Activity of ribosomes and tmRNA of Streptomyces aureofaciens during development and stress conditions induced by changes in temperature and the presence of antibiotics

Streptomycetes are soil microorganisms exposed to various stresses that activate specialized responses whose coordinated action promotes growth under adverse conditions. Ribosomes having a highly cooperative structure are potential target for control mechanisms that generate signal and activate adaptive regulons or developmental programs. We examined how Streptomyces aureofaciens producing tetracycline responds to the presence of antibiotics and stresses induced by the changes in temperature. Tetracycline interacts with 16S RNA and decreases its thermodynamic stability. The drug also inhibits binding of ternary complex Phe-tRNA.EF-Tu.GTP to purified ribosomes. We have found that antibiotics that cause ribosome stall or pause could increase the requirement for tmRNA in the process transtranslation. Increase in tmRNA level was also demonstrated upon downshift in temperature.