[New aspects of the pleiotropic action of the genes coding Saccharomyces cerevisiae exopolyphosphatases].

Inactivation of the key genes, which are responsible for the enzymes of polyphosphates degradation, exopolyphosphatases ppx1 and ppn1, caused both an increase of polyphosphates content in Saccharomyces cerevisiae cells and an increase in chain length of acid-soluble and alkali-soluble fractions. It had no effect on the frequency of volutine granules metachromasy that was based on the interaction of dye molecules with ionic groups of polyphosphates. At the same time, a mutant strain reaction to nystatin differed from the reaction of the parental and wild-type strains when the metachromasy was absent. Obtained data may indicate a pleiotropic effect of ppx1 and ppn1 genes, which encode the major exopolyphosphatase of Saccharomyces cerevisiae and affect the reaction of cells to external factors through changes in the metabolism of polyphosphates.

[Effects of cellobiose lipid B on Saccharomyces cerevisiae cells: K+ leakage and inhibition of polyphosphate accumulation].

Cellobiose lipid B, a natural fungicide produced by the yeast Pseudozyma fusiformata, induces the leakage of K+ and ATP from cells of Saccharomyces cerevisiae. The presence of glucose decreases the effective concentration of cellobiose lipid B. The concentration of cellobiose lipid B was selected that results in a high rate of K+ leakage and a five- to sevenfold decrease in the intracellular ATP content, while the accumulation of acid-soluble polyphosphates decreased only by half. These results indicate the possibility of synthesis of these polymers independently of the ATP level and of the ion gradient on the plasma membrane.

[Antifungal cellobiose lipid secreted by the epiphytic yeast Pseudozyma graminicola].

The yeast Pseudozyma graminicola isolated from plants inhibited growth of almost all ascomycetes and basidiomycetes tested (over 270 species of ca. 100 genera) including pathogenic species. This yeast secreted a fungicidal agent, which was identified as a glycolipid composed of cellobiose residue with two O-substituents (acetyl and 3-hydroxycaproic acid) and 2,15,16-trihydroxypalmitic acid. The release of ATP from the glycolipid-treated cells indicated that this glycolipid impaired the permeability of the cytoplasmic membrane. Basidiomycetes were more sensitive to the cellobiose lipid than ascomycetes.

[Fungicidal activity of cellobiose lipids from cultural fluid of yeast Cryptococcus humicola and Pseudozyma fusiformata].

Cellobiose lipids of yeast fungi Cryptococcus humicola and Pseudozyma fusiformata have similar fungicidal activities against different yeast, including pathogenic Cryptococcus and Candida species. Basidiomycetic yeast reveals maximum sensitivity to these preparations; e.g., cells of cryptococcus Filobasidiella neoformans almost completely die after 30-min incubation in a glycolipid solution at a concentration of 0.02 mg/ml. The same effect toward ascomycetous yeast, including pathogenic Candida species, is achieved only at five to eight times higher concentrations of glycolipids. The cellobiose lipid from P. fusiformata, which, unlike glycolipid from Cr. humicola, has hydroxycaproic acid residue as O-subtituent of cellobiose and additional 15-hydroxy group in aglycone, inhibits the growth of the studied mycelial fungi more efficiently than the cellobiose lipid from Cr. humicola.

[Decrease of phosphate concentration in the medium by Brevibacterium casei cells].

Brevibacteria able to decrease phosphate concentration in the medium are of interest for the study of the role of bacteria in the phosphorus cycle and for development of biotechnology of phosphate removal from waste. Brevibacterium casei, Brevibacterium linens, and Brevibacterium epidermidis grown in media with initial phosphorus concentrations of 1-11 mM were shown to decrease its concentration by 90%. The composition of the incubation medium required for B. casei to carry out this process was established. This process occurs in the absence of glucose but requires the presence of Mg2+, NH4+, and alpha-ketoglutarate. The latter two components may be replaced by amino acids metabolized to NH4+ and alpha-ketoglutarate: histidine, arginine, glutamine, proline, or glutamic acid. No formation of insoluble phosphate salts was observed when the media were incubated under the same conditions with heat-inactivated cells or without cells at pH 7-8.5.

[Inactivation of the ppn1 gene exerts different effects on the metabolism of inorganic polyphosphates in the cytosol and the vacuoles of the yeast Saccharomyces cerevisiae].

