Action of heliomycin on protein and mucleic acid synthesis in Staphylococcus aureus]

Heliomycin inhibited synthesis of RNA in Staph. aureua which was clearly shown in the study of the antibiotic effect on RNA synthesis in the lag phase of the culture development: heliomycin markedly lowered the maximum RNA level in the biomass observed in the culture at the beginning of the exponential growth. On further growth of the culture heliomycin induced a significant retardness of the process of the natural decrease in the RNA biomass level resulting in increased content of RNA in the cells growing in the presence of heliomycin as compared to the control culture. Retarded natural decrease in the RNA biomass level in the presence of heliomycin was observed also on the antibiotic addition just at the beginning of the exponential growth, during the period of maximum RNA accumulation in the cells. Heliomycin had no effect on synthesis and biomass levels of DNA. Heliomycin inhibited the protein synthesis and was close to chloramphenicol by the level of inhibition of the summation protein synthesis in the biomass. However, comparison of the effect of the above antibiotics on synthesis of beta-galactosidase, an individual enzyme protein showed that heliomycin was much less active as an inhibitor of protein synthesis in comparison to chloramphenicol.     

Effect of heliomycin on the respiration and oxidative phosphorylation of the liver mitochondria of the rat

The effect of heliomycin and known uncouplers of oxidative phosphorylation on respiration and oxidative phosphorylation was studied comparatively. Heliomycin, as well as 2,4-dinitrophenol, valinomycin and gramicidin S inhibited the mitochondrial synthesis of ATP. This process was inhibited completely by heliomycin at a concentration of 1.5 x 10(-5) M. The synthesis of inorganic pyrophosphate, the other macroergic compound, was also inhibited by heliomycin, ATPase and pyrophosphatase of uncoupled mitochondria being not inhibited by the antibiotic. Like 2,4-dinitrophenol, heliomycin stimulated the synthesis of ATPase and respiration in intact mitochondria. Probably, heliomycin inhibited the synthesis of ATP and pyrophosphate by uncoupling the processes of respiration and oxidative phosphorylation. It was shown earlier that heliomycin, a specific inhibitor of bacterial RNA synthesis, also affected energy metabolism of bacterial cells by inhibiting the synthesis of ATP and active transport.     

Effect of glycerin on the biosynthesis of heliomycin by Streptomyces olivocinereus

Glycerol as the sole carbon source was added to the medium or biosynthesis of heliomycin by Streptomyces olivocinereus and the effect of its concentration on the culture growth and antibiotic production was studied. The culture growth and the amount of the antibiotic synthesized per 1 unit of the fermentation broth were limited by glycerol added in quantities of 0.05 to 1 per cent. Further increasing of the glycerol concentration had no significant effect on the culture growth and antibiotic biosynthesis. The amount of the antibiotic synthesized per 1 unit of the mycelial mass relatively slightly depended on the glycerol concentration. The rate of glycerol consumption by the young 24-hour culture in batch fermentations markedly exceeded that of glycerol consumption by the 48-hour culture. The younger mycelium significantly increased its rate of glycerol consumption when the initial concentration was increased whereas the rate of glycerol consumption by the more mature mycelium did not depend on the initial concentration of the carbon source (within 0.5-2 per cent). The rate of heliomycin biosynthesis practically slightly depended on the initial concentration of glycerol.     

Role of the functional groups of the sibiromycin molecule in DNA binding]

Biological activity of 2 derivatives of sibiromycin, an antibiotic close by its chemical structure to antramycin and their capacity for formation of complexes with DNA was studied. Anhydrosibiromycin like sibiromycin formed a complex with DNA. The antibiotic increased the DNA melting point but to a less extent than sibiromycin. Anhydrosibiromycin had a low activity in the system of DNA-dependent RNA-polymerase. The low biological activity of anhydrosibiromycin must be due to instability of the antibiotic complex with DNA. Methyl ether of sibiromycin by the phenol hydroxyl, the other derivative of sibiromycin had no biological activity and did not interact with DNA. On the basis of experimental data it was suggested that definite functional groups of the sibiromycin participated in DNA binding.     

Anthracycline antibiotic, beromycin. The formation of complexes with DNA and the suppresion of nucleic acid biosynthesis]

Beromycin, an antitumor anthracycline antibiotic formed in vitro complexes with native and denaturated DNA and ribosomal RNA. Beromycin had a comparatively low constant of DNA binding and to a less extent increased the melting temperature and viscosity of DNA than the other anthracycline antibiotics. A peculiar property of beromycin was very slow binding with DNA, the complex formation was completed in 60 minutes. Beromycin had a selective inhibitory effect on synthesis of nucleic acids in bacterial and tumor cells. Beromycin inhibited synthesis of RNA in the DNA-dependent RNA-polymerase reaction when both the native and denaturated DNA were used as the template. A lower biological activity of beromycin as compared to the other anthracycline antibiotics, such as rubomycin or carminomycin may be explained by lower affinity of this antibiotic to DNA.     

