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https://www.readbyqxmd.com/read/29342189/the-microbiota-metabolite-indole-inhibits-salmonella-virulence-involvement-of-the-phopq-two-component-system
#1
Nandita Kohli, Zeni Crisp, Rebekah Riordan, Michael Li, Robert C Alaniz, Arul Jayaraman
The microbial community present in the gastrointestinal tract is an important component of the host defense against pathogen infections. We previously demonstrated that indole, a microbial metabolite of tryptophan, reduces enterohemorrhagic Escherichia coli O157:H7 attachment to intestinal epithelial cells and biofilm formation, suggesting that indole may be an effector/attenuator of colonization for a number of enteric pathogens. Here, we report that indole attenuates Salmonella Typhimurium (Salmonella) virulence and invasion as well as increases resistance to colonization in host cells...
2018: PloS One
https://www.readbyqxmd.com/read/29342151/cd8-signaling-in-microglia-macrophage-m1-polarization-in-a-rat-model-of-cerebral-ischemia
#2
Jan Boddaert, Kenny Bielen, Bart 's Jongers, Ekta Manocha, Laetitia Yperzeele, Patrick Cras, Daniel Pirici, Samir Kumar-Singh
Classical or M1 activity of microglia/macrophages has been described in several neurodegenerative and brain inflammatory conditions and has also been linked to expansion of ischemic injury in post-stroke brain. While different pathways of M1 polarization have been suggested to occur in the post-stroke brain, the precise underlying mechanisms remain undefined. Using a transient middle cerebral artery occlusion (MCAO) rat model, we showed a progressive M2 to M1 polarization in the perilesional brain region with M1 cells becoming one of the dominant subsets by day 4 post-stroke...
2018: PloS One
https://www.readbyqxmd.com/read/29341983/diarrheagenic-escherichia-coli-and-acute-gastroenteritis-in-children-in-davidson-county-tennessee-united-states-a-case-control-study
#3
Aamer Imdad, Monique A Foster, Junaid Iqbal, Christopher Fonnesbeck, Daniel C Payne, Chengxian Zhang, James D Chappell, Natasha Halasa, Oscar G Gómez-Duarte
BACKGROUND: Diarrheagenic Escherichia coli (DEC) are an important cause of acute gastroenteritis in children; however, there is limited information available on the epidemiology, phylogenetics, serotyping, and antibiotic susceptibility of DEC in children in the United States. The aim of this study was to determine the molecular epidemiology of DEC among children with and without acute gastroenteritis in Davidson County, Tennessee. METHODS: This prospective, frequency matched, case-control study recruited subjects 15 days to 17 years of age and detected DEC with polymerase chain reaction from stool samples...
January 16, 2018: Pediatric Infectious Disease Journal
https://www.readbyqxmd.com/read/29341672/helicase-stepping-investigated-with-one-nucleotide-resolution-fluorescence-resonance-energy-transfer
#4
Wenxia Lin, Jianbing Ma, Daguan Nong, Chunhua Xu, Bo Zhang, Jinghua Li, Qi Jia, Shuoxing Dou, Fangfu Ye, Xuguang Xi, Ying Lu, Ming Li
Single-molecule Förster resonance energy transfer is widely applied to study helicases by detecting distance changes between a pair of dyes anchored to overhangs of a forked DNA. However, it has been lacking single-base pair (1-bp) resolution required for revealing stepping kinetics of helicases. We designed a nanotensioner in which a short DNA is bent to exert force on the overhangs, just as in optical or magnetic tweezers. The strategy improved the resolution of Förster resonance energy transfer to 0.5 bp, high enough to uncover differences in DNA unwinding by yeast Pif1 and E...
September 29, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/29341605/prediction-of-active-site-and-distal-residues-in-e-coli-dna-polymerase-iii-alpha-polymerase-activity
#5
Ramya Parasuram, Timothy A Coulther, Judith M Hollander, Elise Keston-Smith, Mary Jo Ondrechen, Penny J Beuning
The process of DNA replication is carried out with high efficiency and accuracy by DNA polymerases. The replicative polymerase in E. coli is DNA Pol III, which is a complex of 10 different subunits that coordinates simultaneous replication on the leading and lagging strands. The 1160-residue Pol III alpha subunit is responsible for the polymerase activity and copies DNA accurately, making one error per 105 nucleotide incorporations. The goal of this research is to determine the residues that contribute to the activity of the polymerase subunit...
