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Search Results: 1 - 10 of 153993 matches for " Elena B. Volokhina "
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Assembly Factor Omp85 Recognizes Its Outer Membrane Protein Substrates by a Species-Specific C-Terminal Motif
Viviane Robert,Elena B. Volokhina,Freya Senf,Martine P. Bos,Patrick Van Gelder,Jan Tommassen
PLOS Biology , 2012, DOI: 10.1371/journal.pbio.0040377
Abstract: Integral β-barrel proteins are found in the outer membranes of Gram-negative bacteria, mitochondria, and chloroplasts. The assembly of these proteins requires a proteinaceous apparatus of which Omp85 is an evolutionary conserved central component. To study its molecular mechanism, we have produced Omp85 from Escherichia coli in inclusion bodies and refolded it in vitro. The interaction of Omp85 with its substrate proteins was studied in lipid-bilayer experiments, where it formed channels. The properties of these channels were affected upon addition of unfolded outer-membrane proteins (OMPs) or synthetic peptides corresponding to their C-terminal signature sequences. The interaction exhibited species specificity, explaining the inefficient assembly of OMPs from Neisseria in E. coli. Accordingly, the in vivo assembly of the neisserial porin PorA into the E. coli outer membrane was accomplished after adapting its signature sequence. These results demonstrate that the Omp85 assembly machinery recognizes OMPs by virtue of their C-terminal signature sequence.
Assembly Factor Omp85 Recognizes Its Outer Membrane Protein Substrates by a Species-Specific C-Terminal Motif
Viviane Robert,Elena B Volokhina,Freya Senf,Martine P Bos,Patrick Van Gelder,Jan Tommassen
PLOS Biology , 2006, DOI: 10.1371/journal.pbio.0040377
Abstract: Integral β-barrel proteins are found in the outer membranes of Gram-negative bacteria, mitochondria, and chloroplasts. The assembly of these proteins requires a proteinaceous apparatus of which Omp85 is an evolutionary conserved central component. To study its molecular mechanism, we have produced Omp85 from Escherichia coli in inclusion bodies and refolded it in vitro. The interaction of Omp85 with its substrate proteins was studied in lipid-bilayer experiments, where it formed channels. The properties of these channels were affected upon addition of unfolded outer-membrane proteins (OMPs) or synthetic peptides corresponding to their C-terminal signature sequences. The interaction exhibited species specificity, explaining the inefficient assembly of OMPs from Neisseria in E. coli. Accordingly, the in vivo assembly of the neisserial porin PorA into the E. coli outer membrane was accomplished after adapting its signature sequence. These results demonstrate that the Omp85 assembly machinery recognizes OMPs by virtue of their C-terminal signature sequence.
Species-Specificity of the BamA Component of the Bacterial Outer Membrane Protein-Assembly Machinery
Elena B. Volokhina, Jan Grijpstra, Frank Beckers, Erika Lindh, Viviane Robert, Jan Tommassen, Martine P. Bos
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0085799
Abstract: The BamA protein is the key component of the Bam complex, the assembly machinery for outer membrane proteins (OMP) in gram-negative bacteria. We previously demonstrated that BamA recognizes its OMP substrates in a species-specific manner in vitro. In this work, we further studied species specificity in vivo by testing the functioning of BamA homologs of the proteobacteria Neisseria meningitidis, Neisseria gonorrhoeae, Bordetella pertussis, Burkholderia mallei, and Escherichia coli in E. coli and in N. meningitidis. We found that no BamA functioned in another species than the authentic one, except for N. gonorrhoeae BamA, which fully complemented a N. meningitidis bamA mutant. E. coli BamA was not assembled into the N. meningitidis outer membrane. In contrast, the N. meningitidis BamA protein was assembled into the outer membrane of E. coli to a significant extent and also associated with BamD, an essential accessory lipoprotein of the Bam complex.Various chimeras comprising swapped N-terminal periplasmic and C-terminal membrane-embedded domains of N. meningitidis and E. coli BamA proteins were also not functional in either host, although some of them were inserted in the OM suggesting that the two domains of BamA need to be compatible in order to function. Furthermore, conformational analysis of chimeric proteins provided evidence for a 16-stranded β-barrel conformation of the membrane-embedded domain of BamA.
