shuttle-vectors-based-on-pans-a-small-endogenous-plasmid-of-the-unicellular-cyanobacterium-synechococcus-elongatus-pcc-7942
#5
You Chen, Arnaud Taton, Michaela Go, Ross E London, Lindsey M Pieper, Susan S Golden, James W Golden
To facilitate development of synthetic biology tools for genetic engineering of cyanobacterial strains, we constructed pANS-derived self-replicating shuttle vectors that are based on the minimal replication element of the Synechococcus elongatus strain PCC 7942 plasmid pANS. To remove the possibility of homologous recombination events between the shuttle plasmids and the native pANS plasmid, the endogenous pANS was cured through plasmid incompatibility-mediated spontaneous loss. A heterologous toxin-antitoxin cassette was incorporated into the shuttle vectors for stable plasmid maintenance in the absence of antibiotic selection...
October 14, 2016: Microbiology
https://www.readbyqxmd.com/read/27896818/coupling-immunity-and-programmed-cell-suicide-in-prokaryotes-life-or-death-choices
#6
Eugene V Koonin, Feng Zhang
Host-pathogen arms race is a universal, central aspect of the evolution of life. Most organisms evolved several distinct yet interacting strategies of anti-pathogen defense including resistance to parasite invasion, innate and adaptive immunity, and programmed cell death (PCD). The PCD is the means of last resort, a suicidal response to infection that is activated when resistance and immunity fail. An infected cell faces a decision between active defense and altruistic suicide or dormancy induction, depending on whether immunity is "deemed" capable of preventing parasite reproduction and consequent infection of other cells...
November 29, 2016: BioEssays: News and Reviews in Molecular, Cellular and Developmental Biology
https://www.readbyqxmd.com/read/27872077/identification-of-inca-c-plasmid-replication-and-maintenance-genes-and-development-of-a-plasmid-multi-locus-sequence-typing-scheme
#7
Steven J Hancock, Minh-Duy Phan, Kate M Peters, Brian M Forde, Teik Min Chong, Wai-Fong Yin, Kok-Gan Chan, David L Paterson, Timothy R Walsh, Scott A Beatson, Mark A Schembri
Plasmids of incompatibility group IncA/C are becoming increasingly prevalent within pathogenic Enterobacteriaceae. They are associated with the dissemination of multiple clinically relevant resistance genes, including blaCMY and blaNDM Current typing methods for IncA/C plasmids offer limited resolution. In this study, we present the complete sequence of a blaNDM-1-positive IncA/C plasmid, pMS6198A, isolated from a multi-drug resistant uropathogenic Escherichia coli strain. Hyper-saturated transposon mutagenesis, coupled with transposon directed insertion site sequencing (TraDIS) was employed to identify conserved genetic elements required for replication and maintenance of pMS6198A...
November 21, 2016: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/27858580/toxins-mazf-and-mqsr-cleave-escherichia-coli-ribosomal-rna-precursors-at-multiple-sites
#8
Toomas Mets, Markus Lippus, David Schryer, Aivar Liiv, Villu Kasari, Anton Paier, Ülo Maiväli, Jaanus Remme, Tanel Tenson, Niilo Kaldalu
The endoribonuclease toxins of the E. coli toxin-antitoxin systems arrest bacterial growth and protein synthesis by targeting cellular mRNAs. As an exception, E. coli MazF was reported to cleave also 16S rRNA at a single site and separate an anti-Shine-Dalgarno sequence-containing RNA fragment from the ribosome. We noticed extensive rRNA fragmentation in response to induction of the toxins MazF and MqsR, which suggested that these toxins can cleave rRNA at multiple sites. We adapted differential RNA-sequencing to map the toxin-cleaved 5'- and 3'-ends...
November 18, 2016: RNA Biology
https://www.readbyqxmd.com/read/27853887/identification-of-a-vapbc-toxin-antitoxin-system-in-a-thermophilic-bacterium-thermus-thermophilus-hb27
#9
Yuqi Fan, Takayuki Hoshino, Akira Nakamura
There are 12 putative toxin-antitoxin (TA) loci in the Thermus thermophilus HB27 genome, including four VapBC and three HicBA families. Expression of these seven putative toxin genes in Escherichia coli demonstrated that one putative VapC toxin TTC0125 and two putative HicA toxins, TTC1395 and TTC1705, inhibited cell growth, and co-expression with cognate antitoxin genes rescued growth, indicating that these genes function as TA loci. In vitro analysis with the purified TTC0125 and total RNA/mRNA from E. coli and T...
