Synthesis of a brain-specific protein (S100 protein) in a lectin-resistant mutant of a rat glial cell line (C6)

The synthesis of S100 protein increases toward the end of the exponential phase of growth of clonal rat glial cells C6 in monolayer culture. Moreover the synthesis of this protein can be increased by treatment of C6 cells with the lectin succinylated concanavalin A (succinyl ConA). In order to study the relationship between these two inductions of S100 protein we have isolated a cell line resistant to ConA from a population of C6 cells. The resistant cells (C6-ConAsuitr) have less succinyl ConA receptors than C6 cells.In contrast to C6 cells, the synthesis of S100 protein does not increase in C6-ConAsuitr cells after treatment with succinyl ConA. However in both cell types the synthesis of S100 protein increases toward the end of the exponential phase of growth.These results suggest firstly that the induction of S100 protein in C6 cells by succinyl ConA is mediated by an interaction of the lectin with its membrane receptors and secondly that the initial steps in the induction of S100 protein by the lectin are different from the initial steps in the induction of this protein which occurs toward the end of the exponential phase of growth in monolayer culture.     

Regulation of synthesis of a brain-specific protein in monolayer cultures of clonal rat glial cells

C6 cells were grown in monolayer culture under conditions permitting continued exponential cell division after attainment of a density at which extensive intercellular contacts were formed. An increase in the relative synthesis of S100 protein coincided with the time of formation of extensive intercellular contacts and preceded the onset of the stationary phase of growth by three generations. These observations suggested that the induction of S100 protein synthesis was mediated by cell contact and not by an arrest of cellular growth. The mechanism of this induction was first studied in a homologous non-initiating cell-free protein-synthesizing system from C6 cells, using fixed amounts of free amino acids or fully charged rat liver aminoacyl-tRNA as a source of precursors for protein synthesis. Real synthesis of total soluble proteins decreased as the cells progressed from logarithmic to stationary growth while synthesis of S100 protein increased during this period. The capacity of poly(A)+ RNA from logarithmic and stationary cultures to direct the synthesis of S100 protein was estimated in a cell-free protein-synthesizing system derived from wheat embryos. Increased synthesis of S100 protein in stationary cultures was directly correlated with an increase in translatable S100 protein mRNA.     

Changes in protein content per cell during growth of mouse L cells

The relationship between cell density and protein content per cell was examined in monolayer and suspension cultures of mouse L cells. In monolayer cultures, the protein content per cell reached a maximum at 6 h after plating and retained this level for 18 h. Thereafter, the protein content per cell declined gradually during the exponential growth phase and finally returned to the initial level at the stationary phase. The changes were neither due to the effect of trypsinization nor to the exhaustion of the medium. The protein content per cell in a sparse culture was always greater than that in a dense culture for monolayer culture of L cells. In suspension culture the increase of protein content per cell during the lag phase was similar to that found in monolayer cultures. However, the gradual decline of protein content per cell observed during the exponential phase of monolayer cultures was not detected during that of a suspension culture. The results suggest that the decrease of protein content per cell in monolayer cultures may be related to some function of cell plasma membrane which could be inhibited by a cell-to-cell contact.     

Lectin-mediated stimulation of DNA synthesis in cultures of embryonic neural retina cells

Plant lectins and other agents which are mitogenic for lymphocytes and fibroblasts were tested for their effects on DNA synthesis in primary monolayer cultures of neural retina cells from 10-day chick embryos. Concanavalin A (ConA), phytohemagglutinin (PHA), wheat germ agglutinin (WGA), and anti-retina cell antiserum significantly stimulated [³H]TdR incorporation; the maximum increase was reached 15 h after exposure of the cultures to these agents. Cells stimulated by ConA to synthesize DNA subsequently divided. The divalent succinyl derivative of ConA had a considerably lesser effect than the native tetramer, suggesting that cross-linking of cell surface components may be an important aspect of the changes that lead to the stimulation of DNA synthesis in these cells.Using [¹²⁵I]ConA, the average number of ConA-binding sites per 10-day retina cell was estimated to be 1.7 × 10⁶ (under the culture conditions employed); binding of the lectin to 25–50% of these sites was sufficient to elicit the maximal stimulation of DNA synthesis. Continuous association of the lectin with the cell surface for up to 8 h was essential for the maximal effect, since removal of the lectin from the cell surface (with α-methyl mannose) prior to this time reduced or prevented the stimulation of DNA synthesis.The stimulation by ConA of DNA synthesis in these cultures was dependent on the cell density and was reduced or absent at lower than optimal densities. Examination of this effect suggested that the frequency of intercellular contacts or specific cell associations play a role in the responsiveness of these cells to stimulation of DNA synthesis by ConA.     

