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https://www.readbyqxmd.com/read/28993337/whole-transcriptome-and-genomic-analysis-of-extensively-drug-resistant-mycobacterium-tuberculosis-clinical-isolates-identifies-downregulation-of-etha-as-a-mechanism-of-ethionamide-resistance
#1
Lynne de Welzen, Vegard Eldholm, Kashmeel Maharaj, Abigail L Manson, Ashlee M Earl, Alexander S Pym
Genetic based drug susceptibility testing has improved the diagnosis of drug-resistant tuberculosis, but is limited by our lack of knowledge of all resistance mechanisms. Next generation sequencing has assisted in identifying the principal genetic mechanisms of resistance for many drugs, but a significant proportion of phenotypic drug resistance is unexplained genetically. Few studies have formally compared the transcriptome of susceptible and resistant M. tuberculosis We carried out comparative whole genome transcriptomics on extensively drug-resistant (XDR) clinical isolates using RNA-sequencing (RNAseq) to find novel transcriptional mediated mechanisms of resistance...
October 9, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28986943/crystal-structure-of-mycobacterium-tuberculosis-vapc20-toxin-and-its-interactions-with-cognate-antitoxin-vapb20-suggest-a-model-for-toxin-antitoxin-assembly
#2
Amar Deep, Soni Kaundal, Sakshi Agarwal, Ramandeep Singh, Krishan Gopal Thakur
VapBCs, virulence-associated proteins, are the most abundant type II toxin-antitoxin (TA) systems in prokaryotes. Under normal conditions, toxin and antitoxin interact to form a heterooctameric complex, which upon binding to operator sites, inhibits their own expression. Under stress conditions, the VapB antitoxin is degraded by cellular proteases to release a free VapC toxin, which in turn inhibits cell growth mainly by targeting protein translation. However, the intermediate steps involved in the assembly of the heterooctameric complex have not been resolved...
October 7, 2017: FEBS Journal
https://www.readbyqxmd.com/read/28985291/mobile-genetic-elements-and-evolution-of-crispr-cas-systems-all-the-way-there-and-back
#3
Eugene V Koonin, Kira S Makarova
The CRISPR-Cas systems of bacterial and archaeal adaptive immunity show multifaceted evolutionary relationships with at least five classes of mobile genetic elements (MGE). First, the adaptation module of CRISPR-Cas that is responsible for the formation of the immune memory apparently evolved from a Casposon, a self-synthesizing transposon that employs the Cas1 protein as the integrase and might have brought additional cas genes to the emerging immunity loci. Second, a large subset of type III CRISPR-Cas systems recruited a reverse transcriptase from a Group II intron, providing for spacer acquisition from RNA...
September 18, 2017: Genome Biology and Evolution
https://www.readbyqxmd.com/read/28979246/variable-persister-gene-interactions-with-p-ppgpp-for-persister-formation-in-escherichia-coli
#4
Shuang Liu, Nan Wu, Shanshan Zhang, Youhua Yuan, Wenhong Zhang, Ying Zhang
Persisters comprise a group of phenotypically heterogeneous metabolically quiescent bacteria with multidrug tolerance and contribute to the recalcitrance of chronic infections. Although recent work has shown that toxin-antitoxin (TA) system HipAB depends on stringent response effector (p)ppGppin persister formation, whether other persister pathways are also dependent on stringent response has not been explored. Here we examined the relationship of (p)ppGpp with 15 common persister genes (dnaK, clpB, rpoS, pspF, tnaA, sucB, ssrA, smpB, recA, umuD, uvrA, hipA, mqsR, relE, dinJ) using Escherichia coli as a model...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28972558/treatments-for-pulmonary-ricin-intoxication-current-aspects-and-future-prospects
#5
REVIEW
Yoav Gal, Ohad Mazor, Reut Falach, Anita Sapoznikov, Chanoch Kronman, Tamar Sabo
Ricin, a plant-derived toxin originating from the seeds of Ricinus communis (castor beans), is one of the most lethal toxins known, particularly if inhaled. Ricin is considered a potential biological threat agent due to its high availability and ease of production. The clinical manifestation of pulmonary ricin intoxication in animal models is closely related to acute respiratory distress syndrome (ARDS), which involves pulmonary proinflammatory cytokine upregulation, massive neutrophil infiltration and severe edema...
