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https://www.readbyqxmd.com/read/29157080/secretory-autophagy-holds-the-key-to-lysozyme-secretion-during-bacterial-infection-of-the-intestine
#1
Elizabeth Delorme-Axford, Daniel J Klionsky
In 2013, Dr. Lora Hooper and colleagues described the induction of antibacterial macroautophagy/autophagy in intestinal epithelial cells as a cytoprotective host defense mechanism against invading Salmonella enterica serovar Typhimurium (S. Typhimurium). Canonical autophagy functions in a primarily degradative capacity to safeguard cells and ensure survival during stress conditions, including pathogen infection. In contrast, secretory autophagy has emerged as an alternative nondegradative mechanism for cellular trafficking and unconventional protein secretion...
November 20, 2017: Autophagy
https://www.readbyqxmd.com/read/29150501/glna-truncation-in-salmonella-enterica-results-in-a-small-colony-variant-phenotype-attenuated-host-cell-entry-and-reduced-expression-of-flagellin-and-spi-1-associated-effector-genes
#2
Philipp Aurass, Juliane Düvel, Susanne Karste, Ulrich Nübel, Wolfgang Rabsch, Antje Flieger
Many pathogenic bacteria use sophisticated survival strategies to overcome harsh environmental conditions. One is the formation of slow-growing subpopulations termed small colony variants (SCVs). Here we characterize an SCV, which spontaneously emerged from an axenic Salmonella enterica serovar Typhimurium water culture. We found that the SCV harbors a frameshift mutation in the glutamine synthetase gene glnA leading to a ∼90% truncation of the corresponding protein. Glutamine synthetase, a central enzyme in nitrogen assimilation, converts glutamate and ammonia to glutamine...
November 17, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29146500/motility-biofilm-formation-apoptotic-effect-and-virulence-gene-expression-of-atypical-salmonella-typhimurium-outside-and-inside-caco-2-cells
#3
Ibtissem Chakroun, Abdelkarim Mahdhi, Patricia Morcillo, Hector Cordero, Alberto Cuesta, Amina Bakhrouf, Kacem Mahdouani, M Ángeles Esteban
Disease outbreaks related to waterborne pathogen contamination throughout the world as well as challenges that lie ahead for addressing persistent infection are of renewed interest. In this research, we studied the effects of prolonged exposure of Salmonella enterica serovar Typhimurium to the cues encountered in the extracellular environment particularly in seawater microcosm on bacterial virulence and subsequent infection in Caco-2 cells. Our data show a significant difference in biofilm formation, swimming and swarming motilities between normal and stressed cells of S...
November 13, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/29142277/genetic-metabolomic-and-transcriptomic-analyses-of-the-de-novo-l-cysteine-biosynthetic-pathway-in-the-enteric-protozoan-parasite-entamoeba-histolytica
#4
Ghulam Jeelani, Dan Sato, Tomoyoshi Soga, Tomoyoshi Nozaki
The de novo L-cysteine biosynthetic pathway is critical for the growth, antioxidative stress defenses, and pathogenesis of bacterial and protozoan pathogens, such as Salmonella typhimurium and Entamoeba histolytica. This pathway involves two key enzymes, serine acetyltransferase (SAT) and cysteine synthase (CS), which are absent in mammals and therefore represent rational drug targets. The human parasite E. histolytica possesses three SAT and CS isozymes; however, the specific roles of individual isoforms and significance of such apparent redundancy remains unclear...
November 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29140975/natural-variation-of-a-sensor-kinase-controlling-a-conserved-stress-response-pathway-in-escherichia-coli
#5
Manuela Roggiani, Srujana S Yadavalli, Mark Goulian
Previous studies have shown that exponentially growing Escherichia coli can detect mild acidity (~pH 5.5) and, in response, synthesize enzymes that protect against severe acid shock. This adaptation is controlled by the EvgS/EvgA phosphorelay, a signal transduction system present in virtually every E. coli isolate whose genome has been sequenced. Here we show that, despite this high level of conservation, the EvgS/EvgA system displays a surprising natural variation in pH-sensing capacity, with some strains entirely non-responsive to low pH stimulus...
