A genetic selection reveals functional metastable structures embedded in a toxin-encoding mRNA

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Abstract

Post-transcriptional regulation plays important roles to finely tune gene expression in bacteria. In particular, regulation of type I toxin-antitoxin (TA) systems is achieved through sophisticated mechanisms involving toxin mRNA folding. Here, we set up a genetic approach to decipher the molecular underpinnings behind the regulation of a type I TA in Helicobacter pylori. We used the lethality induced by chromosomal inactivation of the antitoxin to select mutations that suppress toxicity. We found that single point mutations are sufficient to allow cell survival. Mutations located either in the 5' untranslated region or within the open reading frame of the toxin hamper its translation by stabilizing stem-loop structures that sequester the Shine-Dalgarno sequence. We propose that these short hairpins correspond to metastable structures that are transiently formed during transcription to avoid premature toxin expression. This work uncovers the co-transcriptional inhibition of translation as an additional layer of TA regulation in bacteria.

Data availability

Sequencing data have been deposited in GEO under accession code GSE121423

The following data sets were generated

1. Masachis S
2. Tourasse NJ
3. Lays C
4. Faucher M
5. Chabas S
6. Iost I
7. Darfeuille F
(2018) High-throughput suppressor selection of a type I toxin-antitoxin system in Helicobacter pylori
NCBI Gene Expression Omnibus, GSE121423.

https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE121423

Article and author information

Author details

Sara Masachis

ARNA laboratory, INSERM U1212, CNRS UMR5320, University of Bordeaux, Bordeaux, France

Competing interests
The authors declare that no competing interests exist.
Nicolas J Tourasse

ARNA laboratory, INSERM U1212, CNRS UMR5320, University of Bordeaux, Bordeaux, France

Competing interests
The authors declare that no competing interests exist.
Claire Lays

ARNA laboratory, INSERM U1212, CNRS UMR5320, University of Bordeaux, Bordeaux, France

Competing interests
The authors declare that no competing interests exist.
Marion Faucher

ARNA laboratory, INSERM U1212, CNRS UMR5320, University of Bordeaux, Bordeaux, France

Competing interests
The authors declare that no competing interests exist.
Sandrine Chabas

ARNA laboratory, INSERM U1212, CNRS UMR5320, University of Bordeaux, Bordeaux, France

Competing interests
The authors declare that no competing interests exist.
Isabelle Iost

ARNA laboratory, INSERM U1212, CNRS UMR5320, University of Bordeaux, Bordeaux, France

Competing interests
The authors declare that no competing interests exist.
Fabien Darfeuille

ARNA laboratory, INSERM U1212, CNRS UMR5320, University of Bordeaux, Bordeaux, France

For correspondence
fabien.darfeuille@inserm.fr

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-1167-6113

Funding

Agence Nationale de la Recherche (ANR-12-BSV5-0025-Bactox1)

Sandrine Chabas
Isabelle Iost
Fabien Darfeuille

H2020 Marie Skłodowska-Curie Actions (642738)

Sara Masachis
Fabien Darfeuille

Agence Nationale de la Recherche (ANR-12-BSV6-007- asSUPYCO)

Sandrine Chabas
Isabelle Iost
Fabien Darfeuille

Institut National de la Santé et de la Recherche Médicale (U1212)

Sara Masachis
Nicolas J Tourasse
Marion Faucher
Sandrine Chabas
Isabelle Iost
Fabien Darfeuille

Centre National de la Recherche Scientifique (UMR 5320)

Isabelle Iost
Fabien Darfeuille

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.