Toxin-antitoxin systems: why so many, what for?
Toxin-antitoxin (TA) systems are small genetic modules that are abundant in bacterial genomes. Three types have been described so far, depending on the nature and mode of action of the antitoxin component. While type II systems are surprisingly highly represented because of their capacity to move by horizontal gene transfer, type I systems appear to have evolved by gene duplication and are more constrained. Type III is represented by a unique example located on a plasmid. Type II systems promote stability of mobile genetic elements and might act at the selfish level. Conflicting hypotheses about chromosomally encoded systems, from programmed cell death and starvation-induced stasis to protection against invading DNA and stabilization of large genomic fragments have been proposed.
Laboratoire de Génétique et Physiologie Bactérienne, Faculté des Sciences, Institut de Biologie et de Médecine Moléculaires, Université Libre de Bruxelles, Belgium. lvmelder@ulb.ac.be
Laurence
L
Van Melderen
D001419:Bacteria / Q000235:genetics*; D001426:Bacterial Proteins / Q000378:metabolism*; D001427:Bacterial Toxins / Q000378:metabolism*; D016923:Cell Death; D004269:DNA, Bacterial / Q000378:metabolism; D042822:Genomic Instability; D010957:Plasmids
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004269:DNA, Bacterial