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toxin and antitoxin

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https://www.readbyqxmd.com/read/28334932/ribosome-dependent-vibrio-cholerae-mrnase-higb2-is-regulated-by-a-%C3%AE-strand-sliding-mechanism
#1
San Hadži, Abel Garcia-Pino, Sarah Haesaerts, Dukas Jurenas, Kenn Gerdes, Jurij Lah, Remy Loris
Toxin-antitoxin (TA) modules are small operons involved in bacterial stress response and persistence. higBA operons form a family of TA modules with an inverted gene organization and a toxin belonging to the RelE/ParE superfamily. Here, we present the crystal structures of chromosomally encoded Vibrio cholerae antitoxin (VcHigA2), toxin (VcHigB2) and their complex, which show significant differences in structure and mechanisms of function compared to the higBA module from plasmid Rts1, the defining member of the family...
February 28, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28334797/molecular-mechanism-governing-ratio-dependent-transcription-regulation-in-the-ccdab-operon
#2
Alexandra Vandervelde, Igor Drobnak, San Hadži, Yann G-J Sterckx, Thomas Welte, Henri De Greve, Daniel Charlier, Rouslan Efremov, Remy Loris, Jurij Lah
Bacteria can become transiently tolerant to several classes of antibiotics. This phenomenon known as persistence is regulated by small genetic elements called toxin-antitoxin modules with intricate yet often poorly understood self-regulatory features. Here, we describe the structures of molecular complexes and interactions that drive the transcription regulation of the ccdAB toxin-antitoxin module. Low specificity and affinity of the antitoxin CcdA2 for individual binding sites on the operator are enhanced by the toxin CcdB2, which bridges the CcdA2 dimers...
February 17, 2017: Nucleic Acids Research
https://www.readbyqxmd.com/read/28334216/deletion-of-mazf-increases-staphylococcus-aureus-biofilm-formation-in-an-ica-dependent-manner
#3
Fuminori Kato, Yusuke Yabuno, Yoshihiro Yamaguchi, Motoyuki Sugai, Masayori Inouye
Toxin-antitoxin (TA) systems are composed of a toxin that inhibits an essential cellular process (e.g., DNA replication, transcription, membrane integrity) and its cognate antitoxin that neutralizes the effect of the toxin. Staphylococcus aureus harbors two types of chromosomally encoded TA systems, namely mazEFsa encoding a UACAU-specific mRNA interferase and two paralogous genes of yefM-yoeBsa encoding a ribosome-dependent endoribonuclease system. However, little is known about the physiological role of MazEFsa and YefM-YoeBsa in S...
March 8, 2017: Pathogens and Disease
https://www.readbyqxmd.com/read/28320039/the-role-of-peganum-harmala-ethanolic-extract-and-type-ii-toxin-antitoxin-system-in-biofilm-formation
#4
Nasrin Valizadeh, Firuzeh Valian, Nourkhoda Sadeghifard, Shahriar Karami, Iraj Pakzad, Hossein Kazemian, Sobhan Ghafourian
Toxin antitoxin system is a regulatory system that antitoxin inhibits the toxin. We aimed to determine the role of TA loci in biofilm formation in K. pneumoniae clinical and environmental isolates; also inhibition of biofilm formation by Peganum harmala. So, 40 K. pneumoniae clinical and environmental isolates were subjected for PCR to determine the frequency of mazEF, relEB, and mqsRA TA loci. Biofilm formation assay subjected for all isolates. Then, P. harmala was tested against positive biofilm formation strains...
March 20, 2017: Drug Research
https://www.readbyqxmd.com/read/28303133/corrigendum-what-is-the-link-between-stringent-response-endoribonuclease-encoding-type-ii-toxin-antitoxin-systems-and-persistence
#5
Bhaskar C M Ramisetty, Dimpy Ghosh, Moumita Roy Chowdhury, Ramachandran S Santhosh
[This corrects the article on p. 1882 in vol. 7, PMID: 27933045.].
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28298445/the-structure-and-function-of-mycobacterium-tuberculosis-mazf-mt6-provides-insights-into-conserved-features-of-mazf-endonucleases
#6
Eric D Hoffer, Stacey J Miles, Christine M Dunham
Toxin-antitoxin systems are ubiquitous in prokaryotic and archaea genomes and regulate growth in response to stress. E. coli contains at least 36 putative toxin-antitoxin gene pairs, and some pathogens such as Mycobacterium tuberculosis (Mtb) have over 90 toxin-antitoxin operons. E. coli MazF cleaves free mRNA after encountering stress and nine Mtb MazF family members cleave mRNA, tRNA, or rRNA. Moreover, Mtb MazF-mt6 cleaves 23S rRNA Helix 70 to inhibit protein synthesis. The overall tertiary folds of these MazFs are predicted to be similar, therefore it is unclear how they recognize structurally distinct RNAs...
