[Effect of nucleocapsid on multimerization of gypsy structural protein Gag].

The structural protein (Gag) of the gypsy Drosophila retrovirus lacks matrix, but contains capsid and nucleocapsid domains. The Gag forms virus-like particles in a bacterial cell; besides, its capsid alone is able to form aggregates. However, aggregates assembled from the capsid were variable in size and displayed much less organization than particles formed by the whole Gag. The nucleocapsid exerts influence on the organization and structure of particles, and this function is directed by sequence of amino acid residues at its N-terminus (a nucleocapsid proximal part). The particle assembling occurs in the presence of any RNAs or single stranded DNA oligonucleotides.

[Adaptation of yeasts to salt stress (review)]. / Adaptatsiia drozhzhei k solevomu stressu (obzor).

Mechanisms underlying adaptation of various yeasts to salt stress were summarized. Stress response involves modulation of enzymatic activities and changes in gene expression. Elevated salinity of the environment can be regarded as a two-factor stress process that includes an osmotic component leading to loss of cellular turgor and a toxic component inhibiting a set of functions due to an increase in the intracellular concentration of Na+. Adaptation of yeast cells to these stress conditions obligatorily involves the accumulation of osmotically active compounds (mainly glycerol) to counterbalance an increased external osmotic pressure and the modification of plasma membrane transport systems to extrude Na+ from the cell.

[Import of a modified form of a cytochrome P450scc precursor into mitochondria from various sources]. / Import modifitsirovannoi formy predshestvennika tsitokhroma P450scc v mitokhondrii iz razlichnykh istochnikov.

An Escherichia coli strain providing hypersynthesis of a recombinant cytochrome P450scc precursor supplemented with the extra MetArgGlySerHis6GlyIleArg sequence at the NH2-terminus (6His-pP450scc) has been constructed. A procedure for isolation and purification of 6His-pP450scc from the cell homogenate has been elaborated. It has been found that the recombinant precursor is imported into isolated rat liver and rat heart mitochondria as well as into yeast mitochondria. The import is coupled with proteolytic processing resulting in the mature size form of cytochrome P450scc. Modification of the targeting P450scc presequence resulting in its increased positive charge is supposed to relieve tissue-specific restrictions on the P450scc import into mitochondria.

[Yeast mitochondria: distinguishing features, and contribution to solving the general problems of bioenergetics. (Review)]. / Mitokhondrii drozhzhei: otlichitel'nye svoistva, vklad v reshenie obshchikh problem bioénergetiki. (Obzor).

The data obtained by the author during more than 30 years of studies of yeast energy metabolism at cellular and mitochondrial levels are summarized. The data suggest that tightly coupled yeast mitochondria represent not only a fully functional, but often a preferable model system for studying many problems of bioenergetics.

[Cyclosporin biosynthesis and dynamics of bioenergetic processes in cyclosporin-producing strain]. / Biosintez tsiklosporina i dinamika bioénergeticheskikh protsessov u produtsenta tsiklosporina.

An attempt was made to show a correlation between definite bioenergetic parameters of the cells of the cyclosporine-producing culture and biosynthesis of cyclosporine. It was found that the three strains producing cyclosporine used in the study had an alternative cyanide-resistant pathway along with the classical cytochrome chain. In the strain forming only traces of the cyclopeptide during fermentation of the cyanide-resistant respiration constituted 60 to 80%. In the isogenic highly productive strains the cyanide-resistant respiration appeared to be markedly decreased beginning from the 1st day of fermentation and during the maximum biosynthesis of cyclosporine (on day 4 or 5 of fermentation) it reached zero. The ATP content in the cells of the highly productive strain, despite its decrease by the antibiotic biosynthesis peak, remained at a much higher level than that in the strain producing only traces of cyclosporine. A procedure for isolating functionally active mitochondria from the protoplasts was developed and a bioenergetic characterization of the mitochondria isolated from the strains with different antibiotic productions is presented.

[The protoplasts of Acremonium chrysogenum. Biochemical and morphological studies]. / Protoplasty Acremonium chrysogenum. Biokhimicheskie i morfologicheskie issledovaniia.

