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https://www.readbyqxmd.com/read/28797211/disulfide-bonds-a-key-modification-in-bacterial-extracytoplasmic-proteins
#1
S F Lee, L Davey
Disulfide bonds are a common posttranslational modification that contributes to the folding and stability of extracytoplasmic proteins. Almost all organisms, from eukaryotes to prokaryotes, have evolved enzymes to make and break these bonds. Accurate and efficient disulfide bond formation can be vital for protein function; therefore, the enzymes that catalyze disulfide bond formation are involved in multiple biological processes. Recent advances clearly show that oral bacteria also have the ability to from disulfide bonds, and this ability has an effect on a range of dental plaque-related phenotypes...
August 1, 2017: Journal of Dental Research
https://www.readbyqxmd.com/read/28765557/the-voltage-dependent-anion-channels-vdac-of-mycobacterium-avium-phagosome-are-associated-with-bacterial-survival-and-lipid-export-in-macrophages
#2
Lia Danelishvili, Jessica J J Chinison, Tuan Pham, Rashmi Gupta, Luiz E Bermudez
Mycobacterium avium subsp. hominissuis is associated with infection of immunocompromised individuals as well as patients with chronic lung disease. M. avium infects macrophages and actively interfere with the host killing machinery such as apoptosis and autophagy. Bacteria alter the normal endosomal trafficking, prevent the maturation of phagosomes and modify many signaling pathways inside of the macrophage by secreting effector molecules into the cytoplasm. To investigate whether M. avium needs to attach to the internal surface of the vacuole membrane before releasing efferent molecules, vacuole membrane proteins were purified and binding to the surface molecules present in intracellular bacteria was evaluated...
August 1, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28760827/copper-homeostasis-networks-in-the-bacterium-pseudomonas-aeruginosa
#3
Julia Quintana, Lorena Novoa-Aponte, José M Argüello
Bacterial copper (Cu(+)) homeostasis enables both precise metallation of diverse cuproproteins and control of variable metal levels. To this end, protein networks mobilize Cu(+) to cellular targets with remarkable specificity. However, the understanding of these processes is rather fragmented. Here, we use genome-wide transcriptomic analysis by RNA-Seq to characterize the response of Pseudomonas aeruginosa to external 0.5 mM CuSO4, a condition that did not generate pleiotropic effects. Pre-steady (5 min) and steady state (2 h) Cu(+) fluxes, resulted in distinct transcriptome landscapes...
July 31, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28758649/evidence-for-differentiated-ionic-and-surface-contact-effects-driving-bacterial-inactivation-by-way-of-genetically-modified-bacteria
#4
Sami Rtimi, Victor Nadtochenko, Inessa Khmel, John Kiwi
New evidence is presented for the bacterial inactivation of E. coli presenting normal porins on sputtered Ag-Cu surfaces compared with similar E. coli porinless bacteria. Inactivation at a reduced rate was observed on the genetically modified porinless bacteria interacting via surface contact with metal/oxides without the intervention of metal-ions.
July 31, 2017: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/28751669/in-vivo-loss-of-carbapenem-resistance-by-extensively-drug-resistant-klebsiella-pneumoniae-during-treatment-via-porin-expression-modification
#5
Suzanne Bialek-Davenet, Noémie Mayer, Julia Vergalli, Marion Duprilot, Sylvain Brisse, Jean-Marie Pagès, Marie-Hélène Nicolas-Chanoine
Klebsiella pneumoniae, an Enterobacteriaceae that mostly causes hospital-acquired infections, belongs to the recently published WHO's list of antibiotic-resistant pathogens that pose the greatest threat to human health. Indeed, K. pneumoniae is the enterobacterial species most concerned by both resistance to extended-spectrum cephalosporins, due to extended-spectrum β-lactamase (ESBL) production, and resistance to carbapenems, i.e. the β-lactams with the broadest activity. Carbapenem resistance is related not only to carbapenemase production, but also the production of ESBL or AmpC and the loss of general porins...
July 27, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28750163/salt-gradient-modulation-of-microrna-translocation-through-a-biological-nanopore
#6
Josip Ivica, Philip T F Williamson, Maurits R R de Planque
In resistive pulse sensing of microRNA biomarkers, selectivity is achieved with polynucleotide-extended DNA probes, with the unzipping of a miRNA-DNA duplex in the nanopore recorded as a resistive current pulse. As the assay sensitivity is determined by the pulse frequency, we investigated the effect of cis/trans electrolyte concentration gradients applied over α-hemolysin nanopores. KCl gradients were found to exponentially increase the pulse frequency, while reducing the preference for 3'-first pore entry of the duplex and accelerating duplex unzipping, all manifestations of an enhanced electrophoretic force...
