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https://www.readbyqxmd.com/read/28637172/identification-of-four-type-ii-toxin-antitoxin-systems-in-actinobacillus-pleuropneumoniae
#1
Chengkun Zheng, Xigong Zhao, Ting Zeng, Manman Cao, Jiali Xu, Guolin Shi, Jinquan Li, Huanchun Chen, Weicheng Bei
Toxin-antitoxin systems are small genetic elements that are widely prevalent in the genomes of bacteria and archaea. These modules have been identified in various bacteria and proposed to play an important role in bacterial physiology and virulence. However, their presence in the genomes of Actinobacillus species has received no attention. In this study, we describe the identification of four type II TA systems in Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia. Reverse transcription PCR analysis revealed that the genes encoding the toxin and antitoxin are co-transcribed...
June 20, 2017: FEMS Microbiology Letters
https://www.readbyqxmd.com/read/28635589/regulation-of-escherichia-coli-pathogenesis-by-alternative-sigma-factor-n
#2
James T Riordan, Avishek Mitra
σ(N) (also σ(54)) is an alternative sigma factor subunit of the RNA polymerase complex that regulates the expression of genes from many different ontological groups. It is broadly conserved in the Eubacteria with major roles in nitrogen metabolism, membrane biogenesis, and motility. σ(N) is encoded as the first gene of a five-gene operon including rpoN (σ(N)), ptsN, hpf, rapZ, and npr that has been genetically retained among species of Escherichia, Shigella, and Salmonella. In an increasing number of bacteria, σ(N) has been implicated in the control of genes essential to pathogenic behavior, including those involved in adherence, secretion, immune subversion, biofilm formation, toxin production, and resistance to both antimicrobials and biological stressors...
June 2017: EcoSal Plus
https://www.readbyqxmd.com/read/28633020/apoptosis-and-compensatory-proliferation-signaling-are-coupled-by-crki-containing-microvesicles
#3
Kajal H Gupta, Josef W Goldufsky, Stephen J Wood, Nicholas J Tardi, Gayathri S Moorthy, Douglas Z Gilbert, Janet P Zayas, Eunsil Hahm, Mehmet M Altintas, Jochen Reiser, Sasha H Shafikhani
Apoptosis has been implicated in compensatory proliferation signaling (CPS), whereby dying cells induce proliferation in neighboring cells as a means to restore homeostasis. The nature of signaling between apoptotic cells and their neighboring cells remains largely unknown. Here we show that a fraction of apoptotic cells produce and release CrkI-containing microvesicles (distinct from exosomes and apoptotic bodies), which induce proliferation in neighboring cells upon contact. We provide visual evidence of CPS by videomicroscopy...
June 19, 2017: Developmental Cell
https://www.readbyqxmd.com/read/28630160/listeriolysin-o-from-bazooka-to-swiss-army-knife
#4
REVIEW
Suzanne E Osborne, John H Brumell
Listeria monocytogenes (Lm) is a Gram-positive facultative intracellular pathogen. Infections in humans can lead to listeriosis, a systemic disease with a high mortality rate. One important mechanism of Lm dissemination involves cell-to-cell spread after bacteria have entered the cytosol of host cells. Listeriolysin O (LLO; encoded by the hly gene) is a virulence factor present in Lm that plays a central role in the cell-to-cell spread process. LLO is a member of the cholesterol-dependent cytolysin (CDC) family of toxins that were initially thought to promote disease largely by inducing cell death and tissue destruction-essentially acting like a 'bazooka'...
August 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28630151/assembly-mechanism-of-the-%C3%AE-pore-forming-toxin-cytolysin-a-from-escherichia-coli
#5
REVIEW
Daniel Roderer, Rudi Glockshuber
The cytolytic toxin cytolysin A (ClyA) from Escherichia coli is probably one of the best-characterized examples of bacterial, α-pore-forming toxins (α-PFTs). Like other PFTs, ClyA exists in a soluble, monomeric form that assembles to an annular, homo-oligomeric pore complex upon contact with detergent or target membranes. Comparison of the three-dimensional structures of the 34 kDa monomer and the protomer in the context of the dodecameric pore complex revealed that ClyA undergoes one of the largest conformational transitions described for proteins so far, in which 55% of the residues change their position and 16% of the residues adopt a different secondary structure in the protomer...
