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stress response membrane bacteria

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https://www.readbyqxmd.com/read/28526842/revealing-genome-scale-transcriptional-regulatory-landscape-of-ompr-highlights-its-expanded-regulatory-roles-under-osmotic-stress-in-escherichia-coli-k-12-mg1655
#1
Sang Woo Seo, Ye Gao, Donghyuk Kim, Richard Szubin, Jina Yang, Byung-Kwan Cho, Bernhard O Palsson
A transcription factor (TF), OmpR, plays a critical role in transcriptional regulation of the osmotic stress response in bacteria. Here, we reveal a genome-scale OmpR regulon in Escherichia coli K-12 MG1655. Integrative data analysis reveals that a total of 37 genes in 24 transcription units (TUs) belong to OmpR regulon. Among them, 26 genes show more than two-fold changes in expression level in an OmpR knock-out strain. Specifically, we find that: 1) OmpR regulates mostly membrane-located gene products involved in diverse fundamental biological processes, such as narU (encoding nitrate/nitrite transporter), ompX (encoding outer membrane protein X), and nuoN (encoding NADH:ubiquinone oxidoreductase); 2) by investigating co-regulation of entire sets of genes regulated by other stress-response TFs, stresses are surprisingly independently regulated among each other; and, 3) a detailed investigation of the physiological roles of the newly discovered OmpR regulon genes reveals that activation of narU represents a novel strategy to significantly improve osmotic stress tolerance of E...
May 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28515717/the-leaderless-bacteriocin-enterocin-k1-is-highly-potent-against-enterococcus-faecium-a-study-on-structure-target-spectrum-and-receptor
#2
Kirill V Ovchinnikov, Per Eugen Kristiansen, Daniel Straume, Marianne S Jensen, Tamara Aleksandrzak-Piekarczyk, Ingolf F Nes, Dzung B Diep
Enterocin K1 (EntK1), enterocin EJ97 (EntEJ97), and LsbB are three sequence related leaderless bacteriocins. Yet LsbB kills only lactococci while EntK1 and EntEJ97 target wider spectra with EntK1 being particularly active against Enterococcus faecium, including nosocomial multidrug resistant isolates. NMR study of EntK1 showed that it had a structure very similar to LsbB - both having an amphiphilic N-terminal α-helix and an unstructured C-terminus. The α-helix in EntK1 is, however, about 3-4 residues longer than that of LsbB...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28513097/evidence-for-a-peptidoglycan-like-structure-in-orientia-tsutsugamushi
#3
Sharanjeet Atwal, Suparat Giengkam, Suwittra Chaemchuen, Jack Dorling, Nont Kosaisawe, Michael VanNieuwenhze, Somponnat Sampattavanich, Peter Schumann, Jeanne Salje
Bacterial cell walls are composed of the large cross-linked macromolecule peptidoglycan, which maintains cell shape and is responsible for resisting osmotic stresses. This is a highly conserved structure and the target of numerous antibiotics. Obligate intracellular bacteria are an unusual group of organisms that have evolved to replicate exclusively within the cytoplasm or vacuole of a eukaryotic cell. They tend to have reduced amounts of peptidoglycan, likely due to the fact that their growth and division takes place within an osmotically protected environment, and also due to a drive to reduce activation of the host immune response...
May 17, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28512454/new-insights-into-the-regulation-of-cell-surface-signaling-activity-acquired-from-a-mutagenesis-screen-of-the-pseudomonas-putida-iuty-sigma-anti-sigma-factor
#4
Karlijn C Bastiaansen, Cristina Civantos, Wilbert Bitter, María A Llamas
Cell-surface signaling (CSS) is a signal transfer system that allows Gram-negative bacteria to detect environmental signals and generate a cytosolic response. These systems are composed of an outer membrane receptor that senses the inducing signal, an extracytoplasmic function sigma factor (σ(ECF)) that targets the cytosolic response by modifying gene expression and a cytoplasmic membrane anti-sigma factor that keeps the σ(ECF) in an inactive state in the absence of the signal and transduces its presence from the outer membrane to the cytosol...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28512090/the-vibrio-cholerae-vexgh-rnd-efflux-system-maintains-cellular-homeostasis-by-effluxing-vibriobactin
#5
Dillon E Kunkle, X Renee Bina, James E Bina
Resistance-nodulation-division (RND) superfamily efflux systems have been widely studied for their role in antibiotic resistance, but their native biological functions remain poorly understood. We previously showed that loss of RND-mediated efflux in Vibrio cholerae resulted in activation of the Cpx two-component regulatory system, which mediates adaptation to stress resulting from misfolded membrane proteins. Here, we investigated the mechanism linking RND-mediated efflux to the Cpx response. We performed transposon mutagenesis screening of RND-deficient V...