Analysis of Rare Variants in the C3 Gene in Patients with Age-Related Macular Degeneration
Maheswara R. Duvvari, Codrut C. Paun, Gabri?lle H. S. Buitendijk, Nicole T. M. Saksens, Elena B. Volokhina, Tina Ristau, Frederieke E. Schoenmaker-Koller, Johannes P. H. van de Ven, Joannes M. M. Groenewoud, Lambertus P. W. J. van den Heuvel, Albert Hofman, Sascha Fauser, André G. Uitterlinden, Caroline C. W. Klaver, Carel B. Hoyng, Eiko K. de Jong, Anneke I. den Hollander
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0094165
Abstract: Age-related macular degeneration (AMD) is a progressive retinal disorder affecting over 33 million people worldwide. Genome-wide association studies (GWASs) for AMD identified common variants at 19 loci accounting for 15–65% of the heritability and it has been hypothesized that the missing heritability may be attributed to rare variants with large effect sizes. Common variants in the complement component 3 (C3) gene have been associated with AMD and recently a rare C3 variant (Lys155Gln) was identified which exerts a large effect on AMD susceptibility independent of the common variants. To explore whether additional rare variants in the C3 gene are associated with AMD, we sequenced all coding exons in 84 unrelated AMD cases. Subsequently, we genotyped all identified variants in 1474 AMD cases and 2258 controls. Additionally, because of the known genetic overlap between AMD and atypical hemolytic uremic syndrome (aHUS), we genotyped two recurrent aHUS-associated C3 mutations in the entire cohort. Overall, we identified three rare variants (Lys65Gln (P = 0.04), Arg735Trp (OR = 17.4, 95% CI = 2.2–136; P = 0.0003), and Ser1619Arg (OR = 5.2, 95% CI = 1.0–25; P = 0.05) at the C3 locus that are associated with AMD in our EUGENDA cohort. However, the Arg735Trp and Ser1619Arg variants were not found to be associated with AMD in the Rotterdam Study. The Lys65Gln variant was only identified in patients from Nijmegen, the Netherlands, and thus may represent a region-specific AMD risk variant.
Review of "ESP in European Higher Education. Integrating Language and Content"
Elena Bárcena
Ibérica , 2009,
Abstract:
Corporate Identity as a Factor of Corporate Security
Elena B. Perelygina
Psychology in Russia : State of Art , 2011,
Abstract: Forming-upof the corporate identity is based on cognitive, affective and conative elements of corporate culture. The group as an entity choosing goals and values ensures a certain response to standards and values of corporate culture within the parameters of its social responsibility. Corporate security as security of community and cooperation acts as a form of organizational and ethical approach to developing socially responsible attitude of government and business.
Response of Two Brassica Species to the Toxic Effect of Different Copper Concentration  [PDF]
Khalid H. Alobaidi, Elena B. Bashmakova, Valentina P. Kholodova
Journal of Environmental Protection (JEP) , 2015, DOI: 10.4236/jep.2015.67065
Abstract: One of the most important challenges in the ecosystem nowadays is the adaptation of plants to damaged environmental factors. Among them, an important attention is paid to the toxic effects of high concentrations of heavy metals (HM). Copper is essentially but highly toxic HM. In the work, first we established, plant's resistance comparison of the two studied Brassica species Brassica—B. alba, and B. napus—in higher concentrations of copper in the environment, and demonstrated that the two plants were potentially useful for phytoremediation of moderately polluted areas with copper. In plants of the genus Brassica grow in a hydroponic culture, experiments showed that the tested species referred to indicator plants. Results show the stability of the studied plants to the toxic effects of excessive copper levels, due to their proline accumulation ability. Studied plants, B. alba, and B. napus, can be used in selection practice as baselines to generate new plant varieties with increased resistance to heavy metals salts.