August 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28630149/molecular-mechanism-of-pore-formation-by-aerolysin-like-proteins
#6
REVIEW
Marjetka Podobnik, Matic Kisovec, Gregor Anderluh
Aerolysin-like pore-forming proteins are an important family of proteins able to efficiently damage membranes of target cells by forming transmembrane pores. They are characterized by a unique domain organization and mechanism of action that involves extensive conformational rearrangements. Although structures of soluble forms of many different members of this family are well understood, the structures of pores and their mechanism of assembly have been described only recently. The pores are characterized by well-defined β-barrels, which are devoid of any vestibular regions commonly found in other protein pores...
August 5, 2017: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
https://www.readbyqxmd.com/read/28628666/the-effector-avrrxo1-phosphorylates-nad-in-planta
#7
Teja Shidore, Corey D Broeckling, Jay S Kirkwood, John J Long, Jiamin Miao, Bingyu Zhao, Jan E Leach, Lindsay R Triplett
Gram-negative bacterial pathogens of plants and animals employ type III secreted effectors to suppress innate immunity. Most characterized effectors work through modification of host proteins or transcriptional regulators, although a few are known to modify small molecule targets. The Xanthomonas type III secreted avirulence factor AvrRxo1 is a structural homolog of the zeta toxin family of sugar-nucleotide kinases that suppresses bacterial growth. AvrRxo1 was recently reported to phosphorylate the central metabolite and signaling molecule NAD in vitro, suggesting that the effector might enhance bacterial virulence on plants through manipulation of primary metabolic pathways...
June 19, 2017: PLoS Pathogens
https://www.readbyqxmd.com/read/28623367/bovine-antibodies-targeting-primary-and-recurrent-clostridium-difficile-disease-are-a-potent-antibiotic-alternative
#8
Melanie L Hutton, Bliss A Cunningham, Kate E Mackin, Shelley A Lyon, Meagan L James, Julian I Rood, Dena Lyras
The increased incidence of antibiotic resistant 'superbugs' has amplified the use of broad spectrum antibiotics worldwide. An unintended consequence of antimicrobial treatment is disruption of the gastrointestinal microbiota, resulting in susceptibility to opportunistic pathogens, such as Clostridium difficile. Paradoxically, treatment of C. difficile infections (CDI) also involves antibiotic use, leaving patients susceptible to re-infection. This serious health threat has led to an urgent call for the development of new therapeutics to reduce or replace the use of antibiotics to treat bacterial infections...
June 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28620370/environmental-t4-family-bacteriophages-evolve-to-escape-abortive-infection-via-multiple-routes-in-a-bacterial-host-employing-altruistic-suicide-through-type-iii-toxin-antitoxin-systems
#9
Bihe Chen, Chidiebere Akusobi, Xinzhe Fang, George P C Salmond
Abortive infection is an anti-phage mechanism employed by a bacterium to initiate its own death upon phage infection. This reduces, or eliminates, production of viral progeny and protects clonal siblings in the bacterial population by an act akin to an "altruistic suicide." Abortive infection can be mediated by a Type III toxin-antitoxin system called ToxINPa consisting of an endoribonuclease toxin and RNA antitoxin. ToxINPa is a heterohexameric quaternary complex in which pseudoknotted RNA inhibits the toxicity of the toxin until infection by certain phages causes destabilization of ToxINPa, leading to bacteriostasis and, eventually, lethality...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28620033/scissor-sisters-regulation-of-adam10-by-the-tspanc8-tetraspanins
#10
REVIEW
Alexandra L Matthews, Justyna Szyroka, Richard Collier, Peter J Noy, Michael G Tomlinson
A disintegrin and metalloprotease 10 (ADAM10) is a ubiquitously expressed transmembrane protein which is essential for embryonic development through activation of Notch proteins. ADAM10 regulates over 40 other transmembrane proteins and acts as a 'molecular scissor' by removing their extracellular regions. ADAM10 is also a receptor for α-toxin, a major virulence factor of Staphylococcus aureus Owing to the importance of its substrates, ADAM10 is a potential therapeutic target for cancer, neurodegenerative diseases such as Alzheimer's and prion diseases, bacterial infection and inflammatory diseases such as heart attack, stroke and asthma...