May 16, 2017: MBio
https://www.readbyqxmd.com/read/28505496/inactivation-of-gram-bacteria-salmonella-enterica-by-chlorophyllin-based-photosensitization-mechanism-of-action-and-new-strategies-to-enhance-the-inactivation-efficiency
#6
Irina Buchovec, Viktorija Lukseviciūtė, Rita Kokstaite, Danute Labeikyte, Laura Kaziukonyte, Zivile Luksiene
This study is focused on the enhancement of susceptibility of Gram (-) bacteria S. enterica to chlorophyllin-based (Chl) photosensitization combining it with other antimicrobial tools. In order to find best combinations, the mechanism by which Chl-based photosensitization inactivates bacteria must be identified. Data confirmed that photosensitization (Chl 1.5×10(-5)M, for 1-120min, 405nm, 0-46.1J/cm(2)) reduced S. enterica population, just by 2.05 log (CFU/ml). Fluorimetric measurements indicated that just minor part of Chl was bound to Salmonella in suspension...
May 9, 2017: Journal of Photochemistry and Photobiology. B, Biology
https://www.readbyqxmd.com/read/28495615/a-novel-function-of-tlr4-in-mediating-the-immunomodulatory-effect-of-benzanthrone-an-environmental-pollutant
#7
Prachi Tewari, Payal Mandal, Ruchi Roy, Somya Asthana, Premendra D Dwivedi, Mukul Das, Anurag Tripathi
Our prior studies have reported that Benzanthrone (BA) manifests inflammatory responses in the spleen of Balb/c mice. The present investigation was carried out to study the impact of BA on macrophages, which are the primary scavenger cells in the body that act as a connecting link between innate and adaptive immunity. Parenteral administration of BA (daily for one week) to mice resulted in enhanced levels of nitric oxide (NO) and overexpression of inflammatory markers (COX-2, MMP-9 and PGE-2) in macrophages; however the level of MHC class-I and MHC class-II receptors were down regulated...
May 8, 2017: Toxicology Letters
https://www.readbyqxmd.com/read/28484043/the-long-hunt-for-pssr-looking-for-a-phospholipid-synthesis-transcriptional-regulator-finding-the-ribosome
#8
J Bartoli, L My, Lucid Belmudes, Yohann Couté, J P Viala, E Bouveret
The phospholipid (PL) composition of bacterial membranes varies as a function of growth rate and in response to changes in the environment. While growth adaptation can be explained by biochemical feedbacks in the PL synthesis pathway, recent transcriptome studies have revealed that the expression of PL synthesis genes can also be tuned in response to various stresses. We previously showed that the BasRS two-component pathway controls expression of the diacylglycerol kinase gene dgkA in Escherichia coli (Wahl et al, Mol...
May 8, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28467057/conditional-chaperone-client-interactions-revealed-by-genetically-encoded-photo-cross-linkers
#9
Shuai Zhang, Dan He, Zhi Lin, Yi Yang, Haiping Song, Peng R Chen
The cell envelope is an integral and essential component of Gram-negative bacteria. As the front line during host-pathogen interactions, it is directly challenged by host immune responses as well as other harsh extracellular stimuli. The high permeability of the outer-membrane and the lack of ATP energy system render it difficult to maintain important biological activities within the periplasmic space under stress conditions. The HdeA/B chaperone machinery is the only known acid resistant system found in bacterial periplasm, enabling enteric pathogens to survive through the highly acidic human stomach and establish infections in the intestine...
May 3, 2017: Accounts of Chemical Research
https://www.readbyqxmd.com/read/28450373/rnaseq-analysis-of-the-drosophila-response-to-the-entomopathogenic-nematode-steinernema
#10
Shruti Yadav, Sean Daugherty, Amol Carl Shetty, Ioannis Eleftherianos
Drosophila melanogaster is an outstanding model to study the molecular and functional basis of host-pathogen interactions. Currently our knowledge of microbial infections in D. melanogaster is well understood, however the response of flies to nematode infections is still in its infancy. Here we have used the potent parasitic nematode Steinernema carpocapsae that lives in mutualism with its endosymbiotic bacteria X. nematophila to examine the transcriptomic basis of the interaction between D. melanogaster and entomopathogenic nematodes...
