pSM19035-encoded ζ toxin induces stasis followed by death in a subpopulation of cells Lioy, Virginia S. and Martín, M. Teresa and Camacho, Ana G. and Lurz, Rudi and Antelmann, Haike and Hecker, Michael and Hitchin, Ed and Ridge, Yvonne and Wells, Jerry M. and Alonso, Juan C.,, 152, 2365-2379 (2006), doi = https://doi.org/10.1099/mic.0.28950-0, publicationName = Microbiology Society, issn = 1350-0872, abstract= 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., language=, type=