In life's constant battle for survival, it takes one to kill but two to conquer. Toxin-antitoxin or toxin-antidote (TA) elements are genetic dyads that cheat the laws of inheritance to guarantee their transmission to the next generation. This seemingly simple genetic arrangement-a toxin linked to its antidote-is capable of quickly spreading and persisting in natural populations. TA elements were first discovered in bacterial plasmids in the 1980s and have recently been characterized in fungi, plants, and animals, where they underlie genetic incompatibilities and sterility in crosses between wild isolates. In this review, we provide a unified view of TA elements in both prokaryotic and eukaryotic organisms and highlight their similarities and differences at the evolutionary, genetic, and molecular levels. Finally, we propose several scenarios that could explain the paradox of the evolutionary origin of TA elements and argue that these elements may be key evolutionary players and that the full scope of their roles is only beginning to be uncovered.
|Number of pages
|Annual Review of Genetics
|Published - 23 Nov 2020
Bibliographical noteFunding Information:
The authors would like to thank Scott W. Emmons for discussions regarding the possible origins of TA elements, Belen Pacheco Fiallos for figure illustrations, and Sonya Widen for critical reading. A.B. is supported by the Austrian Academy of Sciences and the European Research Council grant number ERC-2019-StG-851470, E.B.-D. is supported by National Institutes of Health (NIH) grant number K99-HG010369, and L.K. is supported by the Howard Hughes Medical Institute and NIH grant number R01 HG004321.
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- gene drive
- genetic conflict
- segregation distortion
- selfish genetic elements