Protein synthesis, ribosomal protein S6 phosphorylation in vitro and the effects of amiloride: SDS gel electrophoresis studies in the Yoshida ascites tumor (AH 130) grown in vivo

Cell-free cytosolic extracts from the Yoshida (AH 130) rat ascites hepatoma cell line, grown in vivo, showed high ribosomal protein S6 kinase activity in vitro, as measured by transfer of 32P to exogenous 40S rat liver ribosomal subunits, in both exponential growing and stationary phase cells. A significant decrease of protein synthesis (3H-leucine incorporation into total cell protein) was found to occur in cells reaching the stationary phase of growth, suggesting that S6 phosphorylation was not tightly coupled to the rate of the intraperitoneal cell growth and of protein synthesis in these tumor cells. When the cell-free cytosolic extracts were prepared from cells exposed to amiloride, at concentrations that inhibit the Na+/H+ exchange, a decrease of S6 kinase activity was observed only in exponential growing cells, suggesting the possibility of coupling of the Na+/H+ exchange with phosphorylation of intracellular proteins in these tumor cells. Actually, stationary phase cells showed unchanged S6 kinase activity under the same conditions, possibly due to the extremely low Na+/H+ exchange activity, previously demonstrated (Cell Biol. Int. Rep., 1985, 9, 1017-1025). The present experiments support the hypothesis that the regulation of protein synthesis is not tightly coupled to phosphorylation-dephosphorylation cycles, at least of ribosomal protein S6, in cells characterized by a rather uncontrolled growth such as the Yoshida (AH 130) rat ascites hepatoma. In this connection, an elevated degree of protein phosphorylation, such as that of the ribosomal protein S6, could be a general phenomenon of neoplastic transformation.     

Lectins modulate the internalization of recombinant interferon-alpha A and the induction of 2',5'-oligo(A) synthetase

After binding to specific cell surface receptors, interferon-alpha (IFN-alpha) along with its receptor is internalized by the cells. However, the physiological significance of the internalization of IFN is not known. We have found that the lectin concanavalin A (ConA), which does not inhibit the binding of 125I-rIFN-alpha A, inhibits both the internalization of 125I-rIFN-alpha A and the rIFN-alpha A-induced increase in the levels of 2',5'-oligo(A) synthetase mRNA and enzymatic activity in the B lymphoblastoid cell line Daudi. The reduced level of IFN-induced 2',5'-oligo(A) synthetase in ConA-treated cells was due neither to direct inhibition of the enzymatic activity nor to generalized inhibition of protein or RNA synthesis. The dose-response curves were similar for the effect of ConA to inhibit 125I-rIFN-alpha A internalization and 2',5'-oligo(A) synthetase induction. The correlation between the ConA-mediated inhibition of both 125I-rIFN-alpha A internalization and 2',5'-oligo(A) synthetase induction suggests that internalization of rIFN-alpha A plays a role in the responses to rIFN-alpha A. However, since ConA inhibits protein mobility in the plasma membrane, it is possible that ConA is also preventing aggregation of IFN receptors or interactions between IFN receptors and signal transducing proteins in the plasma membrane that may be necessary for responses to IFN.     

Synthesis of the nuclear protein cyclin (PCNA) and its relationship with DNA replication

Synthesis of the nuclear protein cyclin (MW 36 000) and DNA in quiescent mouse fibroblasts is coordinately induced by serum and purified growth factors. Inhibition of DNA synthesis by hydroxyurea or aphidicolin in serum-stimulated quiescent cells does not affect the induction of cyclin. The levels of cyclin synthesis decrease rapidly at the end of the S phase. Immunofluorescence studies reveal that there are dramatic changes in the nuclear distribution of cyclin during S phase and that these depend on DNA synthesis or events during S phase. These observations strengthen the notion that cyclin is an important component of the events leading to DNA replication.     

