Prokaryotic toxin-antitoxin stress response loci.
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.
Gerdes
Kenn
K
Department of Biochemistry and Molecular Biology, University of Southern Denmark, DK-5230 Odense M, Denmark. kgerdes@bmb.sdu.dk
Christensen
Susanne K
SK
Løbner-Olesen
Anders
A
D000992:Antitoxins / Q000235:genetics*; D017209:Apoptosis; D001419:Bacteria / Q000235:genetics*; D001427:Bacterial Toxins / Q000235:genetics*; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D009169:Mycobacterium tuberculosis / Q000235:genetics; D009876:Operon; D010957:Plasmids; D012333:RNA, Messenger / Q000235:genetics
D000992:Antitoxins; D001427:Bacterial Toxins; D012333:RNA, Messenger