June 15, 2017: Biochemical Society Transactions
https://www.readbyqxmd.com/read/28619514/the-frequency-of-th17%C3%A2-cells-in-the-small-intestine-exhibits-a-day-night-variation-dependent-on-circadian-clock-activity
#11
Ha Pham Thu Le, Yuki Nakamura, Kyoko Oh-Oka, Kayoko Ishimaru, Shotaro Nakajima, Atsuhito Nakao
Interleukin-17-producing CD4(+) T helper (Th17) cells are a key immune lineage that protects against bacterial and fungal infections at mucosal surfaces. At steady state, Th17 cells are abundant in the small intestinal mucosa of mice. There are several mechanisms for regulating the population of Th17 cells in the small intestine, reflecting the importance of maintaining their numbers in the correct balance. Here we demonstrate the existence of a time-of-day-dependent variation in the frequency of Th17 cells in the lamina propria of the small intestine in wild-type mice, which was not observed in mice with a loss-of-function mutation of the core circadian gene Clock or in mice housed under aberrant light/dark conditions...
June 12, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28614372/intestinal-organoids-model-human-responses-to-infection-by-commensal-and-shiga-toxin-producing-escherichia-coli
#12
Sayali S Karve, Suman Pradhan, Doyle V Ward, Alison A Weiss
Infection with Shiga toxin (Stx) producing Escherichia coli O157:H7 can cause the potentially fatal complication hemolytic uremic syndrome, and currently only supportive therapy is available. Lack of suitable animal models has hindered study of this disease. Induced human intestinal organoids (iHIOs), generated by in vitro differentiation of pluripotent stem cells, represent differentiated human intestinal tissue. We show that iHIOs with addition of human neutrophils can model E. coli intestinal infection and innate cellular responses...
2017: PloS One
https://www.readbyqxmd.com/read/28611954/super-resolution-imaging-of-protein-secretion-systems-and-the-cell-surface-of-gram-negative-bacteria
#13
REVIEW
Sachith D Gunasinghe, Chaille T Webb, Kirstin D Elgass, Iain D Hay, Trevor Lithgow
Gram-negative bacteria have a highly evolved cell wall with two membranes composed of complex arrays of integral and peripheral proteins, as well as phospholipids and glycolipids. In order to sense changes in, respond to, and exploit their environmental niches, bacteria rely on structures assembled into or onto the outer membrane. Protein secretion across the cell wall is a key process in virulence and other fundamental aspects of bacterial cell biology. The final stage of protein secretion in Gram-negative bacteria, translocation across the outer membrane, is energetically challenging so sophisticated nanomachines have evolved to meet this challenge...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28607468/clostridium-difficile-flagella-induce-a-pro-inflammatory-response-in-intestinal-epithelium-of-mice-in-cooperation-with-toxins
#14
Jameel Batah, Hussein Kobeissy, Phuong Trang Bui Pham, Cécile Denève-Larrazet, Sarah Kuehne, Anne Collignon, Claire Janoir-Jouveshomme, Jean-Christophe Marvaud, Imad Kansau
Clostridium difficile is the most important enteropathogen involved in gut nosocomial post-antibiotic infections. The emergence of hypervirulent strains has contributed to increased mortality and morbidity of CDI. The C. difficile toxins contribute directly to CDI-associated lesions of the gut, but other bacterial factors are needed for the bacteria to adhere and colonize the intestinal epithelium. The C. difficile flagella, which confer motility and chemotaxis for successful intestinal colonization, could play an additional role in bacterial pathogenesis by contributing to the inflammatory response of the host and mucosal injury...
June 12, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28603695/the-pag-gene-of-pxo1-is-involved-in-capsule-biosynthesis-of-bacillus-anthracis-pasteur-ii-strain
#15
Xudong Liang, Jin Zhu, Zhongzhi Zhao, Feng Zheng, Huijuan Zhang, Jianchun Wei, Yon Ji, Yinduo Ji
The poly-γ-D-glutamic acid capsule and anthrax toxins are major virulence factors of Bacillus anthracis. Genes responsible for capsule biosynthesis are located on pXO2, whereas genes encoding the toxins, which are composed of edema factors, lethal factors, and protective antigens (PA), are located on pXO1. In this study, we found that the pag null mutation not only eliminated the production of the protective antigen, it also eliminated the ability of the B. anthracis Pasteur II strain to form capsules. qPCR analysis revealed that the deletion of pag decreased the transcription levels of the capABCD operon and its regulatory genes acpA and acpB...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28599879/uncommon-toxic-microbial-metabolite-patterns-in-traditionally-home-processed-maize-dish-fufu-consumed-in-rural-cameroon
#16
Wilfred A Abia, Benedikt Warth, Chibundu N Ezekiel, Bojan Sarkanj, Paul C Turner, Doris Marko, Rudolf Krska, Michael Sulyok
Toxins of microbial origin frequently contaminate foodstuffs worldwide and pose a serious hazard to humans. This study reports on LCMS/MS quantification of multiple fungal and bacterial toxins, from household sampling of 50 traditionally prepared maize-fufu samples from Bamunka village, western highlands of Cameroon. Seventy-four metabolites including aflatoxin B1 (AFB1) (12/50: mean 0.9, range n.d-1.8 μg kg(-1)), cereulide (50/50: mean 37; range 1-236 μg kg(-1)), deoxynivalenol (DON) (50/50: mean 23, range 14-55 μg kg(-1)), fumonisin B1 (FB1) (50/50: mean: 151, range 48-709 μg kg(-1)), nivalenol (NIV) (50/50; mean 268, range 116-372 μg kg(-1)), patulin (PAT) (15/50:mean 105, range 12-890 μg kg(-1)) and zearalenone (ZEN) (50/50: mean 49, range 5-150) were detected; and of note every sample contained at least 27 toxic compounds...
