These T-A genes are tucked in near the genes to be protected. T-A genes contain instructions for both a toxin and its antitoxin. As long as the cell is producing both, all is well.

However, if for some reason the piece of DNA where the T-A gene is located gets damaged or lost, the production of toxin and antitoxin comes to a halt and a time bomb starts ticking.

Because the toxin is more stable than the antitoxin, it is broken down more slowly by the cell's clean-up mechanisms. Once the antitoxin is all gone, there is still enough toxin left to kill the bacterium.

The upshot for the species is that bacteria that loses their T-A gene -- and probably have sustained damage to the important genes just next to it -- can no longer reproduce, said a VUB release.

Now that we finally know how the time bomb functions (or more exactly, one of the time bombs, as there are several closely related T-A systems), biomedical scientists can start looking for substances to start the time bomb of pathogens ticking.

A new class of antibiotics might come out of it.

The research is slated for publication in the journal Molecular Cell.