A dual role in regulation and toxicity for the disordered N-terminus of the toxin GraT

Ariel Talavera Perez, Hedvig Tamman, Andres Ainelo, Albert Konijnenberg, San Hadzi, Frank Sobott, Abel Garcia Pino, Rita Horak, Remy Loris

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)


Bacterial toxin-antitoxin (TA) modules are tightly regulated to maintain growth in favorable conditions or growth arrest during stress. A typical regulatory strategy involves the antitoxin binding and repressing its own promoter while the toxin often acts as a co-repressor. Here we show that Pseudomonas putida graTA-encoded antitoxin GraA and toxin GraT differ from other TA proteins in the sense that not the antitoxin but the toxin possesses a flexible region. GraA auto-represses the graTA promoter: two GraA dimers bind cooperatively at opposite sides of the operator sequence. Contrary to other TA modules, GraT is a de-repressor of the graTA promoter as its N-terminal disordered segment prevents the binding of the GraT 2 A 2 complex to the operator. Removal of this region restores operator binding and abrogates GraT toxicity. GraTA represents a TA module where a flexible region in the toxin rather than in the antitoxin controls operon expression and toxin activity.

Original languageEnglish
Article number972
Pages (from-to)972
Number of pages13
JournalNat Commun
Issue number1
Publication statusPublished - 27 Feb 2019


  • Antitoxins/genetics
  • Bacterial Proteins/chemistry
  • Bacterial Toxins/genetics
  • DNA, Bacterial/chemistry
  • Genes, Bacterial
  • Intrinsically Disordered Proteins/chemistry
  • Models, Molecular
  • Nucleic Acid Conformation
  • Operon
  • Promoter Regions, Genetic
  • Protein Binding
  • Protein Folding
  • Protein Structure, Quaternary
  • Pseudomonas putida/genetics
  • Static Electricity
  • Toxin-Antitoxin Systems/genetics


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