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toxin antitoxin

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https://www.readbyqxmd.com/read/28213763/the-lactobacillus-rhamnosus-and-lactobacillus-fermentum-strains-from-human-biotopes-characterized-with-mlst-and-toxin-antitoxin-gene-polymorphism
#1
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
#2
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
#3
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...
February 10, 2017: Journal of Invertebrate Pathology
https://www.readbyqxmd.com/read/28174313/atp-dependent-persister-formation-in-escherichia-coli
#4
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
https://www.readbyqxmd.com/read/28164393/importance-of-the-e-coli-dinj-antitoxin-carboxy-terminus-for-toxin-suppression-and-regulated-proteolysis
#5
Ajchareeya Ruangprasert, Tatsuya Maehigashi, Stacey J Miles, Christine M Dunham
Toxin-antitoxin genes play important roles in the regulation of bacterial growth during stress. One response to stress is selective proteolysis of antitoxin proteins which releases their cognate toxin partners causing rapid inhibition of growth. The features of toxin-antitoxin complexes that are important to inhibit toxin activity as well as to release the active toxin remain elusive. Furthermore, it is unclear how antitoxins are selected for proteolysis by cellular proteases. Here, we test the minimal structural requirements of the E...
February 6, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28164379/peptide-nucleotide-antibiotic-microcin-c-is-a-potent-inducer-of-stringent-response-and-persistence-in-both-sensitive-and-producing-cells
#6
Julia Piskunova, Etienne Maisonneuve, Elsa Germain, Kenn Gerdes, Konstantin Severinov
Microcin C (McC) is a peptide-nucleotide antibiotic that inhibits aspartyl-tRNA synthetase. Here, we show that McC is a strong inducer of persistence in Escherichia coli. Persistence induced by McC is mediated by (p)ppGpp and requires chromosomally encoded toxin-antitoxin modules. McC-producing cells have increased persistence levels due to a combined effect of McC imported from the cultured medium and intracellularly synthesized antibiotic. McC-producing cells also induce persistence in sensitive cells during co-cultivation, underscoring complex interactions in bacterial communities where an antagonistic compound produced by one community member can benefit other members by increasing their ability to withstand antibiotics...
February 6, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28159786/bacteriophage-%C3%AE-m1-of-pectobacterium-evolves-to-escape-two-bifunctional-type-iii-toxin-antitoxin-and-abortive-infection-systems-through-mutations-in-a-single-viral-gene
#7
Tim R Blower, Ray Chai, Rita Przybilski, Shahzad Chindhy, Xinzhe Fang, Samuel E Kidman, Hui Tan, Ben F Luisi, Peter C Fineran, George P C Salmond
: Some bacteria, when infected by their viral parasites (bacteriophages), undergo a suicidal response that also terminates productive viral replication (abortive infection; Abi). This response can be viewed as an altruistic act protecting the uninfected bacterial clonal population. Abortive infection can occur through the action of Type III protein-RNA toxin-antitoxin (TA) systems, such as ToxINPa from the phytopathogen, Pectobacterium atrosepticum Rare spontaneous mutants evolved in the generalized transducing phage, ΦM1, which escaped ToxINPa-mediated abortive infection in P...
February 3, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28124913/hidden-states-within-disordered-regions-of-the-ccda-antitoxin-protein
#8
Virginia M Burger, Alexandra Vandervelde, Jelle Hendrix, Albert Konijnenberg, Frank Sobott, Remy Loris, Collin M Stultz
The bacterial toxin-antitoxin system CcdB-CcdA provides a mechanism for the control of cell death and quiescence. The antitoxin protein CcdA is a homodimer composed of two monomers that each contain a folded N-terminal region and an intrinsically disordered C-terminal arm. Binding of the intrinsically disordered C-terminal arm of CcdA to the toxin CcdB prevents CcdB from inhibiting DNA gyrase and thereby averts cell death. Accurate models of the unfolded state of the partially disordered CcdA antitoxin can therefore provide insight into general mechanisms whereby protein disorder regulates events that are crucial to cell survival...
