Bacterial toxin RelE induces apoptosis in human cells.

The bacterial protein RelE severely restricts prokaryotic cell growth, probably by acting as a global inhibitor of translation. It is ubiquitous in prokaryotes as part of the RelE-RelB toxin-antitoxin system, and may be activated by nutritional stress. When the relE gene from Escherichia coli was expressed inducibly in a human osteosarcoma cell line, it was shown to retard growth and to lead to cell death by apoptosis. RelE is therefore unusual among bacterial toxins in possessing broad activity against both prokaryotes and eukaryotes, perhaps by acting on evolutionarily conserved components of the translation machinery.