Probable aspartic protease that is responsible for the proteolytic cleavage of the RNA polymerase sigma E factor (SigE/spoIIGB) to yield the active peptide in the mother cell during sporulation. Responds to a signal from the forespore that is triggered by the extracellular signal protein SpoIIR. Self-associates. Interacts with SigE (Probable). Interacts with SpoIIR. Localized to the sporulation septum. Does not affect the localization of SigE. Belongs to the peptidase U4 family.