Ribosome-controlled transcription termination is essential for the production of antibiotic microcin C.
Bottom Line: Ribosome binding also makes the mccA RNA exceptionally stable.Together, these two effects-ribosome-induced transcription termination and stabilization of the message-account for very high abundance of the mccA transcript that is essential for McC production.The general scheme appears to be evolutionary conserved as ribosome-induced transcription termination also occurs in a homologous operon from Helicobacter pylori.
Affiliation: Institute of Gene Biology of the Russian Academy of Sciences, Moscow, Russia Waksman Institute for Microbiology and Department of Molecular Biology and Biochemistry, Rutgers, the State University of New Jersey, Piscataway, NJ, USA St. Petersburg State Polytechnical University, St. Petersburg, Russia.Show MeSH
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Mentions: The data presented above can be explained by either transcription termination or transcript processing between the mccA and the mccB ORFs. A processing event would be expected to generate a new 5′ end that should be detectable by primer extension with oligonucleotides annealing to mccB. No such primer extension product was detected (data not shown), suggesting that transcription termination is likely responsible for the appearance of the short mccA transcript. The high ratio of monocistronic to polycistronic mccA transcripts may result from very efficient transcription termination in the intergenic region or it may be caused by differential transcript stability (a combination of these two effects is also possible). To determine transcript stabilities, McC-producing cells were treated with rifampicin, an inhibitor of transcription initiation, and decay of mcc RNA abundance was followed over time by Northern blotting (for mccA transcript) and primer extension (for polycistronic transcript). The results are presented in Figure 3A. As can be seen, the half-life of polycistronic transcript was several minutes, i.e. comparable to half-lives of most E. coli mRNAs (20). In contrast, the short mccA transcript was exceedingly stable (almost no change in transcript abundance after a 20-min incubation with rifampicin). The exceptional stability of the mccA transcript may be responsible for the abnormally low (∼3%) ratio of TEX-resistant transcripts revealed by dRNA-seq (Figure 2A), since transcripts that persist for a long time could lose their 5′ triphosphate moiety (21).
Affiliation: Institute of Gene Biology of the Russian Academy of Sciences, Moscow, Russia Waksman Institute for Microbiology and Department of Molecular Biology and Biochemistry, Rutgers, the State University of New Jersey, Piscataway, NJ, USA St. Petersburg State Polytechnical University, St. Petersburg, Russia.