March 15, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28292710/bacterial-persistence-from-a-system-level-perspective
#7
REVIEW
Jakub Leszek Radzikowski, Hannah Schramke, Matthias Heinemann
In recent years, our understanding about bacterial persistence has significantly advanced: we comprehend the persister phenotype better, more triggers for persistence entry have been found, and more insights in the involvement and role of toxin-antitoxin systems and other molecular mechanisms have been unravelled. In this review, we attempt to put these findings into an integrated, system-level perspective. From this point of view, persistence can be seen as a response to a strong perturbation of metabolic homeostasis, either triggered environmentally, or by means of intracellular stochasticity...
March 11, 2017: Current Opinion in Biotechnology
https://www.readbyqxmd.com/read/28282873/crystal-structure-of-the-receptor-binding-domain-of-botulinum-neurotoxin-type-ha-also-known-as-type-fa-or-h
#8
Guorui Yao, Kwok-Ho Lam, Kay Perry, Jasmin Weisemann, Andreas Rummel, Rongsheng Jin
Botulinum neurotoxins (BoNTs), which have been exploited as cosmetics and muscle-disorder treatment medicines for decades, are well known for their extreme neurotoxicity to humans. They pose a potential bioterrorism threat because they cause botulism, a flaccid muscular paralysis-associated disease that requires immediate antitoxin treatment and intensive care over a long period of time. In addition to the existing seven established BoNT serotypes (BoNT/A-G), a new mosaic toxin type termed BoNT/HA (aka type FA or H) was reported recently...
March 8, 2017: Toxins
https://www.readbyqxmd.com/read/28280011/draft-genome-sequence-of-agrococcusbaldri-strain-marseille-p2731
#9
Pamela Afouda, Gregory Dubourg, Noemie Labas, Didier Raoult, Pierre-Edouard Fournier
Agrococcus baldri strain Marseille-P2731 was isolated from a Siberian permafrost specimen dated around 10 million years. The 3,021,022-bp genome of strain Marseille-P2731, with a 71.82% G+C content, includes 2,844 protein-coding genes, 72 toxin/antitoxin modules, nine bacteriocin-encoding genes, and 1,266 genes associated with mobilome.
March 9, 2017: Genome Announcements
https://www.readbyqxmd.com/read/28279904/toxin-antitoxin-systems-reversible-toxicity
#10
REVIEW
Alexander Mj Hall, Bridget Gollan, Sophie Helaine
Toxin-antitoxin (TA) systems encoded on the plasmids and chromosomes of bacteria are emerging as key players in stress adaptation. In particular, they have been implicated in the induction of persisters non-growing cells that can evade antibiotic exposure. TA toxins operate by a diverse range of mechanisms, either destructive or conservative, leading to the reversible growth arrest of bacterial cells. Whilst the molecular mechanisms of intoxication are now well understood, we still have very little information on how corrupted cells reawaken...
March 6, 2017: Current Opinion in Microbiology
https://www.readbyqxmd.com/read/28271484/higher-order-structure-in-bacterial-vapbc-toxin-antitoxin-complexes
#11
Kirstine L Bendtsen, Ditlev E Brodersen
Toxin-antitoxin systems are widespread in the bacterial kingdom, including in pathogenic species, where they allow rapid adaptation to changing environmental conditions through selective inhibition of key cellular processes, such as DNA replication or protein translation. Under normal growth conditions, type II toxins are inhibited through tight protein-protein interaction with a cognate antitoxin protein. This toxin-antitoxin complex associates into a higher-order macromolecular structure, typically heterotetrameric or heterooctameric, exposing two DNA binding domains on the antitoxin that allow auto-regulation of transcription by direct binding to promoter DNA...
2017: Sub-cellular Biochemistry
https://www.readbyqxmd.com/read/28270261/exploring-the-parameters-of-post-segregational-killing-using-heterologous-expression-of-secreted-toxin-barnase-and-antitoxin-barstar-in-an-escherichia-coli-case-study
#12
Dorien S Coray, Brigitta Kurenbach, Jack A Heinemann
Post-segregational killing (PSK) is a phenotype determined by plasmids using a toxin and an antitoxin 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...
February 2017: Microbiology
https://www.readbyqxmd.com/read/28267580/carriage-of-type-ii-toxin-antitoxin-systems-by-the-growing-group-of-incx-plasmids
#13
Paula Bustamante, Jonathan R Iredell
The stable maintenance of certain plasmids in bacterial populations has contributed significantly to the current worldwide antibiotic resistance (AbR) emergency. IncX plasmids, long underestimated in this regard, have achieved recent notoriety for their roles in transmission of resistance to carbapenem and colistin, the last-line antibiotics for Gram-negative infections. Toxin-antitoxin (TA) systems contribute to stable maintenance of many AbR plasmids, and a few TA systems have been previously described in the IncX plasmids...
March 3, 2017: Plasmid
https://www.readbyqxmd.com/read/28266056/hica-toxin-of-escherichia-coli-derepresses-hicab-transcription-to-selectively-produce-hicb-antitoxin
#14
Kathryn J Turnbull, Kenn Gerdes
Antitoxins encoded by type II toxin - antitoxin (TA) modules neutralize cognate toxins by direct protein - protein contact and in addition, regulate TA operon transcription by binding to operators in the promoter regions. On top of the simple negative feed-back regulation, canonical type II TA operons are regulated by a mechanism called "Conditional Cooperativity" (CC). In CC, the cellular toxin:antitoxin (T:A) ratio controls the transcription-rate such that low T:A ratios favour repression and high T:A ratios favour de-repression of TA operon transcription...