February 8, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28119479/diversity-and-functionality-of-plasmid-borne-vagcd-toxin-antitoxin-systems-of-klebsiella-pneumoniae
#9
Marion Duprilot, Dominique Decre, Nathalie Genel, Laurence Drieux, Wladimir Sougakoff, Guillaume Arlet
OBJECTIVES: To explore the VagCD toxin-antitoxin (TA) systems encoded on plasmids in multiresistant Klebsiella pneumoniae strains. METHODS: Previously sequenced K. pneumoniae plasmids were used for in silico analysis and a collection of 63 resistant K. pneumoniae strains was used for epidemiological study. Functional analysis was done after separate cloning of the toxin gene under the control of the arabinose-inducible promoter of pBAD43 and of the antitoxin gene under the control of the constitutive promoter of pUC19...
January 23, 2017: Journal of Antimicrobial Chemotherapy
https://www.readbyqxmd.com/read/28115385/freshwater-cyanobacterial-interactions-with-bacterial-antagonists
#10
Omneya Ahmed Osman, Sara Beier, Manfred Grabherr, Stefan Bertilsson
: Cyanobacterial and algal mass development or "blooms" have severe effects on freshwater and marine systems around the world. Many of these phototrophs produce a variety of potent toxins, contribute to oxygen depletion, and affect water quality in several ways. Coexisting antagonists such as cyanolytic bacteria, hold the potential to suppress, or even terminate such blooms, yet the nature of this interaction is not well studied. We isolated 31 cyanolytic bacteria affiliated with the genera Pseudomonas, Stenotrophomonas, Acinetobacter and Delftia from three eutrophic freshwater lakes in Sweden, and selected four phylogenetically diverse bacterial strains with strong to moderate lytic activity...
January 23, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28113053/mazef-toxin-antitoxin-proteins-alter-e-coli-cell-morphology-and-infrastructure-during-persister-formation-and-regrowth
#11
Junho Cho, Anita Carr, Lisa Whitworth, Brent Johnson, Kevin Scott Wilson
When exposed to antibiotics, many bacteria respond by activating intracellular "toxin" proteins, which arrest cell growth and induce formation of persister cells that survive antibiotics. After antibiotics are removed, persisters can regrow by synthesizing "antitoxin" proteins that sequester toxin proteins. In E. coli, MazE antitoxin sequesters the activity of MazF toxin, which extensively cleaves cellular RNAs. Although the functions of MazEF proteins are well characterized, there is surprisingly little known about their effects on cell structure...
January 22, 2017: Microbiology
https://www.readbyqxmd.com/read/28104802/the-ssl2245-sll1130-toxin-antitoxin-system-mediates-heat-induced-programmed-cell-death-in-synechocystis-sp-pcc6803
#12
Afshan Srikumar, Pilla Sankara Krishna, Dokku Sivaramakrishna, Stefan Kopfmann, Wolfgang R Hess, Musti J Swamy, Sue Lin-Chao, Jogadhenu S S Prakash
Two putative heat responsive genes, ssl2245 and sll1130 constitute an operon that also has characteristics of a toxin-antitoxin system, thus joining several enigmatic features. Closely related orthologs of Ssl2245 and Sll1130 exist in widely different bacteria, which thrive under environments with large fluctuations in temperature and salinity, among which some are thermo-epilithic biofilm forming cyanobacteria. Transcriptome analyses revealed that the CRISPR genes as well as several hypothetical genes were commonly up-regulated in Δssl2245 and Δsll1130 mutants...
January 19, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28098783/the-influence-of-the-toxin-antitoxin-mazef-on-growth-and-survival-of-listeria-monocytogenes-under-stress
#13
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
#14
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. Here, we reprogrammed the bacterial TA systems as the toxin counter-selectable cassette regulated by an antitoxin switch (TCCRAS) for genetic modifications in the extensively studied and utilized Gram-positive bacteria, B. subtilis and Corynebacterium glutamicum. In the five characterized type II TA systems, the RelBE complex can specifically and efficiently regulate cell growth and death by the conditionally controlled antitoxin RelB switch, thereby serving as a novel counter-selectable cassette to establish the TCCRAS system...
January 26, 2017: ACS Synthetic Biology
https://www.readbyqxmd.com/read/28089288/the-role-of-reactive-oxygen-species-in-antibiotic-mediated-killing-of-bacteria
#15
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
#16
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
#17
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
#18
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 7, 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-with-type-ii-and-type-iii-systems
#19
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
#20
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
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