Mechanism of Activation of UvrD Helicase by a Processivity Factor MutL

E. coli UvrD is a superfamily 1A helicase/translocase involved in DNA repair, recombination, and replication. I investigated the role of E. coli MutL, a regulatory protein involved in methyl-directed mismatch DNA repair, in the regulation of UvrD-catalyzed DNA unwinding. Using single molecule fluorescence resonance energy transfer (FRET) and single round stopped-flow DNA unwinding experiments I demonstrated that MutL can activate latent UvrD monomer helicase activity and also stimulate UvrD dimer helicase activity. Furthermore, using analytical ultracentrifugation experiments I determined that a single MutL dimer is sufficient to activate UvrD monomer helicase. DNA unwinding experiments with a series of DNA substrates of varying duplex length under single round unwinding conditions showed that MutL increases the amount of duplex DNA unwound by UvrD in a single binding event. Therefore, MutL acts as a processivity factor by binding to and presumably moving along with UvrD during unwinding. I also showed that MutL requires contacts with the 3’ ssDNA tail for optimal activation of UvrD helicase activity. The C-terminal tail of UvrD is highly variable among SF1A helicases and suggested to interact with MutL, however, the truncated UvrDΔ73 mutant lacking its C-terminal tail is activated by MutL, indicating that the disordered C-terminal domain is not essential for stimulation. I also found that MutL is unable to activate the helicase activity of the structurally similar E. coli Rep helicase, indicating that MutL stimulation is specific to UvrD. Furthermore, MutL also fails to activate the helicase activity of chimeric UvrD containing the 2B sub-domain of Rep helicase. This result demonstrates that MutL activation of the monomeric UvrD helicase is regulated specifically by the 2B sub-domain of UvrD. Using single molecule and ensemble FRET experiments I showed that MutL binding to a UvrD monomer-DNA complex induces partial closing of the 2B sub-domain. Transient kinetic studies of MutL-induced activation of the UvrD helicase and MutL-induced changes in the UvrD 2B sub-domain showed that formation of the partially closed state is on the pathway to forming the active helicase. The kinetic analysis of these two sets of experiments revealed that under the experimentally used MutL concentrations the active MutL-UvrD species are formed predominantly through the conformational selection pathway (\u3e90%) and to a lesser degree through the induced fit pathway (\u3c10%)

MATHEMATICAL, SOFTWARE AND HARDWARE SUPPORT OF THE CONCEPTUAL MODEL OF THE INFORMATION SYSTEM OF PRECISION AGRICULTURE

This study analyzes the current situation of application of precision farming technologies and solutions by agricultural enterprises of the Republic of Kazakhstan. The main players and used solutions have been identified. The statistics of application, as well as the potential of use is examined. Within the framework of the analysis of the applied solutions the advantages and disadvantages of competitors in the market were determined. It was defined that the applied systems provide the possibility of remote management, but EGISTIC is more focused on the management of all processes of the farm, including the warehouse, while John Deere is focused on the management and analytics of agricultural machinery. EGISTIC offers features for warehousing and inventory planning, something not found in the base version of John Deere Operations Center. John Deere focuses on data sharing which can be important for large farms or groups of farmers. EGISTIC makes extensive use of satellite imagery to analyze field conditions which can be a great asset for identifying problem areas and planning interventions. Depending on the specific needs and priorities of an agribusiness, one system may be preferable to another. If machinery management is the main focus, John Deere might be the best choice. If in-depth analysis of field conditions and inventory control is important, EGISTIC may be more appropriate. By analyzing, the directions for research are highlighted. A conceptual model of information system for precision farming is developed. Hardware for realization of the conceptual model is possible on the basis of universal programmable logic controller of modular architecture being developed. Within the limits of the given research the conceptual model of the universal programmable logic controller of modular architecture and the structural model of the software of the universal programmable logic controller of modular architecture have been developed. The interaction with the conceptual adaptive model of information and communication system is also considered. This paper analyzes the key principles and functions of both the universal programmable logic controller and the information and communication system, as well as their possible integration within a single concept

A genome-wide analysis of Escherichia coli responses to fosfomycin using TraDIS-Xpress reveals novel roles for phosphonate degradation and phosphate transport systems

BACKGROUND: Fosfomycin is an antibiotic that has seen a revival in use due to its unique mechanism of action and efficacy against isolates resistant to many other antibiotics. In Escherichia coli, fosfomycin often selects for loss-of-function mutations within the genes encoding the sugar importers, GlpT and UhpT. There has, however, not been a genome-wide analysis of the basis for fosfomycin susceptibility reported to date. METHODS: Here we used TraDIS-Xpress, a high-density transposon mutagenesis approach, to assay the role of all genes in E. coli involved in fosfomycin susceptibility. RESULTS: The data confirmed known fosfomycin susceptibility mechanisms and identified new ones. The assay was able to identify domains within proteins of importance and revealed essential genes with roles in fosfomycin susceptibility based on expression changes. Novel mechanisms of fosfomycin susceptibility that were identified included those involved in glucose metabolism and phosphonate catabolism (phnC-M), and the phosphate importer, PstSACB. The impact of these genes on fosfomycin susceptibility was validated by measuring the susceptibility of defined inactivation mutants. CONCLUSIONS: This work reveals a wider set of genes that contribute to fosfomycin susceptibility, including core sugar metabolism genes and two systems involved in phosphate uptake and metabolism previously unrecognized as having a role in fosfomycin susceptibility

