Tyrosine Phosphorylation of the UDP-Glucose Dehydrogenase of Escherichia coli Is at the Crossroads of Colanic Acid Synthesis and Polymyxin Resistance

BACKGROUND:In recent years, an idiosyncratic new class of bacterial enzymes, named BY-kinases, has been shown to catalyze protein-tyrosine phosphorylation. These enzymes share no structural and functional similarities with their eukaryotic counterparts and, to date, only few substrates of BY-kinases have been characterized. BY-kinases have been shown to participate in various physiological processes. Nevertheless, we are at a very early stage of defining their importance in the bacterial cell. In Escherichia coli, two BY-kinases, Wzc and Etk, have been characterized biochemically. Wzc has been shown to phosphorylate the UDP-glucose dehydrogenase Ugd in vitro. Not only is Ugd involved in the biosynthesis of extracellular polysaccharides, but also in the production of UDP-4-amino-4-deoxy-L-arabinose, a compound that renders E. coli resistant to cationic antimicrobial peptides. METHODOLOGY/PRINCIPAL FINDINGS:Here, we studied the role of Ugd phosphorylation. We first confirmed in vivo the phosphorylation of Ugd by Wzc and we demonstrated that Ugd is also phosphorylated by Etk, the other BY-kinase identified in E. coli. Tyrosine 71 (Tyr71) was characterized as the Ugd site phosphorylated by both Wzc and Etk. The regulatory role of Tyr71 phosphorylation on Ugd activity was then assessed and Tyr71 mutation was found to prevent Ugd activation by phosphorylation. Further, Ugd phosphorylation by Wzc or Etk was shown to serve distinct physiological purposes. Phosphorylation of Ugd by Wzc was found to participate in the regulation of the amount of the exopolysaccharide colanic acid, whereas Etk-mediated Ugd phosphorylation appeared to participate in the resistance of E. coli to the antibiotic polymyxin. CONCLUSIONS/SIGNIFICANCE:Ugd phosphorylation seems to be at the junction between two distinct biosynthetic pathways, illustrating the regulatory potential of tyrosine phosphorylation in bacterial physiology

Role of Intraspecies Recombination in the Spread of Pathogenicity Islands within the Escherichia coli Species

Horizontal gene transfer is a key step in the evolution of bacterial pathogens. Besides phages and plasmids, pathogenicity islands (PAIs) are subjected to horizontal transfer. The transfer mechanisms of PAIs within a certain bacterial species or between different species are still not well understood. This study is focused on the High-Pathogenicity Island (HPI), which is a PAI widely spread among extraintestinal pathogenic Escherichia coli and serves as a model for horizontal transfer of PAIs in general. We applied a phylogenetic approach using multilocus sequence typing on HPI-positive and -negative natural E. coli isolates representative of the species diversity to infer the mechanism of horizontal HPI transfer within the E. coli species. In each strain, the partial nucleotide sequences of 6 HPI–encoded genes and 6 housekeeping genes of the genomic backbone, as well as DNA fragments immediately upstream and downstream of the HPI were compared. This revealed that the HPI is not solely vertically transmitted, but that recombination of large DNA fragments beyond the HPI plays a major role in the spread of the HPI within E. coli species. In support of the results of the phylogenetic analyses, we experimentally demonstrated that HPI can be transferred between different E. coli strains by F-plasmid mediated mobilization. Sequencing of the chromosomal DNA regions immediately upstream and downstream of the HPI in the recipient strain indicated that the HPI was transferred and integrated together with HPI–flanking DNA regions of the donor strain. The results of this study demonstrate for the first time that conjugative transfer and homologous DNA recombination play a major role in horizontal transfer of a pathogenicity island within the species E. coli

Methodical Basis of Technical and Economic Assessments of Technological Processes Virobnitstva Ta Modernizacy Corpuses of Pancrevail Automobiles

