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stress response membrane bacteria

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https://www.readbyqxmd.com/read/28720734/lack-of-acrb-efflux-function-confers-loss-of-virulence-on-salmonella-enterica-serovar-typhimurium
#1
Xuan Wang-Kan, Jessica M A Blair, Barbara Chirullo, Jonathan Betts, Roberto M La Ragione, Alasdair Ivens, Vito Ricci, Timothy J Opperman, Laura J V Piddock
AcrAB-TolC is the paradigm resistance-nodulation-division (RND) multidrug resistance efflux system in Gram-negative bacteria, with AcrB being the pump protein in this complex. We constructed a nonfunctional AcrB mutant by replacing D408, a highly conserved residue essential for proton translocation. Western blotting confirmed that the AcrB D408A mutant had the same native level of expression of AcrB as the parental strain. The mutant had no growth deficiencies in rich or minimal medium. However, compared with wild-type SL1344, the mutant had increased accumulation of Hoechst 33342 dye and decreased efflux of ethidium bromide and was multidrug hypersusceptible...
July 18, 2017: MBio
https://www.readbyqxmd.com/read/28702643/antioxidant-ace-inhibitory-and-antimicrobial-activity-of-fermented-goat-milk-activity-and-physicochemical-property-relationship-of-the-peptide-components
#2
Miriam Moreno-Montoro, Manuel Olalla-Herrera, José Ángel Rufián-Henares, Rafael Giménez Martínez, Beatriz Miralles, Triana Bergillos, Miguel Navarro-Alarcón, Paula Jauregi
Increasing evidence on goat milk and the health benefits of its derived products beyond its nutritional value show its potential as a functional food. In this study, goat milk fractions were tested for their total antioxidant capacity using different methods (ORAC, ABTS, DPPH and FRAP), as well as their angiotensin-I-converting-enzyme inhibitory and antimicrobial (against Escherichia coli and Micrococcus luteus) activities. Different whey fractions (whey, cation exchange membrane permeate P and retentate R) of two fermented skimmed goat milks (ultrafiltered goat milk fermented with the classical starter bacteria or with the classical starter plus the Lactobacillus plantarum C4 probiotic strain) were assessed...
July 13, 2017: Food & Function
https://www.readbyqxmd.com/read/28674071/-major-tom-to-ground-control-how-lipoproteins-communicate-extra-cytoplasmic-stress-to-the-decision-center-of-the-cell
#3
Géraldine Laloux, Jean-François Collet
The envelope of bacteria is a complex multi-layered shield that ensures multiple essential functions, including protecting the cell from external assaults. Hence, bacterial cells have evolved intricate mechanisms, called envelope stress response systems (ESRS), to monitor all kinds of perturbations affecting the integrity of their envelope and mount an appropriate response to contain or repair the damage. In the model bacterium Escherichia coli, several ESRS are built around a two-component system, in which envelope stress triggers a phosphotransfer between a sensor protein in the inner membrane of the envelope and a response regulator in the cytoplasm...
July 3, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28674070/bacillus-subtilis-intramembrane-protease-rasp-activity-in-escherichia-coli-and-in-vitro
#4
Daniel Parrell, Yang Zhang, Sandra Olenic, Lee Kroos
RasP is a predicted intramembrane metalloprotease of Bacillus subtilis that has been proposed to cleave the stress response anti-sigma factors RsiW and RsiV, the cell division protein FtsL, and remnant signal peptides, within their transmembrane segments. To provide evidence for direct effects of RasP on putative substrates, we developed a heterologous coexpression system. Since expression of catalytically-inactive RasP E21A inhibited expression of other membrane proteins in Escherichia coli, we added extra transmembrane segments to RasP E21A, which allowed accumulation of most other membrane proteins...
July 3, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28674068/structural-and-functional-analysis-of-the-escherichia-coli-acid-sensing-histidine-kinase-evgs
#5
Hrishiraj Sen, Nikhil Aggarwal, Chibueze Ishionwu, Nosheen Hussain, Chandni Parmar, Mohammed Jamshad, Vassiliy N Bavro, Peter A Lund
The EvgS/EvgA two component system of E. coli is activated in response to low pH and alkali metals, and regulates many genes including the glutamate dependent acid resistance system and a number of efflux pumps. EvgS, the sensor kinase, is one of five unconventional histidine kinases in E. coli, and has a large periplasmic domain and a cytoplasmic PAS domain in addition to phospho-acceptor, HK and dimerization, internal receiver, and phosphotransfer domains. Mutations that constitutively activate the protein at pH 7 map to the PAS domain...