Elaboration of the method of "quiescent cells" for the study of heliomycin-synthesizing system of Streptomyces olivocinereus

A resting cell procedure was developed for S. olivocinereus. Washed mycelium of S. olivocinereus produced heliomycin for a short incubation period of 1.5 hours in a nitrogen-free medium containing a buffer solution, salts, a source of carbon and an inhibitor of protein synthesis. With the developed procedure production of heliomycin in the system of resting cells was investigated. For this purpose mycelium collected during various phases of S. olivocinereus development in batch cultures was used. It was found that in the batch cultures the rate of heliomycin production by the 24th hour of the development was comparable with that of the antibiotic accumulation in the resting cell system. After that period it markedly decreased by the 48th hour. This deviation in the dynamics of heliomycin production in batch cultures and the resting cell system can serve as a basis for further studies on heliomycin biosynthesis control by the carbon source.     

Characteristics of the intrinsic luminescence of Actinomyces olivocinereus--producer of heliomycin]

Some characteristics of UV-induced luminescence were studied with Actinomyces olivocinereus producing the antibiotic heliomycin. The luminescence of the growth medium was found to be caused not by heliomycin, but by some other factors. The luminescence of heliomycin in the colonies was quenched as a result of its screening with melanin pigments located in a layer between the aerial and substrate mycelium.     

Effect of population density on Actinomyces resistomycificus biosynthesis of heliomycin and resistoflavin]

Determination of heliomycin and resistoflavin contents in colonies of Act. resistomycilicus grown on pads with different density showed that the population density may be a factor controlling the level of the antibiotic biosynthesis by Act. resistomycificus and directing it along production of heliomycin or resistoflavin.     

Effect of distamycin a on the structure and template activity of DNA in RNA - polymerase system

It is shown that native and denatured DNA form complexes with the oligopeptide-antibiotic distamycin A. The pronounced inhibition of the incorporation of AMP into RNA in the DNA directed RNA-polymerase system is due to the interference of the antibiotic with DNA.     

Effect of brain cytosol proteins of embryonal and adult animals on RNA-polymerase activity of isolated brain nuclei]

Cytosol and its fractions obtained by the precipitation with ammonium sulphate and ion-exchange chromatography have been studied for their effect on the RNA-polymerase activity of isolated nuclei. We observed the discrepancies in the action of total cytosol of embryonal, newborn or adult animals on the label's incorporation in RNA. It was found that some fractions increased DNA-polymerase activity of isolated nuclei in cattle embryonal cytosol. The same fractions obtained from adult cytosol did not act in such a way. It was found that most fractions obtained from cytosol of adult brain inhibited the RNA-polymerase activity of brain nuclei.     

Kinetic aspects of the relation of the growth of the producer and the biosynthesis of heliomycin depending on the carbon source in the medium

Kinetic parameters of Streptomyces olivocinereus 11-98 growth and biosynthesis of heliomycin were studied. It was shown that carbon sources such as glycerol, mannitol and ramnose were the most favourable for the antibiotic biosynthesis. These carbon sources belonged to the group of substances providing high growth rates of the culture. Ranging of the culture growth rates and antibiotic production levels revealed a set of carbon sources providing a converse relationship between the growth rate and antibiotic biosynthesis i.e. L-arabinose, potassium gluconate, raffinose and sucrose. It was suggested that these compounds were catabolic type regulators of heliomycin biosynthesis.     

Properties of the rat liver DNA-dependent RNA-polymerase stored at -25 degrees C in the presence of glycerol or polyethyleneglycol-400

The effect of slow freezing (1-2 degrees C/min) was studied as applied to the template activity of DNA in the RNA-polymerase reaction. It was found out that the activity of each RNA-polymerase form decreases after 24-hour storage by freezing at -25 degrees C in the presence of glycol or polyethylene glycol-400. The study of the enzyme in the glycerol concentration gradient showed sedimentation constant changes.     

