Essential protein that may act as a regulatory protease that is conditionally activated upon appropriate environmental triggers. Acts on substrates that are at least partially unfolded. The cleavage site P1 residue is normally between a pair of hydrophobic residues, such as Val-|-Val. The C-terminal region exhibits both monomeric and trimeric forms in solution. The periplasmic region consists of a protease domain (PD) and a PDZ domain, connected by a ten-residue linker (PubMed:30198900). Interactions between the PDZ domain and the catalytic domain lead to an inactive conformation (PubMed:30511675). Belongs to the peptidase S1C family.