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https://www.readbyqxmd.com/read/28094462/orientation-of-the-ompf-porin-in-planar-lipid-bilayers
#1
Sandra Antonia Ionescu, Sejeong Lee, Nicholas Housden, Renata Kaminska, Colin Kleanthous, Hagan Bayley
Outer membrane protein F (OmpF) is an abundant trimeric general diffusion porin that plays a central role in the transport of antibiotics and colicins across the outer membrane of E. coli. Individual OmpF trimers in planar lipid bilayers (PLB) show one of two current-voltage asymmetries, implying that insertion occurs with either the periplasmic or the extracellular end first. A method for establishing the orientation of OmpF in PLB was developed based on the targeted covalent modification, with membrane-impermeant reagents, of peripheral cysteine residues introduced near the periplasmic or the extracellular entrance...
January 17, 2017: Chembiochem: a European Journal of Chemical Biology
https://www.readbyqxmd.com/read/28091521/mechanisms-of-intrinsic-resistance-and-acquired-susceptibility-of-pseudomonas-aeruginosa-isolated-from-cystic-fibrosis-patients-to-temocillin-a-revived-antibiotic
#2
Hussein Chalhoub, Daniel Pletzer, Helge Weingart, Yvonne Braun, Michael M Tunney, J Stuart Elborn, Hector Rodriguez-Villalobos, Patrick Plésiat, Barbara C Kahl, Olivier Denis, Mathias Winterhalter, Paul M Tulkens, Françoise Van Bambeke
The β-lactam antibiotic temocillin (6-α-methoxy-ticarcillin) shows stability to most extended spectrum β-lactamases, but is considered inactive against Pseudomonas aeruginosa. Mutations in the MexAB-OprM efflux system, naturally occurring in cystic fibrosis (CF) isolates, have been previously shown to reverse this intrinsic resistance. In the present study, we measured temocillin activity in a large collection (n = 333) of P. aeruginosa CF isolates. 29% of the isolates had MICs ≤ 16 mg/L (proposed clinical breakpoint for temocillin)...
January 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28076882/characterization-of-salmonella-typhi-ompc-and-ompf-porins-engineered-with-hiv-gp41-epitope-on-the-surface-loops
#3
Madhuranayaki Thulasingam, Subha Damodharan, Gopal Madhana Vigneshwari, Eswari P J Pandaranayaka, Luke Elizabeth Hanna, Ramakrishnan Usha, Sankaran Krishnaswamy
Porins form trimers in the outer membrane and help transport nutrients and waste products across the bacterial cell membrane. Porin loops are suitable candidates as display systems due to their high immunogenicity and presentation at the bacterial cell surface. In this study, Salmonella typhi porins (OmpC and OmpF) engineered with the Kennedy peptide from gp41 of HIV were characterised. The chimeric OmpC carrying the Kennedy peptide in loop7 did not trimerise, whereas the chimeric OmpF with the epitope in loop5 formed trimers and also was recognised by the antibodies in the HIV patient serum...
January 11, 2017: Proteins
https://www.readbyqxmd.com/read/28072422/the-fitness-costs-and-trade-off-shapes-associated-with-the-exclusion-of-nine-antibiotics-by-ompf-porin-channels
#4
Katherine Phan, Thomas Ferenci
The trade-off relationship between antibiotic exclusion and nutrient access across the Gram-negative outer membrane is determined by structural constraints in porin channels. The precise nutritional cost of exclusion is unknown for different antibiotics, as are the shapes of the nutrition-susceptibility trade-off. Using a library of 10 engineered isogenic Escherichia coli strains with structural modifications of OmpF porin expressed at a constant level, susceptibilities were measured for nine antibiotics and the nutritional fitness costs estimated by competitions in chemostats...
January 10, 2017: ISME Journal
https://www.readbyqxmd.com/read/28067226/syntrophic-anaerobic-photosynthesis-via-direct-interspecies-electron-transfer
#5
Phuc T Ha, Stephen R Lindemann, Liang Shi, Alice C Dohnalkova, James K Fredrickson, Michael T Madigan, Haluk Beyenal
Microbial phototrophs, key primary producers on Earth, use H2O, H2, H2S and other reduced inorganic compounds as electron donors. Here we describe a form of metabolism linking anoxygenic photosynthesis to anaerobic respiration that we call 'syntrophic anaerobic photosynthesis'. We show that photoautotrophy in the green sulfur bacterium Prosthecochloris aestaurii can be driven by either electrons from a solid electrode or acetate oxidation via direct interspecies electron transfer from a heterotrophic partner bacterium, Geobacter sulfurreducens...
