50S RIBOSOMAL-SUBUNIT SYNTHESIS AND TRANSLATION ARE EQUIVALENT TARGETS FOR ERYTHROMYCIN INHIBITION IN STAPHYLOCOCCUS-AUREUS

Macrolide antibiotics like erythromycin can prevent the formation of t he 50S ribosomal subunit in growing bacterial cells, in addition to th eir inhibitory effect on translation. The significance of this novel f inding has been further investigated. The 50% inhibitory doses of eryt hromycin for the inhibition of translation and 50S subunit assembly in Staphylococcus aureus cells were measured and were found to be identi cal. Together they account quantitatively for the observed effects of erythromycin on cell growth rates. There is also a direct relationship between the loss of rRNA from the 50S subunit and its accumulation as oligoribonucleotides in cells. The importance of this second site for erythromycin inhibition of bacterial cell growth is discussed.