Effect of vitamin E on transcription in isolated nuclei and rat liver chromatin in normal status and in E-hypovitaminosis]

The effect of alpha-tocopherol on the RNA-polymerase activity in isolated rat nuclei and chromatin from normal and E-deficient rats and the possible role of tocopherol-binding proteins in this process were studied. Some differences in the RNA-polymerase activities of the nuclei were found; however, in vitro added alpha-tocopherol had no effect on the level of the label incorporation into RNA. No effect of alpha-tocopherol on this process was observed after addition of cytosol either. Analysis of chromatins from normal and E-deficient rats revealed no differences in their RNA-polymerase activities. In vitro added alpha-tocopherol increased the RNA-polymerase activity of normal (but not of vitamin E-deficient) rats. Some differences in the RNA-polymerase activities were noted after addition to the incubation medium of the Triton X-100-solubilized nuclear fraction specifically binding alpha-tocopherol. This effect was enhanced in the presence of exogenous alpha-tocopherol. The susceptibility of chromatin from normal and E-deficient rats to DNAse I hydrolysis was also found to be different. It was concluded that vitamin E can influence the RNA-polymerase activity of the nuclei and chromatin as well as the chromatin structure and that alpha-tocopherol-binding proteins are necessary for the vitamin E effect on the RNA-polymerase activity to be manifested.     

Clinical and laboratory comparisons of tetracycline penetration through the blood-cerebrospinal fluid barrier in central nervous system diseases]

The data on tetracycline penetration from the blood into the serebrospinal fluid of patients with different diseases of the central nervous system are presented. Clinico-laboratory comparisons showed that the antibiotic penetration did not depend on the character and severity of the main disease of the brain (tumor, trauma, abscess). No dependence on the surgical intervention was either found. The index of tetracycline penetration from the blood into the liquor did not depend on the drug administration route, i.e. intramuscularly or orally. The presence of the post-operative meningitis increased permeability of the brain membranes for tetracycline.     

Specific modification of DNA at E. coli RNA-polymerase binding sites

Specific modification of promoter regions of DNA has been studied. Plasmid pK56B1 DNA has been used as a model to test RNA-polymerase binding with DNA under various conditions. RNA-polymerase is shown to form specific complexes with DNA which are stable in solutions with a moderate ionic strength (0.1-0.2 M NaCl), under pH 5-8 in the presence of 0.5 M O-methylhydroxylamine of O-delta-aminooxybutylhydroxylamine. Escherichia coli JM103 cells have been transfected with DNAs treated with 0.5 M O-methylhydroxylamine at 37 degrees C, pH 5.2. The inactivation effects of the mutagen on single-stranded DNA of bacteriophage M13 m p1, double-stranded form of this bacteriophage (replicative form-RF) and on the complex of RNA-polymerase with RF DNA have been compared. The obtained data confirmed the specificity of reagent action with DNA sites binding with the enzyme. Selectivity of promoters modification has been confirmed also by the analysis of M13 m p1 DNA mutations induced in lacZ' gene by delta-aminooxybutylhydroxylamine effect on the DNA complex with DNA-polymerase.     

Effect of etimizol on the RNA synthesizing activity of brain cell nuclei during the learning process in rats

A study was made of the effect of the central nervous system stimulant ethymizol on RNA-polymerase activity of cell nuclei of the rat cerebral cortex and hippocampus during learning with different reinforcements. Ethymizol stimulated the incorporation of 3H-UTP in the TCA-insoluble fraction of hippocampal nuclei during training of the animals in the avoidance response to the light in a Y-shaped mize and training in the reaction of spontaneous alternation of food reinforcements in a complex mize, and decreased the ratio brain cortex/hippocampus RNA-polymerase activity. The data obtained are discussed from the standpoint that the action of ethymizol is consequent on the activation of the genome of nervous cells.     

Daunomycin modifies the sequence-selective recognition of DNA by actinomycin.

The antitumour antibiotic actinomycin D normally binds to DNA by intercalation at sequences containing the CpG step, but in the presence of daunomycin it has been reported to interact with poly(dA-dT). This observation has neither been confirmed nor explained. Here we have used a photoreactive 7-azido derivative of actinomycin to study the effect of daunomycin on its binding to three DNA fragments. Daunomycin did indeed alter the binding of actinomycin to the DNA, such that the antibiotic was displaced from its primary GpC sites onto secondary sites in the DNA, though not to AT regions especially. These findings suggest a possible scientific explanation for the increased toxicity seen during combination chemotherapy with these two drugs.     

Structure of heliomycin produced by Streptomyces heliomycini and antibiotic 11-98 produced by Streptomyces olivocinereus

The data on UV, 1H NMR and mass spectroscopy confirmed that heliomycin produced by S. heliomycini and antibiotic 11-98 produced by S. olivocinereus were identical with resistomycin. The major minor component produced by S. heliomycini was shown to be resistoflavin which was also confirmed by physicochemical methods.