July 3, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28666873/overexpression-of-mica-induces-production-of-ompc-enriched-outer-membrane-vesicles-that-protect-against-salmonella-challenge
#6
Hyun-Il Choi, Moonjeong Kim, Jinseong Jeon, Jin Kwan Han, Kwang-Sun Kim
Outer membrane vesicles (OMVs) derived from bacteria are promising candidates for subunit vaccines. Stresses that modulate the composition of outer membrane proteins (OMPs) are important for OMV synthesis. Small RNAs (sRNAs) expressed in response to stress regulate OMPs, although the mechanism underlying sRNA-mediated OMV biogenesis and its utility for developing vaccine platforms remains to be elucidated. Here, we characterized the role of a sRNA, MicA, which regulates OmpA, a major OMP involved in both production of OMVs and reactive immunity against Salmonella challenge...
June 27, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28649237/outer-membrane-vesicles-omvs-of-gram-negative-bacteria-a-perspective-update
#7
REVIEW
Arif Tasleem Jan
Outer Membrane Vesicles (OMVs) of Gram-negative bacteria are spherical membrane-enclosed entities of endocytic origin. Reported in the consortia of different bacterial species, production of OMVs into extracellular milieu seems essential for their survival. Enriched with bioactive proteins, toxins, and virulence factors, OMVs play a critical role in the bacteria-bacteria and bacteria-host interactions. Emergence of OMVs as distinct cellular entities helps bacteria in adaptating to diverse niches, in competing with other bacteria to protect members of producer species and more importantly play a crucial role in host-pathogen interaction...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28646114/staphylococcus-aureus-strain-newman-photoinactivation-and-cellular-response-to-sunlight-exposure
#8
Jill S McClary, Lauren M Sassoubre, Alexandria B Boehm
Sunlight influences microbial water quality of surface waters. Previous studies have investigated photoinactivation mechanisms and cellular photostress responses of fecal indicator bacteria (FIB), including Escherichia coli and enterococci, but further work is needed to characterize photostress responses of bacterial pathogens. Here we investigate the photoinactivation of Staphylococcus aureus (strain Newman), a pigmented, waterborne pathogen of emerging concern. We measured photodecay using standard culture-based assays and cellular membrane integrity; and investigated photostress response by measuring the relative number of mRNA transcripts of select oxidative stress, DNA repair, and metabolism genes...
June 23, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28611746/adaptations-to-high-salt-in-a-halophilic-protist-differential-expression-and-gene-acquisitions-through-duplications-and-gene-transfers
#9
Tommy Harding, Andrew J Roger, Alastair G B Simpson
The capacity of halophiles to thrive in extreme hypersaline habitats derives partly from the tight regulation of ion homeostasis, the salt-dependent adjustment of plasma membrane fluidity, and the increased capability to manage oxidative stress. Halophilic bacteria, and archaea have been intensively studied, and substantial research has been conducted on halophilic fungi, and the green alga Dunaliella. By contrast, there have been very few investigations of halophiles that are phagotrophic protists, i.e., protozoa...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28607072/adaptor-protein-mediates-dynamic-pump-assembly-for-bacterial-metal-efflux
#10
Ace George Santiago, Tai-Yen Chen, Lauren A Genova, Won Jung, Alayna M George Thompson, Megan M McEvoy, Peng Chen
Multicomponent efflux complexes constitute a primary mechanism for Gram-negative bacteria to expel toxic molecules for survival. As these complexes traverse the periplasm and link inner and outer membranes, it remains unclear how they operate efficiently without compromising periplasmic plasticity. Combining single-molecule superresolution imaging and genetic engineering, we study in living Escherichia coli cells the tripartite efflux complex CusCBA of the resistance-nodulation-division family that is essential for bacterial resistance to drugs and toxic metals...
