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https://www.readbyqxmd.com/read/29094406/liprotides-assist-in-folding-of-outer-membrane-proteins
#1
Jannik Nedergaard Pedersen, Jan Skov Pedersen, Daniel E Otzen
Proteins and lipids can form complexes called liprotides, in which the partially denatured protein forms a shell encasing a lipid core. This effectively stabilizes a lipid micelle in an aqueous solvent and suggests that liprotides may provide a suitable vessel for membrane proteins. Accordingly we have investigated if liprotides consisting of α-lactalbumin and oleate could aid folding of four different outer membrane proteins (OMPs) tOmpA, PagP, BamA and OmpF. tOmpA was able to fold in the presence of the liprotide, and folding did not occur if only oleate or α-lactalbumin were added...
November 1, 2017: Protein Science: a Publication of the Protein Society
https://www.readbyqxmd.com/read/29079441/in-silico-and-in-vitro-analysis-of-cross-reactivity-between-yersinia-pseudotuberculosis-ompf-porin-and-thyroid-stimulating-hormone-receptor
#2
Olga Portnyagina, Elena Zelepuga, Valentina Khomenko, Elena Solov'eva, Tamara Solov'eva, Olga Novikova
This work is devoted to the ascertainment of serological cross-reactivity between OmpF porin from Yersinia pseudotuberculosis (YpOmpF) and human thyroid-stimulating hormone receptor (hTSHR). Extracts containing hTSHR were isolated from surgical thyroid tissue of patients with clinical and diagnostic signs of diffuse toxic goiter. Monoclonal antibodies to hTSHR (mAbs) were shown to interact both with antigens in thyroid tissue extracts and with YpOmpF. Models of spatial structures of trimer and monomer complexes of YpOmpF with antibodies to hTSHR were also constructed...
October 24, 2017: International Journal of Biological Macromolecules
https://www.readbyqxmd.com/read/29055550/the-phylogenetic-group-antimicrobial-susceptibility-and-virulence-genes-of-escherichia-coli-from-clinical-bovine-mastitis
#3
Dexian Zhang, Zehui Zhang, Chengcheng Huang, Xiang Gao, Zhuang Wang, Yaochuan Liu, Chunlian Tian, Wei Hong, Shengli Niu, Mingchun Liu
Bovine mastitis is still a central problem on dairy farms despite control programs, and Escherichia coli is a crucial pathogen during the development of bovine mastitis. The virulence genes, antimicrobial susceptibility, and mortality of mice infected with different E. coli isolates from bovine mastitis were determined in this study. According to the presence of the specific genes chuA, yjaA, and TspE4.C2, these isolates mainly belonged to 2 different groups: group A (47/79) and group B1 (22/79). The ompC gene was detected in all the isolates, followed by fimH (89...
October 18, 2017: Journal of Dairy Science
https://www.readbyqxmd.com/read/29045862/the-two-state-prehensile-tail-of-the-antibacterial-toxin-colicin-n
#4
Christopher L Johnson, Alexandra S Solovyova, Olli Hecht, Colin Macdonald, Helen Waller, J Günter Grossmann, Geoffrey R Moore, Jeremy H Lakey
Intrinsically disordered regions within proteins are critical elements in many biomolecular interactions and signaling pathways. Antibacterial toxins of the colicin family, which could provide new antibiotic functions against resistant bacteria, contain disordered N-terminal translocation domains (T-domains) that are essential for receptor binding and the penetration of the Escherichia coli outer membrane. Here we investigate the conformational behavior of the T-domain of colicin N (ColN-T) to understand why such domains are widespread in toxins that target Gram-negative bacteria...
