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V A Spiridonova

Publications and source records attributed to V A Spiridonova.

18 recordsLinked to original sources
PubMed1999

A study of the thermophilic ribosomal protein S7 binding to the truncated S12-S7 intercistronic region provides more insight into the mechanism of regulation of the str operon of E. coli(1).

A study of the ability of His6-tagged ribosomal protein S7 of Thermus thermophilus to interact with the truncated S12-S7 intercistronic region of str mRNA of Escherichia coli has been described. A minimal S7 binding mRNA fragment is a part of the composite hairpin, with the termination codon of the S12 cistron on one side and the initiation codon of the next S7 cistron on the other. It has a length in the range of 63-103 nucleotides. The 63 nucleotide mRNA fragment, which corresponds to a putative S7 binding site, binds very poorly with S7. Tight RNA structure models, which behave as integral systems and link the S7 binding site with the translational regulation region of the hairpin, are suggested. This observation provides more insight into the mechanism of S7-directed autogenous control of translational coupling of str mRNA.

Ammonium Chloride↗
PubMed1998

An extremely high conservation of RNA-protein S7 interactions during prokaryotic ribosomal biogenesis.

Direct determination of RNA-protein complex structures is often facilitated by the use of thermophilic proteins; however E. coli is the most investigated system so far. A hybrid approach is to form heterologous complexes of E. coli RNA with thermophilic proteins. The rationale for this approach to RNA-protein interactions in ribosomes is based on the ability of the thermophilic protein S7 to replace a homologous counterpart in vivo. In vitro, the protein S7 of Thermus thermophilus is able to form complexes with both the minimal 16S rRNA fragment and the intercistronic region of the str operon mRNA from E. coli (Kd = 1.4 x 10(7) M and 1.1 x 10(-7) M respectively). The interaction of Thermus S7 with the E. coli intercistronic mRNA is surprising, because this region does not exist in the thermophilic str operon. It suggests a high degree of conservation of an RNA-binding site on S7.

Bacterial Proteins↗
PubMed1996

[Synthesis in Escherichia coli and certain properties of hybrid protein consisting of a modified precursor of adrenodoxin reductase and shortened precursor of adrenodoxin].

Some aspects of formation and functioning of the cholesterol hydroxylase system were studied. A hybrid protein was synthesized in E. coli composed of the modified form of the (NADPH)adrenodoxin reductase precursor (N-terminal domain) and the shortened adrenodoxin precursor (C-terminal domain). The modified reductase precursor contained 12 extra amino acid residues at the N-terminus and the N-terminally shortened adrenodoxin precursor had 17 C-terminal amino acids of its targeting presequence. The hybrid reduced cytochrome P450scc in a reconstituted system. Thus, neither the extra 44 amino acids at the N-terminus of the reductase nor the 17 amino acid linker affected the interaction of the active sites in the hybrid protein. These modifications do not interfere with the binding of prosthetic groups and formation of the active sites of two enzymes in the E. coli cells. Modified N-terminal sequence of the hybrid does not affect its import into heterologous mitochondria.

Adrenal Cortex↗
PubMed1995

In vivo assembly of plasmid-expressed ribosomal protein S7 of Thermus thermophilus into Escherichia coli ribosomes and conditions of its overexpression.

Researchers still have great difficulty in isolating individual ribosomal proteins from the ribosome in quantities high enough for structural research. To this end, when studying protein S7, we created an E. coli overproducer of the recombinant protein S7 of Thermus thermophilus. The vector for expression was pQE-32 having a strong promoter of E. coli phage T5 and six triplets of His at the 5'-end. This N-terminal six His tag of the fusion protein is responsible for binding to Ni-NTA-resin and allows purifying the protein in one step. The yield of the recombinant protein was 20% and more of the total cellular proteins. In addition we have shown that the recombinant thermophilic protein is incorporated in vivo into the ribosome of E. coli despite the fact that these proteins (thermophilic and mesophilic) have a rather low homology, only 52%. This fact provides a base for the system to study functions of individual proteins.

Amino Acid Sequence↗
PubMed1994

[Design of heterologous mitochondria: import of cattle cytochrome P-450SCC precursors in plant mitochondria].

It has been shown that pre-P-450scc of bovine adrenal cortex mitochondria synthesized in a rabbit reticulocyte lysate cell-free system, is translocated into isolated soybean cotyledon mitochondria, thereby taking the mature form size. This finding is suggestive of the occurrence of a specific receptor and maturase for pre-P-450scc in plant mitochondria. Thus, plant mitochondria can be used as recipients for the mammalian cholesterol hydroxylase system in an attempt to study the mechanism of its formation and preservation.

Adrenal Cortex↗
PubMed1989

Ribosomal protein gene cluster of Halobacterium halobium: nucleotide sequence of the genes coding for S3 and L29 equivalent ribosomal proteins.

A 1643 base pair fragment encoding the S3 and L29 equivalent ribosomal proteins has been sequenced from the archaebacterium Halobacterium halobium. The incomplete open reading frame present upstream from the S3 gene encodes a protein homologous to the eubacterial ribosomal protein L22. The initiation codons of the S3 and L29 genes overlap with the termination codons of the upstream genes. A tight physical organization suggests that these genes are transcribed as a polycistronic operon. Peculiarities of the protein structure and gene organization are discussed.

