Effect of Erythromycin on Polylysin Synthesis Directed by Polyadenyline Acid in an Escherichia coliCell-free System

Abstract

1. The effect of erythromycin on polyadenylic acid (poly A) directed polylysine synthesis was examined in cell-free extracts from E. coliK-12. 2. The inhibition by erythromycin of ¹⁴C-lysine incorporation into trichloroacetic acid-tungstate (W-TCA) insoluble materials was dependent on the amount of ribosomes in the system. 3. Changes in amount of 105,000×gsupernatant fraction and E. colitransfer RNA (tRNA) showed no influence on the inhibition of ¹⁴C-lysine incorporation by erythromycin. 4. Paper chromatographic analysis of the reaction products demonstrated that increasing additions of erythromycin caused decreased synthesis of highly polymerized polylysine and at the same time resulted in the accumulation of di- and trilysine. 5. In the presence of an excessive amount of erythromycin, only di- and trilysine were observed as main products on paper chromatogram. 6. The amounts of these peptides were increased by addition of E. colitRNA. From ¹⁴C-lysyl-tRNA, more than 30% of lysine was incorporated into di- and trilysine in the presence of large amounts of nonradioactive lysine and erythromycin. 7. These results are interpreted to indicate that erythromycin interacts with ribosomes and this interaction causes a loss of the activity of ribosomes to synthesize highly polymerized polylysine but leaves their ability to form small lysine peptides such as di- and trilysine still intact.