March 7, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28261163/commentary-what-is-the-link-between-stringent-response-endoribonuclease-encoding-type-ii-toxin-antitoxin-systems-and-persistence
#15
COMMENT
Laurence Van Melderen, Thomas K Wood
No abstract text is available yet for this article.
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28257056/interaction-of-type-iv-toxin-antitoxin-systems-in-cryptic-prophages-of-escherichia-coli-k-12
#16
Zhongling Wen, Pengxia Wang, Chenglong Sun, Yunxue Guo, Xiaoxue Wang
Toxin/antitoxin (TA) systems are widespread in prokaryotic chromosomes and in mobile genetic elements including plasmids and prophages. The first characterized Type IV TA system CbtA/CbeA was found in cryptic prophage CP4-44 in Escherichia coli K-12. Two homologous TA loci of CbtA/CbeA also reside in cryptic prophages of E. coli K-12, YkfI/YafW in CP4-6 and YpjF/YfjZ in CP4-57. In this study, we demonstrated that YkfI and YpjF inhibited cell growth and led to the formation of "lemon-shaped" cells. Prolonged overproduction of YkfI led to the formation of "gourd-shaped" cells and immediate cell lysis...
March 1, 2017: Toxins
https://www.readbyqxmd.com/read/28213763/the-lactobacillus-rhamnosus-and-lactobacillus-fermentum-strains-from-human-biotopes-characterized-with-mlst-and-toxin-antitoxin-gene-polymorphism
#17
E U Poluektova, R A Yunes, M V Epiphanova, V S Orlova, V N Danilenko
The diversity of Lb. rhamnosus and Lb. fermentum strains isolated from feces, saliva, and the vaginal cavity of 18-22-year-old healthy women residing in central regions of the Russian Federation has been characterized. The results obtained using multilocus sequence typing were identical to those obtained with the analysis of genetic and genomic polymorphism in TA systems. Different as well as identical Lb. rhamnosus and Lb. fermentum sequence types (ST) were isolated from various parts of the body of the same person...
February 17, 2017: Archives of Microbiology
https://www.readbyqxmd.com/read/28213540/characterization-of-the-physical-and-functional-interplay-between-mazf1-bif-and-its-noncognate-antitoxins-from-bifidobacterium-longum
#18
Yanxia Wei, Yang Li, Fan Yang, Qiong Wu, Dianbin Liu, Xiangyang Li, Hui Hua, Xiaomei Liu, Yugang Wang, Kuiyang Zheng, Renxian Tang
Bifidobacterium longum strain JDM301, a widely used commercial strain in China, encodes at least two MazEF-like modules and one RelBE-like toxin-antitoxin (TA) systems in its chromosome, designated as MazE1F1(Bif), MazE2F2(Bif) and RelBE(Bif), respectively. Bacterial TA systems play an important role in several stress responses, but the relationship between these TA systems is largely unknown. In this study, the interaction between MazF1(Bif) and MazE2(Bif) or RelB(Bif) was assessed in B. longum strain JDM301...
February 17, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28193447/identification-and-bacterial-characteristics-of-xenorhabdus-hominickii-anu101-from-an-entomopathogenic-nematode-steinernema-monticolum
#19
Youngjin Park, Sangjin Kang, Md Sadekuzzaman, Hyeonghwan Kim, Jin-Kyo Jung, Yonggyun Kim
An entomopathogenic nematode, Steinernema monticolum, was collected in Korea. Its identity was confirmed by morphological and molecular characters. Its symbiotic bacterium, Xenorhabdus hominickii ANU101, was isolated and assessed in terms of bacterial characteristics. Sixty-eight different carbon sources were utilized by X. hominickii ANU101 out of 95 different sources from a Biolog assay. Compared to other Xenorhabdus species, X. hominickii ANU101 was relatively susceptible to high temperatures and did not grow above 34°C...
March 2017: Journal of Invertebrate Pathology
https://www.readbyqxmd.com/read/28174313/atp-dependent-persister-formation-in-escherichia-coli
#20
Yue Shan, Autumn Brown Gandt, Sarah E Rowe, Julia P Deisinger, Brian P Conlon, Kim Lewis
Persisters are dormant variants that form a subpopulation of cells tolerant to antibiotics. Persisters are largely responsible for the recalcitrance of chronic infections to therapy. In Escherichia coli, one widely accepted model of persister formation holds that stochastic accumulation of ppGpp causes activation of the Lon protease that degrades antitoxins; active toxins then inhibit translation, resulting in dormant, drug-tolerant persisters. We found that various stresses induce toxin-antitoxin (TA) expression but that induction of TAs does not necessarily increase persisters...
February 7, 2017: MBio
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