Details

Autor(en) / Beteiligte

• Kurasz, Jennifer E
• Hartman, Christine E
• Samuels, David J
• Mohanty, Bijoy K
• Deleveaux, Anquilla
• Mrázek, Jan
• Karls, Anna C
• Silhavy, Thomas J.

Titel

Genotoxic, Metabolic, and Oxidative Stresses Regulate the RNA Repair Operon of Salmonella enterica Serovar Typhimurium

Ist Teil von

• Journal of bacteriology, 2018-12, Vol.200 (23)

Ort / Verlag

United States: American Society for Microbiology

Erscheinungsjahr

2018

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• The σ regulon in serovar Typhimurium includes a predicted RNA repair operon encoding homologs of the metazoan Ro60 protein (Rsr), Y RNAs (YrlBA), RNA ligase (RtcB), and RNA 3'-phosphate cyclase (RtcA). Transcription from σ -dependent promoters requires that a cognate bacterial enhancer binding protein (bEBP) be activated by a specific environmental or cellular signal; the cognate bEBP for the σ -dependent promoter of the operon is RtcR. To identify conditions that generate the signal for RtcR activation in Typhimurium, transcription of the RNA repair operon was assayed under multiple stress conditions that result in nucleic acid damage. RtcR-dependent transcription was highly induced by the nucleic acid cross-linking agents mitomycin C (MMC) and cisplatin, and this activation was dependent on RecA. Deletion of or resulted in decreased cell viability relative to that of the wild type following treatment with MMC. Oxidative stress from peroxide exposure also induced RtcR-dependent transcription of the operon. Nitrogen limitation resulted in RtcR-independent increased expression of the operon; the effect of nitrogen limitation required NtrC. The adjacent toxin-antitoxin module, , was cotranscribed with the RNA repair operon but was not required for RtcR activation, although YafQ endoribonuclease activated RtcR-dependent transcription. Stress conditions shown to induce expression the RNA repair operon of ( ) did not stimulate expression of the Typhimurium RNA repair operon. Similarly, MMC did not induce expression of the operon, although when expressed in Typhimurium, RtcR responds effectively to the unknown signal(s) generated there by MMC exposure. Homologs of the metazoan RNA repair enzymes RtcB and RtcA occur widely in eubacteria, suggesting a selective advantage. Although the enzymatic activities of the eubacterial RtcB and RtcA have been well characterized, the physiological roles remain largely unresolved. Here we report stress responses that activate expression of the σ -dependent RNA repair operon ( ) of Typhimurium and demonstrate that expression of the operon impacts cell survival under MMC-induced stress. Characterization of the requirements for activation of this tightly regulated operon provides clues to the possible functions of operon components , enhancing our understanding of how this human pathogen copes with environmental stressors.