CELL-CELL SIGNALING PATHWAY ACTIVATING A DEVELOPMENTAL TRANSCRIPTION FACTOR IN BACILLUS-SUBTILIS

Transcription in the mother cell at early stages of sporulation in Bac illus subtilis is controlled by sigma(E), a sigma factor that is synth esized in the predivisional cell as an inactive larger precursor, pro- sigma(E). Activation of sigma(E) depends on sigma(F), the factor that governs transcription in the forespore. Genetic experiments have indic ated that transduction of the activation signal from the forespore to the mother cell requires the products of some genes belonging to the s igma(F)-controlled regulon. We have identified and characterized a sig ma(F)-dependent gene, csfX, encoding a protein necessary and sufficien t for triggering processing of pro-sigma(E). The CsfX protein contains a typical amino-terminal signal sequence suggesting that, although sy nthesized in the forespore, it may act across the septum to activate t he membrane-bound enzyme that is responsible for pro-sigma(E) processi ng in the mother cell.