При производстве и модернизации специальных бронированная автомобилей важное место занимают электросварочные работы на броневых конструкциях. В настоящее время они являются единственным высокопроизводительным способом надежного соединения деталей. Но при этом им присущи серьезные недостатки, обусловленные принципиальными особенностями сварки, а именно, существенным отличием физико-механических свойств сварного соединения от свойств свариваемых деталей, в результате чего, качество сварного соединения (которое состоит из сварного шва и зоны термического воздействия) существенно ниже, чем качество металла корпуса машины. На основании анализа опыта применения бронированных специализированных машин и требований к защищенности данной группы техники предложен методический подход выбора способов сварки корпусов бронированная автомобилей. Предложенная методика может быть базовой для создания специализированного программного обеспечения в области поиска рациональных подходов к выбору технологий производства и модернизации бронированная автомобилей

Methodical Bases for Assessing the Material of Armored Corps of Panzer Specialized Vehicles

At the article an analysis of the experience of the use of special-purpose car armored vehicles and the requirements for the protection of this group of equipment was conducted. A methodical approach is proposed for comparative evaluation of materials of their cases, which provides the necessary level of protection against the impact of the factors, in order to optimize the choice based on financial costs, qualitative characteristics and production technology. The article proposes to use the method of the progressive standard as a basic approach for comparing materials of bodies of armored vehicles

Modern Methods for Forecasting the Technical Condition of Aviation Equipment

The article discusses methodological approaches to predicting changes in the technical state of aircraft structures based on the results of statistical processing of data received from repair and operating organizations. The results of forecasting changes in time of the parameters of the state of aviation equipment by the methods of linear and nonlinear forecasting during operation according to the technical state are presented. The possibility of the practical application of the proposed methods in determining the maintenance system and the required amount of additional work during the operation of aviation equipment is shown

Methods for Evaluating the Effectiveness of Logistics Support for Groups of Heterogeneous Forces (Troops)

The occupation of Crimea and the Russian Federation's support for separatist movements in the Luhansk and Donetsk regions showed the fallacy of the until recently current assessments of the military-political situation that has developed around Ukraine, as well as internal and external threats to the national interests of the state. An analysis of the anti-terrorist operation in the Donetsk and Lugansk regions (Operation of the Joint Forces) shows that the system of logistics, technical, medical and other types of support needed to be quickly adapted to the real situation, forms and methods of using units (subdivisions) at different stages of its implementation. In the context of European integration and new tasks of the Armed Forces of Ukraine related to the participation of Ukraine in anti-terrorist operations, in peacekeeping activities under the auspices of NATO and the UN, there is a need to reform the troops (forces), types of logistics, technical and medical support in accordance with the requirements of NATO standards. This article has developed a methodology for assessing the effectiveness of logistical support for a grouping of heterogeneous forces (troops) of the Naval Forces in a special period. In the course of the research conducted by the authors, the basic provisions of the theory of complex technical systems, the theory of artificial intelligence, the taxonomic method, as well as general scientific methods of analysis and synthesis were used. The above methodology makes it possible to evaluate the effectiveness of the logistics support system for a grouping of heterogeneous forces (troops) of the Naval Forces in a special period, to determine measures aimed at improving logistics support. On the basis of this methodology, the authors will develop recommendations for improving the logistics support for the grouping of heterogeneous forces (troops) of the Naval Forces in the Azov operational zone in a special period