August 11, 2017: Analytical Chemistry
https://www.readbyqxmd.com/read/28749972/investigating-asymmetric-salt-profiles-for-nanopore-dna-sequencing-with-biological-porin-mspa
#7
Ian C Nova, Ian M Derrington, Jonathan M Craig, Matthew T Noakes, Benjamin I Tickman, Kenji Doering, Hugh Higinbotham, Andrew H Laszlo, Jens H Gundlach
Nanopore DNA sequencing is a promising single-molecule analysis technology. This technique relies on a DNA motor enzyme to control movement of DNA precisely through a nanopore. Specific experimental buffer conditions are required based on the preferred operating conditions of the DNA motor enzyme. While many DNA motor enzymes typically operate in salt concentrations under 100 mM, salt concentration simultaneously affects signal and noise magnitude as well as DNA capture rate in nanopore sequencing, limiting standard experimental conditions to salt concentrations greater than ~100 mM in order to maintain adequate resolution and experimental throughput...
2017: PloS One
https://www.readbyqxmd.com/read/28741465/engineering-of-chimeric-protein-based-on-e-protein-domain-iii-of-tick-borne-encephalitis-virus-and-ompf-porin-of-yersinia-pseudotuberculosis
#8
Anna M Stenkova, Natalia S Chopenko, Ludmila A Davydova, Andrey N Mazeika, Evgeniya P Bystritskaya, Olga Y Portnyagina, Stanislav D Anastyuk, Dmitrii S Kulbatskii, Ekaterina N Lyukmanova, Dmitriy A Dolgikh, Eduard Y Kostetsky, Nina M Sanina
Tick-borne encephalitis poses a serious public health threat in the endemic regions. The disease treatment is restricted to symptomatic therapy, so great expectations are in the development of the prophylactic and therapeutic vaccines. The domain III of E protein of the tick-borne encephalitis virus is the main antigenic domain which includes virus-specific epitopes recognized by neutralizing antibodies. We have expressed, isolated and characterized the chimeric protein based on the fusion of domain III of E protein of the tick-borne encephalitis virus and bacterial porin OmpF from Yersinia pseudotuberculosis...
July 24, 2017: Protein and Peptide Letters
https://www.readbyqxmd.com/read/28739787/resistance-to-ceftazidime-avibactam-is-due-to-transposition-of-kpc-in-a-porin-deficient-strain-of-klebsiella-pneumoniae-with-increased-efflux-activity
#9
Kirk Nelson, Peera Hemarajata, Dongxu Sun, Debora Rubio-Aparicio, Ruslan Tsivkovski, Shangxin Yang, Robert Sebra, Andrew Kasarskis, Hoan Nguyen, Blake M Hanson, Shana Leopold, George Weinstock, Olga Lomovskaya, Romney M Humphries
Ceftazidime-avibactam is an antibiotic with activity against serine beta-lactamases, including KPC. Recently, reports have emerged of KPC-producing isolates resistant to this antibiotic, including a report of a wild-type KPC-3 producing sequence type 258 Klebsiella pneumoniae that was resistant to ceftazidime-avibactam. We describe a detailed analysis of this isolate, in the context of two other closely related KPC-3 producing isolates, recovered from the same patient. Both isolates encoded a non-functional OmpK35, whereas we demonstrate a novel T333N mutation in OmpK36, present in the ceftazidime-avibactam resistant isolate, reduced activity of this porin and impacted ceftazidime-avibactam susceptibility...
July 24, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28731269/biofilm-formation-and-antibiotic-resistance-in-klebsiella-pneumoniae-urinary-strains
#10
Claudia Vuotto, Francesca Longo, Chiara Pascolini, Gianfranco Donelli, Maria Pia Balice, Maria Francesca Libori, Valentina Tiracchia, Antonino Salvia, Pietro Emanuele Varaldo
AIMS: Multi-drug resistant Klebsiella pneumoniae has become a relevant healthcare-associated pathogen. Capsule, type 1 and 3 fimbriae (mrkA gene), type 2 quorum-sensing system (luxS), synthesis of D-galactan I (wbbM), LPS transport (wzm) and poly-beta-1,6-N-acetyl-D-glucosamine (pgaA) seem involved in K. pneumoniae biofilm. Non-enzymatic antibiotic resistance is related to non-expression or mutation of porins (OmpK35 and OmpK36), and efflux pump (acrB) over-expression. The aim of this study was to analyse some virulence factors of K...