April 26, 2017: G3: Genes—Genomes—Genetics
https://www.readbyqxmd.com/read/28444395/effects-of-n-acetyl-l-cysteine-on-the-membrane-vesicle-release-and-growth-of-respiratory-pathogens
#11
Charlotte Volgers, Birke J Benedikter, Gert E Grauls, Pauline H M Hellebrand, Paul H M Savelkoul, Frank R M Stassen
Bacterial infections contribute to the disease progression of chronic obstructive pulmonary disease by stimulating mucus production in the airways. This increased mucus production and other symptoms are often alleviated when patients are treated with mucolytics such as N-acetyl-L-cysteine (NAC). Moreover, NAC has been suggested to inhibit bacterial growth. Bacteria can release membrane vesicles (MVs) in response to stress, and recent studies report a role for these proinflammatory MVs in the pathogenesis of airways disease...
May 1, 2017: FEMS Microbiology Letters
https://www.readbyqxmd.com/read/28443079/pleomorphism-and-viability-of-the-lyme-disease-pathogen-borrelia-burgdorferi-exposed-to-physiological-stress-conditions-a-correlative-cryo-fluorescence-and-cryo-scanning-electron-microscopy-study
#12
Marie Vancová, Nataliia Rudenko, Jiří Vaněček, Maryna Golovchenko, Martin Strnad, Ryan O M Rego, Lucie Tichá, Libor Grubhoffer, Jana Nebesářová
To understand the response of the Lyme disease spirochete Borrelia burgdorferi exposed to stress conditions and assess the viability of this spirochete, we used a correlative cryo-fluorescence and cryo-scanning microscopy approach. This approach enables simple exposition of bacteria to various experimental conditions that can be stopped at certain time intervals by cryo-immobilization, examination of cell viability without necessity to maintain suitable culture conditions during viability assays, and visualization of structures in their native state at high magnification...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28439041/cues-from-the-membrane-bacterial-glycerophospholipids
#13
Zachary D Dalebroux
In this issue of Journal of Bacteriology, Rowlett et al. unveil new Escherichia coli circuitry linking membrane glycerophospholipid (GPL) homeostasis to bacterial stress response and adaptation mechanisms. Glycerophospholipids comprise critical components of the dual-membrane envelope of Gram-negative bacteria and participate in many processes. The new evidence suggests that in some instances distinct E. coli GPL molecules function for distinct biochemistry, and bacteria sense perturbations in membrane GPL concentrations to coordinate survival strategies...
April 24, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28439040/the-impact-of-membrane-phospholipid-alterations-in-escherichia-coli-on-cellular-function-and-bacterial-stress-adaptation
#14
Veronica W Rowlett, Venkata K P S Mallampalli, Anja Karlstaedt, William Dowhan, Heinrich Taegtmeyer, William Margolin, Heidi Vitrac
Bacteria have evolved multiple strategies to sense and rapidly adapt to challenging and ever-changing environmental conditions. The ability to alter membrane lipid composition, a key component of the cellular envelope, is crucial for bacterial survival and adaptation in response to environmental stress. However, the precise roles played by membrane phospholipids in bacterial physiology and stress adaptation are not fully elucidated. The goal of this study was to define the role of membrane phospholipids in adaptation to stress and maintenance of bacterial cell fitness...
April 24, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28432035/expression-of-pattern-recognition-receptors-and-activation-of-the-non-canonical-inflammasome-pathway-in-brain-pericytes
#15
Ádám Nyúl-Tóth, Mihály Kozma, Péter Nagyőszi, Krisztina Nagy, Csilla Fazakas, János Haskó, Kinga Molnár, Attila E Farkas, Attila G Végh, György Váró, Péter Galajda, Imola Wilhelm, István A Krizbai
Cerebral pericytes are mural cells embedded in the basement membrane of capillaries. Increasing evidence suggests that they play important role in controlling neurovascular functions, i.e. cerebral blood flow, angiogenesis and permeability of the blood-brain barrier. These cells can also influence neuroinflammation which is highly regulated by the innate immune system. Therefore, we systematically tested the pattern recognition receptor expression of brain pericytes. We detected expression of NOD1, NOD2, NLRC5, NLRP1-3, NLRP5, NLRP9, NLRP10 and NLRX mRNA in non-treated cells...
