One fascinating
aspect of the regulation of endospore formation is another
regulatory event in which sporulating cells cannibalize their own
species. Those cells in which Spo0A has already become activated
secrete a protein that lyses nearby cells whose Spo0A protein has
not yet become activated. This toxic protein is accompanied by a
second protein that delays sporulation of neighboring cells. Cells
committed to sporulation also make an antitoxin protein to protect
themselves against the effects of their own toxin. When lysed,
their sacrificed sister cells are used as a source of nutrients for
developing endospores. Shortages of certain nutrients, in particular
phosphate, increase transcription of the toxin-encoding gene.