Stimulation of Enzyme Synthesis by Sublethal Concentrations of Chloramphenicol Is Not Mediated by Ribonucleotide Pools

Abstract

Growth of Salmonella typhimurium LT-2 strain pyrA81 in minimal medium containing 0.8 μg of chloramphenicol (CAP) per ml resulted in a 50 to 100% increase in the steady-state nucleotide pools in the cells. When such a culture was starved for uracil, the pyrimidine nucleotide pools decayed much more slowly in CAP-treated cells than in controls. An attempt was made to determine whether this effect of CAP on nucleotide pools could account for enhanced enzyme derepression observed under the same conditions (8). Treatment with low levels of puromycin also resulted in elevation of nucleotide pools but did not lead to enhanced enzyme synthesis. CAP treatment during arginine starvation has been shown to enhance enzyme synthesis, but nucleotide pools were not significantly affected by CAP nor was the stringent response relieved under these conditions. Thus, the effects of CAP on enzyme synthesis cannot be the result of effects of the antibiotic on nucleotide pools in all cases. The elevation of nucleotide pools was shown not to be due to enhanced conversion of exogeneous uracil into nucleotides, but to result from the enhanced turnover of ribonucleic acid in CAP-treated cells.

Energy and calcium ion dependence of proteolysis during sporulation of Bacillus subtilis cells

“…It must be stressed that either or both of these apparent requirements may be indirect effects which have their impacts on the proteolytic system through secondary agents. (9). These results point out that the drug may have actions other than the inhibition of protein synthesis.…”

Stimulation of Derepressed Enzyme Synthesis in Bacteria by Growth on Sublethal Concentrations of Chloramphenicol

“…This "chloramphenicol-RNA" can be degraded, at least in the presence of high levels of CAP (13,22 starvation and provide an additional pool of pyrimidine nucleotides for mRNA synthesis. Tests of this hypothesis are presented in the accompanying paper (12).…”

“…These alterations in metabolism then permit enhanced enzyme synthesis during subsequent starvation. The possible nature of the process affected by CAP is considered below and in the accompanying paper (12).…”

“…The results reported here describe the nature of this apparently paradoxical effect of CAP on enzyme synthesis. An accompanying paper (12) (5 ,g/ml) and concentrations of CAP from 0 to 2.5 ,ug/ml.…”

“…Cultures were grown on minimal medium supplemented with limiting arginine (12 ,ug/ml) and all other amino acids in excess (100 ,ug/ml). In stringent strain CP78, derepression of OTCase synthesis was enhanced twofold by CAP treatment (Table 3).…”