November 16, 2016: Extremophiles: Life Under Extreme Conditions
https://www.readbyqxmd.com/read/27827369/chaperone-addiction-of-toxin-antitoxin-systems
#10
Patricia Bordes, Ambre Julie Sala, Sara Ayala, Pauline Texier, Nawel Slama, Anne-Marie Cirinesi, Valérie Guillet, Lionel Mourey, Pierre Genevaux
Bacterial toxin-antitoxin (TA) systems, in which a labile antitoxin binds and inhibits the toxin, can promote adaptation and persistence by modulating bacterial growth in response to stress. Some atypical TA systems, known as tripartite toxin-antitoxin-chaperone (TAC) modules, include a molecular chaperone that facilitates folding and protects the antitoxin from degradation. Here we use a TAC module from Mycobacterium tuberculosis as a model to investigate the molecular mechanisms by which classical TAs can become 'chaperone-addicted'...
November 9, 2016: Nature Communications
https://www.readbyqxmd.com/read/27826018/analysis-of-pcerc7-a-small-antibiotic-resistance-plasmid-from-a-commensal-st131-escherichia-coli-defines-a-diverse-group-of-plasmids-that-include-various-segments-adjacent-to-a-multimer-resolution-site-and-encode-the-same-nika-relaxase-accessory-protein-enabling
#11
Robert A Moran, Ruth M Hall
The ampicillin resistance plasmid pCERC7, carrying transposon Tn2 with an IS4 insertion, was detected in the draft genome of a commensal Escherichia coli isolate. The genome data also revealed that this isolate belongs to ST131, clade B. pCERC7 is 9712bp comprised of a 3319bp backbone, Tn2::IS4 (6388bp) and 5bp of target site duplication, and was present at a copy number of 40. pCERC7 is related to several plasmids composed of only the backbone, or the backbone with the Tn2 insertion in the same position. These plasmids have been found previously in Escherichia coli or Salmonella enterica recovered in several different countries from as early as the 1970s...
November 4, 2016: Plasmid
https://www.readbyqxmd.com/read/27825516/adaptation-of-escherichia-coli-traversing-from-the-faecal-environment-to-the-urinary-tract
#12
Karen L Nielsen, Marc Stegger, Paul A Godfrey, Michael Feldgarden, Paal S Andersen, Niels Frimodt-Møller
The majority of extraintestinal pathogenic Escherichia coli (ExPEC) causing urinary tract infections (UTI) are found in the patient's own gut flora, but only limited knowledge is available on the potential adaptation that may occur in the bacteria in order to traverse the perineum and successfully infect the urinary tract. Here, matching pairs of faecal and UTI isolates from 42 patients were compared pairwise using in-depth whole-genome sequencing to investigate whether genetic changes were evident for successful colonization in these two different environments...
November 4, 2016: International Journal of Medical Microbiology: IJMM
https://www.readbyqxmd.com/read/27819667/deletion-of-toxin-antitoxin-systems-in-the-evolution-of-shigella-sonnei-as-a-host-adapted-pathogen
#13
Gareth McVicker, Christoph M Tang
Pathogenic Shigella spp. are the leading cause of bacterial dysentery, with Shigella flexneri and Shigella sonnei accounting for around 90% of cases worldwide. Although S. flexneri causes most disease in low-income countries (following ingestion of contaminated food and/or water), S. sonnei predominates in wealthy countries and is mainly spread from person to person. Although both species contain a large virulence plasmid, pINV, that is essential for the organism to cause disease, little is known about its maintenance...
November 7, 2016: Nature Microbiology
https://www.readbyqxmd.com/read/27818282/isolation-of-bacteriophages-and-their-application-to-control-pseudomonas-aeruginosa-in-planktonic-and-biofilm-models
#14
Magdalena Kwiatek, Sylwia Parasion, Paweł Rutyna, Lidia Mizak, Romuald Gryko, Marcin Niemcewicz, Alina Olender, Małgorzata Łobocka
Pseudomonas aeruginosa is frequently identified as a cause of diverse infections and chronic diseases. It forms biofilms and has natural resistance to several antibiotics. Strains of this pathogen resistant to new-generation beta-lactams have emerged. Due to the difficulties associated with treating chronic P. aeruginosa infections, bacteriophages are amongst the alternative therapeutic options being actively researched. Two obligatorily lytic P. aeruginosa phages, vB_PaeM_MAG1 (MAG1) and vB_PaeP_MAG4 (MAG4), have been isolated and characterized...
November 4, 2016: Research in Microbiology
https://www.readbyqxmd.com/read/27806927/molecular-mechanisms-of-bacterial-persistence-and-phenotypic-antibiotic-resistance
#15
Cui Peng, Xu Tao, Zhang Wenhong, Zhang Ying
Bacterial persistence refers to a state of reduced metabolic activity that endows a subpopulation of isogenic bacteria with multidrug tolerance. Persisters are phenotypic variants but not mutants. Since its discovery in 1944, bacterial persistence has not received enough attention until recently when its implications in persistent infections and biofilm infections become apparent. Much research has been done in recent years to investigate the mechanisms underlying bacterial persistence and phenotypic antibiotic resistance...
