Regulation of Synthesis of the Bacillus subtilis Transition-Phase, Spore-Associated Antibacterial Protein TasA

Previously, we identified a novel component of Bacillus subtilis spores, called TasA, which possesses antibacterial activity. TasA is made early in spore formation, as cells enter stationary phase, and is secreted into the medium as well as deposited into the spore. Here, we show that tasA expression can occur as cells enter stationary phase even under sporulation-repressing conditions, indicating that TasA is a transition-phase protein. tasA and two upstream genes, yqxM and sipW, likely form an operon, transcription of which is under positive control by the transition-phase regulatory genes spo0A and spo0H and negative control by the transition phase regulatory gene abrB. These results are consistent with the suggestion that yqxM, sipW, and tasA constitute a transition phase operon that could play a protective role in a variety of cellular responses to stress during late-exponential-phase and early-stationary-phase growth in B. subtilis.