November 15, 2017: PLoS Genetics
https://www.readbyqxmd.com/read/29138484/non-canonical-activation-of-ompr-drives-acid-and-osmotic-stress-responses-in-single-bacterial-cells
#6
Smarajit Chakraborty, Ricksen S Winardhi, Leslie K Morgan, Jie Yan, Linda J Kenney
Unlike eukaryotes, bacteria undergo large changes in osmolality and cytoplasmic pH. It has been described that during acid stress, bacteria internal pH promptly acidifies, followed by recovery. Here, using pH imaging in single living cells, we show that following acid stress, bacteria maintain an acidic cytoplasm and the osmotic stress transcription factor OmpR is required for acidification. The activation of this response is non-canonical, involving a regulatory mechanism requiring the OmpR cognate kinase EnvZ, but not OmpR phosphorylation...
November 14, 2017: Nature Communications
https://www.readbyqxmd.com/read/29138083/adaptations-in-the-physiological-heterogeneity-and-viability-of-shigella-dysenteriae-shigella-flexneri-and-salmonella-typhimurium-after-exposure-to-simulated-gastric-acid-fluid
#7
Atheesha Singh, Tobias George Barnard
Stomach acidity is an important barrier of the human body to protect itself from microbial pathogens entering the small intestine and causing infection. This study examined the survival adaptations of non-acid adapted diarrheal Shigella and Salmonella strains in an environment mimicking the human stomach. The bacterial responses to the challenge of acidic simulated gastric fluid were studied using flow cytometry physiological heterogeneity, membrane integrity and survival (culturability) respectively. Flow cytometry showed that bacterial cells, when exposed to gastric fluid, transformed distinctly, into physiologically heterogeneous sub-populations: intact, stressed and damaged cells, when stained with propidium iodide and thiazole orange...
November 11, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/29118452/magnesium-homeostasis-protects-salmonella-against-nitrooxidative-stress
#8
Travis J Bourret, Lin Liu, Jeff A Shaw, Maroof Husain, Andrés Vázquez-Torres
The PhoPQ two-component regulatory system coordinates the response of Salmonella enterica serovar Typhimurium to diverse environmental challenges encountered during infection of hosts, including changes in Mg(2+) concentrations, pH, and antimicrobial peptides. Moreover, PhoPQ-dependent regulation of gene expression promotes intracellular survival of Salmonella in macrophages, and contributes to the resistance of this pathogen to reactive nitrogen species (RNS) generated from the nitric oxide produced by the inducible nitric oxide (NO) synthase of macrophages...
November 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29117268/general-response-of-salmonella-enterica-serovar-typhimurium-to-desiccation-a-new-role-for-the-virulence-factors-sopd-and-ssed-in-survival
#9
Alice Maserati, Ryan C Fink, Antonio Lourenco, Matthew L Julius, Francisco Diez-Gonzalez
Salmonella can survive for long periods under extreme desiccation conditions. This stress tolerance poses a risk for food safety, but relatively little is known about the molecular and cellular regulation of this adaptation mechanism. To determine the genetic components involved in Salmonella's cellular response to desiccation, we performed a global transcriptomic analysis comparing S. enterica serovar Typhimurium cells equilibrated to low water activity (aw 0.11) and cells equilibrated to high water activity (aw 1...
2017: PloS One
https://www.readbyqxmd.com/read/29114257/the-rice-high-affinity-k-transporter-oshkt2-4-mediates-mg-2-homeostasis-under-high-mg-2-conditions-in-transgenic-arabidopsis
#10
Chi Zhang, Hejuan Li, Jiayuan Wang, Bin Zhang, Wei Wang, Hongxuan Lin, Sheng Luan, Jiping Gao, Wenzhi Lan
Rice (Oryza sativa; background Nipponbare) contains nine HKT (high-affinity K(+) transport)-like genes encoding membrane proteins belonging to the superfamily of Ktr/TRK/HKT. OsHKTs have been proposed to include four selectivity filter-pore-forming domains homologous to the bacterial K(+) channel KcsA, and are separated into OsHKT1s with Na(+)-selective activity and OsHKT2s with Na(+)-K(+) symport activity. As a member of the OsHKT2 subfamily, OsHKT2;4 renders Mg(2+) and Ca(2+) permeability for yeast cells and Xenopus laevis oocytes, besides K(+) and Na(+)...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/29112725/peptide-transporter-yjiy-influences-the-expression-of-the-virulence-gene-mgtc-to-regulate-biofilm-formation-in-salmonella
#11
Preeti Garai, Kasturi Chandra, Jayanta Chatterjee, Dipshikha Chakravortty
Biofilm is one of the coping strategies of Salmonella against antimicrobial environmental stresses including nutrient starvation. However, channeling of the cue of starvation towards biofilm formation is not understood well. Our study shows that a carbon starvation gene, yjiY, coding for a peptide transporter, influences the expression of a virulence associated gene, mgtC, in Salmonella, to regulate biofilm formation. We demonstrate here that the mutant strain, ΔyjiY, is unable to form biofilm due to the increased expression of mgtC...
