Phosphate starvation induces the sporulation killing factor of Bacillus subtilis

Bacillus subtilis produces and exports a peptide sporulation killing factor (SkfA) that induces lysis of sibling cells. skfA is part of the skf operon (skfA-H), which is responsible for immunity to SkfA, as well as for production and export of SkfA. Here we report that transcription of skfA is markedly induced when cells of B. subtilis are subjected to phosphate starvation. The role of Phol? in regulation of the skf operon was confirmed by in vitro gel shift assays, which showed that this operon is a new member of the Phol? regulon. A putative stem-loop structure in the skfA-skfB intergenic region is proposed to act as a stabilizer of an skfA-specific transcript.