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Bacterial toxin

Mark R H Hurst, Amy Beattie, Sandra A Jones, Aurelie Laugraud, Chikako van Koten, Lincoln Harper
A highly virulent Serratia proteamaculans strain, AGR96X, exhibiting specific pathogenicity against larvae of the New Zealand grass grub ( Costelytra giveni ; Coleoptera: Scarabaeidae) and the New Zealand manuka beetle ( Pyronota festiva and P. setosa ; Coleoptera: Scarabaeidae), was isolated from a diseased grass grub larva. A 12-day median lethal dose of 4.89 ± 0.92 × 103 cells per grass grub larva was defined for AGR96X, and death occurred within 5--12 days following ingestion of a high bacterial dose...
March 16, 2018: Applied and Environmental Microbiology
Quintin Borgersen, David T Bolick, Glynis L Kolling, Matthew Aijuka, Fernando Ruiz-Perez, Richard L Guerrant, James P Nataro, Araceli E Santiago
Enteroaggregative E. coli (EAEC) is associated with food-borne outbreaks of diarrhea and growth faltering among children in developing countries. A Shiga toxin-producing EAEC strain of serotype O104:H4 strain caused one of the largest outbreaks of a food-borne infection in Europe in 2011. The outbreak was traced to contaminated fenugreek sprouts, yet the mechanisms whereby such persistent contamination of sprouts could have occurred are not clear. We found that under ambient conditions of temperature and in minimal media, pathogenic Shiga toxin-producing EAEC O104:H4 227-11 and non-Shiga toxin-producing 042 strains both produce high levels of exopolysaccharide structures (EPS) that are released to the external milieu...
March 15, 2018: Gut Microbes
Gibeom Kwon, Sungho Ghil
Warm temperature acclimation-associated 65-kDa protein (Wap65) is known to respond to elevated water temperatures and the corresponding gene from several fish species has been cloned. Expression of Wap65 gene is induced by various physiological stresses, such as increase in water temperature, immune response and heavy metal exposure. Two isolated Wap65 genes, Wap65-1 and Wap65-2, display distinct tissue distribution and physiological functions despite high sequence homology. In a previous study, we identified the Wap65-1 gene (kmWap65-1) from Kumgang fat minnow, Rhynchocypris kumgangensis, a small freshwater fish endemic to Korea...
March 15, 2018: Journal of Experimental Zoology. Part A, Ecological and Integrative Physiology
Verity A Jackson, Dimphna H Meijer, Maria Carrasquero, Laura S van Bezouwen, Edward D Lowe, Colin Kleanthous, Bert J C Janssen, Elena Seiradake
Teneurins are ancient cell-cell adhesion receptors that are vital for brain development and synapse organisation. They originated in early metazoan evolution through a horizontal gene transfer event when a bacterial YD-repeat toxin fused to a eukaryotic receptor. We present X-ray crystallography and cryo-EM structures of two Teneurins, revealing a ~200 kDa extracellular super-fold in which eight sub-domains form an intricate structure centred on a spiralling YD-repeat shell. An alternatively spliced loop, which is implicated in homophilic Teneurin interaction and specificity, is exposed and thus poised for interaction...
March 14, 2018: Nature Communications
Dilruba Sharmin, Yong Guo, Tomoyasu Nishizawa, Shoko Ohshima, Yoshinori Sato, Yusuke Takashima, Kazuhiko Narisawa, Hiroyuki Ohta
Endohyphal bacteria (EHB), dwelling within fungal hyphae, markedly affect the growth and metabolic potential of their hosts. To date, two EHB belonging to the family Burkholderiaceae have been isolated and characterized as new taxa, Burkholderia rhizoxinica (HKI 454T ) and Mycoavidus cysteinexigens (B1-EBT ), in Japan. Metagenome sequencing was recently reported for Mortierella elongata AG77 together with its endosymbiont M. cysteinexigens (Mc-AG77) from a soil/litter sample in the USA. In the present study, we elucidated the complete genome sequence of B1-EBT and compared it with those of Mc-AG77 and HKI 454T ...
