The effects of trimethoprim and erythromycin on polysome metabolism in Escherichia coli.

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.