January 9, 2017: Nature Communications
https://www.readbyqxmd.com/read/28054667/yersinia-pestis-halotolerance-illuminates-plague-reservoirs
#6
Maliya Alia Malek, Idir Bitam, Anthony Levasseur, Jérôme Terras, Jean Gaudart, Said Azza, Christophe Flaudrops, Catherine Robert, Didier Raoult, Michel Drancourt
The plague agent Yersinia pestis persists for years in the soil. Two millennia after swiping over Europe and North Africa, plague established permanent foci in North Africa but not in neighboring Europe. Mapping human plague foci reported in North Africa for 70 years indicated a significant location at <3 kilometers from the Mediterranean seashore or the edge of salted lakes named chotts. In Algeria, culturing 352 environmental specimens naturally containing 0.5 to 70 g/L NaCl yielded one Y. pestis Orientalis biotype isolate in a 40 g/L NaCl chott soil specimen...
January 5, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28031200/low-frequency-of-ceftazidime-avibactam-resistance-among-enterobacteriaceae-isolates-carrying-blakpc-collected-in-hospitals-from-the-united-states-from-2012-to-2015
#7
Mariana Castanheira, Rodrigo E Mendes, Helio S Sader
KPC-producing Enterobacteriaceae isolates have been increasingly reported worldwide and therapeutic options to treat infections caused by these organisms are limited. We evaluated the activity of ceftazidime-avibactam and comparators against 456 Enterobacteriaceae isolates carrying blaKPC collected from 79 United States hospitals during 2012-2015. Overall, ceftazidime-avibactam (MIC50/90, 0.5/2 μg/mL; 99.3% susceptible) and tigecycline (MIC50/90, 0.5/1 μg/mL; 98.9% at ≤2 μg/mL) were the most active agents...
December 28, 2016: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28018863/immunization-with-the-mipa-skp-or-etec_2479-antigens-confers-protection-against-enterotoxigenic-e-coli-strains-expressing-different-colonization-factors-in-a-mouse-pulmonary-challenge-model
#8
Michael P Hays, Amit Kumar, Francisco J Martinez-Becerra, Philip R Hardwidge
Achieving cross-protective efficacy against multiple bacterial strains or serotypes is an important goal of vaccine design. Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrheal disease in underdeveloped nations. We have been interested in identifying and characterizing ETEC antigens that generate protective immune responses independent of ETEC colonization factor (CF) expression. Our previous studies used proteomics to identify the ETEC MipA, Skp, and ETEC_2479 proteins as effective in protecting mice from homologous challenge with ETEC H10407 using a pulmonary inoculation model...
2016: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/27965634/structural-elucidation-and-molecular-docking-of-a-novel-antibiotic-compound-from-cyanobacterium-nostoc-sp-mgl001
#9
Niveshika, Ekta Verma, Arun K Mishra, Angad K Singh, Vinay K Singh
Cyanobacteria are rich source of array of bioactive compounds. The present study reports a novel antibacterial bioactive compound purified from cyanobacterium Nostoc sp. MGL001 using various chromatographic techniques viz. thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). Further characterization was done using electrospray ionization mass spectroscopy (ESIMS) and nuclear magnetic resonance (NMR) and predicted structure of bioactive compound was 9-Ethyliminomethyl-12-(morpholin - 4 - ylmethoxy) -5, 8, 13, 16-tetraaza-hexacene - 2, 3 dicarboxylic acid (EMTAHDCA)...
2016: Frontiers in Microbiology
https://www.readbyqxmd.com/read/27916604/carbapenem-resistant-and-cephalosporin-susceptible-a-worrisome-phenotype-among-pseudomonas-aeruginosa-clinical-isolates-in-brazil
#10
Eloiza Helena Campana, Danilo Elias Xavier, Fernanda Villas-Boas Petrolini, Jhonatha Rodrigo Cordeiro-Moura, Maria Rita Elmor de Araujo, Ana Cristina Gales
The mechanisms involved in the uncommon resistance phenotype, carbapenem resistance and broad-spectrum cephalosporin susceptibility, were investigated in 25 Pseudomonas aeruginosa clinical isolates that exhibited this phenotype, which were recovered from three different hospitals located in São Paulo, Brazil. The antimicrobial susceptibility profile was determined by CLSI broth microdilution. β-lactamase-encoding genes were investigated by PCR followed by DNA sequencing. Carbapenem hydrolysis activity was investigated by spectrophotometer and MALDI-TOF assays...