November 3, 2017: FEMS Microbiology Letters
https://www.readbyqxmd.com/read/29108563/the-effect-of-heat-stress-on-intestinal-integrity-and-salmonella-invasion-in-broiler-birds
#12
Alhanof Alhenaky, Anas Abdelqader, Mohannad Abuajamieh, Abdur-Rahman Al-Fataftah
The intestinal mucosa works as a barrier to protect the internal environment of the animal from bacteria and bacterial toxins found in the gut lumen. Heat stress may harm this function. Therefore, we designed the current experiment to investigate the effect of heat stress on intestinal integrity, physiological and immunological responses and Salmonella invasion in broiler chickens. At 26 days of age, 72 birds were randomly distributed into 3 treatments, with 8 replicates per treatment and 3 birds per replicate...
December 2017: Journal of Thermal Biology
https://www.readbyqxmd.com/read/29101197/population-wide-survey-of-salmonella-enterica-response-to-high-pressure-processing-reveals-a-diversity-of-responses-and-tolerance-mechanisms
#13
Sandeep Tamber
High pressure processing is a non-thermal method of food preservation that uses pressure to inactivate microorganisms. To ensure the effective validation of process parameters, it is important that the design of challenge protocols consider the potential for resistance in a particular species. Herein, the response of 99 diverse Salmonella enterica strains to high pressure is reported. Members of this population belong to one of 24 serovars and were isolated from various Canadian sources over a period of 26 years...
November 3, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29098411/distinguishing-between-metabolically-active-and-dormant-bacteria-on-paper
#14
Stephanie A Hice, Miguel C Santoscoy, Michelle L Soupir, Rebecca Cademartiri
Switching between metabolically active and dormant states provides bacteria with protection from environmental stresses and allows rapid growth under favorable conditions. This rapid growth can be detrimental to the environment, e.g., pathogens in recreational lakes, or to industrial processes, e.g., fermentation, making it useful to quickly determine when the ratio of dormant to metabolically active bacteria changes. While a rapid increase in metabolically active bacteria can cause complications, a high number of dormant bacteria can also be problematic, since they can be more virulent and antibiotic-resistant...
November 2, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/29091182/quinolone-resistant-gyrase-mutants-demonstrate-decreased-susceptibility-to-triclosan
#15
Mark A Webber, Michelle M C Buckner, Liam S Redgrave, Gyles Ifill, Lesley A Mitchenall, Carly Webb, Robyn Iddles, Anthony Maxwell, Laura J V Piddock
Objectives: Cross-resistance between antibiotics and biocides is a potentially important driver of MDR. A relationship between susceptibility of Salmonella to quinolones and triclosan has been observed. This study aimed to: (i) investigate the mechanism underpinning this; (ii) determine whether the phenotype is conserved in Escherichia coli; and (iii) evaluate the potential for triclosan to select for quinolone resistance. Methods: WT E. coli, Salmonella enterica serovar Typhimurium and gyrA mutants were used...
October 1, 2017: Journal of Antimicrobial Chemotherapy
https://www.readbyqxmd.com/read/29089020/transcriptomic-study-of-salmonella-enterica-subspecies-enterica-serovar-typhi-biofilm
#16
Khee Chian Jason Chin, Todd Duane Taylor, Maxime Hebrard, Kogaan Anbalagan, Marjan Ganjali Dashti, Kia Kien Phua
BACKGROUND: Typhoid fever is an acute systemic infection of humans caused by Salmonella enterica subspecies enterica serovar Typhi (S. Typhi). In chronic carriers, the bacteria survive the harsh environment of the gallbladder by producing biofilm. The phenotype of S. Typhi biofilm cells is significantly different from the free-swimming planktonic cells, and studies have shown that they are associated with antibiotic resistance, immune system evasion, and bacterial persistence. However, the mechanism of this transition and the events leading to biofilm formation are unknown...