Development and validation of a RP-HPLC method for the quantisation studies of metronidazole and furazolidone from product Enteroguard M
Elena Gabriela Oltean,,Milea, B.
Medicamentul Veterinar , 2010,
Abstract: An isocratic high-performance liquid chromatography (HPLC) procedure was developed for quantitative determination of metronidazole and furazolidone in tablet dosage forms of ENTEROGUARD M. HPLC separation was carried out by reversed phase chromatography Kromasil C18 (250mm x 4,6mm i.d.; 5μm particle size), held at 25°C. The mobile phase consisted of methanol/ 0,1% phosphoric acid aq. (20/80v/v), run at flow rate of 1 mL/ min and with UV detection at 317nm. Method validation investigated parameters such as linearity (r2 = 0.9999), range, precision, accuracy and specificity. The described method can be successfully applied for the analysis of ENTEROGUARD M tablets.
Polymer Translocation Through a Long Nanopore
Elena Slonkina,Anatoly B. Kolomeisky
Physics , 2002, DOI: 10.1063/1.1560932
Abstract: Polymer translocation through a nanopore in a membrane investigated theoretically. Recent experiments on voltage-driven DNA and RNA translocations through a nanopore indicate that the size and geometry of the pore are important factors in polymer dynamics. A theoretical approach is presented which explicitly takes into account the effect of the nanopore length and diameter for polymer motion across the membrane. It is shown that the length of the pore is crucial for polymer translocation dynamics. The present model predicts that for realistic conditions (long nanopores and large external fields) there are two regimes of translocation depending on polymer size: for polymer chains larger than the pore length, the velocity of translocation is nearly constant, while for polymer chains smaller than the pore length the velocity increases with decreasing polymer size. These results agree with experimental data.
Involvement of Autoimmune Diseases in the Pathogenesis of Chronic Immune Thrombocytopenic Purpura  [PDF]
M?d?lina Mocanu, Magda B?descu, Manuela Ciocoiu, Codru?a B?descu, Cristina Elena Iancu, Oana B?dulescu
Journal of Biomedical Science and Engineering (JBiSE) , 2015, DOI: 10.4236/jbise.2015.83014
Abstract: Chronic immune thrombocytopenic purpura (ITP) is a condition based on an immune-mediated mechanism that determines the premature hyperdestruction of the thrombocytes in peripheral blood, as well as their deficient synthesis at the level of the bone marrow. The chronic immune purpura could be of primary, idiopathic cause, as well as of secondary cause, occurring in the context of other pathologies. The characteristic of the primary form of the disease is the presence of isolated thrombocytopenia, defined by a platelet count under 100,000/mm3 in peripheral blood, in the absence of supporting causes for thrombocytopenia. In the secondary form of the disease, the decreased platelet count is due to associated pathologies involving an immune mechanism, responsible for the occurrence of thrombocytopenia. This study aims to emphasize the involvement of autoimmune diseases, such as systemic lupus erythematosus (SLE), dermatomyositis, rheumatoid polyarthritis or antiphospholipid syndrome in the pathogenesis of secondary thrombocytopenia. Furthermore, the study was conducted on a sample of 40 patients, divided into two groups: The first group comprising asymptomatic patients diagnosed with thrombocytopenia following routine tests, and the second group comprising patients with hemorrhagiparous symptomatology (petechiae, ecchymoses, epistaxis, gingivorrhagia), who went to the doctor in order to determine the etiology of the hemorrhagiparous syndrome. The average value of the thrombocytopenia of the patients included in the study was of 60.20 ± 19.75 × 103/μL. Laboratory investigations performed in order to establish the etiology of thrombocytopenia showed that 80% of patients presented positive antiplatelet antibodies. Moreover, 20% of the patients in the study showed positive anti-double-stranded DNA, 20% were identified with IgG anticardiolipin antibodies, while antinuclear antibodies were present in 10% of the patients.
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