March 14, 2018: Microbes and Environments
Hwa Young Kim, Sang-Mi Yu, Sang Chul Jeong, Sang Sun Yoon, Young Taek Oh
The stringent response (SR), which is activated by accumulation of (p)ppGpp under conditions of growth-inhibiting stresses, plays an important role ongrowth and virulence in Vibrio cholerae . Herein, we carried out a genome-wide screen using transposon random mutagenesis to identify genes controlled by SR in (p)ppGpp-overproducing mutant strain. One of the identified SR target genes was the flaC encoding flagellin. Genetic studies using flaC and SR mutants demonstrated that FlaC involved in bacterial growth, toxin production, and normal flagellum function under conditions of high (p)ppGpp levels, suggesting FlaC plays an important role in SR-induced pathogenicityin V...
March 15, 2018: Journal of Microbiology and Biotechnology
Sylwia Bloch, Bożena Nejman-Faleńczyk, Karolina Pierzynowska, Ewa Piotrowska, Alicja Węgrzyn, Christelle Marminon, Zouhair Bouaziz, Pascal Nebois, Joachim Jose, Marc Le Borgne, Luciano Saso, Grzegorz Węgrzyn
Oxidative stress may be the major cause of induction of Shiga toxin-converting (Stx) prophages from chromosomes of Shiga toxin-producing Escherichia coli (STEC) in human intestine. Thus, we aimed to test a series of novel antioxidant compounds for their activities against prophage induction, thus, preventing pathogenicity of STEC. Forty-six compounds (derivatives of carbazole, indazole, triazole, quinolone, ninhydrine, and indenoindole) were tested. Fifteen of them gave promising results and were further characterized...
December 2018: Journal of Enzyme Inhibition and Medicinal Chemistry
Karissa L Cross, Payal Chirania, Weili Xiong, Clifford J Beall, James G Elkins, Richard J Giannone, Ann L Griffen, Adam M Guss, Robert L Hettich, Snehal S Joshi, Elaine M Mokrzan, Roman K Martin, Igor B Zhulin, Eugene J Leys, Mircea Podar
The human oral microbiota encompasses representatives of many bacterial lineages that have not yet been cultured. Here we describe the isolation and characterization of previously uncultured Desulfobulbus oralis , the first human-associated representative of its genus. As mammalian-associated microbes rarely have free-living close relatives, D. oralis provides opportunities to study how bacteria adapt and evolve within a host. This sulfate-reducing deltaproteobacterium has adapted to the human oral subgingival niche by curtailing its physiological repertoire, losing some biosynthetic abilities and metabolic independence, and by dramatically reducing environmental sensing and signaling capabilities...
March 13, 2018: MBio
Seav-Ly Tran, Claire Jenkins, Valérie Livrelli, Stephanie Schüller
Shiga toxin-producing Escherichia coli (STEC) are characterized by the release of potent Shiga toxins (Stx), which are associated with severe intestinal and renal disease. Although all STEC strains produce Stx, only a few serotypes cause infection in humans. To determine which virulence traits in vitro are linked to human disease in vivo, 13 Stx2a-producing STEC strains of seropathotype (SPT) A or B (associated with severe human intestinal disease and outbreaks) and 6 strains of SPT D or E (rarely or not linked to human disease) were evaluated in a microaerobic human colonic epithelial infection model...
March 13, 2018: Microbiology
Krishnan Raghunathan, Nora J Foegeding, Anne M Campbell, Timothy L Cover, Melanie D Ohi, Anne K Kenworthy
Helicobacter pylori , a Gram-negative bacterium, is a well-known risk factor for gastric cancer. H. pylori vacuolating cytotoxin A (VacA) is a secreted pore-forming toxin that induces a wide range of cellular responses. Like many other bacterial toxins, VacA has been hypothesized to utilize lipid rafts to gain entry into host cells. Here, we use Giant Plasma Membrane Vesicles (GPMVs) as a model system to understand the preferential partitioning of VacA into lipid rafts. We show that a wild-type toxin predominantly associates with the raft phase...