October 3, 2017: Toxins
https://www.readbyqxmd.com/read/28972145/structural-analyses-of-the-mazef4-toxin-antitoxin-pair-in-mycobacterium-tuberculosis-provide-evidence-for-a-unique-extracellular-death-factor
#6
Do-Hwan Ahn, Ki-Young Lee, Sang Jae Lee, Sung Jean Park, Hye-Jin Yoon, Soon-Jong Kim, Bong-Jin Lee
The bacterial toxin-antitoxin MazEF system in the tuberculosis (TB)-causing bacterium Mycobacterium tuberculosis is activated under unfavorable conditions, including starvation, antibiotic exposure, and oxidative stress. This system contains the ribonucleolytic enzyme MazF and has emerged as a promising drug target for TB treatments targeting the latent stage of M. tuberculosis infection and reportedly mediates a cell death process via a peptide called extracellular death factor (EDF). Although it is well established that the increase in EDFmediated toxicity of MazF drives a cell-killing phenomenon, the molecular details are poorly understood...
October 2, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28970172/plasmid-pum505-encodes-a-toxin-antitoxin-system-conferring-plasmid-stability-and-increased-pseudomonas-aeruginosa-virulence
#7
K C Hernández-Ramírez, V M Chávez-Jacobo, M I Valle-Maldonado, J A Patiño-Medina, S P Díaz-Pérez, I E Jácome-Galarza, R Ortiz-Alvarado, V Meza-Carmen, M I Ramírez-Díaz
Pseudomonas aeruginosa plasmid pUM505 possesses a pathogenicity island that contains the pumAB genes that encode products with sequence similarity to Toxin-Antitoxin (TA) modules. RT-PCR assays on the overlapping regions of the pumAB genes generated a bicistronic messenger RNA, suggesting that they form an operon. When the pumAB genes were cloned into the pJET vector, recombinant plasmid pJET-pumAB was maintained under nonselective conditions in Escherichia coli cells after six daily subcultures, whereas pJET without pumAB genes was lost...
September 29, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28950904/development-of-an-antibiotic-marker-free-platform-for-heterologous-protein-production-in-streptomyces
#8
Laura Sevillano, Margarita Díaz, Ramón I Santamaría
BACKGROUND: The industrial use of enzymes produced by microorganisms is continuously growing due to the need for sustainable solutions. Nevertheless, many of the plasmids used for recombinant production of proteins in bacteria are based on the use of antibiotic resistance genes as selection markers. The safety concerns and legal requirements surrounding the increased use of antibiotic resistance genes have made the development of new antibiotic-free approaches essential. RESULTS: In this work, a system completely free of antibiotic resistance genes and useful for the production of high yields of proteins in Streptomyces is described...
September 26, 2017: Microbial Cell Factories
https://www.readbyqxmd.com/read/28948108/mazf-activation-promotes-translational-heterogeneity-of-the-grca-mrna-in-escherichia-coli-populations
#9
Nela Nikolic, Zrinka Didara, Isabella Moll
Bacteria adapt to adverse environmental conditions by altering gene expression patterns. Recently, a novel stress adaptation mechanism has been described that allows Escherichia coli to alter gene expression at the post-transcriptional level. The key player in this regulatory pathway is the endoribonuclease MazF, the toxin component of the toxin-antitoxin module mazEF that is triggered by various stressful conditions. In general, MazF degrades the majority of transcripts by cleaving at ACA sites, which results in the retardation of bacterial growth...
2017: PeerJ
https://www.readbyqxmd.com/read/28945748/genetic-plasticity-of-the-shigella-virulence-plasmid-is-mediated-by-intra-and-inter-molecular-events-between-insertion-sequences
#10
Giulia Pilla, Gareth McVicker, Christoph M Tang
Acquisition of a single copy, large virulence plasmid, pINV, led to the emergence of Shigella spp. from Escherichia coli. The plasmid encodes a Type III secretion system (T3SS) on a 30 kb pathogenicity island (PAI), and is maintained in a bacterial population through a series of toxin:antitoxin (TA) systems which mediate post-segregational killing (PSK). The T3SS imposes a significant cost on the bacterium, and strains which have lost the plasmid and/or genes encoding the T3SS grow faster than wild-type strains in the laboratory, and fail to bind the indicator dye Congo Red (CR)...