Lymphocyte commitment to DNA replication induced by concanavalin A

Commitment of lymphocytes to DNA replication induced by ConA was investigated by adding α-MM (a saccharide that competes with the lectin's lymphocyte binding sites) at various times to lymphocyte cultures that had been treated with a wide range of ConA concentrations. After 24 h of culture, α-MM addition has essentially no effect on cells treated with optimal concentrations of ConA, results in a marked blastogenic response of cells treated with supra-optimal (non-mitogenic) concentrations of ConA, and severely inhibits blastogenesis of cells treated with suboptimal concentrations of the lectin. Furthermore, the time of commitment is progressively shortened as the concentration of mitogen is increased. Thus, cells were committed to DNA replication as early as 5 h after incubation with supra-optimal concentrations of ConA. Induction of commitment does not occur when cells are incubated with ConA at 4 °C. Extensive crosslinking of membrane sites appears to be associated with the induction of early commitment by ConA, since the bivalent succinyl ConA failed to exhibit this effect. These findings indicate the need for re-evaluation of previous studies utilizing competing saccharides to determine kinetics of cell commitment to DNA replication.     

Cell surface changes in transformed human lymphocytes : I. ConA and E-PHA induced unique changes in surface topography

Binding studies with six purified plant lectins were used to investigate membrane alterations that occur in lymphocyte transformation. Normal human peripheral blood lymphocytes transformed with E-Phytohemagglutinin (E-PHA) or concanavalin-A (Con-A) generally possessed increased numbers of lectin receptors. When this increase was corrected for the expanded surface area of transformed lymphocytes, it appeared that E-PHA and ConA each produced a unique and complex reorganization of cell surface topography. Surface alterations occurred independently of DNA synthesis, cell proliferation, and microtubule or microfilament function. Puromycin inhibited emergence of new lectin receptors on cells transformed with E-PHA, but not with ConA. Lymphocytes incubated with either lectin showed increased incorporation of [¹⁴C]galactose into trypsin-sensitive cell surface glycoproteins. This incorporation was abolished by puromycin in cells stimulated by E-PHA but not by ConA. These studies demonstrate that although both lectins induce similar morphological alterations in human lymphocytes, at the molecular level the structural changes induced in the cell membrane by these two lectins differ considerably. Furthermore, these structural alterations are mediated via different mechanisms in the two groups of cells. De novo protein synthesis is required for cell surface reorganization in PHA-stimulated cells, but not in cells stimulated by ConA. The effect of ConA appears to be to enhance attachment of saccharide structures to pre-synthesized membrane proteins.     

伴刀豆蛋白A及其衍生物对培养软骨细胞蛋白多糖代谢的影响

观察了ＣｏｎＡ对培养软骨细胞ＰＧ合成代谢的影响。证实ＣｏｎＡ能够使培养的软骨细胞高分子硫酸化ＰＧ的合成增加３～４倍,其分子量、硫酸化部位和硫酸化程度与对照组相比无明显差异,是具有正常结构的软骨型ＰＧ。ＣｏｎＡ对低分子型ＰＧ的合成未见明显的影响。ＣｏｎＡ促进ＰＧ合成的作用可由ＭｅＭａｎ完全解除,比具有同样效应的激素、生长因子都强,并有明显的凝集素特异性。推测ＣｏｎＡ的作用可能与软骨细胞膜或细胞内的分化诱导因子的受体或软骨中存在的ＣｏｎＡ软骨细胞分化因子有关。     

Changes in ribosome function induced by protein kinase associated with ribosomes of Streptomyces collinus producing kirromycin.