April 18, 2017: Brain, Behavior, and Immunity
https://www.readbyqxmd.com/read/28431522/comparative-proteomic-analysis-of-neisseria-meningitidis-wildtype-and-dpra-null-mutant-strains-links-dna-processing-to-pilus-biogenesis
#16
Getachew Tesfaye Beyene, Shewit Kalayou, Tahira Riaz, Tone Tonjum
BACKGROUND: DNA processing chain A (DprA) is a DNA binding protein which is ubiquitous in bacteria, and is required for DNA transformation to various extents among bacterial species. However, the interaction of DprA with competence and recombination proteins is poorly understood. Therefore, the proteomes of whole Neisseria meningitidis (Nm) wildtype and dprA mutant cells were compared. Such a comparative proteomic analysis increases our understanding of the interactions of DprA with other Nm components and may elucidate its potential role beyond DNA processing in transformation...
April 21, 2017: BMC Microbiology
https://www.readbyqxmd.com/read/28428950/endogenous-and-exogenous-kdpf-peptide-increases-susceptibility-of-mycobacterium-bovis-bcg-to-nitrosative-stress-and-reduces-intramacrophage-replication
#17
Mariana Rosas Olvera, Eric Vivès, Virginie Molle, Anne-Béatrice Blanc-Potard, Laila Gannoun-Zaki
Emerging antibiotic resistance in pathogenic bacteria like Mycobacterium sp., poses a threat to human health and therefore calls for the development of novel antibacterial strategies. We have recently discovered that bacterial membrane peptides, such as KdpF, possess anti-virulence properties when overproduced in pathogenic bacterial species. Overproduction of the KdpF peptide in Mycobacterium bovis BCG decreased bacterial replication within macrophages, without presenting antibacterial activity. We propose that KdpF functions as a regulatory molecule and interferes with bacterial virulence, potentially through interaction with the PDIM transporter MmpL7...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/28421043/outlining-core-pathways-of-amyloid-toxicity-in-bacteria-with-the-repa-wh1-prionoid
#18
Laura Molina-García, María Moreno-Del Álamo, Pedro Botias, Zaira Martín-Moldes, María Fernández, Alicia Sánchez-Gorostiaga, Aída Alonso-Del Valle, Juan Nogales, Jesús García-Cantalejo, Rafael Giraldo
The synthetic bacterial prionoid RepA-WH1 causes a vertically transmissible amyloid proteinopathy in Escherichia coli that inhibits growth and eventually kills the cells. Recent in vitro studies show that RepA-WH1 builds pores through model lipid membranes, suggesting a possible mechanism for bacterial cell death. By comparing acutely (A31V) and mildly (ΔN37) cytotoxic mutant variants of the protein, we report here that RepA-WH1(A31V) expression decreases the intracellular osmotic pressure and compromise bacterial viability under either aerobic or anaerobic conditions...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28416660/redefining-the-essential-trafficking-pathway-for-outer-membrane-lipoproteins
#19
Marcin Grabowicz, Thomas J Silhavy
The outer membrane (OM) of Gram-negative bacteria is a permeability barrier and an intrinsic antibiotic resistance factor. Lipoproteins are OM components that function in cell wall synthesis, diverse secretion systems, and antibiotic efflux pumps. Moreover, each of the essential OM machines that assemble the barrier requires one or more lipoproteins. This dependence is thought to explain the essentiality of the periplasmic chaperone LolA and its OM receptor LolB that traffic lipoproteins to the OM. However, we show that in strains lacking substrates that are toxic when mislocalized, both LolA and LolB can be completely bypassed by activating an envelope stress response without compromising trafficking of essential lipoproteins...
May 2, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28408482/small-regulatory-bacterial-rnas-regulating-the-envelope-stress-response
#20
REVIEW
Gracjana Klein, Satish Raina
Most bacteria encode a large repertoire of RNA-based regulatory mechanisms. Recent discoveries have revealed that the expression of many genes is controlled by a plethora of base-pairing noncoding small regulatory RNAs (sRNAs), regulatory RNA-binding proteins and RNA-degrading enzymes. Some of these RNA-based regulated processes respond to stress conditions and are involved in the maintenance of cellular homeostasis. They achieve it by either direct posttranscriptional repression of several mRNAs, including blocking access to ribosome and/or directing them to RNA degradation when the synthesis of their cognate proteins is unwanted, or by enhanced translation of some key stress-regulated transcriptional factors...
April 15, 2017: Biochemical Society Transactions
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