January 17, 2018: Biochemistry
https://www.readbyqxmd.com/read/29341594/designing-flavoprotein-gfp-fusion-probes-for-analyte-specific-ratiometric-fluorescence-imaging
#6
Devin A Hudson, Jeffrey L Caplan, Colin Thorpe
The development of genetically encoded fluorescent probes for analyte-specific imaging has revolutionized our understanding of intracellular processes. Current classes of intracellular probes depend on the selection of binding domains that either undergo conformational changes on analyte binding or can be linked to thiol redox chemistry. Here we have designed novel probes by fusing a flavoenzyme, whose fluorescence is quenched on reduction by the analyte of interest, with a GFP domain to allow for rapid and specific ratiometric sensing...
January 17, 2018: Biochemistry
https://www.readbyqxmd.com/read/29341389/detection-of-escherichia-coli-in-ready-to-eat-fresh-vegetables-using-broad-host-range-recombinant-phages
#7
Hoang A Hoang, Nguyen T C Quy, Nguyen V T Chi
AIM: To construct a simple method to detect E. coli in ready-to-eat fresh vegetables using broad-host-range recombinant phages. METHODS AND RESULTS: Firstly, a gene encoding Cytochrome c Peroxidase (CCP) chromogenic enzyme was inserted into genomes of wild-type phages IP008 and IP052 to produce recombinant phages IP008BK and IP052BK. They were then used in the production of the chromogenic enzyme (CCP) through infection into E. coli. The method was then examined in the colorimetric detection of E...
January 16, 2018: Journal of Applied Microbiology
https://www.readbyqxmd.com/read/29341247/secretory-expression-of-negative-regulatory-region-of-human-notch1-in-e-coli-and-preparation-of-a-functional-polyclonal-antibody
#8
Dengyang Zhang, Tianzhu Sun, Jingyun Yan, Xuanjun Wang, Jun Sheng
Notch signaling is a highly conserved pathway existed in multicellular organisms. It plays roles in normal human body development, human cancer initiation, progression and metastasis. The Notch negative regulatory region (NRR) is critical for Notch signaling, and cleavage at the S2 site in the NRR ultimately leads to the activation of Notch signaling. To study the function of human NRR1, we expressed the recombinant human NRR1 (rhNRR1) domain in Escherichia coli. After purification, rhNRR1 was obtained with approximately 94% purity according to SDS-PAGE analysis...
January 17, 2018: Biotechnology and Applied Biochemistry
https://www.readbyqxmd.com/read/29341217/acetoacetate-and-ethyl-acetoacetate-as-novel-inhibitors-of-bacterial-biofilm
#9
S M Horne, M Schroeder, J Murphy, B M Prüβ
Acetoacetate (AAA) was identified as a biofilm inhibitor in a previous study, where the effect of 190 carbon and nitrogen sources on biofilm amounts by Escherichia coli O157:H7 was determined. With this study, we tested the effect of AAA on growth and biofilm amounts of Cronobacter sakazakii, Serratia marcescens, and Yersinia enterocolitica. AAA reduced growth and biofilm amounts of the three pathogens, albeit at rather high concentrations of 10 to 35 mg ml-1 . AAA at a concentration of 5 mg ml-1 reduced Y...
January 16, 2018: Letters in Applied Microbiology
https://www.readbyqxmd.com/read/29341168/in-search-of-a-counter-you-can-count-on-relative-efficacy-of-human-visual-and-automated-colony-counting
#10
Linda M Young, Dustin J Rieman, Lisa Walden, Vicki Abrams Motz
To evaluate comparative efficiency of traditional vs. automated colony counting methods, cultures of Escherichia coli (ATCC 25945), Staphylococcus epidermidis (ATCC 12225), Streptococcus pyogenes (ATCC19615), and Streptococcus pneumoniae (ATCC49619) were prepared as pure cultures and mixed cultures at 0.5 McFarland standard and serial dilutions were performed. Plates were inoculated in triplicate with 50 CFUs, 125 CFUs, 250 CFUs and 500 CFUs and counted by four researchers, visually and using each of the automated counters...