Inactivation of the PPN1 gene, encoding one of the enzymes involved in polyphosphate metabolism in the yeast Saccharomyces cerevisiae, was found to decrease exopolyphosphatase activity in the cytosol and vacuoles. This effect was more pronounced in the stationary growth phase than in the phase of active growth. The gene inactivation resulted in elimination of a approximately 440-kDa exopolyphosphatase in the vacuoles but did not influence a previously unknown vacuolar exopolyphosphatase with a molecular mass of >1000 kDa, which differed from the former enzyme in the requirement for bivalent cations and sensitivity to heparin. Inactivation of the PPN1 gene did not influence the level of polyphosphates in the cytosol but increased it more than twofold in the vacuoles. In this case, the polyphosphate chain length in the cytosol increased from 10-15 to 130 phosphate residues both in the stationary and active growth phases. In the vacuoles, the polyphosphate length increased only in the stationary growth phase. A conclusion can be made that the PPN1 gene product has different effects on polyphosphate metabolism in the cytosol and the vacuoles.

[The effect of inactivation of the exo- and endopolyphosphatase genes PPX1 and PPN1 on the level of different polyphosphates in the yeast Saccharomyces cerevisiae].

The inactivation of the PPX1 and PPN1 genes, which encode the major enzymes of polyphosphate degradation (exopolyphosphatase and endopolyphosphatase, respectively), was found to exert different effects on the content of different polyphosphates in the yeast Saccharomyces cerevisiae. The content of relatively low-molecular-weight acid-soluble polyphosphates in mutant yeast strains is inversely proportional to the exopolyphosphatase activity of the cytosol. At the same time, the mutation of these genes exerts no effect on salt-soluble polyphosphates. The content of high-molecular-weight alkali-soluble polyphosphates increases twofold in a mutant with inactivated genes of both exopolyphosphatase and endopolyphosphatase. The data obtained confirm the earlier suggestion that the metabolic pathways of particular polyphosphates in yeasts are different.

[Peculiarities of metabolism and functions of high-molecular inorganic polyphosphates in yeasts as representatives of lower eukaryotes].

The review presents the recent data demonstrating the important role high-molecular inorganic polyphosphates in regulatory processes in a yeast cell. It has been shown that polyphosphates are localized in different cell compartments, where they are metabolized by a special set of enzymes. The review presents the evidence in favor of the concept of multiple functions of these biopolymers in a cell, as well as the data on the pleiotropic effects of mutations in the genes encoding the enzymes of polyphosphate metabolism.

[The fungicidal activity of an extracellular glycolipid from Sympodiomycopsis paphiopedili sugiyama et al]. / Fungitsidnaia aktivnost' vnekletochnogo glikolipida Sympodiomycopsis paphiopedili sugiyama et al.

The yeast Sympodiomycopsis paphiopedili (Ustilaginomycetes) produces an extracellular glycolipid, which possesses the maximum antifungal activity at the pH of the medium equal to 4.0-4.5. Among the approximately 300 tested species of yeastlike and mycelial fungi, more than 80% (including species pathogenic for plants, animals, and humans) were found to be susceptible to this glycolipid.

[Mechanisms of the alkaloid aurantioclavine excretion and uptake during Penicillium nalgiovense VKM F-229 growth]. / O mekhanizme ékskretsii i transporta alkaloida aurantioklavina v protsesse rosta griba Penicillium nalgiovense VKM F-229.

The biphasic dynamics of the alkaloid aurantioclavine in the culture liquid of Penicillium nalgiovense VKM F-229 is shown to be due to the diauxic growth of the fungus on two carbon sources, succinate and mannitol. In the phase of active growth on succinate, the fungus synthesizes aurantioclavine and excretes it into the medium in an energy-independent manner, as a result of which the concentration of the alkaloid in the culture liquid rises. During the phase of metabolic adaptation to the other carbon source, mannitol, the concentration of aurantioclavine in the culture liquid falls, probably due to the energy-dependent uptake of the alkaloid by fungal cells. The reversible excretion of aurantioclavine in P. nalgiovense indicates that these are regulated processes and depend on the growth parameters and the physiological state of the fungus.

[Magnesium orthophosphate, a new form of reserve phosphates in the halophilic archaeon Halobacterium salinarium]. / Ortofosfat magniia--novaia forma rezervirovaniia fosfata u galofi'noi arkhei Halobacterium salinarium.

The accumulation and utilization of reserve phosphates in the extremely halophilic archaeon Halobacterium salinarium were studied. The growth of H. salinarium was found to depend on the initial concentration of inorganic phosphate (Pi) in the culture medium and its content in the inoculum. Growing cells consumed 85-95% of Pi from the medium. Unlike the reserve phosphates of many other microorganisms, which are mainly polyphosphates, the reserve phosphates of H. salinarium cells contain no more than 15% polyphosphates, the rest being magnesium orthophosphate. The excessive consumption of Pi from the medium changed cell morphology and caused the death of part of the cell population. The cells that remained viable could grow in a Pi-deficient medium, utilizing about 70% of reserve magnesium phosphate as the phosphorus source.

