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The effects of trimethoprim and erythromycin on polysome metabolism in Escherichia coli
Abstract:
Trimethoprim and erythromycin were shown to have different overall effects on in vivo polysome metabolism in Escherichia coli. In a rel A+-rel A pair of strains, trimethoprim treatment induces a reduction of polysome level to a variable extent, similarly to aminoacyl tRNA deprivation of cells, but persisting polysomes remain dynamic structures in a state of continual turnover. In contrast, erythromycin stabilizes polysome level to a high value in either kind of strain, but maintained polysomes appear as "frozen" structures unable to undergo ribosome translocation.
Insights
Trimethoprim reduces polysome levels in Escherichia coli, maintaining dynamic turnover. Erythromycin, however, stabilizes polysomes, freezing their structure and halting ribosome movement.
Area of Science:
- Molecular Biology
- Microbiology
- Bacterial Physiology
Background:
- Polysomes are crucial for protein synthesis, representing actively translating mRNA.
- Understanding polysome metabolism is key to comprehending bacterial responses to antibiotics.
- Escherichia coli serves as a model organism for studying bacterial gene expression.
Purpose of the Study:
- To investigate the distinct effects of trimethoprim and erythromycin on in vivo polysome metabolism in Escherichia coli.
- To elucidate the impact of these antibiotics on polysome dynamics and ribosome translocation.
Main Methods:
- Comparative analysis of polysome levels and dynamics in Escherichia coli strains (rel A+ and rel A-) treated with trimethoprim and erythromycin.
- Assessment of polysome turnover and ribosome translocation under antibiotic stress.
Main Results:
- Trimethoprim treatment led to a variable reduction in polysome levels, akin to aminoacyl tRNA deprivation, with persisting polysomes showing dynamic turnover.
- Erythromycin stabilized polysome levels, but these polysomes became static 'frozen' structures, inhibiting ribosome translocation.
Conclusions:
- Trimethoprim and erythromycin exert fundamentally different effects on bacterial polysome metabolism.
- Trimethoprim affects polysome quantity and dynamics, while erythromycin impacts polysome stability and function, leading to distinct cellular responses.