Recombinant phosphoribosyl pyrophosphate synthetases from <Emphasis Type="Italic">Thermus thermophilus</Emphasis> HB27: Isolation and properties

Two genes of T. thermophilus HB27, TT_C1184 and TT_C1274, encoding proteins with phosphoribosyl pyrophosphate synthetase activity were cloned in an expressing vector pET23d+. Escherichia coli strains overproducing two relevant proteins in soluble forms were obtained. The methods of isolation of thermophilic phosphoribosyl pyrophosphate synthetases Tth PRPPS1 and Tth PRPPS2 were developed. The activities of these enzymes were determined as a function of concentration of metal ions, inorganic phosphate, and temperature. The kinetic parameters for basic natural substrates were calculated; the substrate specificity for different carbohydrate 5-phosphates of D-series was studied. It was shown that the two proteins differ significantly in these characteristics. According to the results and comparison of amino acid sequences of new proteins with those of other phosphoribosyl pyrophosphate synthetases, both enzymes belong to class I PRPPS.     

Analysis of dominant spring mutations in rye

The dominant mutant genes responsible for the spring habit were studied in seven rye plants according to the developed scheme of two-step crosses and analysis of the F2 progeny. The genotypes with a particular genetic formula (heterozygote) were obtained by crossing the studied plants with the winter rye Korotkostebel'naya 69 carrying the recessive genes that control the winter habit of plants. Heterozygotes yielded by different combinations were crossed with each other. The F1 hybrids were either self-pollinated to obtain F2 progeny or crossed with the winter rye. Analysis of the progeny suggests that all seven plants carry the same gene.     

Immunological activity and toxicity of a peroral vaccine made from mutant Re Salmonella minnesota

The possibility of the oral use of heated corpuscular vaccine prepared from S. minnesota mutant R 595 (chemotype Re) for protection against Pseudomonas aeruginosa has been studied. Oral immunization in 3 doses, each containing 10(9) cells of the vaccine strain, has been shown to protect mice from death after the intravenous injection of P. aeruginosa culture in a dose of 5 LD50 and induce a rise in the titers of antibodies to Re-glycolipid (Re-hemagglutinins). After multiple oral administration Re-vaccine shows low acute and chronic toxicity and induces local and systemic immunological transformation.     

Role of immune complexes in thyroid diseases]

To elucidate the immune complex (thyroglobulin-antibody, Tg-Ab) role in thyroid hormone formation, in vitro iodination of Tg--AB immune complex, bovine intact Tg and that of the patient with euthyroid goiter and partially purified AB to Tg were studied. We compared the amount of iodamine acids (MIT, DIT, T4/mole of Tg) forming during iodination in immune complex with other samples. The results suggest that Tg being in complex with antibodies (up to 30-40 mole of antibodies/mole of Tg) is iodinated forming the enough amount of MIT, decreased amount of DIT and T4. A MIT fraction increase is connected with additional iodination of complex antibodies. We suggest that such processes may take place in the patient body and be involved in pathogenesis of thyroid disease.     

Protein aggregates as depots for the release of biologically active compounds

Protein misfolding and aggregation is one of the most serious problems in cell biology, molecular medicine, and biotechnology. Misfolded proteins interact with each other or with other proteins in non-productive or damaging ways. However, a new paradigm arises that protein aggregation may be exploited by nature to perform specific functions in different biological contexts. From this consideration, acceleration of stress-induced protein aggregation triggered by any factor resulting in the formation of soluble aggregates may have paradoxical positive consequences. Here, we suggest that amorphous aggregates can act as a source for the release of biologically active proteins after removal of stress conditions. To address this concept, we investigated the kinetics of thermal aggregation in vitro of yeast alcohol dehydrogenase (ADH) as a model substrate in the presence of two amphiphilic peptides: Arg-Phe or Ala-Phe-Lys. Using dynamic light scattering (DLS) and turbidimetry, we have demonstrated that under mild stress conditions the concentration-dependent acceleration of ADH aggregation by these peptides results in formation of large but soluble complexes of proteins prone to refolding.     

From Genetics of Intraspecific Differences to Genetics of Intraspecific Similarity

Based on the Mendelian approach to heredity, modern genetics describes inheritance of characters belonging to the category of intraspecific difference. the other large category of characters,intraspecific similarity, stays out of investigation. In this review, the genome part responsible for intraspecific similarity is considered as invariant and regulatory. An approach to studying the invariant part of the Drosophila melanogaster genome is formulated and the results of examining this genome part are presented. The expression of mutations at genes in the invariant genome part is different from that of Mendelian genes. We conclude that these genes are present in the genome in multiple copies and they are functionally haploid in the diploid genome. Severe abnormalities of development appearing in the progeny of mutant parents suggest that the mutant genes are genes regulating ontogeny. A hypothesis on an elementary ontogenetic event is advanced and the general scheme of ontogeny is presented. A concept on two types of gene allelism (cis- and trans-allelism) is formulated. This approach opens a possibility for studying genetic material responsible for the formation of intraspecific similarity characters at different taxonomic levels on the basis of crossing individuals of the same species.     

The effects of stabilizing mutations in the central part of the α-chain of tropomyosin on the structural and functional properties of αβ-tropomyosin heterodimers

The effects of the D137L/G126R double mutation in the central part of the tropomyosin α-chain via the simultaneous replacement of two highly conserved non-canonical residues, viz., Asp137 and Gly126, by canonical residues Leu and Arg, respectively, on the properties of the αβ-tropomyosin heterodimer have been studied. It has been shown using circular dichroism that this mutation substantially increases the thermal stability of αβ-tropomyosin heterodimers, which, nevertheless, remains lower than that of αα-tropomyosin homodimers with these mutations in both α-chains. The stability of tropomyosin complexes with F-actin has also been studied by measuring the temperature dependences of their dissociation, which is detected by a decrease in light scattering. It has been revealed that αβ-tropomyosin heterodimers carrying the D137L/G126R mutation in the α-chain dissociate from the surface of actin filaments at a higher temperature than ββ-homodimers but at a lower temperature than αα-homodimers with these mutations in both α-chains. It has also been shown using the in vitro motility assay that D137L/G126R substitution in the α-chain increases the sliding velocity of regulated actin filaments in the case of αα-homodimers, while it noticeably decreases the velocity in the case of αβ-tropomyosin heterodimers. Thus, we can conclude that mutations in one of the chains of the tropomyosin dimeric molecule may have different effects on the properties of tropomyosin homodimers and heterodimers.     

Analysis of dominant spring mutations in rye

The dominant mutant genes responsible for the spring habit were studied in seven rye plants according to the developed scheme of two-step crosses and analysis of the F₂ progeny. The genotypes with a particular genetic formula (heterozygote) were obtained by crossing the studied plants with the winter rye Korotkostebel’naya 69 carrying the recessive genes that control the winter habit of plants. Heterozygotes yielded by different combinations were crossed with each other. The F₁ hybrids were either self-pollinated to obtain F₂ progeny or crossed with the winter rye. Analysis of the progeny suggests that all seven plants carry the same gene.