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V A Likhoshvaĭ

Publications and source records attributed to V A Likhoshvaĭ.

10 recordsLinked to original sources
PubMed1997

[Regulation of translation of the distal lacZ gene in polycistronic mRNA by the ribosome stream from the proximal gene].

Four series of plasmids (pNSI, pNSII, pNLI, and pNLII) with artificial polycistrons containing the lacZ test gene were constructed. These plasmids coded for polycistronic mRNAs with two different types of cistron (orfZ and lacZ) coupling: in pNSI and pNLI, the orfZ termination codon and the lacZ initiation codon overlapped (type I); in pNSII and pNLII, the orfZ termination codon, was located upstream of the lacZ SD sequence. The length of the orfZ cistron was 60 bp in pNSI and pNSII or 300 bp in pNLI and pNLII. Plasmids with the same type of cistron coupling contained the same lacZ translation initiation region, whereas the structure of the orfZ translation initiation region varied, thereby providing varying efficiency of the orfZ gene translation. The effect of these variations on the efficiency of the lacZ gene translation was evaluated by direct measurement of the beta-galactosidase activity in Escherichia coli cells transformed with the corresponding plasmids. We found that the level of translation of the distal lacZ gene depended on the ribosome stream from the proximal gene and was maximal at the optimal ribosome stream level, which, in turn, depended on the type of cistron coupling.

Genes↗
PubMed1990

[Model polycistron operon for studying conjugated translation in E. coli cells. The role of a stream of ribosomes].

The role of "stream" of ribosomes upon translation of polycistronic mRNAs has been studied using an artificial polycistron. It has been found that the levels of activation of cistron Ci + 1 out of two adjacent cistrons (Ci and Ci + 1) depends, in addition to earlier described effects of mutual arrangement of initiation and termination signals, also on efficiency of translation of the foregoing cistron Ci. The results obtained lead to the conclusion that in polycistronic systems the levels of translation of cistron Ci + 1 can be regulated by "stream" of ribosomes resulted from translation of the proximal cistron Ci.

Base Sequence↗
PubMed1988

[Effectiveness of distal gene translation in polycistrons depends upon the arrangement of regulatory signals on a template].

The role of the translational terminator and initiator signals arrangement for two adjacent genes in polycistronic mRNA has been studied. Semisynthetic beta-galactosidase gene (lacZ) of E. coli and fragment of phage M13 DNA (with promoter PVIII, gene IX, and part of gene VIII) were used for constructing of the IX-VIII-lacZ artificial polycistronic operon. Cloning of the constructs into pBR322 vector resulted in a number of pLZ381N plasmids differing by the mutual arrangement of gene VIII translation terminator codon and SD site and initiator codon (SD-ATG-region) of lacZ gene. The mutual arrangement of gene VIII terminator codon and SDlacZ-ATG region has been altered by means of deletions and insertions that have not affected lacZ translation initiation signals. The beta-galactosidase (beta-Gal) synthesis in E. coli harbouring different types of pLZ381N plasmids has been found to depend on type of cistron coupling (gene VIII and lacZ). The overlapping of terminator and initiator codons (ATGA) for genes VIII and lacZ (type I of polycistrons) provide approximately equal translational level for both cistrons. On the other side, levels of beta-Gal synthesis in case of polycistrons type II (gene VIII stop-codon position at the beginning of SDlacZ or 10 nucleotides upstream) were 20-30 times as high as for type I. Differences in beta-Gal levels have also been found for variants of VIII-lacZ coupling in types IV and III polycistrons (the SDlacZ-ATG region in 27-50 nucleotides downstream from the proximal cistron VIII stop-codon, which, in turn, is 41 nucleotides upstream this terminator). These data cannot be explained on the basis of possible secondary structure including the SDlacZ-ATG region and other parts of polycistronic mRNA. In all these cases similarly stable stem-loop structures have been found. Therefore, the arrangement of the translation termination and initiation signals for two adjacent genes in essential for distal gene translation efficiency. One can imagine that ribosome or its 30S subpartical, stalling on the proximal gene terminator codon, affects the distal gene translation initiation.

Coliphages↗
PubMedDate not supplied

[A generalized chemical-kinetic method for modeling gene networks].

Development of methods for mathematical simulation of biological systems and building specific simulations is an important trend of bioinformatics development. Here we describe the method of generalized chemokinetic simulation generating flexible and adequate simulations of various biological systems. Adequate simulations of complex nonlinear gene networks--control system of cholesterol by synthesis in the cell and erythrocyte differentiation and maturation--are given as the examples. The simulations were expressed in terms of unit processes--biochemical reactions. Optimal sets of parameters were determined and the systems were numerically simulated under various conditions. The simulations allow us to study possible functional conditions of these gene networks, calculate consequences of mutations, and define optimal strategies for their correction including therapeutic ones. Graphical user interface for these simulations is available at http://wwwmgs.bionet.nsc.ru/systems/MGL/GeneNet/.

Algorithms↗
PubMedDate not supplied

[On connection of a graph of a gene network with qualitative modes of function].

Theoretical investigation of properties of assumed gene networks constructed from elementary units of two types, genetic elements and control links, was carried out. A test was formulated for a subclass of such networks with cyclic structure called S(n,k)-networks allowing calculation-free prediction of the network limiting properties (the presence/absence and number of stationery and/or cyclic functioning modes) from a graph of the network structure. The obtained data can be useful for constructing gene networks with predefined properties.

Genetics↗
PubMedDate not supplied

[Integrated computer system for regulating eukaryotic gene expression].

The review describes several modules of the GeneExpress integrated computer system concerning the regulation of gene expression in eukaryotes. Approaches to the presentation of experimental data in databases are considered. The employment of GeneExpress in computer analysis and modeling of the organization and function of genetic systems is illustrated with examples. GeneExpress is available at http://wwwmgs.bionet.nsc.ru/mgs/gnw/.

Animals↗
PubMedDate not supplied

[Molecular weight distribution of polymeric DNA-products, formed upon the action of matrix enzymes].

Models of processive and distributive DNA synthesis and degradation catalysed by matrix enzymes were investigated. Distribution of polymer products dependent on the reaction model chosen, on the type of the matrix and on the enzyme-matrix initial concentration ratio were determined by methods of numerical modeling. Conditions were found where the scattering of the reaction polymer products was minimal. The homopolymer matrix choice of experimental condition may generate a distribution of product that obeys the Poisson distribution. Numerical investigations of polymerization (hydrolysis) processes showed that for a number of heteropolymer matrixes a distribution may exist with scattering much less than that for homopolymer matrixes. Conditions are found when processive and distributive models give different distributions of the reaction product.

Base Sequence↗