Present address: Genome Exploration Research Group, RIKEN Genomic Sciences Center, RIKEN Yokohama Institute, Yokohama 230-0045, Japan.
An antisense RNA controls synthesis of an SOS-induced toxin evolved from an antitoxin
Article first published online: 24 APR 2007
Volume 64, Issue 3, pages 738–754, May 2007
How to Cite
Kawano, M., Aravind, L. and Storz, G. (2007), An antisense RNA controls synthesis of an SOS-induced toxin evolved from an antitoxin. Molecular Microbiology, 64: 738–754. doi: 10.1111/j.1365-2958.2007.05688.x
Re-use of this article is permitted in accordance with the Creative Commons Deed, Attribution 2.5, which does not permit commercial exploitation.
- Issue published online: 24 APR 2007
- Article first published online: 24 APR 2007
- Accepted 5 March, 2007.
Only few small, regulatory RNAs encoded opposite another gene have been identified in bacteria. Here, we report the characterization of a locus where a small RNA (SymR) is encoded in cis to an SOS-induced gene whose product shows homology to the antitoxin MazE (SymE). Synthesis of the SymE protein is tightly repressed at multiple levels by the LexA repressor, the SymR RNA and the Lon protease. SymE co-purifies with ribosomes and overproduction of the protein leads to cell growth inhibition, decreased protein synthesis and increased RNA degradation. These properties are shared with several RNA endonuclease toxins of the toxin-antitoxin modules, and we show that the SymE protein represents evolution of a toxin from the AbrB fold, whose representatives are typically antitoxins. We suggest that SymE promotion of RNA cleavage may be important for the recycling of RNAs damaged under SOS-inducing conditions.