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Three new RelE-homologous mRNA interferases of Escherichia coli differentially induced by environmental stresses

Lookup NU author(s): Mikkel Christensen-Dalsgaard, Mikkel Jorgensen, Professor Kenn Gerdes



Prokaryotic toxin – antitoxin (TA) loci encode mRNA interferases that inhibit translation, either by cleaving mRNA codons at the ribosomal A site or by cleaving any RNA site-specifically. So far, seven mRNA interferases of Escherichia coli have been identified, four of which cleave mRNA by a translation-dependent mechanism. Here, we experimentally confirmed the presence of three novel TA loci in E. coli. We found that the yafNO, higBA (ygjNM) and ygiUT loci encode mRNA interferases related to RelE. YafO and HigB cleaved translated mRNA only, while YgiU cleaved RNA site-specifically at GC[A/U], independently of translation. Thus, YgiU is the first RelE-related mRNA interferase that cleaves mRNA independently of translation, in vivo. All three loci were induced by amino acid starvation, and inhibition of translation although to different degrees. Carbon starvation induced only two of the loci. The yafNO locus was induced by DNA damage, but the transcription originated from the dinB promoter. Thus, our results showed that the different TA loci responded differentially to environmental stresses. Induction of the three loci depended on Lon protease that may sense the environmental stresses and activate TA loci by cleavage of the antitoxins. Transcription of the three TA operons was autoregulated by the antitoxins.

Publication metadata

Author(s): Christensen-Dalsgaard M, Jorgensen MG, Gerdes K

Publication type: Article

Publication status: Published

Journal: Molecular Microbiology

Year: 2010

Volume: 75

Issue: 2

Pages: 333-348

Date deposited: 27/05/2010

ISSN (print): 0950-382X

ISSN (electronic): 1365-2958

Publisher: Wiley-Blackwell Publishing Ltd.


DOI: 10.1111/j.1365-2958.2009.06969.x


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