October 17, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/29038444/structural-basis-for-maintenance-of-bacterial-outer-membrane-lipid-asymmetry
#5
Javier Abellón-Ruiz, Shreyas S Kaptan, Arnaud Baslé, Beatrice Claudi, Dirk Bumann, Ulrich Kleinekathöfer, Bert van den Berg
The Gram-negative bacterial outer membrane (OM) is a unique bilayer that forms an efficient permeation barrier to protect the cell from noxious compounds (1)(,)(2) . The defining characteristic of the OM is lipid asymmetry, with phospholipids comprising the inner leaflet and lipopolysaccharides comprising the outer leaflet (1-3) . This asymmetry is maintained by the Mla pathway, a six-component system that is widespread in Gram-negative bacteria and is thought to mediate retrograde transport of misplaced phospholipids from the outer leaflet of the OM to the cytoplasmic membrane (4) ...
October 16, 2017: Nature Microbiology
https://www.readbyqxmd.com/read/28960650/carbene-footprinting-reveals-binding-interfaces-of-a-multimeric-membrane-spanning-protein
#6
Lucio Manzi, Andrew S Barrow, Jonathan T S Hopper, Renata Kaminska, Colin Kleanthous, Carol V Robinson, John E Moses, Neil J Oldham
Mapping the interaction sites between membrane-spanning proteins is a key challenge in structural biology. In this study a carbene-footprinting approach was developed and applied to identify the interfacial sites of a trimeric, integral membrane protein, OmpF, solubilised in micelles. The diazirine-based footprinting probe is effectively sequestered by, and incorporated into, the micelles, thus leading to efficient labelling of the membrane-spanning regions of the protein upon irradiation at 349 nm. Areas associated with protein-protein interactions between the trimer subunits remained unlabelled, thus revealing their location...
September 27, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28932951/structure-elucidation-and-in-silico-docking-studies-of-a-novel-furopyrimidine-antibiotics-synthesized-by-endolithic-bacterium-actinomadura-sp-al2
#7
Kaushik Bhattacharjee, Shakti Kumar, Narasinga Rao Palepu, Pradeep Kumar Patra, Kollipara Mohan Rao, Santa Ram Joshi
On screening of endolithic actinobacteria from a granite rock sample of Meghalaya for antibacterial compound, a novel antibacterial compound CCp1 was isolated from the fermentation broth of Actinomadura sp. AL2. On purification of the compound based on chromatographic techniques followed by characterization with FT-IR, UV-visible, (1)H NMR, (13)C NMR and mass spectrometry, the molecular formula of the compound was generated as C20H17N3O2, a furopyrimidine derivative. In vitro antibacterial activity of the compound was evaluated against both Gram positive and negative bacteria by agar well diffusion assay...
September 20, 2017: World Journal of Microbiology & Biotechnology
https://www.readbyqxmd.com/read/28930428/ion-transport-in-confined-geometries-below-the-nanoscale-access-resistance-dominates-protein-channel-conductance-in-diluted-solutions
#8
Antonio Alcaraz, M Lidón López, María Queralt-Martín, Vicente M Aguilella
Synthetic nanopores and mesoscopic protein channels have common traits like the importance of electrostatic interactions between the permeating ions and the nanochannel. Ion transport at the nanoscale occurs under confinement conditions so that the usual assumptions made in microfluidics are challenged, among others, by interfacial effects such as access resistance (AR). Here, we show that a sound interpretation of electrophysiological measurements in terms of channel ion selective properties requires the consideration of interfacial effects, up to the point that they dominate protein channel conductance in diluted solutions...
October 24, 2017: ACS Nano
https://www.readbyqxmd.com/read/28890516/molecular-characterization-of-non-carbapenemase-producing-escherichia-coli-clinical-isolates-with-reduced-carbapenem-susceptibility-from-a-thai-university-hospital
#9
Sawitree Nuramrum, Aroonwadee Chanawong, Kamonwan Lunha, Aroonlug Lulitanond, Arunnee Sangka, Chotechana Wilailuckana, Sunpetch Angkititrakul, Nicha Charoensri, Lumyai Wonglakorn, Prajuab Chaimanee, Ploenchan Chetchotisakd
Twelve non-replicate carbapenemase-negative ertapenem-non-susceptible (CNENS) Escherichia coli isolates from a Thai university hospital between 2010 and 2014 were characterized and compared with two carbapenemase-producing E. coli isolates from the same hospital. Eight unique PFGE patterns were obtained. All produced CTX-M-15 β-lactamase and two isolates co-expressed either CMY-2 cephalosporinase or increased efflux pump. Amino acid sequence analysis revealed that OmpF defect (seven isolates) due to mutations generating premature proteins or an IS1 insertion was more prevalent than in OmpC (no truncated proteins found)...
