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https://www.readbyqxmd.com/read/28199365/click-chemistry-approach-to-study-mycoloylated-proteins-evidence-for-porb-and-porc-porins-mycoloylation-in-corynebacterium-glutamicum
#1
Hanane Issa, Emilie Huc-Claustre, Thamila Reddad, Nolwenn Bonadé Bottino, Maryelle Tropis, Christine Houssin, Mamadou Daffé, Nicolas Bayan, Nathalie Dautin
Protein mycoloylation is a recently identified, new form of protein acylation. This post-translational modification consists in the covalent attachment of mycolic acids residues to serine. Mycolic acids are long chain, α-branched, β-hydroxylated fatty acids that are exclusively found in the cell envelope of Corynebacteriales, a bacterial order that includes important genera such as Mycobacterium, Nocardia or Corynebacterium. So far, only 3 mycoloylated proteins have been identified: PorA, PorH and ProtX from C...
2017: PloS One
https://www.readbyqxmd.com/read/28198105/antibiotic-dependent-perturbations-of-extended-spectrum-beta-lactamase-producing-klebsiella-pneumoniae-proteome
#2
Moo-Jin Suh, Sarah L Keasey, Ernst E Brueggemann, Robert G Ulrich
Extended spectrum beta-lactamase producing Klebsiella pneumoniae (ESBL-KP) causes life-threatening infections in susceptible and immuno-compromised individuals. Because of the emergence of multidrug resistance and tolerance, it is crucial to better understand the mechanisms by which ESBL-KP can adapt to antibiotic stress. The aim of this study was to provide an overview of the global proteome changes occurring in ESBL-KP in response to sub-lethal concentrations of the antibiotics doxycycline (DC, bacteriostatic) and streptomycin (SM, bactericidal), which both impair ribosomal synthesis of bacterial proteins...
February 15, 2017: Proteomics
https://www.readbyqxmd.com/read/28177769/a-deletion-variant-partially-complements-a-porin-less-strain-of-i-neurospora-crassa-i
#3
Fraser G Ferens, Victor Spicer, Oleg V Krokhin, Anna Motnenko, William A T Summers, Deborah A Court
Mitochondrial porin, the voltage-dependent anion channel, plays an important role in metabolism and other cellular functions within eukaryotic cells. To further the understanding of porin structure and function, <i>Neurospora crassa</i> wild-type porin was replaced with a deletion variant lacking residues 238-242 (238porin). 238porin was assembled in the mitochondrial outer membrane, but the steady state levels were only about 3% of those of the wild-type protein. The strain harbouring 238porin displayed cytochrome deficiencies and expressed alternative oxidase...
November 2, 2016: Biochemistry and Cell Biology, Biochimie et Biologie Cellulaire
https://www.readbyqxmd.com/read/28157293/a-whole-cell-based-assay-to-evaluate-structure-permeation-relationships-for-carbapenem-passage-through-the-pseudomonas-aeruginosa-porin-oprd
#4
Ramkumar Iyer, Mark A Sylvester, Camilo Velez-Vega, Ruben Tommasi, Thomas F Durand-Reville, Alita A Miller
The global emergence of antibiotic resistance, especially in Gram-negative bacteria, is an urgent threat to public health. Discovery of novel classes of antibiotics with activity against these pathogens has been impeded by a fundamental lack of understanding of the molecular drivers underlying small molecule uptake. Although it is well-known that outer membrane porins represent the main route of entry for small, hydrophilic molecules across the Gram-negative cell envelope, the structure-permeation relationship for porin passage has yet to be defined...
February 3, 2017: ACS Infectious Diseases
https://www.readbyqxmd.com/read/28155846/rationalizing-the-permeation-of-polar-antibiotics-into-gram-negative-bacteria
#5
Mariano Andrea Scorciapino, Silvia Acosta-Gutierrez, Dehbia Benkerrou, Tommaso D'Agostino, Giuliano Malloci, Susruta Samanta, Igor Bodrenko, Matteo Ceccarelli
The increasing level of antibiotic resistance in Gram-negative bacteria, together with the lack of new potential drug scaffolds in the pipeline, make the problem of infectious diseases a global challenge for modern medicine. The main reason that Gram-negative bacteria are particularly challenging is the presence of an outer cell-protecting membrane, which is not present in Gram-positive species. Such an asymmetric bilayer is a highly effective barrier for polar molecules. Several protein systems are expressed in the outer membrane to control the internal concentration of both nutrients and noxious species, in particular: (i) water-filled channels that modulate the permeation of polar molecules and ions according to concentration gradients, and (ii) efflux pumps to actively expel toxic compounds...