March 12, 2018: Infection and Immunity
Jacklyn R Hurst, Katherine J Kasper, Akshay N Sule, John K McCormick
Streptococcus pyogenes is a human-specific and globally prominent bacterial pathogen that despite causing numerous human infections, this bacterium is normally found in an asymptomatic carrier state. This review provides an overview of both bacterial and human factors that likely play an important role in nasopharyngeal colonization and pharyngitis, as well as the development of acute rheumatic fever and rheumatic heart disease. Here we highlight a recently described role for bacterial superantigens in promoting acute nasopharyngeal infection, and discuss how these immune system activating toxins could be crucial to initiate the autoimmune process in rheumatic heart disease...
March 9, 2018: Infection, Genetics and Evolution
Sakshi Agarwal, Prabhakar Tiwari, Amar Deep, Saqib Kidwai, Shamba Gupta, Krishan Gopal Thakur, Ramandeep Singh
Toxin-antitoxin (TA) systems are bicistronic genetic modules that are ubiquitously present in bacterial genomes. Mycobacterium tuberculosis (Mtb) genome encodes for 90 putative TA systems and these are considered to be associated with maintenance of bacterial genomic stability or its survival under unfavorable environment. Majority of these in Mtb have been annotated as belonging to the Virulence associated protein B and C (VapBC) family. However, their precise role in bacterial physiology has not been elucidated...
February 24, 2018: Journal of Infectious Diseases
Andrea Osimani, Vesna Milanović, Federica Cardinali, Cristiana Garofalo, Francesca Clementi, Marina Pasquini, Paola Riolo, Sara Ruschioni, Nunzio Isidoro, Nino Loreto, Elena Franciosi, Kieran Tuohy, Annalisa Petruzzelli, Martina Foglini, Claudia Gabucci, Franco Tonucci, Lucia Aquilanti
Tenebrio molitor represents one of the most popular species used for the large-scale conversion of plant biomass into protein and is characterized by high nutritional value. In the present laboratory study, the bacterial biota characterizing a pilot production chain of fresh T. molitor larvae was investigated. To this end, different batches of fresh mealworm larvae, their feeding substrate (wheatmeal) and frass were analyzed by viable microbial counts, PCR-DGGE and Illumina sequencing. Moreover, the occurrence of Coxiella burnetii, Pseudomonas aeruginosa and Shiga toxin-producing E...
March 7, 2018: International Journal of Food Microbiology
Kathryn A Patras, Victor Nizet
Group B Streptococcus (GBS) colonizes the gastrointestinal and vaginal epithelium of a significant percentage of healthy women, with potential for ascending intrauterine infection or transmission during parturition, creating a risk of serious disease in the vulnerable newborn. This review highlights new insights on the bacterial virulence determinants, host immune responses, and microbiome interactions that underpin GBS vaginal colonization, the proximal step in newborn infectious disease pathogenesis. From the pathogen perspective, the function GBS adhesins and biofilms, β-hemolysin/cytolysin toxin, immune resistance factors, sialic acid mimicry, and two-component transcriptional regulatory systems are reviewed...
2018: Frontiers in Pediatrics
Bin Yang, Shaomeng Wang, Jianxiao Huang, Zhiqiu Yin, Lingyan Jiang, Wenqi Hou, Xiaomin Li, Lu Feng
Enterohemorrhagic Escherichia coli O157:H7 is a major human enteric pathogen capable of causing large outbreaks of severe infections that induce bloody diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome. Its genome contains 177 unique O islands (OIs) including those carrying the main virulence elements, Shiga toxin-converting phages (OI-45 and OI-93) and locus for enterocyte effacement (OI-148). However, many of these islands harbor only genes of unknown function. Here, we demonstrate that OI-29 encodes a newly discovered transcriptional activator, Z0639 (named GmrA), that is required for motility and flagellar synthesis in O157:H7...
