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https://www.readbyqxmd.com/read/29306652/influence-of-the-surrounding-environment-in-re-naturalized-%C3%AE-barrel-membrane-proteins
#1
Maximilien Lopes-Rodrigues, Jordi Triguero, Juan Torras, Eric A Perpète, Catherine Michaux, David Zanuy, Carlos Alemán
Outer-membrane porins are currently being used to prepare bioinspired nanomembranes for selective ion transport by immobilizing them into polymeric matrices. However, the fabrication of these protein-integrated devices has been found to be strongly influenced by the instability of the β-barrel porin structure, which depends on surrounding environment. In this work, molecular dynamics simulations have been used to investigate the structural stability of a representative porin, OmpF, in three different environments: (i) aqueous solution at pH=7; (ii) a solution of neutral detergent in a concentration similar to the critical micelle concentration; and (iii) the protein embedded into a neutral detergent bilayer...
January 2, 2018: Biophysical Chemistry
https://www.readbyqxmd.com/read/29232619/engineering-of-protein-nanopores-for-sequencing-chemical-or-protein-sensing-and-disease-diagnosis
#2
REVIEW
Shaoying Wang, Zhengyi Zhao, Farzin Haque, Peixuan Guo
Biological systems contain highly-ordered structures performing diverse functions. The elegant structures of biomachines have inspired the development of nanopores as single molecule sensors. Over the years, the utility of nanopores for detecting a wide variety of analytes have rapidly emerged for sensing, sequencing and diagnostic applications. Several protein channels with diverse shapes and sizes, such as motor channels from bacteriophage Phi29, SPP1, T3, and T4, as well as α-hemolysin, MspA, aerolysin, FluA, OmpF/G, CsgG, ClyA, have been continually investigated and developed as nanopores...
December 9, 2017: Current Opinion in Biotechnology
https://www.readbyqxmd.com/read/29223157/self-organization-of-recombinant-membrane-porin-ompf-from-yersinia-pseudotuberculosis-in-aqueous-environments
#3
E V Sidorin, V A Khomenko, N Yu Kim, P S Dmitrenok, A M Stenkova, O D Novikova, T F Solov'eva
Recombinant porin OmpF (an integral protein of bacterial outer membrane) from Yersinia pseudotuberculosis was synthesized in Escherichia coli cells as inclusion bodies. By combining the methods of anion-exchange and gel filtration chromatographies, recombinant OmpF (rOmpF) was isolated as an individual protein in its denatured state, and its characteristic properties (molecular mass, N-terminal amino acid sequence, and hydrodynamic radius of the protein in 8 M urea solution) were determined. According to the data of gel filtration, dynamic light scattering, optical spectroscopy, and binding of the hydrophobic fluorescent probe 8-anilino-1-naphthalenesulfonic acid, the rOmpF is fully unfolded in 8 M urea and exists in random coil conformation...
November 2017: Biochemistry. Biokhimii︠a︡
https://www.readbyqxmd.com/read/29211019/dual-regulation-of-the-small-rna-micc-and-the-quiescent-porin-ompn-in-response-to-antibiotic-stress-in-escherichia-coli
#4
Sushovan Dam, Jean-Marie Pagès, Muriel Masi
Antibiotic resistant Gram-negative bacteria are a serious threat for public health. The permeation of antibiotics through their outer membrane is largely dependent on porin, changes in which cause reduced drug uptake and efficacy. Escherichia coli produces two major porins, OmpF and OmpC. MicF and MicC are small non-coding RNAs (sRNAs) that modulate the expression of OmpF and OmpC, respectively. In this work, we investigated factors that lead to increased production of MicC. micC promoter region was fused to lacZ, and the reporter plasmid was transformed into E...
December 6, 2017: Antibiotics
https://www.readbyqxmd.com/read/29188707/increasing-extracellular-free-fatty-acid-production-in-escherichia-coli-by-disrupting-membrane-transport-systems
#5
Kwang Soo Shin, Sung Kuk Lee
Transposon mutagenesis was used to identify three mutants of E. coli that exhibited increased free fatty acid (FFA) production, which resulted from the disruption of genes related to membrane transport. Deletion of envR, gusC, and mdlA individually in a recombinant E. coli strain resulted in 1.4-, 1.8-, and 1.2-fold increases in total FFA production, respectively. In particular, deletion of envR increased the percentage of extracellular FFA to 46%, compared with 29% for the control strain. Multiple deletion of envR, gusC, mdlA, ompF, and fadL had a synergistic effect on FFA production, resulting in high extracellular FFA production, comprising up to 50% of total FFA production...
November 30, 2017: Journal of Agricultural and Food Chemistry
https://www.readbyqxmd.com/read/29166022/dynamics-of-ompf-trimer-formation-in-the-bacterial-outer-membrane-of-escherichia-coli
#6
Huilin Ma, Aliza Khan, Shikha Nangia
The self-assembly of outer membrane protein F (OmpF) in the outer membrane of Escherichia coli Gram-negative bacteria was studied using multiscale molecular dynamics simulations. To facilitate the long timescale required for protein assembly, coarse-grained parameterization of E. coli outer membrane lipids was first developed. The OmpF monomers formed stable dimers at specific protein-protein interactions sites irrespective of the lipid membrane environment. The dimer intermediate was asymmetric but provided a template to form a symmetric trimer...
November 22, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/29164072/a-new-strain-collection-for-improved-expression-of-outer-membrane-proteins
#7
Ina Meuskens, Marcin Michalik, Nandini Chauhan, Dirk Linke, Jack C Leo
Almost all integral membrane proteins found in the outer membranes of Gram-negative bacteria belong to the transmembrane β-barrel family. These proteins are not only important for nutrient uptake and homeostasis, but are also involved in such processes as adhesion, protein secretion, biofilm formation, and virulence. As surface exposed molecules, outer membrane β-barrel proteins are also potential drug and vaccine targets. High production levels of heterologously expressed proteins are desirable for biochemical and especially structural studies, but over-expression and subsequent purification of membrane proteins, including outer membrane proteins, can be challenging...
2017: Frontiers in Cellular and Infection Microbiology
https://www.readbyqxmd.com/read/29094406/liprotides-assist-in-folding-of-outer-membrane-proteins
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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