September 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28943257/immuno-detection-of-cleaved-snap-25-from-differentiated-mouse-embryonic-stem-cells-provides-a-sensitive-assay-for-determination-of-botulinum-a-toxin-and-antitoxin-potency
#11
G Yadirgi, P Stickings, S Rajagopal, Y Liu, D Sesardic
Botulinum toxin type A is a causative agent of human botulism. Due to high toxicity and ease of production it is classified by the Centres for Disease Control and Prevention as a category A bioterrorism agent. The same serotype, BoNT/A, is also the most widely used in pharmaceutical preparations for treatment of a diverse range of neuromuscular disorders. Traditionally, animals are used to confirm the presence and activity of toxin and to establish neutralizing capabilities of countermeasures in toxin neutralization tests...
September 21, 2017: Journal of Immunological Methods
https://www.readbyqxmd.com/read/28941941/novel-toxins-from-type-ii-toxin-antitoxin-systems-with-acetyltransferase-activity
#12
REVIEW
Dukas Jurėnas, Abel Garcia-Pino, Laurence Van Melderen
Type II toxin-antitoxin (TA) systems are widespread in bacterial and archeal genomes. These modules are very dynamic and participate in bacterial genome evolution through horizontal gene transfer. TA systems are commonly composed of a labile antitoxin and a stable toxin. Toxins appear to preferentially inhibit the protein synthesis process. Toxins use a variety of molecular mechanisms and target nearly every step of translation to achieve their inhibitory function. This review focuses on a recently identified TA family that includes acetyltransferase toxins...
September 20, 2017: Plasmid
https://www.readbyqxmd.com/read/28935987/toward-the-identification-of-a-type-i-toxin-antitoxin-system-in-the-plasmid-dna-of-dairy-lactobacillus-rhamnosus
#13
Claudia Folli, Alessia Levante, Riccardo Percudani, Davide Amidani, Stefania Bottazzi, Alberto Ferrari, Claudio Rivetti, Erasmo Neviani, Camilla Lazzi
Plasmids carry genes that give bacteria beneficial traits and allow them to survive in competitive environments. In many cases, they also harbor toxin-antitoxin (TA) systems necessary for plasmid maintenance. TA systems are generally characterized by a stable "toxin", a protein or peptide capable of killing the cell upon plasmid loss and by an unstable "antitoxin", a protein or a non-coding RNA that inhibits toxin activity. Here we report data toward the identification of a RNA-regulated TA system in the plasmid DNA of L...
September 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28935494/-an-atypical-case-of-necrotizing-staphylococcal-pneumonia
#14
E Bertreau, S Grard, T Baudry, N Freymond
INTRODUCTION: Some strains of Staphylococcus aureus produce a toxin known as Panton-Valentine leukocidin. These strains notably cause a necrotizing pneumonia which is associated with a high mortality. OBSERVATION: A 70-year-old woman presented with sub-acute onset dyspnea, low-grade fever, and hemoptysis after a trip to Dubai and New Zealand. Computed tomography showed bilateral necrotizing pneumonia, suggesting the diagnosis of pneumonia caused by S. aureus producing Panton-Valentine toxin...
September 18, 2017: Revue des Maladies Respiratoires
https://www.readbyqxmd.com/read/28931012/cbta-toxin-of-escherichia-coli-inhibits-cell-division-and-cell-elongation-via-direct-and-independent-interactions-with-ftsz-and-mreb
#15
Danielle M Heller, Mrinalini Tavag, Ann Hochschild
The toxin components of toxin-antitoxin modules, found in bacterial plasmids, phages, and chromosomes, typically target a single macromolecule to interfere with an essential cellular process. An apparent exception is the chromosomally encoded toxin component of the E. coli CbtA/CbeA toxin-antitoxin module, which can inhibit both cell division and cell elongation. A small protein of only 124 amino acids, CbtA, was previously proposed to interact with both FtsZ, a tubulin homolog that is essential for cell division, and MreB, an actin homolog that is essential for cell elongation...
September 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28929958/-screening-of-corynebacterium-diphtheriae-corynebacterium-ulcerans-and-corynebacterium-pseudotuberculosis-in-throat-swab-specimens-of-children-with-upper-respiratory-tract-infections
#16
Zeynep Gökçe Gayretli Aydın, Gönül Tanır, Selin Nar Ötgün, Meral Turan, Türkan Aydın Teke, Ayşe Kaman, Selçuk Kılıç
Although a significant decrease has been reported in the incidence of diphteria in many regions of the world following the routine diphtheria immunization programs, the emergence of new cases indicated that toxigenic strains are still circulating in the community. Diphtheria vaccine does not provide protection against asymptomatic carriage and colonization of non-toxigenic Corynebacterium diphtheriae. It is a known fact that invasive infections may arise from non-toxigenic C.diphtheriae strains that the non-toxigenic strains can become toxigenic strains leading to diphteria...