December 1, 2016: Brazilian Journal of Infectious Diseases
https://www.readbyqxmd.com/read/27915087/genetically-unrelated-multidrug-and-carbapenem-resistant-citrobacter-freundii-detected-in-outpatients-admitted-to-a-portuguese-hospital
#11
Cátia Santos, Elmano Ramalheira, Gabriela Da Silva, Sónia Mendo
OBJECTIVES: Non-clonal, carbapenem- and multidrug-resistant Citrobacter freundii isolates were collected from unrelated outpatients admitted to a Portuguese hospital emergency department. One patient lived in a nursing home and was never hospitalised, whereas the other patient was repeatedly hospitalised in this hospital. The aim of this study was to unveil the molecular mechanisms associated with the carbapenem resistance of these isolates and to assess its potential dissemination. METHODS: Isolate identification was performed by VITEK(®)2 and was confirmed by 16S rDNA sequencing...
November 15, 2016: Journal of Global Antimicrobial Resistance
https://www.readbyqxmd.com/read/27901137/energy-transduction-and-signal-averaging-of-fluctuating-electric-fields-by-a-single-protein-ion-channel
#12
C Verdia-Baguena, V Gomez, J Cervera, P Ramirez, S Mafe
We demonstrate the electrical rectification and signal averaging of fluctuating signals using a biological nanostructure in aqueous solution: a single protein ion channel inserted in the lipid bilayer characteristic of cell membranes. The conversion of oscillating, zero time-average potentials into directional currents permits charging of a load capacitor to significant steady-state voltages within a few minutes in the case of the outer membrane porin F (OmpF) protein, a bacterial channel of Escherichia coli...
December 21, 2016: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/27887765/activity-of-ceftazidime-avibactam-against-multidrug-resistance-enterobacteriaceae-expressing-combined-mechanisms-of-resistance
#13
Inmaculada López-Hernández, Noemí Alonso, Marta Fernández-Martínez, Laura Zamorano, Alba Rivera, Antonio Oliver, M Carmen Conejo, Luis Martínez-Martínez, Ferrán Navarro, Alvaro Pascual
INTRODUCTION: Antimicrobial resistance in Enterobacteriaceae is increasing worldwide and is making treating infections caused by multidrug-resistant Enterobacteriaceae a challenge. The use of β-lactam agents is compromised by microorganisms harboring extended-spectrum β-lactamases (ESBLs) and other mechanisms of resistance. Avibactam is a non β-lactam agent that inhibits clinically relevant β-lactamases, such as ESBL and AmpC. The ceftazidime-avibactam combination (CAZ-AVI) was recently approved for use in certain complicated infections, and may provide a therapeutic alternative for infections caused by these microorganisms...
November 22, 2016: Enfermedades Infecciosas y Microbiología Clínica
https://www.readbyqxmd.com/read/27887202/serological-markers-in-diagnosis-of-pediatric-inflammatory-bowel-disease-and-as-predictors-for-early-tumor-necrosis-factor-blocker-therapy
#14
Christine Olbjørn, Milada Cvancarova Småstuen, Espen Thiis-Evensen, Britt Nakstad, Morten Harald Vatn, Gøri Perminow
OBJECTIVE: To describe the prevalence of serological markers in newly diagnosed treatment-naïve pediatric inflammatory bowel disease (IBD), their utility in differentiating Crohn's disease (CD), ulcerative colitis (UC) and symptomatic non-IBD patients and whether serological markers are associated with early TNF blocker treatment. MATERIAL AND METHODS: Ninety-six children and adolescents <18 years, 58 with IBD and 38 symptomatic non-IBD controls were included...
November 25, 2016: Scandinavian Journal of Gastroenterology
https://www.readbyqxmd.com/read/27881168/loss-of-porin-function-in-dopaminergic-neurons-of-drosophila-is-suppressed-by-buffy
#15
P Githure M'Angale, Brian E Staveley
BACKGROUND: Mitochondrial porin, also known as the voltage-dependent anion channel (VDAC), is a multi-functional channel protein that shuttles metabolites between the mitochondria and the cytosol and implicated in cellular life and death decisions. The inhibition of porin under the control of neuronal Ddc-Gal4 result in short lifespan and in an age-dependent loss in locomotor function, phenotypes that are strongly associated with Drosophila models of Parkinson disease. METHODS: Loss of porin function was achieved through exploitation of RNA interference while derivative lines were generated by homologous recombination and tested by PCR...
