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V V Emel'ianov

Publications and source records attributed to V V Emel'ianov.

17 recordsLinked to original sources
PubMed2000

[Evolutionary relationship of Rickettsia and eukaryotic mitochondria].

To clarify the evolutionary relationship of rickettsiae and mitochondria, the conserved flat heat-shock protein Hsp60 was phylogenetically studied in detail by using PHYLIP and PROTML packages. The ample data set (50 species) included as many as possible representatives from the Rickettsiaceae family, mitochondrial-type homologs from Archezoa and mitochondrial homologs from Protozoa. Rickettsia prowazekii (that is the genus Rickettsia) was shown to be the least diverging member within Rickettsia--a sister group to the monophyletic clade of mitochondria. These findings were also evidenced by the phylogenetic analysis of 16S rRNA. Rickettsia-like endosymbionts (the parasites Paramecium caudatum and the etiological agent of hepatopancreatitis in shrimps) included within the order Rickettsiales appear to have diverged prior to the Rickettsiaceae/mitochondria cluster. Thus, the Rickettsiales does not seem to be a monophyletic group. An idea concerning the nature of obligate intracellular parasitism of rickettsiae is proposed in the paper from the suggested profound similarity of Rickettsiae genus bacteria and mitochondria which could have a common evolutionary history.

Animals↗
PubMed2000

[Characteristics of recombinant fragments of the protective antigen SPA of epidemic typhus pathogens].

Fragments of a gene for species-specific protective antigen SPA of Rickettsia prowazekii earlier cloned in lambda gt11 were recloned into the in-frame expression vector pQE30. Polypeptides encoded by these fragments were shown to be synthesized in Escherichia coli with a yield of up to 100 micrograms/ml of culture and to be accumulated in the cells as inclusion bodies. The partially purified antigens were used in enzyme immunoassay with the sera of humans convalescing from epidemic typhus, tick-borne rickettsioses, and other infectious diseases. One of two recombinant proteins was shown to react in immunoblotting and ELISA with homologous, but not with heterologous, sera. The immunoreactivities in ELISA of the recombinant antigens and heat-denatured SPA proved to be similar, but substantially lower than that of the native SPA. These data as well as the data of other investigators show that serodiagnostics of epidemic typhus using recombinant antigens remains a problem.

Antigens, Bacterial↗
PubMed1999

[Phylogenetic analysis based on groE shows the closest evolutionary relationship between mitochondria and Rickettsia].

The nucleotide sequence of the groE operon of Rickettsia prowazekii, the obligate intracellular parasite of eukaryotes, was determined. The alignment of DNA-inferred amino acid sequences of the Hsp10 and Hsp60 heat-shock proteins with bacterial and mitochondrial homologues revealed the presence within Hsp60 of signatures shared by mitochondria and rickettsiae. Phylogenetic analysis demonstrated that heat-shock proteins of R. prowazekii are the earliest and the least diverging homologues within the family Rickettsiaceae--a sister group to the monophyletic clade of mitochondria. These results are in good agreement with the data obtained when using other molecular chronometers and show the closest relationship between mitochondria and Rickettsia. The possible nature of obligate intracellular parasitism of rickettsiae has been considered on the basis of the assumption that they and mitochondria could have a common evolutionary origin.

Amino Acid Sequence↗
PubMed1992

[Selective solubilization and biochemical analysis of R. prowazekii outer membrane proteins].

Solubilization of proteins from total membranes (a mixture of cytoplasmic and outer membranes) of Rickettsia prowazekii, a typical gram-negative bacterium, was studied using three different detergents. It was shown that isolated outer membranes and sarkosyl-insoluble material contain major polypeptides of 134, 31, 29.5 and 25 kDa as well as minor polypeptides of 78, 60, 42, and 17 kDa, while the total membranes--the same plus a great number of additional minor proteins. The material solubilized by octyl glucoside in the presence of MgCl2 contains exclusively major proteins (134, 31, 29.5, and 25 kDa). No differential solubilization takes place upon membrane treatment with octyl glucoside in the absence of Mg2+ or with Triton X-100. Rickettsial proteins are insensitive to trypsin in both whole cells and total membranes, unless the latter are presolubilized with octyl glucoside. Proteinase K degrades all of the total membrane proteins but only the 134 kDa polypeptide of whole cells. Upon immunoblotting predominantly the major outer membrane proteins (134, 31, and 20.5 kDa) and, to a lesser extent, the minor proteins (60, 42, and 17 kDa) interact with human convalescent serum.

Bacterial Outer Membrane Proteins↗
PubMed1990

[Methods of isolation and polypeptide composition of membrane fractions of Rickettsia prowazekii].

The methods of cell lysis by lysozyme in tris-EDTA-sucrose with the consequent disruption of spheroplasts by the osmotic shock were used to obtain the total membranes from the intact or temperature-inactivated Rickettsia prowazekii. Detergents solubilization methods were used for analysis of outer membrane proteins. Sarcosyl insoluble material is shown to contain the main 134, 31, 29.5 and 25 Kd proteins, the minor 78, 60, 42, 17 Kd proteins, while the mixture of both membranes possess a more complex composition. Treatment of total membranes by the 2% octylglycoside results in elimination of the 31 Kd polypeptide. Inactivated Rickettsia can be used for isolation of the outer layer proteins diminishing the risk of working with this pathogenic microorganism.

