Reevaluation of the Mode of Action of Streptolydigin in Escherichia coli: Induction of Transcription Termination In Vivo

Abstract

Growth of the permeable strain AS19 of Escherichia coli B is more sensitive to the antibiotic streptolydigin than is in vitro ribonucleic acid (RNA) synthesis. The in vivo chain elongation rates of lacZ messenger RNA and ribosomal RNA are not affected at 1.5 x 10-6 M, a concentration that reduces the growth rate threefold. The synthesis of large proteins is inhibited preferentially, and a considerable fraction of the polypeptides synthesized is unstable. The synthesis of complete ,8-galactosidase is inhibited relative to the synthesis of short, unstable polypeptides, which include the first 60 to 70 amino acids of /3-galactosidase. The expression of the following polycistronic transcription units is strongly biased against promoter-distal genes: trp, deo, rpoBC, and rrn. The extent of polarity is proportional to the distance transcribed and to the streptolydigin concentration. Streptolydigin appears to destabilize active transcription complexes irreversibly irrespective of the type of transcript (messenger RNA, ribosomal RNA) and of transcription intensity. We suggest that streptolydigin leads to premature termination of transcription, resulting in release of incomplete transcripts and, thus, a decrease in overall messenger RNA concentration, which becomes limiting for protein synthesis, i.e., for growth.The antibiotic streptolydigin interferes with bacterial ribonucleic acid (RNA) synthesis in vivo and in vitro (32, 34). Mutations to streptolydigin resistance are located in the /B subunit of the RNA polymerase (13,16,32). Together with biochemical evidence (5, 34) this indicates that streptolydigin inhibits RNA synthesis by interaction with the RNA polymerase rather than by binding to the template as does actinomycin D (27). In contrast to rifampin, which acts on initiation of transcription (36, 41), streptolydigin has been shown to interfere with RNA chain elongation (5). Cassani et al. (5) also showed stabilization of the RNA-enzyme-deoxyribonucleic acid (DNA) complex in vitro when using purified RNA polymerase and T4 DNA; the inhibition of RNA chain elongation is reversible in vitro (34).In attempts to apply these in vitro results in vivo, we realized that the effects of streptlydigin

Importance of the tmRNA system for cell survival when transcription is blocked by DNA–protein cross‐links

“…Similarly, biochemical approaches showed that the elongation inhibitor streptolydigin freezes the transcription complex on the DNA template with the RNA product still bound. However, streptolydigin apparently causes rapid, complete and irreversible loss of transcription complexes in vivo (Von Meyenburg et al ., 1978), suggesting that some system(s) exists within the cell to dislodge the frozen RNA polymerase complexes, as we are proposing here for both streptolydigin and DPCs.…”

Regulation of Escherichia coli aspartate transcarbamylase synthesis by guanosine tetraphosphate and pyrimidine ribonucleoside triphosphates

“…This repression is reversed by the addition of DNA-binding agents (e.g., proflavin, norharman, and netropsin), which presumably inhibit the rate of transcriptional elongation (R. J. Neill, Ph.D. thesis, University of California, Berkeley, 1979). In a hisP' strain of S. typhimurium, sublethal concentrations of streptolydigin, which is an inhibitor of transcriptional elongation (33,38), preferentially stimulate pyrB expression (C. L. Turnbough, Jr., unpublished data). These results suggest that the expression of pyrA and pyrB is regulated by the relative rates of transcription and translation presumably of a leader DNA sequence immediately preceding the structural genes.…”

Amino Acid Precursor Supply in the Biosynthesis of the RNA Polymerase Inhibitor Streptolydigin by Streptomyces lydicus

“…1) is an inhibitor of bacterial RNA polymerase ␤-subunit produced by Streptomyces lydicus (27,29) and a potent inhibitor of eukaryotic DNA polymerase terminal deoxynucleotidyltransferase (6,7). The streptolydigin biosynthetic gene cluster has been isolated and characterized from the producer organism (21).…”