October 31, 2017: BMC Genomics
https://www.readbyqxmd.com/read/29079622/fate-of-salmonella-enterica-and-enterohemorrhagic-escherichia-coli-cells-artificially-internalized-into-vegetable-seeds-during-germination
#17
Da Liu, Yue Cui, Ronald Walcott, Jinru Chen
Vegetable seeds contaminated with bacterial pathogens have been linked to fresh produce-associated outbreaks of gastrointestinal infections. This study was undertaken to observe the physiological behavior of Salmonella enterica and enterohemorrhagic Escherichia coli (EHEC) cells, artificially internalized into vegetable seeds during the germination process. Surface-decontaminated seeds of alfalfa, fenugreek, lettuce, and tomato were vacuum-infiltrated with four individual strains of Salmonella or EHEC. Contaminated seeds were germinated at 25°C for 9 days and different sprout/seedling tissues were microbiologically analyzed every other day...
October 27, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/29077972/characterization-and-evaluation-of-lactic-acid-bacteria-candidates-for-intestinal-epithelial-permeability-and-salmonella-typhimurium-colonization-in-neonatal-turkey-poults
#18
Y Yang, J D Latorre, B Khatri, Y M Kown, B W Kong, K D Teague, L E Graham, A D Wolfenden, B D Mahaffey, M Baxter, X Hernandez-Velasco, R Merino-Guzman, B M Hargis, G Tellez
The present study evaluated the microbiological properties of three probiotic candidate strains of lactic acid bacteria (LAB) (128; 131; CE11_2), their effect on intestinal epithelial permeability, and their ability to reduce intestinal colonization of Salmonella Typhimurium (ST) individually or as a batch culture in neonatal turkey poults. Isolates were characterized morphologically and identified using 16S rRNA sequence analyses. Each isolate was evaluated for tolerance and resistance to acidic pH, high osmotic NaCl concentrations, and bile salts in broth medium...
October 25, 2017: Poultry Science
https://www.readbyqxmd.com/read/29057830/time-response-of-oxidative-nitrosative-stress-and-inflammation-in-lps-induced-endotoxaemia-a-comparative-study-of-mice-and-rats
#19
Sebastian Steven, Mobin Dib, Siyer Roohani, Fatemeh Kashani, Thomas Münzel, Andreas Daiber
Sepsis is a severe and multifactorial disease with a high mortality rate. It represents a strong inflammatory response to an infection and is associated with vascular inflammation and oxidative/nitrosative stress. Here, we studied the underlying time responses in the widely used lipopolysaccharide (LPS)-induced endotoxaemia model in mice and rats. LPS (10 mg/kg; from Salmonella Typhosa) was intraperitoneally injected into mice and rats. Animals of every species were divided into five groups and sacrificed at specific points in time (0, 3, 6, 9, 12 h)...
October 18, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29055012/type-i-interferon-enhances-necroptosis-of-salmonella-typhimurium-infected-macrophages-by-impairing-antioxidative-stress-responses
#20
Nina Judith Hos, Raja Ganesan, Saray Gutiérrez, Deniz Hos, Jennifer Klimek, Zeinab Abdullah, Martin Krönke, Nirmal Robinson
Salmonella enterica serovar Typhimurium exploits the host's type I interferon (IFN-I) response to induce receptor-interacting protein (RIP) kinase-mediated necroptosis in macrophages. However, the events that drive necroptosis execution downstream of IFN-I and RIP signaling remain elusive. In this study, we demonstrate that S Typhimurium infection causes IFN-I-mediated up-regulation of the mitochondrial phosphatase Pgam5 through RIP3. Pgam5 subsequently interacts with Nrf2, which sequesters Nrf2 in the cytosol, thereby repressing the transcription of Nrf2-dependent antioxidative genes...
October 20, 2017: Journal of Cell Biology
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