Structural and functional characterization of microcin C resistance peptidase MccF from Bacillus anthracis

Microcin C (McC) is heptapeptide adenylate antibiotic produced by Escherichia coli strains carrying the mccABCDEF gene cluster encoding enzymes, in addition to the heptapeptide structural gene mccA, necessary for McC biosynthesis and self-immunity of the producing cell. The heptapeptide facilitates McC transport into susceptible cells, where it is processed releasing a non-hydrolyzable aminoacyl adenylate that inhibits an essential aminoacyl-tRNA synthetase. The self-immunity gene mccF encodes a specialized serine peptidase that cleaves an amide bond connecting the peptidyl or aminoacyl moieties of, respectively, intact and processed McC with the nucleotidyl moiety. Most mccF orthologs from organisms other than E. coli are not linked to the McC biosynthesis gene cluster. Here, we show that a protein product of one such gene, MccF from Bacillus anthracis (BaMccF), is able to cleave intact and processed McC, and we present a series of structures of this protein. Structural analysis of apo-BaMccF and its adenosine monophosphate complex reveals specific features of MccF-like peptidases that allow them to interact with substrates containing nucleotidyl moieties. Sequence analyses and phylogenetic reconstructions suggest that several distinct subfamilies form the MccF clade of the large S66 family of bacterial serine peptidases. We show that various representatives of the MccF clade can specifically detoxify non-hydrolyzable aminoacyl adenylates differing in their aminoacyl moieties. We hypothesize that bacterial mccF genes serve as a source of bacterial antibiotic resistance.     

Investigation of the breathing pattern structure in competitive exercises of kettlebell lifters

The goal of the research was to determine the characteristics of the breathing pattern in kettlebell lifters. The following main indicators of external respiration were recorded during exercise performance: respiratory rate (RR, f), tidal volume (TV, V _T ), and respiratory minute volume (RMV, V _E ). The dependence of these parameters on the qualification of athletes and competitive exercise intensity was estimated. An SMP-21/01-“R-D” spirograph was used for qualitative and quantitative assessment of the main indicators of breathing patterns in kettlebell lifters. The characteristic changes in breathing of masters of sports (MS) and candidate masters of sport (CMS) were shown mainly for the three parameters, respiratory rate and tidal volume, as well as in the number of breathing cycles per cycle of exercise. Respiratory rate increases and tidal volume decreases at a high-intensity exercise. In international masters of sports (MSIC), the number of breathing cycles per cycle of competitive exercise and, consequently, respiratory rate remain constant independent of physical load. They show the predominance of only one index, tidal volume, which increases from 0.7 ± 0.1 L to 1.2 ± 0.1 L (p < 0.01) with increasing intensity of exercise. We have found transitional forms of breathing patterns in the competitive exercises of kettlebell lifting. The results lay the basis for the development of a novel concept of training and improvement of breathing technique in kettlebell lifting.     

Certain aspects of interactions between cohabiting sibling species Microtus arvalis and M. rossiaemeridionalis

Some aspects of interspecific interactions between sibling species of common vole were studied at the Chernogolovka Scientific Research Station (severtsov Institute for Problems of Ecology and Evolution, Russian Academy of Sciences) from 1992 to 2001. In the marking plot and indoors, East European vole demonstrated high tolerance to the anthropogenic stress considering that it was the most abundant species in the studied area transformed by human economic activity and that it used buildings as temporary shelters. When cohabiting the marking plot, common and East European voles demonstrated different territorial distribution and circadian activity, which can be considered as an adaptation to avoiding competitive interactions of ecologically similar species.     

Stability of plant vacuolar membranes under the conditions of osmotic stress and influence of redox agents

Stability of plant vacuolar membranes (tonoplast), which underwent two types of osmotic stress and also the effect of redox agents (glutathione in its oxidized (GSSG) and reduced (GSH) forms) and nitric oxide (NO) under various pH values, has been investigated. The fatty-acid content of tonoplast has also been determined. It has been shown that stability of vacuoles decreased under hyperosmotic stress but not under hypoosmotic stress. These effects are unlikely caused by the fatty-acid content of vacuolar membranes. Stability of vacuoles changed under various redox conditions; this process was more intensive under the conditions of hypoosmotic stress in the experiments with oxidized glutathione. The influence of nitrogen oxide was different for various kinds of stress: stability of vacuoles decreased substantially under hypoosmotic stress, while under the conditions of hyperosmotic stress NO elevated the stability level of the vacuolar membranes.     

Theoretical study of the effect of several reverse reaction on the kinetics of the primary processes of photosynthesis

A theoretical model of energy migration and electron transport in photosynthesis of higher plants was considered. The set of different equations describing these processes takes into consideration the states of 4 components of electron transport chain and back reactions of electron transfer from the reduced acceptors to the oxidized reaction centres. The numerical integration of these equations was made for various kinetics parameters characterizing the electron transport chain.