tmRNA of Streptomyces collinus and Streptomyces griseus during the growth and in the presence of antibiotics.
Bottom Line: These findings suggest that produced antibiotics induce tmRNA that facilitate reactivation of stalled complex of ribosomes and maintain viability.The effect of antibiotics that inhibit the cell-wall turnover, DNA, RNA or protein synthesis on the level of tmRNA was examined.Antibiotics interfering with ribosomal target sites are more effective at stimulation of the tmRNA level in streptomycetes examined than those affecting the synthesis of DNA, RNA or the cell wall.
Affiliation: Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.Show MeSH
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Mentions: Previously, it was shown that sub‐inhibitory concentrations of several protein synthesis inhibitors induced an increase of the tmRNA in Streptomyces aureofaciens producing tetracycline (Palečkováet al., 2006). We examined the abundance of tmRNA in cells from the exponential phase of growth of S. griseus and S. collinus incubated in the presence of antibiotics that inhibit protein synthesis or other cellular functions as synthesis of DNA, RNA or the cell wall. When the cells of S. griseus (Fig. 4A) were incubated in the presence of streptomycin, the level of tmRNA rapidly increased during the first 10 min and remained unchanged for up to 180 min. At the presence of tetracycline, protein synthesis decreased to 75% of control value without tetracycline (Fig. 4B) and tmRNA synthesis increased more than seven times. Presence of kirromycin led to a gradual increase in tmRNA and after 3 h cultivation the level was three times higher than that of the control value. No significant changes in the level of tmRNA and protein synthesis were observed in the cells incubated with sub‐inhibitory concentration of chloramphenicol. Out of the antibiotics that interfere with other cellular activities than protein synthesis, only nalidixin slightly stimulated the elevation of the tmRNA level (Fig. 4C) and protein synthesis (Fig. 4D). Low stimulative effect on the level of tmRNA also caused vancomycin. Sub‐inhibitory concentrations of rifampicin and ampicillin had no effect on the tmRNA level and protein synthesis. In experiments with S. collinus (Fig. 5A), the presence of tetracycline gave rise to an increase in tmRNA more than five times and the rate of protein synthesis remained the same as in the control experiment without antibiotics (Fig. 5B). The presence of streptomycin had no effect on the tmRNA abundance, but protein synthesis decreased to 40% of control without the drug. The addition of kirromycin to cells from the exponential phase of growth induced an increase of the tmRNA during the first 10 min and then remained unchanged. Chloramphenicol caused a significant increase in the tmRNA after 3 h of cultivation, while protein synthesis decreased to 50% of control value without antibiotics. The presence of sub‐inhibitory concentrations of antibiotics interfering with synthesis of RNA and DNA (Fig. 5C) had no valuable effect on tmRNA abundance. The low level of rifampicin had no effect on tmRNA synthesis, but exerted an influence on the protein synthesis which was reduced by about 40% compared with that of control without antibiotics (Fig. 5D). Slight stimulation effect on tmRNA abundance exhibited ampicillin during the first 60 min of cultivation.
Affiliation: Institute of Microbiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.