2018: Frontiers in Microbiology
Hsiao-Han Lin, Hsin-Mei Huang, Manda Yu, Erh-Min Lai, Hsiao-Lin Chien, Chi-Te Liu
The bacterial type VI secretion system (T6SS) has been considered the armed force of bacteria because it can deliver toxin effectors to prokaryotic or eukaryotic cells for survival and fitness. Although many legume symbiotic rhizobacteria encode T6SS in their genome, the biological function of T6SS in these bacteria is still unclear. To elucidate this issue, we used Azorhizobium caulinodans ORS571 and its symbiotic host Sesbania rostrata as our research model. By using T6SS gene deletion mutants, we found that T6SS provides A...
March 8, 2018: Molecular Plant-microbe Interactions: MPMI
Martin S Bojer, Søren Lindemose, Martin Vestergaard, Hanne Ingmer
Incomplete killing of bacterial pathogens by antibiotics is an underlying cause of treatment failure and accompanying complications. Among those avoiding chemotherapy are persisters being individual cells in a population that for extended periods of time survive high antibiotic concentrations proposedly by being in a quiescent state refractory to antibiotic killing. While investigating the human pathogen Staphylococcus aureus and the influence of growth phase on persister formation, we noted that spent supernatants of stationary phase cultures of S...
2018: Frontiers in Microbiology
Nafiseh Noroozi, Seyed Latif Mousavi Gargari, Shahram Nazarian, Samaneh Sarvary, Razieh Rezaei Adriani
Objectives: Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrheal disease in humans, particularly in children under 5 years and travelers in developing countries.To our knowledge, no vaccine is licensed yet to protect against ETEC infection. Like many Gram-negative pathogens, ETEC can secrete outer membrane vesicles (OMVs). These structures contain various immunogenic virulence proteins such as LT and therefore can be used as vaccine candidates. In this study we attempted to isolate the OMVs of ETEC cultivated at different temperatures and evaluate their immunogenicity and protective efficacy in a murine model of infection...
March 2018: Iranian Journal of Basic Medical Sciences
Valerie S Forsyth, Chelsie E Armbruster, Sara N Smith, Ali Pirani, A Cody Springman, Matthew S Walters, Greta R Nielubowicz, Stephanie D Himpsl, Evan S Snitkin, Harry L T Mobley
Uropathogenic Escherichia coli (UPEC) strains cause most uncomplicated urinary tract infections (UTIs). These strains are a subgroup of extraintestinal pathogenic E. coli (ExPEC) strains that infect extraintestinal sites, including urinary tract, meninges, bloodstream, lungs, and surgical sites. Here, we hypothesize that UPEC isolates adapt to and grow more rapidly within the urinary tract than other E. coli isolates and survive in that niche. To date, there has not been a reliable method available to measure their growth rate in vivo Here we used two methods: segregation of nonreplicating plasmid pGTR902, and peak-to-trough ratio (PTR), a sequencing-based method that enumerates bacterial chromosomal replication forks present during cell division...
March 6, 2018: MBio
Guillaume Méric, Leonardos Mageiros, Ben Pascoe, Dan J Woodcock, Evangelos Mourkas, Sarah Lamble, Rory Bowden, Keith A Jolley, Ben Raymond, Samuel K Sheppard
Bacterial plasmids can vary from small selfish genetic elements to large autonomous replicons that constitute a significant proportion of total cellular DNA. By conferring novel function to the cell, plasmids may facilitate evolution but their mobility may be opposed by co-evolutionary relationships with chromosomes or encouraged via the infectious sharing of genes encoding public goods. Here, we explore these hypotheses through large-scale examination of the association between plasmids and genomes in the phenotypically diverse Bacillus cereus group...
March 6, 2018: Molecular Ecology
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