September 11, 2017: Japanese Journal of Infectious Diseases
https://www.readbyqxmd.com/read/28888366/lipopolysaccharides-promote-binding-and-unfolding-of-the-antibacterial-colicin-e3-rrnase-domain
#10
Allan Mills, Franck Duong
Nuclease colicins are antibacterial proteins produced by certain strains of E. coli to reduce competition from rival strains. These colicins are generally organized with an N-terminal transport (T)-domain, a central receptor binding (R)-domain, and a C-terminal cytotoxic nuclease domain. These colicins are always produced in complex with an inhibitory immunity protein, which dissociates prior entrance of the cytotoxic domain in the target cell. How exactly colicins traverse the cell envelope is not understood, yet this knowledge is important for the design of new antibacterial therapies...
December 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28887208/proteomic-comparison-of-three-clinical-diarrhoeagenic-drug-resistant-escherichia-coli-isolates-grown-on-chromagar%C3%A2-stec-media
#11
John Bosco Kalule, Suereta Fortuin, Bridget Calder, Lourens Robberts, Karen H Keddy, Andrew Nel, Shaun Garnett, Mark Nicol, Digby F Warner, Nelson C Soares, Jonathan M Blackburn
Shiga-toxin-producing Escherichia coli (STEC) and enteropathogenic Escherichia coli (EPEC) are key diarrhoea-causing foodborne pathogens. We used proteomics to characterize the virulence and antimicrobial resistance protein profiles of three clinical pathogenic E. coli isolates (two EPEC [one resistant to ciprofloxacin] and one STEC) cultured on CHROMagar™STEC solid media after minimal laboratory passage. We identified 4767 unique peptides from 1630 protein group across all three clinical E. coli strains...
September 5, 2017: Journal of Proteomics
https://www.readbyqxmd.com/read/28874380/the-global-regulatory-cyclic-amp-receptor-protein-crp-controls-multifactorial-fluoroquinolone-susceptibility-in-salmonella-enterica-serovar-typhimurium
#12
Stefani C Kary, Joshua R K Yoneda, Stephen C Olshefsky, Laura A Stewart, Steven B West, Andrew D S Cameron
Fluoroquinolone antibiotics are prescribed for the treatment of Salmonella enterica infections, but resistance to this family of antibiotics is growing. Here we report that loss of the global regulatory protein cyclic AMP (cAMP) receptor protein (CRP) or its allosteric effector, cAMP, reduces susceptibility to fluoroquinolones. A Δcrp mutation was synergistic with the primary fluoroquinolone resistance allele gyrA83, thus able to contribute to clinically relevant resistance. Decreased susceptibility to fluoroquinolones could be partly explained by decreased expression of the outer membrane porin genes ompA and ompF with a concomitant increase in the expression of the ciprofloxacin resistance efflux pump gene acrB in Δcrp cells...
November 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28818426/investigation-of-the-escherichia-coli-membrane-transporters-involved-in-the-secretion-of-d-lactate-based-oligomers-by-loss-of-function-screening
#13
Camila Utsunomia, Chiaki Hori, Ken'ichiro Matsumoto, Seiichi Taguchi
d-Lactate (LA)-based oligomers (D-LAOs) are unusual oligoesters consisting of d-LA and d-3-hydroxybutyrate that are produced and secreted by engineered Escherichia coli grown on glucose. The cells heterologously express LA-polymerizing polyhydroxyalkanoate synthase and monomer-supplying enzymes. In this study, we attempted to identify the D-LAO secretion route in E. coli, which is thought to be mediated by intrinsic membrane proteins. To this end, a loss-of-function screening of D-LAO secretion was carried out using 209 single-gene membrane protein deletants, which are involved in the transport of organic compounds...