Protein kinase associated with ribosomes of streptomycetes phosphorylates 11 ribosomal proteins. Phosphorylation activity of protein kinase reaches its maximum at the end of exponential phase of growth. When (32)P-labeled cells from the end of exponential phase of growth were transferred to a fresh medium, after 2 h of cultivation ribosomal proteins lost more than 90% of (32)P and rate of polypeptide synthesis increases twice. Protein kinase cross-reacting with antibody raised against protein kinase C was partially purified from 1 M NH(4)Cl wash of ribosomes and used to phosphorylation of ribosomes. Phosphorylation of 50S subunits (L2, L3, L7, L16, L21, L23, and L27) had no effect on the integrity of subunits but affects association with 30 to 70S monosomes. In vitro system derived from ribosomal subunits was used to examine the activity of phosphorylated 50S at poly(U) translation. Replacement unphosphorylated 50S with 50S possessed of phosphorylated r-proteins leads to the reduction of polypeptide synthesis of about 52%. The binding of N-Ac[(14)C]Phe-tRNA to A-site of phosphorylated ribosomes is not affected but the rate of peptidyl transferase is more than twice lower than that in unphosphorylated ribosomes. These results provide evidence that phosphorylation of ribosomal proteins is involved in mechanisms regulating the translational system of Streptomyces collinus.     

Regulation of catalase synthesis in Salmonella typhimurium.

The specific activity of catalase in Salmonella typhimurium and other enteric bacteria decreased during the logarithmic phase of growth and increased at the onset and during the stationary phase. The increase in catalase synthesis at the end of the exponential phase in S. typhimurium cells coincided with the lowest pH value reached by the culture. Maintenance of the pH at a constant neutral value did not alter the typical pattern of synthesis in contradiction of the results previously reported (McCarthy and Hinshelwood. 1959). A sudden decrease in the pH value of an S. typhimurium culture during exponential growth by addition of HC1 did not cause an alteration in the catalase synthesis pattern. Addition of hydrogen peroxide to S. typhimurium cultures within the range 1 muM TO 2MM during the exponential growth phase stimulated catalase synthesis. The extent of catalase synthesis depended on the concentration of hydrogen peroxide; the maximum stimulation was observed at 80 muM. Increased catalase synthesis was not detected for 10 to 15 min after hydrogen peroxide addition. Hydrogen peroxide was produced by S. typhimurium cultures during the exponential and stationary growth phases. However, no direct relationship between hydrogen peroxide accumulation and synthesis of catalase was observed.     

eIF2alpha phosphorylation, stress perception, and the shutdown of global protein synthesis in cultured CHO cells

The perception of environmental stress in animal cells engineered to produce heterologous protein leads to the induction of stress signaling pathways and ultimately apoptosis and cell death. Protein synthesis is regulated in response to various environmental stresses by phosphorylation of the alpha subunit of the eukaryotic initiation factor 2 (eIF2). In this study we have utilized a model system of Chinese hamster ovary cells engineered to secrete recombinant TIMP-1 protein to investigate the relationship between the cellular rate of protein synthesis, eIF2alpha phosphorylation, cellular stress perception, and the rate of cell specific recombinant protein synthesis. The rate of total protein synthesis was maximal after 48 hours of culture, remaining relatively high until 96 hours of culture, after which a decline was observed. Towards the end of culture a marked increase in labeled secreted protein was observed. Total eIF2alpha expression levels were high during the exponential growth phase and decreased slightly towards the end of culture. On the other hand, the relative expression of phosphorylated eIF2alpha showed a bi-phasic response with a small increase in phosphorylated eIF2alpha observed at 48 hours of culture, and a significant increase at 120 hours post-inoculation. The large increase in phosphorylated eIF2alpha coincided with the observed increase in labeled secreted protein and the decline in total cellular protein synthesis. A marked increase in ubiquitination was also observed at 120 hours post-inoculation that coincided with reduced rates of cellular protein synthesis and mRNA translation attenuation. We suggest that eIF2alpha phosphorylation is an indicator of cellular stress perception, which could be exploited in recombinant protein manufacturing to commence feeding and engineering strategies.     

Recombinant interleukin 2 regulates levels of c-myc mRNA in a cloned murine T lymphocyte.

