Research published today in the journal Proceedings of the National Academy of Sciences shows that some bacterial cells carry a molecular 'suicide complex' to kill themselves in the event of lethal infection by viral parasites. Such 'altruistic suicide' prevents or limits viral replication and protects the rest of the bacterial population from subsequent infection.
The new research demonstrates that bacteria accomplish this through a high-risk strategy in which their lethal weapon is kept to hand at all times, but is neutralised until viral infection of the bacterial cell triggers its release from inhibition. In the longer term, the discovery could be exploited to enable the development of new small molecule antibacterial drugs.
The mechanism was discovered in the bacterial plant pathogen Pectobacterium atrosepticum by researchers led by Professors George Salmond and Ben Luisi in the University of Cambridge's Department of Biochemistry. Their work shows that a suicide complex, ToxIN, is not induced but exists all the time in the bacterial cell; to avoid killing the bacterial cell, it is held in a suppressed, inert form until viral infection triggers the release of a protein toxin (ToxN) from an RNA antitoxin (ToxI) partner. The toxin then causes the death of both the bacterium and the infecting virus.