Compartmentalized gene expression during sporulation in Bacillus subtilis.

Two important features of endospore development in Bacillus subtilis--the compartmentalization of mother cell gene expression and the coordination of mother cell gene expression with forespore development--are governed by the highly regulated expression of the sigK gene, which encodes the mother cell-specific RNA polymerase sigma factor sigma K. Compartmentalized expression of sigK is associated both with a chromosomal DNA rearrangement and with the restriction of sigK transcription to the mother cell. A third mode of sigK regulation, which occurs at the level of activation of the sigK gene product by proteolytic processing, serves to couple gene expression between the mother cell and forespore compartments of the developing sporangium.