March 22, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
https://www.readbyqxmd.com/read/28137507/construction-and-evaluation-of-an-edwardsiella-tarda-dna-vaccine-encoding-outer-membrane-protein-c
#6
Fuguo Liu, Xiaoqian Tang, Xiuzhen Sheng, Jing Xing, Wenbin Zhan
Outer membrane protein C is a porin that resides in the outer membrane, and it has been identified as an antigenic protein in many bacteria, such as Escherichia coli, Salmonella typhi, Aeromonas hydrophila and Edwardsiella tarda. In the present work, we aimed at evaluating the immune protective potential of E. tarda OmpC as a DNA vaccine. For this purpose, a recombinant DNA plasmid encoding OmpC (pCG-OmpC) gene was constructed and its vaccine potential was analyzed in a flounder (Paralichthys olivaceus) model...
January 27, 2017: Microbial Pathogenesis
https://www.readbyqxmd.com/read/28133574/panel-strain-of-klebsiella-pneumoniae-for-beta-lactam-antibiotic-evaluation-their-phenotypic-and-genotypic-characterization
#7
Roshan Dsouza, Naina Adren Pinto, InSik Hwang, YoungLag Cho, Dongeun Yong, Jongrak Choi, Kyungwon Lee, Yunsop Chong
Klebsiella pneumoniae is responsible for numerous infections caused in hospitals, leading to mortality and morbidity. It has been evolving as a multi-drug resistant pathogen, acquiring multiple resistances such as such as horizontal gene transfer, transposon-mediated insertions or change in outer membrane permeability. Therefore, constant efforts are being carried out to control the infections using various antibiotic therapies. Considering the severity of the acquired resistance, we developed a panel of strains of K...
2017: PeerJ
https://www.readbyqxmd.com/read/28128097/high-level-resistance-to-meropenem-in-clinical-isolates-of-pseudomonas-aeruginosa-in-the-absence-of-carbapenemases-role-of-active-efflux-and-porin-alterations
#8
Hussein Chalhoub, Yolanda Sáenz, Hector Rodriguez-Villalobos, Olivier Denis, Barbara C Kahl, Paul M Tulkens, Françoise Van Bambeke
High-level carbapenem resistance is worryingly increasing in clinical isolates and is often attributed to carbapenemase expression. This study aimed to determine the mechanisms leading to high-level meropenem resistance in six carbapenemase-negative Pseudomonas aeruginosa isolated from cystic fibrosis (CF) patients and seven carbapenemase-positive isolates from patients suffering from hospital-acquired pneumonia (HAP). MICs were determined in the absence or presence of l-arginine or glycine-glutamate as competitive substrates for OprD (OccD1) or OpdP (OccD3), respectively, or the efflux pump inhibitor Phe-Arg β-naphthylamide (PAβN)...
December 2016: International Journal of Antimicrobial Agents
https://www.readbyqxmd.com/read/28119484/overproduction-of-outer-membrane-protein-a-ompa-by-acinetobacter-baumannii-is-a-risk-factor-for-nosocomial-pneumonia-bacteremia-and-mortality-increase
#9
Viviana Sánchez-Encinales, Rocío Álvarez-Marín, María Eugenia Pachón-Ibáñez, Felipe Fernández-Cuenca, Alvaro Pascual, José Garnacho-Montero, Luis Martínez-Martínez, Jordi Vila, María Mar Tomás, José Miguel Cisneros, Germán Bou, Jesús Rodríguez-Baño, Jerónimo Pachón, Younes Smani
BACKGROUND: OmpA is a porin involved in Acinetobacter baumannii pathogenesis. However, OmpA clinical implication in hospital-acquired infections remains unknown. We aimed to determine whether OmpA overproduction was a risk factor associated with pneumonia, bacteremia, and mortalilty. METHODS: Demographic, microbiological and clinical data from 100 and 246 patients included, respectively, in a unicenter cohort (UC) and a multicenter cohort (MC) were analyzed. Representative isolates were classified in two groups: i-16 UC and 20 MC isolates from colonized patients (CP) by A...
January 24, 2017: Journal of Infectious Diseases
https://www.readbyqxmd.com/read/28094462/orientation-of-the-ompf-porin-in-planar-lipid-bilayers
#10
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
#11
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
#12
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
#13
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
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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...
January 2017: 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
#20
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
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