Prokaryotic toxin-antitoxin stress response loci

Nat Rev Microbiol. 2005 May;3(5):371-82. doi: 10.1038/nrmicro1147.


Although toxin-antitoxin gene cassettes were first found in plasmids, recent database mining has shown that these loci are abundant in free-living prokaryotes, including many pathogenic bacteria. For example, Mycobacterium tuberculosis has 38 chromosomal toxin-antitoxin loci, including 3 relBE and 9 mazEF loci. RelE and MazF are toxins that cleave mRNA in response to nutritional stress. RelE cleaves mRNAs that are positioned at the ribosomal A-site, between the second and third nucleotides of the A-site codon. It has been proposed that toxin-antitoxin loci function in bacterial programmed cell death, but evidence now indicates that these loci provide a control mechanism that helps free-living prokaryotes cope with nutritional stress.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Antitoxins / genetics*
  • Apoptosis
  • Bacteria / genetics*
  • Bacterial Toxins / genetics*
  • Chromosome Mapping
  • Chromosomes, Bacterial
  • Mycobacterium tuberculosis / genetics
  • Operon
  • Plasmids
  • RNA, Messenger / genetics


  • Antitoxins
  • Bacterial Toxins
  • RNA, Messenger