January 16, 2018: Letters in Applied Microbiology
https://www.readbyqxmd.com/read/29340903/characterization-of-ent-kaurene-synthase-and-kaurene-oxidase-involved-in-gibberellin-biosynthesis-from-scoparia-dulcis
#11
Yoshimi Yamamura, Yukari Taguchi, Kei Ichitani, Io Umebara, Ayako Ohshita, Fumiya Kurosaki, Jung-Bum Lee
Gibberellins (GAs) are ubiquitous diterpenoids in higher plants, whereas some higher plants produce unique species-specific diterpenoids. In GA biosynthesis, ent-kaurene synthase (KS) and ent-kaurene oxidase (KO) are key players which catalyze early step(s) of the cyclization and oxidation reactions. We have studied the functional characterization of gene products of a KS (SdKS) and two KOs (SdKO1 and SdKO2) involved in GA biosynthesis in Scoparia dulcis. Using an in vivo heterologous expression system of Escherichia coli, we found that SdKS catalyzed a cyclization reaction from ent-CPP to ent-kaurene and that the SdKOs oxidized ent-kaurene to ent-kaurenoic acid after modification of the N-terminal region for adaptation to the E...
January 16, 2018: Journal of Natural Medicines
https://www.readbyqxmd.com/read/29340897/invasion-and-translocation-of-uropathogenic-escherichia-coli-isolated-from-urosepsis-and-patients-with-community-acquired-urinary-tract-infection
#12
B Owrangi, N Masters, A Kuballa, C O'Dea, T L Vollmerhausen, M Katouli
Uropathogenic Escherichia coli (UPEC) strains are found in high numbers in the gut of patients with urinary tract infections (UTIs). We hypothesised that in hospitalised patients, UPEC strains might translocate from the gut to the blood stream and that this could be due to the presence of virulence genes (VGs) that are not commonly found in UPEC strains that cause UTI only. To test this, E. coli strains representing 75 dominant clonal groups of UPEC isolated from the blood of hospitalised patients with UTI (urosepsis) (n = 22), hospital-acquired (HA) UTI without blood infection (n = 24) and strains isolated from patients with community-acquired (CA)-UTIs (n = 29) were tested for their adhesion to, invasion and translocation through Caco-2 cells, in addition to the presence of 34 VGs associated with UPEC...
January 16, 2018: European Journal of Clinical Microbiology & Infectious Diseases
https://www.readbyqxmd.com/read/29340602/emergence-of-blactx-m-55-associated-with-fosa-rmtb-and-mcr-gene-variants-in-escherichia-coli-from-various-animal-species-in-france
#13
Agnese Lupo, Estelle Saras, Jean-Yves Madec, Marisa Haenni
Objectives: In Asian countries, blaCTX-M-55 is the second most common ESBL-encoding gene. blaCTX-M-55 frequently co-localizes with fosA and rmtB genes on epidemic plasmids, which remain sporadic outside Asia. During 2010-13, we investigated CTX-M-55-producing Escherichia coli isolates and their co-resistance to fosfomycin, aminoglycosides, fluoroquinolones and colistin as part of a global survey of ESBLs in animals in France. Methods: blaCTX-M-55, fosA, rmtB and plasmidic quinolone and colistin resistance genes were characterized by PCR, sequencing and hybridization experiments...
January 10, 2018: Journal of Antimicrobial Chemotherapy
https://www.readbyqxmd.com/read/29340060/assessment-of-antimicrobial-and-wound-healing-effects-of-brevinin-2ta-against-the-bacterium-klebsiella-pneumoniae-in-dermally-wounded-rats
#14
Siqin Liu, Qilin Long, Yang Xu, Jun Wang, Zhongwei Xu, Lei Wang, Mei Zhou, Yuxin Wu, Tianbao Chen, Chris Shaw
Antimicrobial peptides (AMPs) are regarded as promising alternatives for antibiotics due to their inherent capacity to prevent microbial drug resistance. Amphibians are rich source of bioactive molecules, which provide numerous AMPs with various structures as drug candidates. Here, we isolated and identified a novel AMP Brevinin-2Ta (B-2Ta) from the skin secretion of the European frog, Pelophylax kl. esculentus. In vitro studies revealed that it showed broad antimicrobial activities against S. aureus, E. coli and C...
December 19, 2017: Oncotarget
https://www.readbyqxmd.com/read/29339632/identification-of-rifampicin-resistance-mutations-in-escherichia-coli-including-an-unusual-deletion-mutation
#15
Eugene Y Wu, Angela K Hilliker
Rifampicin is an effective antibiotic against mycobacterial and other bacterial infections, but resistance readily emerges in laboratory and clinical settings. We screened Escherichia coli for rifampicin resistance and identified numerous mutations to the gene encoding the β-chain of RNA polymerase (rpoB), including an unusual 9-nucleotide deletion mutation. Structural modeling of the deletion mutant indicates locations of potential steric clashes with rifampicin. Sequence conservation in the region near the deletion mutation suggests a similar mutation may also confer resistance during the treatment of tuberculosis...