THE READINESS OF TEACHERS AND CURRICULA FOR IMPLEMENTATION OF STEM PROGRAMS: THE CASE OF ONE EXPERIMENTAL SCHOOL IN KAZAKHSTAN

The education systems around the world focus on developing students’ soft skills such as critical thinking, innovative thinking, and the ability to quickly retrain. In order to prepare professionals for the global economy, many countries of the world have adopted STEM (science, technology, engineering, and mathematics) education as the basis for the formation of a national curriculum (Yakman & Lee, 2012). The demand for STEM specialists is growing, and education systems in many countries are changing approaches to attract more potential workers to STEM-related areas (Prinsley & Johnston, 2015; Sanders, 2008; Tytler, 2020). This study aimed to explore teachers' perceptions of implementing STEM programs in one of the mainstream schools in Northern Kazakhstan. In addition, the factors supporting and impeding the implementation of STEM programs were studied. A qualitative study design was used to provide an in-depth exploration of teachers' attitudes. This approach first identified to what extent teachers were prepared for the implementation of STEM programs, and then explained their answers in more detail by analyzing the curricula and lesson plans. The findings of the qualitative analysis showed that most teachers had positive beliefs about STEM programs; only a few statements demonstrated skeptical attitudes of teachers towards curriculum reforms. The interview findings demonstrated that teachers were poorly satisfied with the quality of facilities and laboratories. Keywords: STEM curriculum, curriculum reform, teachers' attitudes

Государства Центральной Азии: в поисках корней демократии в истории народов

Авторы статьи рассматривают проблему поиска исторических корней демократии политическими элитами Центральной Азии с целью найти демократическую преемственность и обосновать особен- ность своей модели демократии. В статье также показана оценка отечественных и зарубежных экспертов процессов демократизации в государствах региона через призму поиска первичных демократических ценностей в прошлом для объяснения демократических реформ политической системы в настоящем. Авторы статьи отмечают, что в Казахстане также опираются на свое историческое прошлое т.н. «степную демократию», соз- дания культа героев-демократов – справедливых биев, "народных" ханов, что позволяет выстраивать особую модель демократии, которая учитывает все факторы влияющие на вхождение нашей страны в мировое демократическое сообщество. Так же авторами отмечено, что путь выбранный Казахстаном является более сложным, нежели другими странами Центральной Ази

The reasons of Central Asian youth involvement in terrorist and extremist organizations

Terrorism has become one of the factors of socio-political life, it has become one of the main threats to security in the world. Never before have terrorist attacks brought so many victims and devastations of a huge scale at one time, were not so professionally prepared and coordinated, did not attract such heavy moral, material, financial, political and environmental consequences. However, the problem of terrorism and extremism in modern society is worsened by the fact that more and more terrorist organizations involve young people in their activities. Through the influence of various factors, such as: social, political, economic, the most vulnerable to the ideological influence of young people, replenishes the ranks of extremist and terrorist groups, whose leaders use and manipulate them for their own purposes. Young people become a focal group for terrorists, as the impact on the immature psyche requires less work and gives more success. As a result, they simply become victims, in view of their insolvency and social, material insecurity. The young generation, by its very nature, age and position in society, has those features and features of thinking and behavior that, in certain socio-psychological conditions and purposeful influences, shape extremist personalities. Today there are about 500 illegal terrorist organizations in the world and the activities of extremist individuals, groups and organizations are increasing every day. A distinctive feature of modern international terrorism is globalization, which is based on extremist ideology. The world community is concerned about the growth of terrorist activity which is caused by numerous victims and huge material damage. The conducted research allows to consider the main reasons for participation of young people living in the countries of Central Asia in the activities of terrorist and extremist organizations. The materials of the article can be useful in a comprehensive study of the problem of terrorism and extremism in the territory of the Central Asian region. Key words: terrorism, extremism, youth, Central Asia, antiterrorist activity, recruitment, reasons for involvement

Central Asian transport corridors issue in the scientific literature

The article describes the main views of domestic and foreign experts on the development of transport corridors in Central Asia. The relevance of the problem is explained by the expansion of transport infrastructure in the Central Asian region within the framework of both national and international programs. The participation of Central Asian countries allows to solve a number of problems through the realization of the country’s transit potential. However, in the process of implementing infrastructure projects, regional states face risks that require a correlation of transport policies with the national interests of the countries. This explains the wide scientific interest in this issue. The expert community is increasingly focusing on issues of transport policy of states and international cooperation on transport projects. Despite the large number of works on various aspects of international and regional transport corridors, in the scientific literature there are no works of a complex nature, studying the transport corridors of Central Asia. This also applies to historiographic research. Key words: transport corridors, Central Asia, transit potential, expert community, national interests, risks

Active displacement of RecA filaments by UvrD translocase activity

The UvrD helicase has been implicated in the disas-sembly of RecA nucleoprotein filaments in vivo and in vitro. We demonstrate that UvrD utilizes an ac-tive mechanism to remove RecA from the DNA. Ef-ficient RecA removal depends on the availability of DNA binding sites for UvrD and/or the accessibil-ity of the RecA filament ends. The removal of RecA from DNA also requires ATP hydrolysis by the UvrD helicase but not by RecA protein. The RecA-removal activity of UvrD is slowed by RecA variants with en-hanced DNA-binding properties. The ATPase rate of UvrD during RecA removal is much slower than the ATPase activity of UvrD when it is functioning either as a translocase or a helicase on DNA in the absence of RecA. Thus, in this context UvrD may operate in a specialized disassembly mode