The cellular oncogene c-myc has been implicated in the regulation of growth of normal and neoplastic cells. Recently, it was suggested that c-myc gene expression may control the G0----G1-phase transition in normal lymphocytes that were stimulated to enter the cell cycle by the lectin concanavalin A (ConA). Here we describe the effects of purified recombinant interleukin 2 (rIL2) and of ConA on levels of c-myc mRNA in the noncytolytic murine T-cell clone L2. In contrast to resting (G0) primary cultures of lymphocytes, quiescent L2 cells have a higher RNA content than resting splenocytes and express receptors for interleukin 2 (IL2). Resting L2 cells are therefore best regarded as early G1-phase cells. Purified rIL2 was found to stimulate the rapid accumulation of c-myc mRNA in L2 cells. Levels of c-myc mRNA became maximal within 1 h and declined gradually thereafter. In contrast, ConA induced slower accumulation of c-myc mRNA in L2 cells, with increased levels of c-myc mRNA becoming detectable 4 to 8 h after stimulation. Experiments with the protein synthesis inhibitor cycloheximide demonstrated that the increase in levels of c-myc mRNA that were induced by ConA was a direct effect of this lectin and not secondary to IL2 production. Cyclosporin A, an immunosuppressive agent, markedly reduced the accumulation of c-myc mRNA that was induced by ConA but only slightly diminished the accumulation of c-myc mRNA that was induced by rIL2. Taken together, these data provide evidence that (i) c-myc gene expression can be regulated by at least two distinct pathways in T lymphocytes, only one of which is sensitive to cyclosporine A, and (ii) the accumulation of c-myc mRNA can be induced in T cells by IL2 during the G1 phase of the cell cycle.     

Foreign gene expression (beta-galactosidase) during the cell cycle phases in recombinant CHO cells

Recombinant mammalian cultures for heterologous gene expression typically involve cells traversing the cell cycle. Studies were conducted to characterize rates of accumulation of intracellular foreign protein in single cells during the cell cycle of Chinese hamster ovary (CHO) cells transfected with an expression vector containing the gene for dihydrofolate reductase (dhfr) and the lacZ gene for bacterial beta-galactosidase (a nonsecreated protein). The lacZ gene was under the control of the constitutive cytomegalovirus promoter. These normally attachment-grown cells were adapted to suspension culture in 10(-7) M methotrexate, and a dual-laser flow cytometer was used to simultaneously determine the DNA and foreign protein (beta-galactosidase) content of single living cells. Expression of beta-galactosidase as a function of cell cycle phase was evaluated for cells in the exponential growth phase, early plateau phase, and inhibited traverse of the cell cycle during exponential growth. The results showed that the beta-galactosidase production rate is higher in the S phase than that in the G1 or G2/M phases. Also, when cell cycle progression was stopped at the S phase by addition of aphidicolin, beta-galactosidase content in single cells was higher than that in exponential phase or plateau phase cells and increased with increasing culture time. Although the cells did not continue to divide after aphidicolin addition, the production of beta-galactosidase per unit volume of culture was very similar to that in normal exponential growth. (c) 1993 John Wiley & Sons, Inc.     

Rsistance to streptomycin in a producing strain of Streptomyces griseus.

Streptomyces griseus S 104 was sensitive to streptomycin during exponential growth in a medium which, in the subsequent stationary phase, supported production of the antibiotic in yields above 200 mug/ml. When antibiotic production began cultures developed a tolerance toward their lethal metabolite. This was not due to an increase in pH associated with antibiotic production, since pH effects on streptomycin sensitivity in S. griseus were in the reverse direction. However, the degree of tolerance was directly related to the amount of cell material present. Streptomycin production caused no change in the proportion of resistant variants in the population, nor did it cause the severe inhibition of protein synthesis observed in non-producing cultures exposed to the antibiotic. The lack of an effect on protein synthesis is attributed to the absence of streptomycin with in the cytoplasm since soluble extracts from mycelium harvested in the production phase were inactive when bioassayed immediately after cell disruption. However, they developed antibacterial activity rapidly when heated, and more slowly when incubated at 25 degrees C. The addition of phosphatase inhibitors during incubation prevented the appearance of antibiotic activity, and it was concluded that a small amount of streptomycin phosphate is present in the mycelium during antibiotic production. Differences in (14C) streptomycin uptake suggested that the mycelium was appreciably less permeable to the antibiotic in the production phase than during exponential growth. However, a small amount was taken up and much of it was in the soluble fraction of disrupted cells. Bioassays showed that this 14C-labeled antibiotic within the cells had been partially inactivated, suggesting that conversion of streptomycin to an inactive derivative is involved in the mechanism which protects the organism from its metabolite.     

