prlF and yhaV Encode a New Toxin-Antitoxin System in Escherichia coli

Oliver Schmidt, Verena J. Schuenemann, Nicholas J. Hand, Thomas J. Silhavy, Jörg Martin, Andrei N. Lupas, Sergej Djuranovic

Research output: Contribution to journalArticlepeer-review

82 Scopus citations


Toxin-antitoxin systems consist of a stable toxin, frequently with endonuclease activity, and a small, labile antitoxin, which sequesters the toxin into an inactive complex. Under unfavorable conditions, the antitoxin is degraded, leading to activation of the toxin and resulting in growth arrest, possibly also in bacterial programmed cell death. Correspondingly, these systems are generally viewed as agents of the stress response in prokaryotes. Here we show that prlF and yhaV encode a novel toxin-antitoxin system in Escherichia coli. YhaV, a ribonuclease of the RelE superfamily, causes reversible bacteriostasis that is counteracted by PrlF, a swapped-hairpin transcription factor homologous to MazE. The two proteins form a tight, hexameric complex, which binds with high specificity to a conserved sequence in the promoter region of the prlF-yhaV operon. As homologs of MazE and RelE, respectively, PrlF and YhaV provide an evolutionary connection between the two best-characterized toxin-antitoxin systems in E. coli, mazEF and relEB.

Original languageEnglish (US)
Pages (from-to)894-905
Number of pages12
JournalJournal of Molecular Biology
Issue number4
StatePublished - Sep 28 2007

All Science Journal Classification (ASJC) codes

  • Molecular Biology
  • Biophysics
  • Structural Biology


  • RelE superfamily ribonuclease
  • mRNA decay
  • stress response
  • swapped-hairpin barrel
  • toxin-antitoxin system


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