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

    Research areas

  • 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

ID: 44004771