Amino Acid Sequence↗
PubMed1984

The effect of phospholipids on the activity of mitochondrial pyrophosphatases. Lipidized soluble mitochondrial pyrophosphatase: the coupling factor for oxidation and phosphorylation.

The effect of temperature on the hydrolase activity of mitochondrial pyrophosphatases, i.e. soluble (PPase I) and membrane (PPase II), has been studied. In contrast to the soluble species, the membrane form has inflexions in the Arrhenius curves. However, after lipidization of PPase I by various phospholipids, the curves also acquire inflexion points, which prove similar or identical with the phase separation points of the lipids used. The closeness of the inflexion points of PPase II, containing phosphatidylcholine, and PPase I lipidized by mitochondria phosphatidylcholine, to the phase separation points of this lipid indicates that the inflexions on the PPase II curves should be ascribed to this phospholipid. It has been shown that the hydrolysis of PPi by SMP is affected by the cooperative rearrangements of the entire lipid component of the membrane rather than by the change of the phase state of PPase II phosphatidylcholine. Reconstitution experiments on the PPi synthesis system have shown that after lipidization PPase I is able to incorporate into SMP and become a coupling factor for respiration and PPi synthesis, like PPase II.

Animals↗
PubMed1982

[Effects of lipids on the activity of soluble mitochondrial pyrophosphatase and its conversion to the membrane-bound form].

The effects of lipids on the activity of soluble and membrane-bound pyrophosphatase from beef heart mitochondria were studied. An addition of total mitochondrial lipid, phosphatidyl choline, phosphatidyl ethanolamine or cardiolipin resulted in stimulation of the enzymatic activity and an increase in thermal stability of the soluble enzyme. The maximal activating effect was exerted by the total mitochondrial lipid and phosphatidyl choline. The electrophoretic data suggest that phosphatidyl choline is a component of membrane pyrophosphatase. Preincubation of the soluble enzyme with phosphatidyl choline converted the enzyme into a membrane form, which is capable to carry out the energy-dependent synthesis of PPi in submitochondrial particles.

Animals↗
PubMedDate not supplied

[Aptameric DNA--a new type of thrombin inhibitor].

The formation of complexes between various thrombin preparations and a 30-mer aptamer DNA was comparatively studied, and a correlation between the complex formation and the fibrinogen-hydrolyzing activity of thrombin was found. The aptamer DNA was shown to inhibit the fibrin formation from fibrinogen.

Antithrombins↗
PubMedDate not supplied

[Binding of ribosomal RNAs with ribosomal proteins covalently bound to polymer carriers].

Conditions for covalent binding of ribosome proteins from Escherichia coli with insoluble polymers are found. A number of polymer carriers and several methods of protein binding to them were tested, the best one being the fixation of ribosome proteins on cyanogen bromide-activated Sepharose. Binding is studied with fixed on the polymer total 30S and 50S proteins, with individual S7 and S20 proteins, 16S and 23S RNAs in conditions optimal for the reconstruction of 30S subunits in vitro. It is found that at least some of ribosome proteins, being bound with polymer carrier, retain the ability to recognize their specific sites on RNA.

Binding Sites↗
PubMedDate not supplied

[Study of the binding of the S7 protein with 16S rRNA fragment 926-986/1219-1393 as a key step in the assembly of the small subunit of prokaryotic ribosomes].

Both structural and thermodynamic studies are necessary to understand the ribosome assembly. An initial step was made in studying the interaction between a 16S rRNA fragment and S7, a key protein in assembling the prokaryotic ribosome small subunit. The apparent dissociation constant was obtained for complexes of recombinant Escherichia coli and Thermus thermophilus S7 with a fragment of the 3' domain of the E. coli 16S rRNA. Both proteins showed a high rRNA-binding activity, which was not observed earlier. Since RNA and proteins are conformationally labile, their folding must be considered to correctly describe the RNA-protein interactions.

Amino Acid Sequence↗
PubMedDate not supplied

[The role of lipids in the regulation of ATP and PPi synthesis in mitochondria].

It was demonstrated previously that mitochondria of higher and lower eukaryotes can synthesize, in the course of oxidative phosphorylation, not only ATP but also inorganic pyrophosphate (PPi). Two PPases were isolated from bovine heart mitochondria (soluble--PPase I and membrane--PPase II). Coupling PPase II, in contrast to PPase I, contains phosphatidyl choline, but PPase I is lipidized readily in the presence of different phospholipids. Reconstitution experiments of the PPi synthesis system have shown that after lipidization PPase I is able to incorporate into submitochondrial particles (SMP) and becomes a coupling factor for oxidation and PPi synthesis. It seems that phospholipid is indispensible for incorporation into the membrane and the manifestation of the coupling activity of the enzyme. The effect of lipids on the activity of soluble and membrane-bound pyrophosphatase was studied. It is shown that PPase II phospholipid is involved in the regulation of the hydrolase activity of the isolated enzyme. However, hydrolysis of PPi by SMP and its synthesis by mitochondria are affected by cooperative rearrangements of the entire lipid component of the membrane rather than by changes in the phase state of phosphatidyl choline contained in PPase II. An opposite response of ATP and PPi synthesis to changes in viscosity makes it likely that the viscosity of the mitochondrial inner membrane may control the levelling of these two processes in mitochondria.

Adenosine Triphosphate↗