Heat shock and ceramide have different apoptotic pathways in radiation induced fibrosarcoma (RIF) cells

Heat shock induces various cellular responses including inhibition of protein synthesis, production of heat shock proteins (HSPs) and induction of thermotolerance. The molecular mechanisms of the processes have not been well understood. It has been proposed that ceramide formation during heat shock mediates heat shock induced apoptosis. We examined whether C2-ceramide mimicked the cellular response to heat shock in RIF-1 cells and their thermotolerant derivative TR-RIF-1 cells. Discernible effects between heat shock and C2-ceramide treatments were observed in cellular changes such as total protein synthesis, HSP synthesis, stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) activity and PARP cleavage. Heat shock immediately inhibited cellular protein synthesis, which was recovered by synthesizing HSPs first and then whole proteins later. Heat shock also activated SAPK/JNK and increased PARP cleavage in dose-dependent manner. Thermotolerant TR-RIF-1 cells responded to heat shock more insensitively than RIF-1 cells. On the other hand, C2-ceramide treatment did not accompany any changes induced by heat shock. No discernible differences between RIF-1 and TR-RIF-1 cells were observed by C2-ceramide treatment. We tried to figure out how C2-ceramide interacts with cellular membrane and found that exogenous C2-ceramide was incorporated into the outer monolayer and flipped into the inner monolayer of human erythrocytes in ATP-dependent manner. However, the rate of C2-ceramide incorporation was similar in control and thermotolerant cells. In summary, thermotolerant cells are resistant to heat shock induced apoptotic signaling but not resistant, rather sensitive to membrane disturbing C2-ceramide mediated apoptosis. These results suggest that heat shock and ceramide have different signal transduction pathways.     

Chinese hamster cell variants resistant to the A chain of ricin carry altered ribosome function

Ricin, a toxic lectin from Ricinus communis, is composed of two different polypeptide chains, A and B, and the ricin A chain (RA) blocks protein synthesis. We studied cell lines resistant to cytotoxic action of RA. One low-RA-resistant cell line, AR10, isolated from Chinese hamster ovary (CHO) cells, was resistant to a low dose of RA (1 microgram/ml) and showed a 10-fold-higher resistance to RA and ricin than that of CHO. We further mutagenized AR10 to isolate high-RA-resistant cell lines AR100-6, AR100-9, and AR100-13, which were resistant to higher doses of RA and ricin (100- to 1,000-fold) than CHO was. The binding of [125I]ricin to AR10, AR100-6, AR100-9, and AR100-13 cells was decreased to about 30% of that of CHO. The internalization of [125I]ricin in AR10 cells and in the high-RA-resistant clones was the same. Polyuridylate-dependent polyphenylalanine synthesis, using S-30 extracts from either AR100-9 or AR100-13, was about 100-fold more resistant to the inhibitory action of RA than when CHO, AR10, and AR100-6 cells extracts were used. The protein synthesis with ribosomes (80S) from AR100-9 or AR100-13 was 10- to 100-fold more resistant to RA than it was with parental ribosomes when combined with the S-100 fraction of CHO cells. The polyphenylalanine synthesis assay using the ribosomes constituted from the 60S subunit of AR100-9 and the 40S subunit of CHO indicated that the resistant phenotype of AR100-9 cells is due to an alteration of the 60S ribosomal subunit.     

Modulation of the cell cycle during reversible growth inhibition of 3T3 and SV40-3T3 cells with succinylated concanavalin A

Succinylated concanavalin A (ConA), a non-toxic, non-agglutinating derivative of the jack bean lectin ConA inhibits the growth of both normal and SV40-transformed 3T3 cells. The quantitative but not the qualitative growth inhibitory effect of succinyl-ConA can be modulated by the composition of the growth medium. Succinyl-ConA inhibited cells show a low rate of DNA synthesis and accumulate in the G0/G1 phase of the cell cycle. Upon removal of the succinyl-ConA, inhibited cells re-enter the cell cycle synchronously.     

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.