July 2017: Mikrobiyoloji Bülteni
https://www.readbyqxmd.com/read/28893775/a-nosocomial-outbreak-of-extensively-drug-resistant-xdr-acinetobacter-baumannii-isolates-containing-blaoxa-237-encoded-on-a-plasmid
#17
Andrea M Hujer, Paul G Higgins, Susan D Rudin, Genevieve L Buser, Steven H Marshall, Kyriaki Xanthopoulou, Harald Seifert, Laura J Rojas, T Nicholas Domitrovic, P Maureen Cassidy, Margaret C Cunningham, Robert Vega, Jon P Furuno, Christopher D Pfeiffer, Zintars G Beldavs, Meredith S Wright, Michael R Jacobs, Mark D Adams, Robert A Bonomo
Carbapenem antibiotics are among the mainstay for treating infections caused by Acinetobacter baumannii, especially in the Northwest United States where carbapenem resistant A. baumannii remain relatively rare. However, between June 2012 and October 2014, an outbreak of carbapenem-resistant A. baumannii occurred in 16 patients from 5 healthcare facilities in the state of Oregon. All isolates were defined as extensively-drug resistant (XDR). MLST revealed that the isolates belonged to sequence type 2 (international clone 2, IC2), and were greater than 95% similar by rep-PCR analysis...
September 11, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28876228/hicab-toxin-antitoxin-complex-from-escherichia-coli-expression-and-crystallization
#18
Jingsi Yang, Bingshuang Xu, Zengqiang Gao, Ke Zhou, Peng Liu, Yuhui Dong, Jianjun Zhang, Quansheng Liu
Toxin-antitoxin (TA) systems are widespread in both bacteria and archaea, where they enable cells to adapt to environmental cues. TA systems play crucial roles in various cellular processes, such as programmed cell death, cell growth, persistence and virulence. Here, two distinct forms of the type II toxin-antitoxin complex HicAB were identified and characterized in Escherichia coli K-12, and both were successfully overexpressed and purified. The two proposed forms, HicAB(L) and HicAB(S), differed in the presence or absence of a seven-amino-acid segment at the N-terminus in the antitoxin HicB...
September 1, 2017: Acta Crystallographica. Section F, Structural Biology Communications
https://www.readbyqxmd.com/read/28867361/diphtheric-encephalitis-and-brain-neuroimaging-features
#19
Jen Chun Foo, Kartini Rahmat, Nazimah Ab Mumin, Mia Tuang Koh, Chin Seng Gan, Norlisah Ramli, Choong Yi Fong
We report a rare case of paediatric diphtheria complicated with encephalitis. A 6-year-old boy who did not receive his scheduled diptheria-tetanus-pertusis vaccination presented with one episode of generalised convulsive seizure. His illness was preceded by a 3day history of fever associated with enlarged exudative tonsils with a pseudomembrane. He was commenced on intravenous penicillin and oral erythromycin. However, he developed progressive encephalopathy with focal neurological deficit which required intubation on day 5 of illness...
September 1, 2017: Journal of Clinical Neuroscience: Official Journal of the Neurosurgical Society of Australasia
https://www.readbyqxmd.com/read/28864459/rna-editing-in-bacteria-recodes-multiple-proteins-and-regulates-an-evolutionarily-conserved-toxin-antitoxin-system
#20
Dan Bar-Yaacov, Ernest Mordret, Ruth Towers, Tammy Biniashvili, Clara Soyris, Schraga Schwartz, Orna Dahan, Yitzhak Pilpel
Adenosine (A) to inosine (I) RNA editing is widespread in eukaryotes. In prokaryotes, however, A-to-I RNA editing was only reported to occur in tRNAs but not in protein-coding genes. By comparing DNA and RNA sequences of Escherichia coli, we show for the first time that A-to-I editing occurs also in prokaryotic mRNAs and has the potential to affect the translated proteins and cell physiology. We found 15 novel A-to-I editing events, of which 12 occurred within known protein-coding genes where they always recode a tyrosine (TAC) into a cysteine (TGC) codon...
October 2017: Genome Research
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