June 27, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28604884/ferrous-iron-efflux-systems-in-bacteria
#11
REVIEW
Hualiang Pi, John D Helmann
Bacteria require iron for growth, with only a few reported exceptions. In many environments, iron is a limiting nutrient for growth and high affinity uptake systems play a central role in iron homeostasis. However, iron can also be detrimental to cells when it is present in excess, particularly under aerobic conditions where its participation in Fenton chemistry generates highly reactive hydroxyl radicals. Recent results have revealed a critical role for iron efflux transporters in protecting bacteria from iron intoxication...
July 19, 2017: Metallomics: Integrated Biometal Science
https://www.readbyqxmd.com/read/28593794/cthtra-the-lynchpin-of-the-chlamydial-surface-and-a-promising-therapeutic-target
#12
James W Marsh, Vanissa A Ong, William B Lott, Peter Timms, Joel DA Tyndall, Wilhelmina M Huston
Chlamydia trachomatis is the most prevalent sexually transmitted bacterial infection worldwide and the leading cause of preventable blindness. Reports have emerged of treatment failure, suggesting a need to develop new antibiotics to battle Chlamydia infection. One possible candidate for a new treatment is the protease inhibitor JO146, which is an effective anti-Chlamydia agent that targets the CtHtrA protein. CtHtrA is a lynchpin on the chlamydial cell surface due to its essential and multifunctional roles in the bacteria's stress response, replicative phase of development, virulence and outer-membrane protein assembly...
June 8, 2017: Future Microbiology
https://www.readbyqxmd.com/read/28592862/identification-of-unique-cardiolipin-and-monolysocardiolipin-species-in-acinetobacter-baumannii
#13
Patrizia Lopalco, Julia Stahl, Cosimo Annese, Beate Averhoff, Angela Corcelli
Acidic glycerophospholipids play an important role in determining the resistance of Gram-negative bacteria to stress conditions and antibiotics. Acinetobacter baumannii, an opportunistic human pathogen which is responsible for an increasing number of nosocomial infections, exhibits broad antibiotic resistances. Here lipids of A. baumannii have been analyzed by combined MALDI-TOF/MS and TLC analyses; in addition GC-MS analyses of fatty acid methyl esters released by methanolysis of membrane phospholipids have been performed...
June 7, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28588134/the-rcs-regulated-colanic-acid-capsule-maintains-membrane-potential-in-salmonella-enterica-serovar-typhimurium
#14
Jasmine M Pando, Joyce E Karlinsey, Jimmie C Lara, Stephen J Libby, Ferric C Fang
The Rcs phosphorelay and Psp (phage shock protein) systems are envelope stress responses that are highly conserved in gammaproteobacteria. The Rcs regulon was found to be strongly induced during metal deprivation of Salmonella enterica serovar Typhimurium lacking the Psp response. Nineteen genes activated by the RcsA-RcsB response regulator make up an operon responsible for the production of colanic acid capsular polysaccharide, which promotes biofilm development. Despite more than half a century of research, the physiological function of colanic acid has remained elusive...
June 6, 2017: MBio
https://www.readbyqxmd.com/read/28552524/resveratrol-induces-membrane-and-dna-disruption-via-pro-oxidant-activity-against-salmonella-typhimurium
#15
Wonjong Lee, Dong Gun Lee
Resveratrol is a flavonoid found in various plants including grapes, which has been reported to be active against various pathogenic bacteria. However, antibacterial effects and mechanisms via pro-oxidant property of resveratrol remain unknown and speculative. This research investigated antibacterial mechanism of resveratrol against a food-borne human pathogen Salmonella typhimurium, and confirmed the cell death associated oxidative damage. Resveratrol increased outer membrane permeability and membrane depolarization...
May 25, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/28537416/glutathione-degradation
#16
Anand K Bachhawat, Amandeep Kaur
SIGNIFICANCE: Glutathione degradation has for long been thought to occur only on non-cytosolic pools. This is because there has been only one enzyme known to degrade glutathione (γ-glutamyltranspeptidase), and this localizes to either the plasma membrane (mammals, bacteria) or the vacuolar membrane (yeast, plants) and acts on extracellular or vacuolar pools. The last few years has seen the discovery of several new enzymes of glutathione degradation that function in the cytosol, throwing new light on glutathione degradation...
May 24, 2017: Antioxidants & Redox Signaling
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
#17
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
#18
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
#19
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
#20
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
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