МЕТОДИЧНИЙ ПІДХІД ЩОДО ПОРІВНЯЛЬНОЇ ОЦІНКИ МАТЕРІАЛІВ КОРПУСІВ ПАНЦЕРОВИХ СПЕЦІАЛІЗОВАНИХ АВТОМОБІЛІВ

Based on the analysis of experience with the panzer specialized vehicles and requirements for the protection of this group of material, it‘s suggested the methodological approach for the comparative evaluation of materials for their buildings, which ensures the necessary level of the protection from the effects of damaging factors, to optimize the choice on the basis of the financial cost, quality characteristics and manufacturing technology. In the article as the baseline approach for comparison the armored vehicles body materials buildings, the method of progressive standard has proposed to use.The proposed method can be the basis for creating the specialized software in the field of the searching the rational approaches in the process of upgrading and designing the modern specialized armored vehicles.На основании анализа опыта применения панцирных специализированных автомобилей и требований к защищенности данной группы техники предложен методический подход сравнительной оценки материалов их корпусов, что обеспечивает необходимый уровень защищенности от воздействия поражающих факторов, с целью оптимизации выбора на основе финансовых расходов, качественных характеристик и технологии производства. В статье в качестве базового подхода для проведения сравнения материалов корпусов бронированных машин предлагается использовать метод прогрессирующего эталона.Предложенная методика может быть базовой для создания специализированного программного обеспечения в области поиска рациональных подходов в процессе модернизации и проектирования современных специализированных бронированных автомобилей.На підставі аналізу досвіду застосування панцерових спеціалізованих автомобілів та вимог до захищеності даної групи техніки запропоновано методичний підхід порівняльної оцінки матеріалів їх корпусів, що забезпечує необхідний рівень захищеності від дії уражаючих факторів з метою оптимізації вибору на підґрунті фінансових витрат, якісних характеристик та технології виробництва. У статті в якості базового підходу для проведення порівняння матеріалів корпусів броньованих машин пропонується використовувати метод прогресуючого еталону.Запропонована методика може бути базовою для створення спеціалізованого програмного забезпечення в галузі пошуку раціанальних підходів в процесі модернізації та проектування сучасних броньованих спеціалізованих автомобілів

Interband Photoconductivity of Metamorphic InAs/InGaAs Quantum Dots in the 1.3–1.55-μm Window

Abstract Photoelectric properties of the metamorphic InAs/In x Ga1 − x As quantum dot (QD) nanostructures were studied at room temperature, employing photoconductivity (PC) and photoluminescence spectroscopies, electrical measurements, and theoretical modeling. Four samples with different stoichiometry of In x Ga1 − x As cladding layer have been grown: indium content x was 0.15, 0.24, 0.28, and 0.31. InAs/In0.15Ga0.85As QD structure was found to be photosensitive in the telecom range at 1.3 μm. As x increases, a redshift was observed for all the samples, the structure with x = 0.31 was found to be sensitive near 1.55 μm, i.e., at the third telecommunication window. Simultaneously, only a slight decrease in the QD PC was recorded for increasing x, thus confirming a good photoresponse comparable with the one of In0.15Ga0.75As structures and of GaAs-based QD nanostructures. Also, the PC reduction correlate with the similar reduction of photoluminescence intensity. By simulating theoretically the quantum energy system and carrier localization in QDs, we gained insight into the PC mechanism and were able to suggest reasons for the photocurrent reduction, by associating them with peculiar behavior of defects in such a type of structures. All this implies that metamorphic QDs with a high x are valid structures for optoelectronic infrared light-sensitive devices

Maillard reaction and spontaneous mutagenesis in Escherichia coli

DNA is a fragile organic molecule of finite chemical stability, capable of interacting with a variety of chemicals. In the context of the living cell this DNA reactivity is manifested as mutability. In addition to the chemical mutability, the perpetuation of DNA via imperfect replication is another source of DNA changeability. It is worth mentioning that DNA repair is error-tolerant and always leaves behind some lesions exist. Were repair mechanisms perfect, then the door of evolution would be locked. Risky rather than benign at individual level, mutations are the living things' long term strategy for survival and evolution. The creative power of mutations can explain why organisms have evolved special mechanisms to enhance mutagenesis under certain conditions. Hypermutation in bacteria under stress (SOS response) as well as hypermutation of immunoglobulin genes in response to antigen challenge in vertebrates are key examples. The present study is focused on spontaneous mutagenesis in Escherichia coli K-12. Spontaneous mutations are the net result of DNA damage and repair under normal physiological conditions. Bacterial DNA is loosely packed wi