A procedure for preparing stable A. chrysogenum protoplasts capable of 60 per cent regeneration was developed. Two morphogenetic types of the regeneration were detected. The variants isolated after the protoplast regeneration were characterized by wide ranges of morphological variation. Capacity for the antibiotic production varied from 60 to 160 per cent of the activity of the starting strain. A procedure for isolating functionally active mitochondria from protoplasts of A. chrysogenum was also developed. Their main bioenergetic parameters were studied. In the respiratory chain of the A. chrysogenum mitochondria there were detected three conjugation sites of oxidative phosphorylation.

[Ability of yeast mitochondria to transport magnesium ions]. / O sposobnosti mitokhondrii drozhzhei transportirovat' iony magniia.

Endomyces magnusii mitochondria were shown to be incapable of active Mg2+ transport at 0.1--16 mM concentrations. As was found using the inhibition analysis, when magnesium ions are added to the mitochondria once the phosphorylation cycle is over, the respiration is stimulated because adenylate kinase and H+-ATPase (Mg2+-dependent enzymes) are activated.

[The iron-sulfur center N-2 from NADH-dehydrogenase during direct and reverse electron transport in the mitochondria of rat liver and the yeast Endomyces magnusii]. / Issledovanie zhelezosernogo tsentra N-2 NADN-degidrogenazy pri priamom i obratnom transporte élektronov v mitokhondriiakh pecheni krys i drozhzhei Endomyces magnusii.

A dramatic decrease of the rate of transport of reducing equivalents from NADH to coenzyme Q was observed in the 4th metabolic state (by Chance). It was suggested that this decrease is due to the increase of total time of transition from the structural nonequilibrium state to the equilibrium one of the N-2 center. The structural nonequilibrium state of the center N-2 was observed only under the energy-dependent reverse electron transport, when the substrates for the reduction of coenzyme Q were used.

[Cultivation of Endomyces magnusii yeasts under batch and continuous conditions at an acid pH]. / Kul'tivirovanie drozhzhei Endomyces magnusii v periodicheskikh i nepreryvnykh usloviiakh pri kislom znachenii pH sredy.

The energy parameters of Endomyces magnusii cells and mitochondria were studied under the conditions of batch and continuous cultivation at different pH of the medium containing ethanol. The yeast was found to be capable of growth in the chemostat regime at D=0.2 h-1. Changes in the pH of the medium from 3.0 to 5.6 almost did not change the parameters characterizing oxidative phoshorylation of the mitochondria (the respiration chain contained three phosphorylation points). This correlated with the nearly identical biomass yield and economical coefficient. The content of RNA, DNA and protein remained unchanged at different pH values whereas the content of lipids increased at acid pH.

[Study of the iron-sulfur center N-2 from NADH-dehydrogenase in different metabolic states of the mitochondria from liver and heart]. / Issledovanie zhelezosernogo tsentra N-2 NADN-degidrogenazy v razlichnykh metabolicheskikh sostoianiiakh mitokhondrii pecheni i serdtsa.

The structural--equilibrium and nonequilibrium forms of the center N-2 from NADH-dehydrogenase differ in their parametres of the spin-lattice relaxation. The curves of the temperature dependence of the ESR signal intensity become the effective method of the study of the iron-sulphur proteins. The structural nonequilibrium form of the center N-2 was observed in the "4th" metabolic (by Chance) state, but equilibrium form of the center N-2 prevailed in the "3d" state or in the uncoupled state.

[Reverse electron transfer in mitochondria of the yeast Endomyces magnusii grown on sucrose]. / Obratnyi perenos élektronov v mitokhondriiakh drozhzhei Endomyces magnusii, vyrashchennykh na sakharoze.

Some specific features of cytosol-mitochondria interactions during the growth of the Endomyces magnusii yeast on sucrose media were investigated. Under the given experimental conditions exogenous (cytoplasmic) NADH is the main source of reducing equivalents. Using low temperature EPR spectroscopy, it was demonstrated that exogenous NADH can effectively induce reverse electron transfer in the respiratory chain of the yeast. Fluorimetric assays suggest that End. magnusii mitochondria can utilize the reducing equivalents formed by reverse electron transfer for the reductive amination of alpha-ketoglutarate to form glutamate. The intramitochondrial localization of aminotransferases was postulated.

[Respiratory system of Endomyces magnusii. Properties of mitochondria from cells grown on glycerol]. / Izuchenie dykhatel'noi sintemy Endomyces magnusii. Svoistva mitokhondrii Kletok, vyrashchennykh na glitserine.