July 21, 2017: Journal of Applied Microbiology
https://www.readbyqxmd.com/read/28729124/trends-in-antimicrobial-resistance-in-neisseria-gonorrhoeae-and-molecular-characteristics-of-neisseria-gonorrhoeae-with-decreased-susceptibility-to-ceftriaxone-in-shandong-china-2007-to-2014
#11
Lihong Zhao, Aihua Liu, Ruiying Li, Shuping Zhao
In this study, the trends of AMR in N. gonorrhoeae were analyzed in Shandong Province of China during 2007-2014. Moreover, the ceftriaxone genetic resistance determinants including penA, mtrR, penB, ponA, and pilQ genes were sequenced, and the molecular mechanisms of decreased susceptibility or resistance to ceftriaxone in N. gonorrhoeae were elucidated. Overall, the increasing trends of resistance to PEN, TET, and CIP, and decreasing trends of susceptibility to CRO and AZM were observed in Shandong Province of China between 2007 and 2014...
July 17, 2017: International Journal of Antimicrobial Agents
https://www.readbyqxmd.com/read/28726924/peculiarities-of-thermal-denaturation-of-ompf-porin-from-yersinia-ruckeri
#12
Olga D Novikova, Dmitry K Chistyulin, Valentina A Khomenko, Evgeny V Sidorin, Natalya Yu Kim, Nina M Sanina, Olga Yu Portnyagina, Tamara F Solov'eva, Vladimir N Uversky, Valery L Shnyrov
Irreversible denaturation of membrane proteins in detergent solutions is similar to unfolding of water-soluble multidomain proteins and represents a complex, multistage process. Pore-forming proteins of Gram-negative bacteria are heat-modifiable proteins, i.e., proteins altering their molecular forms (trimers or monomers), and accordingly, their electrophoretic mobilities depending upon denaturation conditions. There are still some contradictory data on the peculiarities of the conformational changes in the porin structure with temperature...
July 20, 2017: Molecular BioSystems
https://www.readbyqxmd.com/read/28723607/production-of-recombinant-porin-from-y-pseudotuberculosis-in-a-water-soluble-form-for-pseudotuberculosis-diagnostics
#13
Vasily A Golotin, Olga Y Portnyagina, Natalia S Chopenko, Natalia Y Kim, Valery A Rasskazov, Olga D Novikova
OmpF porin from the outer membrane of Yersinia pseudotuberculosis was cloned into pET-40b(+) plasmid. Using E. coli Rosetta (DE3) strain, MX-medium, IPTG concentration of 0.2 mM and post-induction cultivation at 14 °C overnight allowed us to obtain a water-soluble form of the recombinant protein (rs-OmpF). Rs-OmpF was shown to have the ordered spatial structure at the levels of secondary and tertiary structure. Rs-OmpF was found to be effective as diagnostic antigen in ELISA for pseudotuberculosis diagnostics...
July 26, 2017: Biological Chemistry
https://www.readbyqxmd.com/read/28717993/probing-the-binding-affinities-of-imipenem-and-ertapenem-for-outer-membrane-carboxylate-channel-d1-occd1-from-p-aeruginosa-simulation-studies
#14
Kamolrat Somboon, Jitti Niramitranon, Prapasiri Pongprayoon
Pseudomonas aeruginosa is an important nosocomial human pathogen. The major difficulty in the fight against this pathogen is the relative impermeability of its outer membrane (OM). Only specific substrates can penetrate through the OM of P. aeruginosa via substrate-specific porins, so this has become one of the most problematic drug-resistant pathogens. Carbapenems are the most effective drugs for treating P. aeruginosa infections. One such carbapenem that is applied in cases of P. aeruginosa infection is imipenem (IMI), which uses outer membrane carboxylate channel D1 (OccD1) as a point of entry into the pathogen...