January 17, 2018: Journal of Molecular Microbiology and Biotechnology
https://www.readbyqxmd.com/read/29339556/evidence-of-a-sequestered-imine-intermediate-during-reduction-of-nitrile-to-amine-by-the-nitrile-reductase-quef-from-escherichia-coli
#16
Jihye Jung, Bernd Nidetzky
In the biosynthesis of the tRNA-inserted nucleoside queuosine, the nitrile reductase QueF catalyzes conversion of 7-cyano-7-deazaguanine (preQ0) to 7-aminomethyl-7-deazaguanine (preQ1), a biologically unique four-electron reduction of a nitrile to an amine. The QueF mechanism involves a covalent thioimide adduct between the enzyme and preQ0 which undergoes reduction to preQ1 in two NADPH-dependent steps, presumably via an imine intermediate. Protecting a labile imine from interception by water is fundamental to QueF catalysis for proper enzyme function...
January 16, 2018: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29339506/development-and-retention-of-a-primordial-moonlighting-pathway-of-protein-modification-in-the-absence-of-selection-presents-a-puzzle
#17
Xinyun Cao, Yaoqin Hong, Lei Zhu, Yuanyuan Hu, John E Cronan
Lipoic acid is synthesized by a remarkably atypical pathway in which the cofactor is assembled on its cognate proteins. An octanoyl moiety diverted from fatty acid synthesis is covalently attached to the acceptor protein, and sulfur insertion at carbons 6 and 8 of the octanoyl moiety form the lipoyl cofactor. Covalent attachment of this cofactor is required for function of several central metabolism enzymes, including the glycine cleavage H protein (GcvH). In Bacillus subtilis, GcvH is the sole substrate for lipoate assembly...
January 16, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29339494/strongly-enhanced-bacterial-bioluminescence-with-the-ilux-operon-for-single-cell-imaging
#18
Carola Gregor, Klaus C Gwosch, Steffen J Sahl, Stefan W Hell
Bioluminescence imaging of single cells is often complicated by the requirement of exogenous luciferins that can be poorly cell-permeable or produce high background signal. Bacterial bioluminescence is unique in that it uses reduced flavin mononucleotide as a luciferin, which is abundant in all cells, making this system purely genetically encodable by the lux operon. Unfortunately, the use of bacterial bioluminescence has been limited by its low brightness compared with other luciferases. Here, we report the generation of an improved lux operon named ilux with an approximately sevenfold increased brightness when expressed in Escherichia coli; ilux can be used to image single E...
January 16, 2018: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29339461/cooperative-immune-suppression-by-escherichia-coli-and-shigella-effector-proteins
#19
Maarten F de Jong, Neal M Alto
The enteric attaching and effacing (A/E) pathogens EHEC and EPEC and invasive pathogens EIEC and Shigella encode Type III secretion systems (T3SS) used to inject effector proteins into human host cells during infection. Among these are a group of effectors required for NF-κB mediated host immune evasion. Recent studies have identified several effector proteins from A/E pathogens and EIEC/Shigella that are involved in suppression of NF-κB and uncovered their cellular and molecular functions. A novel mechanism among these effectors from both groups of pathogens is to coordinate effector function during infection...
January 16, 2018: Infection and Immunity
https://www.readbyqxmd.com/read/29339430/simultaneous-binding-of-multiple-ef-tu-copies-to-translating-ribosomes-in-live-escherichia-coli
#20
Mainak Mustafi, James C Weisshaar
In bacteria, elongation factor Tu is a translational cofactor that forms ternary complexes with aminoacyl-tRNA (aa-tRNA) and GTP. Binding of a ternary complex to one of four flexible L7/L12 units on the ribosome tethers a charged tRNA in close proximity to the ribosomal A site. Two sequential tests for a match between the aa-tRNA anticodon and the current mRNA codon then follow. Because one elongation cycle can occur in as little as 50 ms and the vast majority of aa-tRNA copies are not cognate with the current mRNA codon, this testing must occur rapidly...
January 16, 2018: MBio
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