title: A study of bacterial response to polypeptide antibiotics.
abstract: When Escherichia coli cells are treated with either polymixin or gramicidin at concentrations that block protein and RNA synthesis, they accumulate a significant amount of guanosine tetraphosphate ppGpp. Such accumulation occurs in stringent (relA+) as well as in relaxed (relA) strains and no guanosine pentaphosphate pppGpp is then detected within the cells. These observations suggest that polypeptide antibiotics elicit ppGpp formation through a mechanism different from the stringent control system triggered by amino acid starvation of bacteria. Experiments based on tetracycline action indicate, moreover, that the accumulation of ppGpp under polymixin or gramicidin treatment is connected with a strong restriction of the degradation rate of this nucleotide.
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D004926:Escherichia coli / Q000187:drug effects*; D006096:Gramicidin / Q000494:pharmacology; D006159:Guanosine Tetraphosphate / Q000378:metabolism; D011113:Polymyxins / Q000494:pharmacology; D014176:Protein Biosynthesis; D012313:RNA / Q000096:biosynthesis; D013752:Tetracycline / Q000494:pharmacology
chemical_list: D000900:Anti-Bacterial Agents; D011113:Polymyxins; D006096:Gramicidin; D006159:Guanosine Tetraphosphate; D012313:RNA; D013752:Tetracycline