August 2017: Journal of Molecular Modeling
https://www.readbyqxmd.com/read/28713357/extensively-drug-resistant-klebsiella-pneumoniae-causing-nosocomial-bloodstream-infections-in-china-molecular-investigation-of-antibiotic-resistance-determinants-informing-therapy-and-clinical-outcomes
#15
Wenzi Bi, Haiyang Liu, Rhys A Dunstan, Bin Li, Von Vergel L Torres, Jianming Cao, Lijiang Chen, Jonathan J Wilksch, Richard A Strugnell, Trevor Lithgow, Tieli Zhou
The rise in diversity of antimicrobial resistance phenotypes seen in Klebsiella pneumoniae is becoming a serious antibiotic management problem. We sought to investigate the molecular characteristics and clinical implications of extensively drug-resistant (XDR) K. pneumoniae isolated from different nosocomial bloodstream infections (BSIs) patients from July 2013 to November 2015. Even in combination treatment, meropenem did not protect against mortality of BSIs patients (P = 0.015). In contrast, tigecycline in combination with other antimicrobial agents significantly protected against mortality (P = 0...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28713335/a-novel-regulatory-cascade-involving-blur-ycgz-and-lon-controls-the-expression-of-escherichia-coli-ompf-porin
#16
Valérie Duval, Kimberly Foster, Jennifer Brewster, Stuart B Levy
In Escherichia coli, OmpF is an important outer membrane protein, which serves as a passive diffusion pore for small compounds including nutrients, antibiotics, and toxic compounds. OmpF expression responds to environmental changes such as temperature, osmolarity, nutrients availability, and toxic compounds via complex regulatory pathways involving transcriptional and post-transcriptional regulation. Our study identified a new regulatory cascade that controls the expression of OmpF porin. This pathway involves BluR, a transcriptional regulator repressing the expression of the ycgZ-ymgABC operon...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28708335/heterogeneity-in-non-epitope-loop-sequence-and-outer-membrane-protein-complexes-alters-antibody-binding-to-the-major-porin-protein-porb-in-serogroup-b-neisseria-meningitidis
#17
Kathryn A Matthias, Michael Brad Strader, Hesham F Nawar, Yamei S Gao, Joonseong Lee, Dhilon S Patel, Wonpil Im, Margaret C Bash
PorB is a well-characterized outer membrane protein that is common among Neisseria species and is required for survival. A vaccine candidate, PorB induces antibody responses that are directed against six variable surface-exposed loops that differ in sequence depending on serotype. Although N. meningitidis is naturally competent and porB genetic mosaicism provides evidence for strong positive selection, the sequences of PorB serotypes commonly associated with invasive disease are often conserved, calling into question the interaction of specific PorB loop sequences in immune engagement...
July 14, 2017: Molecular Microbiology
https://www.readbyqxmd.com/read/28696278/outer-membrane-permeability-of-cyanobacterium-synechocystis-sp-pcc-6803-studies-of-passive-diffusion-of-small-organic-nutrients-reveal-the-absence-of-classical-porins-and-intrinsically-low-permeability
#18
Hikaru Kowata, Saeko Tochigi, Hideyuki Takahashi, Seiji Kojima
The outer membrane of heterotrophic Gram-negative bacteria plays a role of selective permeability barrier that prevents the influx of toxic compounds, while allowing the non-specific passage of small, hydrophilic nutrients through porin channels. Compared with the heterotrophic Gram-negative bacteria, the outer membrane properties of cyanobacteria, the Gram-negative photoautotrophs, are not clearly understood. In this study, using small carbohydrates, amino acids, and inorganic ions as permeation probes, we determined the outer membrane permeability of Synechocystis sp...
July 10, 2017: Journal of Bacteriology
https://www.readbyqxmd.com/read/28693438/evaluation-of-recombinant-porin-romp2a-protein-as-a-potential-antigen-candidate-for-serodiagnosis-of-human-brucellosis
#19
Prachi Pathak, Ashu Kumar, Duraipandian Thavaselvam
BACKGROUND: Brucellosis is an important zoonotic disease caused by different Brucella species and human brucellosis is commonly prevalent in different states of India. Among various Brucella species, B. melitensis is most pathogenic to human and included as category B biothreat which can cause infection through aerosol, cut, wounds in skin and contact with infected animals. The diagnosis of human brucellosis is very important for proper treatment and management of disease as there is no vaccine available for human use...
July 11, 2017: BMC Infectious Diseases
https://www.readbyqxmd.com/read/28693313/comparative-proteomic-analysis-of-the-outer-membrane-protein-43-omp43-deficient-bartonella-henselae
#20
Jun-Gu Kang, Hee-Woo Lee, Sungjin Ko, Joon-Seok Chae
Outer membrane proteins (OMPs) of gram-negative bacteria constitute the first line of defense that protects the cells against environmental stresses including chemical, biophysical, and biological attacks. Although 43-kDa outer membrane protein (OMP43) is major porin protein among the Bartonella henselae-derived OMPs, its function remains unknown. In this study, OMP43-deficient mutant B. henselae (Δomp43) was generated to investigate function of OMP43. Interestingly, Δomp43 showed a weaker proliferative ability compared to wild type (WT) of B...
July 10, 2017: Journal of Veterinary Science
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