November 24, 2016: Journal of Biomedical Science
https://www.readbyqxmd.com/read/27857712/some-like-it-hot-heat-resistance-of-escherichia-coli-in-food
#16
REVIEW
Hui Li, Michael Gänzle
Heat treatment and cooking are common interventions for reducing the numbers of vegetative cells and eliminating pathogenic microorganisms in food. Current cooking method requires the internal temperature of beef patties to reach 71°C. However, some pathogenic Escherichia coli such as the beef isolate E. coli AW 1.7 are extremely heat resistant, questioning its inactivation by current heat interventions in beef processing. To optimize the conditions of heat treatment for effective decontaminations of pathogenic E...
2016: Frontiers in Microbiology
https://www.readbyqxmd.com/read/27854150/response-of-escherichia-coli-to-prolonged-berberine-exposure
#17
Nilay Budeyri Gokgoz, Fatma Gizem Avci, Kubra Karaosmanoglu Yoneten, Begum Alaybeyoglu, Elif Ozkirimli, Nihat Alpagu Sayar, Dilek Kazan, Berna Sariyar Akbulut
Berberine is a plant-derived alkaloid possessing antimicrobial activity; unfortunately, its efflux through multidrug resistance pumps reduces its efficacy. Cellular life span of Escherichia coli is generally shorter with prolonged berberine exposure; nevertheless, about 30% of the cells still remain robust following this treatment. To elucidate its mechanism of action and to identify proteins that could be involved in development of antimicrobial resistance, protein profiles of E. coli cells treated with berberine for 4...
November 17, 2016: Microbial Drug Resistance: MDR: Mechanisms, Epidemiology, and Disease
https://www.readbyqxmd.com/read/27836448/multilocus-amplicon-sequencing-of-pseudomonas-aeruginosa-cystic-fibrosis-airways-isolates-collected-prior-to-and-after-early-antipseudomonal-chemotherapy
#18
Sebastian Fischer, Leonie Greipel, Jens Klockgether, Marie Dorda, Lutz Wiehlmann, Nina Cramer, Burkhard Tümmler
BACKGROUND: Early antimicrobial chemotherapy can prevent or at least delay chronic cystic fibrosis (CF) airways infections with Pseudomonas aeruginosa. METHODS: During a 10-year study period P. aeruginosa was detected for the first time in 54 CF patients regularly seen at the CF centre Hannover. Amplicon sequencing of 34 loci of the P. aeruginosa core genome was performed in baseline and post-treatment isolates of the 15 CF patients who had remained P. aeruginosa - positive after the first round of antipseudomonal chemotherapy...
November 8, 2016: Journal of Cystic Fibrosis: Official Journal of the European Cystic Fibrosis Society
https://www.readbyqxmd.com/read/27834373/in-vivo-protein-interaction-network-analysis-reveals-porin-localized-antibiotic-inactivation-in-acinetobacter-baumannii-strain-ab5075
#19
Xia Wu, Juan D Chavez, Devin K Schweppe, Chunxiang Zheng, Chad R Weisbrod, Jimmy K Eng, Ananya Murali, Samuel A Lee, Elizabeth Ramage, Larry A Gallagher, Hemantha D Kulasekara, Mauna E Edrozo, Cassandra N Kamischke, Mitchell J Brittnacher, Samuel I Miller, Pradeep K Singh, Colin Manoil, James E Bruce
The nosocomial pathogen Acinetobacter baumannii is a frequent cause of hospital-acquired infections worldwide and is a challenge for treatment due to its evolved resistance to antibiotics, including carbapenems. Here, to gain insight on A. baumannii antibiotic resistance mechanisms, we analyse the protein interaction network of a multidrug-resistant A. baumannii clinical strain (AB5075). Using in vivo chemical cross-linking and mass spectrometry, we identify 2,068 non-redundant cross-linked peptide pairs containing 245 intra- and 398 inter-molecular interactions...
November 11, 2016: Nature Communications
https://www.readbyqxmd.com/read/27817033/modulation-of-the-reactivity-of-multiheme-cytochromes-by-site-directed-mutagenesis-moving-towards-the-optimization-of-microbial-electrochemical-technologies
#20
Alexandra S Alves, Nazua L Costa, Ming Tien, Ricardo O Louro, Catarina M Paquete
Dissimilatory metal-reducing bacteria perform extracellular electron transfer, a metabolic trait that is at the core of a wide range of biotechnological applications. To better understand how these microorganisms transfer electrons from their metabolism to an extracellular electron acceptor, it is necessary to characterize in detail the key players in this process, the multiheme c-type cytochromes. Shewanella oneidensis MR-1 is a model organism for studying extracellular electron transfer, where the heme protein referred to as small tetraheme cytochrome is one of the most abundant multiheme cytochromes found in the periplasmic space of this bacterium...
January 2017: Journal of Biological Inorganic Chemistry: JBIC
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