Bacterial Outer Membrane Proteins↗
PubMed1985

[Riboflavin operon in Bacillus subtilis contains additional promoters].

Using the methods of molecular cloning permitted to show that riboflavin operon of Bacillus subtilis contains four promoters. Three of them are functionally active in the Bacillus subtilis system. The main promoter of the operon with regulatory region was cloned in plasmid pPL603. Cells containing the constructed plasmid pGM32 are resistant to chloramphenicol. The level of resistance is regulated by concentration of riboflavin (the effector of operon). The following model of rib-operon has been proposed: (Formula: see text).

Bacillus subtilis↗
PubMed1976

[Colicin El synthesis in a cell-free system of paired transcription--translation].

Proteins were synthesized in the cell-free coupled transcription-translation systen (S30) under the control of the DNA-templates of plasmid ColEl, phages T2 and Sd. The most active templates were phage T2 DNA and closed plasmid DNA. Plasmid DNA induced synthesis of 8 individual proteins, one of which was a biologically active antibiotic of protein nature--colicin. The titre of colicin synthesized in such a cell-free system reached 1024 U/ml, this being about 100 times greater than the titre of this antibiotic in the colicinogenic bacteria cultures.

Cell-Free System↗
PubMedDate not supplied

[Cloning and expression in Escherichia coli of three Rickettsia prowazekii genes, coding outer membrane proteins].

Rickettsia prowazekii (virulent Breinl strain) random genomic DNA fragments were cloned in the lambda gt11 expression vector by using non-palindromic adaptors. Several immunoreactive clones were selected after screening 20,000 individual recombinant plaques with human convalescent serum. Some recombinants synthesized the complete 60 K protein, and others synthesized beta-galactosidase fusion polypeptides containing epitopes of 134 K protein of the R. prowazekii outer membrane. The amplified genomic library was screened with monospecific antibodies directed against abundant 31 K and 29.5 K outer membrane proteins. Several recombinant clones expressing full or part of 29.5 K polypeptide, and none expressing 31 K polypeptide were revealed. The serum of a patient convalescing from epidemic typhus did not react in western blot with recombinant 29.5 K protein.

Antibodies, Bacterial↗
PubMedDate not supplied

[A simple method for counting Rickettsia cells].

A simple modification of the method for counting Rickettsiae is described. The Escherichia coli cells (ECC) which served as reference particles were stained in suspension with methylene blue mixed with Rickettsia prowazekii (RP) and quickly sprayed over the glass slide. After fixation the samples were stained according to the technique of Gimenez and examined in the light microscope under oil immersion. Through a grid in the eye-piece it was not so difficult to count red-coloured RP and dark-blue ECC against a background formed by impurities. To calculate RP concentration, the reference particles' concentration was multiplied by the dilution factor of RP suspension by the ratio of RP to ECC enumerated. The statistical approach has shown that the wash of the slides during staining procedure does not change this ratio. Differential staining of Rickettsiae with fuchsin is the main clue of this new method to count them even in the crude preparations of infected yolk sacs.

Animals↗
PubMedDate not supplied

[Probable nature of Rickettsia prowazekii virulence].

A 29.5 kda outer membrane protein (OmpB) of R. prowazekii virulent Breinl strain is known to differ from its counterpart in attenuated Madrid E strain, while OmpB of this latter one and of its virulent variant EVir coincide in mobility. The infectivity of these strains for macrophages was previously shown to be different as well, and to correlate with their virulence. Previously cloned R. prowazekii Breinl strain, 1.644-bp insert from lambda gtll recombinant expressing as OmpB in inducer-independent fashion was sequenced and used as a query to search for similarity in non-redundant GenBank/EMBL/DDBJ Data Base aided by BLASTX mail server. Extensive homology of inferred 282-aa sequence to peptidyl-propyl cis/trans isomerase C (PPIase C) of E. coli belonging to parvulin family of rotamases (foldases), and related proteins such as Campylobacter jejuni cell binding factor 2 (Cbf2), B. subtilis PrsA, and Lactococcus lactis PrtM has been revealed.

Bacterial Outer Membrane Proteins↗
PubMedDate not supplied

[Influence of the dentate fascia on the sensory responses of neurons in hippocampal field CA3].

In experiments with unanaesthetized rabbits the influences of electric stimulation of the dentate fascia (DF) on the extracellularly recorded spontaneous and evoked activity of the CA3 neurones were investigated. Stimulation of a fixed locus in the DF during recording in the CA3 by a microelectrode, shifted along the longitudinal axis of the hippocampus, supported the notion of the topical, "segmental" organization of connections between the DF and CA3. A relatively narrow "active zone" (approximately 700 nm) appeared in the CA3 during the threshold DF stimulation: it was bordered by zones with predominantly inhibitory responses to stimulation. The CA3 neurones in the "active zone" rapidly lost their reactivity to sensory stimuli. In the "inhibitory" and "zero" zones the normal level of reactivity to sensory stimuli was preserved.

Animals↗