June 6, 2017: Food and Chemical Toxicology
https://www.readbyqxmd.com/read/28598837/rhamnolipids-microbial-virulence-factors-in-alzheimer-s-disease
#17
Eleni Andreadou, Anastasia A Pantazaki, Makrina Daniilidou, Magda Tsolaki
Alzheimer's disease (AD) has been attributed to chronic bacterial infections. The recognition of human microbiota as a substantial contributor to health and disease is relatively recent and growing. During evolution, mammals live in a symbiotic state with myriads of microorganisms that survive at a diversity of tissue micro-surroundings. Microbes produce a plethora of secretory products [amyloids, lipopolysaccharides, virulence factors rhamnolipids (RLs), toxins, and a great number of neuroactive compounds]...
June 3, 2017: Journal of Alzheimer's Disease: JAD
https://www.readbyqxmd.com/read/28597303/current-pathogenic-escherichia-coli-foodborne-outbreak-cases-and-therapy-development
#18
REVIEW
Shih-Chun Yang, Chih-Hung Lin, Ibrahim A Aljuffali, Jia-You Fang
Food contamination by pathogenic microorganisms has been a serious public health problem and a cause of huge economic losses worldwide. Foodborne pathogenic Escherichia coli (E. coli) contamination, such as that with E. coli O157 and O104, is very common, even in developed countries. Bacterial contamination may occur during any of the steps in the farm-to-table continuum from environmental, animal, or human sources and cause foodborne illness. To understand the causes of the foodborne outbreaks by E. coli and food-contamination prevention measures, we collected and investigated the past 10 years' worldwide reports of foodborne E...
June 9, 2017: Archives of Microbiology
https://www.readbyqxmd.com/read/28597156/molecular-characterization-of-indigenous-bacillus-thuringiensis-strains-isolated-from-kashmir-valley
#19
A L Reyaz, L Gunapriya, P Indra Arulselvi
Bacillus thuringiensis (Bt) being an eco-friendly bioinsecticide is effectively used in pest management strategies and, therefore, isolation and identification of new strains effective against a broad range of target pests is important. In the present study, new indigenous B. thuringiensis strains were isolated and investigated so that these could be used as an alternative and/or support the current commercial strains/cry proteins in use. For this, 159 samples including soil, leaf and spider webs were collected from ten districts of Kashmir valley (India)...
June 2017: 3 Biotech
https://www.readbyqxmd.com/read/28596760/in-depth-profiling-of-mvfr-regulated-small-molecules-in-pseudomonas-aeruginosa-after-quorum-sensing-inhibitor-treatment
#20
Giuseppe Allegretta, Christine K Maurer, Jens Eberhard, Damien Maura, Rolf W Hartmann, Laurence Rahme, Martin Empting
Pseudomonas aeruginosa is a Gram-negative bacterium, which causes opportunistic infections in immuno-compromised individuals. Due to its multiple resistances toward antibiotics, the development of new drugs is required. Interfering with Quorum Sensing (QS), a cell-to-cell communication system, has shown to be highly efficient in reducing P. aeruginosa pathogenicity. One of its QS systems employs Pseudomonas Quinolone Signal (PQS) and 4-hydroxy-2-heptylquinoline (HHQ) as signal molecules. Both activate the transcriptional regulator MvfR (Multiple Virulence Factor Regulator), also called PqsR, driving the production of QS molecules as well as toxins and biofilm formation...
2017: Frontiers in Microbiology
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