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Figure 7 | BMC Microbiology

Figure 7

From: Transcriptional cross-activation between toxin-antitoxin systems of Escherichia coli

Figure 7

Toxin-antitoxin systems are subject to both auto- and cross-regulation. Cognate regulatory interactions are in red and non-cognate interactions are in blue. According to the established model, cognate antitoxin and toxin, which are encoded by co-transcribed genes, form a tight complex and antitoxin inhibits the toxin through direct protein-protein interaction. Antitoxin, both alone and in complex with the toxin, binds to the operator DNA and auto-represses transcription of the TA operon. Free toxin in excess disrupts this DNA-protein interaction and induces transcriptional de-repression. We show that transcription of TA genes can be induced also by non-cognate toxins. Moreover, cleavage of the TA mRNA by both cognate and non-cognate toxins results in accumulation of the toxin-encoding mRNA fragments. Translation of these fragments can lead to accumulation of free toxin.

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