August 14, 2017: Journal of Bioscience and Bioengineering
https://www.readbyqxmd.com/read/28752705/-bacterial-outer-membrane-vesicles-as-nano-carriers-to-study-immunological-activities
#14
Chen Qi, W U Min, Bai Hongzhen, Guo Zeling, Zhou Jun, Wang Qingqing, Tang Guping
Objective: To prepare a nano-carrier based on combining bacterial outer membrane vesicles (OMV) with three block polymer pluronic F127 (PEO100-PPO65-PEO100) (OMV-F127) and to investigate its immunological activity. Methods: Attenuated salmonella (sal) was cultivated. OMV were separated by centrifugal ultrafiltration or ultrasonication, and OMV-F127 was prepared by mechanical extrudation method. The protein contents and compositions were tested with BCA and SDS-PAGE; the morphology of OMV, F127 and OMV-F127 were observed with FM and TEM; the particle sizes and their zeta potential were determined with DLS...
March 25, 2017: Zhejiang da Xue Xue Bao. Yi Xue Ban, Journal of Zhejiang University. Medical Sciences
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
#15
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/28730802/sensing-single-molecule-penetration-into-nanopores-pushing-the-time-resolution-to-the-diffusion-limit
#16
Igor V Bodrenko, Jiajun Wang, Samuele Salis, Mathias Winterhalter, Matteo Ceccarelli
To quantify small molecule penetration into and eventually permeation through nanopores, we applied an improved excess-noise analysis of the ion current fluctuation caused by entering molecules. The kinetic parameters of substrate entry and exit are derived from a two-state Markov model, analyzing the substrate concentration dependence of the average ion current and its variance. Including filter corrections allows one to detect the transition rates beyond the cutoff frequency, fc, of the instrumental ion-current filter...
August 25, 2017: ACS Sensors
https://www.readbyqxmd.com/read/28728309/escherichia-coli-outer-membrane-protein-f-ompf-an-immunogenic-protein-induces-cross-reactive-antibodies-against-escherichia-coli-and-shigella
#17
Xiao Wang, Da Teng, Qingfeng Guan, Ruoyu Mao, Ya Hao, Xiumin Wang, Junhu Yao, Jianhua Wang
Diarrhea caused by pathogenic Escherichia coli (E. coli) is one of the most serious infectious diseases in humans and animals. Due to antibiotics resistance and the lack of efficient vaccine, more attention should be paid to find potential versatile vaccine candidates to prevent diseases. In this study, the sequence homology analysis indicated that OmpF from E. coli CVCC 1515 shares a high identity (90-100%) with about half of the E. coli (46.7%) and Shigella (52.8%) strains. Then the recombinant OmpF was supposed to be developed as a versatile vaccine to prevent E...
December 2017: AMB Express
https://www.readbyqxmd.com/read/28726924/peculiarities-of-thermal-denaturation-of-ompf-porin-from-yersinia-ruckeri
#18
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...
August 22, 2017: Molecular BioSystems
https://www.readbyqxmd.com/read/28723607/production-of-recombinant-porin-from-y-pseudotuberculosis-in-a-water-soluble-form-for-pseudotuberculosis-diagnostics
#19
Vasily Golotin, Olga Portnyagina, Natalia Chopenko, Natalia Kim, Valery Rasskazov, Olga 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...
October 26, 2017: Biological Chemistry
https://www.readbyqxmd.com/read/28713335/a-novel-regulatory-cascade-involving-blur-ycgz-and-lon-controls-the-expression-of-escherichia-coli-ompf-porin
#20
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
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