Some peculiarities of oxidation of various substrates by tightly coupled highly energized mitochondria from the yeast Endomyces magnusii were studied. During cell growth on glycerol the formation of NADH and alpha-glycerophosphate in the hyaloplasm is paralleled with an adaptive synthesis of highly active dehydrogenases in the mitochondria. The dehydrogenases oxidize these substrates and are localized on the outer surface of the inner mitochondrial membrane. The reducing equivalents of the dehydrogenases enter the respiratory chain at the ubiquinone level by a shunt via the rotenone-sensitive site of the respiratory chain. Terminal oxidation of exogenous NADH, alpha-glycerophosphate and NAD-dependent substrates occurs in the cytochrome chain and is tightly coupled with phosphorylation. The ADP/O value is close to theoretical ones. Oxidation of succinate is partly mediated by alternate cyanide-resistant oxidase; the shunt-off of the electron flow between two alternate pathways is controlled by ADP. The tight coupling and theoretical efficiency of phosphorylation under succinate oxidation can take place only in the presence of salycyl hydroxamate, an alternate pathway inhibitor. A possible physiological role of alternate oxidase and the peculiarities of oxidation control at the individual substrate level are discussed.

[Effect of inhibitors of mitochondrial protein synthesis on the growth of Endomyces magnusii cells]. / Vliianie ingibitorov mitokhondrial'nogo belkovogo sinteza na rost kletok Endomyces magnusii.

The purpose of this work was to study the role of the glycolytic system in maintaining the growth and division of Endomyces magnusii cells. The system of oxidative phosphorylation was blocked by adding the inhibitor of mitochondrial translation, erythromycin, and the inhibitor of mitochondrial transcription, ethidium bromide, to the cultural broth. The two inhibitors of mitochondrial protein synthesis entirely prevented the growth and division of yeast cells in liquid and solid media when either fermentable or nonfermentable substrates were used as carbon sources. Two conclusions have been drawn: (1) glycolysis cannot support the growth of Endomyces magnusii cells and (2) the system of oxidative phosphorylation plays an important role in the energy metabolism of this organism.

[Possible role of the respiratory system of Fusidium coccineum in regulating fusidic acid biosynthesis]. / Vozmozhnaia rol' dykhatel'noi sistemy Fusidium cocineum v reguliatsii biosinteza fuzidievoi kisloty.

The respiration system was studied in three strains of the fungus Fusidium coccineum differing in their capability to synthesize fusidic acid. In all of the three strains, the system of oxidative phoshorylation predominated in supplying the cells with energy. In the strains with low and zero activities, the terminal oxidation of reduced equivalents occurred mainly via the respiration chain with cytochrome oxidase as a terminal component. In the strain with a high activity, there was an alternative cyanide resistant pathway, along with the classical cytochrome chain, and the complete switching to the alternative pathway coincided with the period of the antibiotic maximal accumulation. The induction of the alternative pathway in the strain with a high activity did not involve inhibition of the cytochrome region of the respiration chain. It was shown for the first time that the antibiotic synthesis and the character of cell differentiation can be changed by modifying the pathways of oxidation with specific inhibitors such as chloramphenicol and salicyl hydroxamate. Apparently, there is some general mechanism involved in regulating the production of the antibiotic, cell differentiation, and switching to the alternative oxidative pathway.

[Respiratory system of Endomyces magnusii growing on media with a high fermented sugar content]. / Dykhatel'naia sistema Endomyces magnusii pri roste na sredakh s vysokoi kontsentratsiei sbrazhivaemogo sakhara.

No repression of the synthesis of respiration enzymes was found in the petite--negative yeast Endomyces magnusii under the action of high concentrations of a fermented sugar in the growth medium. Transfer of the cells from 0.3% to 5% sucrose (or glucose) did not result in a decrease in their respiration activity or molar content of cytochromes a+a3 (components of the respiratory chain most sensitive to the glucose repression in other yeast species). The respiration of intact cells grown on 5% sucrose (glucose) was inhibited by 80--94% with cyanide and by 90--98% with cyanide plus salicyl hydroxamate. These data indicate that mitochondria play a predominant role in the oxidative activity of cells. Mitochondria from cells grown on 5% sucrose (glucose) hardly differ in their metabolic activity, effectiveness of oxidative phosphorylation, coupling, and regulation of the metabolic state from mitochondria isolated from completely derepressed cells (the stationary state from mitochondria isolated from completely derepressed cells (the stationary phase of growth, complete exhaustion of the substrate in the course of growth in a medium containing 0.6% sucrose).