October 20, 2016: Yi Chuan, Hereditas
https://www.readbyqxmd.com/read/27800482/stabilization-of-the-virulence-plasmid-pslt-of-salmonella-typhimurium-by-three-maintenance-systems-and-its-evaluation-by-using-a-new-stability-test
#16
Damián Lobato-Márquez, Laura Molina-García, Inma Moreno-Córdoba, Francisco García-Del Portillo, Ramón Díaz-Orejas
Certain Salmonella enterica serovars belonging to subspecies I carry low-copy-number virulence plasmids of variable size (50-90 kb). All of these plasmids share the spv operon, which is important for systemic infection. Virulence plasmids are present at low copy numbers. Few copies reduce metabolic burden but suppose a risk of plasmid loss during bacterial division. This drawback is counterbalanced by maintenance modules that ensure plasmid stability, including partition systems and toxin-antitoxin (TA) loci...
2016: Frontiers in Molecular Biosciences
https://www.readbyqxmd.com/read/27797963/molecular-characterization-of-the-psinb-plasmid-of-the-arsenite-oxidizing-metallotolerant-sinorhizobium-sp-m14-insight-into-the-heavy-metal-resistome-of-sinorhizobial-extrachromosomal-replicons
#17
Krzysztof Romaniuk, Lukasz Dziewit, Przemyslaw Decewicz, Sebastian Mielnicki, Monika Radlinska, Lukasz Drewniak
Sinorhizobium sp. M14 is an As(III)-oxidizing, psychrotolerant strain, capable of growth in the presence of extremely high concentrations of arsenic and many other heavy metals. Metallotolerant abilities of the M14 strain depend upon the presence of two extrachromosomal replicons, pSinA (∼ 109 kb) and pSinB (∼ 300 kb). The latter was subjected to complex analysis. The performed analysis demonstrated that the plasmid pSinB is a narrow-host-range repABC-type replicon, which is fully stabilized by the phd-vapC-like toxin-antitoxin stabilizing system...
October 18, 2016: FEMS Microbiology Ecology
https://www.readbyqxmd.com/read/27795326/the-role-of-o2-in-the-growth-of-rhizobium-leguminosarum-bv-viciae-3841-on-glucose-and-succinate
#18
Rachel M Wheatley, Vinoy K Ramachandran, Barney A Geddes, Benjamin J Perry, Chris K Yost, Philip S Poole
: Insertion sequencing (INSeq) analysis of Rhizobium leguminosarum bv. viciae 3841 (Rlv3841) grown on glucose or succinate at both 21% and 1% O2 was used to understand how O2 concentration alters metabolism. Two transcriptional regulators were required for growth on glucose (pRL120207 (eryD) and RL0547 (phoB)), five on succinate (pRL100388, RL1641, RL1642, RL3427 and RL4524 (ecfL)) and three on 1% O2 (pRL110072, RL0545 (phoU) and RL4042). A novel toxin-antitoxin system was identified that could be important for generation of new plasmid-less rhizobial strains...
October 17, 2016: Journal of Bacteriology
https://www.readbyqxmd.com/read/27793962/incfiik-plasmid-harbouring-an-amplification-of-16s-rrna-methyltransferase-encoding-gene-rmth-associated-with-mobile-element-iscr2
#19
Racha Beyrouthy, Frederic Robin, Monzer Hamze, Richard Bonnet
OBJECTIVES: To investigate the resistance mechanisms and genetic support underlying the high resistance level of the Klebsiella pneumoniae strain CMUL78 to aminoglycoside and β-lactam antibiotics. METHODS: Antibiotic susceptibility was assessed by the disc diffusion method and MICs were determined by the microdilution method. Antibiotic resistance genes and their genetic environment were characterized by PCR and Sanger sequencing. Plasmid contents were analysed in the clinical strain and transconjugants obtained by mating-out assays...
October 28, 2016: Journal of Antimicrobial Chemotherapy
https://www.readbyqxmd.com/read/27790409/higb-of-pseudomonas-aeruginosa-enhances-killing-of-phagocytes-by-up-regulating-the-type-iii-secretion-system-in-ciprofloxacin-induced-persister-cells
#20
Mei Li, Yuqing Long, Ying Liu, Yang Liu, Ronghao Chen, Jing Shi, Lu Zhang, Yongxin Jin, Liang Yang, Fang Bai, Shouguang Jin, Zhihui Cheng, Weihui Wu
Bacterial persister cells are dormant and highly tolerant to lethal antibiotics, which are believed to be the major cause of recurring and chronic infections. Activation of toxins of bacterial toxin-antitoxin systems inhibits bacterial growth and plays an important role in persister formation. However, little is known about the overall gene expression profile upon toxin activation. More importantly, how the dormant bacterial persisters evade host immune clearance remains poorly understood. Here we demonstrate that a Pseudomonas aeruginosa toxin-antitoxin system HigB-HigA is required for the ciprofloxacin induced persister formation...
2016: Frontiers in Cellular and Infection Microbiology
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