pSM19035-encoded ζ toxin induces stasis followed by death in a subpopulation of cells

Virginia S. Lioy, M.T. Martín, Ana G. Camacho, Rudi Lurz, Haike Antelmann, Michael Hecker, Ed Hitchin, Yvonne Ridge, Jerry M. Wells, Juan C. Alonso*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

46 Citations (Scopus)


The toxin-antitoxin operon of pSM19035 encodes three proteins: the ω global regulator, the ε labile antitoxin and the stable ζ toxin. Accumulation of ζ toxin free of ε antitoxin induced loss of cell proliferation in both Bacillus subtilis and Escherichia coli cells. Induction of a ζ variant (ζY83C) triggered stasis, in which B. subtilis cells were viable but unable to proliferate, without selectively affecting protein translation. In E. coli cells, accumulation of free ζ toxin induced stasis, but this was fully reversed by expression of the ε antitoxin within a defined time window. The time window for reversion of ζ toxicity by expression of ε antitoxin was dependent on the initial cellular level of ζ. After 240 min of constitutive expression, or inducible expression of high levels of ζ toxin for 30 min, expression of ε failed to reverse the toxic effect exerted by ζ in cells growing in minimal medium. Under the latter conditions, ζ inhibited replication, transcription and translation and finally induced death in a fraction (∼50%) of the cell population. These results support the view that ζ interacts with its specific target and reversibly inhibits cell proliferation, but accumulation of ζ might lead to cell death due to pleiotropic effects.

Original languageEnglish
Pages (from-to)2365-2379
Number of pages15
Issue number8
Publication statusPublished - 1 Aug 2006
Externally publishedYes


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