[Pseudozyma fusiformata BKM Y-2821--a producer of antifungal glycolipid]. / Pseudozyma fusiformata BKM Y-2821--produtsent ntifugal'nogo glikolipida.

The yeast Pseudozyma fusiformata (the order Ustilaginales) produces an extracellular low-molecular-weight protease-resistant thermostable fungicide, which was active against more than 80% of the 280 yeast and yeastlike species tested. The fungicide, extracted with methanol and purified by column and thin-layer chromatography, was found to consist of glucose and saturated fatty acids.

[Inorganic polyphosphates and phosphohydrolases from Halobacterium salinarium]. / Neorganicheskie polifosfaty i fosfogidrolazy Halobacterium salinarium.

Halobacterium salinarium grown in a liquid medium consumed up to 75% of phosphates originally present in the growth medium and accumulated up to 100 mumol Pi/g wet biomass by the time it entered the growth retardation phase. The content of acid-soluble oligophosphates in the biomass was maximum at the early stage of active growth and drastically decreased when cells reached the growth-retardation phase. The total content of alkali-soluble and acid-insoluble polyphosphates changed very little throughout the cultivation period (five days). The polyphosphate content of H. salinarium cells was close to that of yeasts and eubacteria. The pyrophosphatase, polyphosphatase, and nonspecific phosphatase activities of H. salinarium cells were several times lower than those of the majority of eubacteria. The specific activity of pyrophosphatase, the most active hydrolase of H. salinarium, gradually increased during cultivation, reaching 540 mU/mg protein by the end of the cultivation period. Half of the total pyrophosphatase activity of this halobacterium was localized in the cytosol. The molecular weight of pyrophosphatase, evaluated by gel filtration, was 86 kDa. The effective Km of this enzyme with respect to pyrophosphate was 115 microM.

[Characteristics of polyphosphatase activity of isolated mitochondria from Saccharomyces cerevisiae]. / Kharakteristika polifosfataznoi aktivnosti izolirovannykh mitokhondrii drozhzhei Saccharomyces cerevisiae.

Saccharomyces cerevisiae mitochondria have a polyphosphatase activity which is insensitive to a number of inhibitors of mitochondrial ATPase and pyrophosphatase (PPase). Heparin (20 micrograms/ml) and EDTA (0.5 mM) do not inhibit ATPase and PPase activities but completely suppressed mitochondrial polyphosphatase activity. The mitochondrial polyphosphatase activity is maximal at neutral pH; it is inhibited by monovalent cations in the presence of Tris+ (K+ > Na+ > NH4+), and stimulated by bivalent metal cations (Co2+ > Mg2+ > Zn2+ > Mn2+). The polyphosphatase activity does not significantly depend on polyphosphate chain length from 9 to 208 but is more than one order of magnitude higher than activity with tripolyphosphate. Some properties of mitochondrial polyphosphatase activity differ from the characteristics of polyphosphatases of cell envelope, cytosol, vacuoles and nuclei of the same S. cerevisiae strain.

[Purification and characteristics of Saccharomyces cerevisiae cytosol polyphosphatase]. / Ochistka i kharakteristika polifosfatazy tsitozolia drozhzhei Saccharomyces cerevisiae.

The polyphosphatase with specific activity of 283 units/mg was purified 3450-fold to homogeneity with 3.8% yield from cytosol of Saccharomyces cerevisiae yeast. Polyphosphatase is monomeric 40 kD protein. The enzyme hydrolyzes polyphosphates of various chain length including tripolyphosphate but ATP, pyrophosphate, and p-nitrophenyl phosphate are not the substrates. Enzyme activity is maximal at 50 degrees C and pH 6.5-8.5. Several cations of bivalent metals stimulated the enzyme activity 8-66-fold (Co2+ > Mn2+ > Mg2+ > Zn2+ > Fe2+). The enzyme is inactive in the presence of Ca2+ or Cu2+. Heparin, antibodies against cell-envelope polyphosphatase, and Cu2+ or Zn2+ in the presence of Mg2+ are potent inhibitors of cytosolic polyphosphatase. Cytosolic polyphosphatase is similar to purified cell-envelope polyphosphatase but differs in some properties from nuclear, vacuolar, and mitochondrial polyphosphatase of the very same yeast.