Establishment of prespore-specific gene expression in Bacillus subtilis: localization of SpoIIE phosphatase and initiation of compartment-specific proteolysis.

Immunofluorescence microscopy was used to study the establishment of compartment-specific transcription during sporulation in Bacillus subtilis. Analysis of the distribution of the anti-anti-sigma factor, SpoIIAA, in a variety of mutant backgrounds supports a model in which the SpoIIE phosphatase, which activates SpoIIAA by dephosphorylation, is sequestered onto the prespore face of the asymmetric septum. Thus, prespore-specific gene expression apparently arises as a result of the compartmentalization of SpoIIE protein. The results also suggest the existence of at least two compartment-specific programs of proteolysis, one dependent on the mother cell-specific sigma factor sigma E and the other dependent on the prespore-specific sigma factor sigma F.