Rhomboid-type serine protease that catalyzes intramembrane proteolysis. Important for normal cell division and sporulation. May act as a glucose exporter. Cleaves type-1 transmembrane domains using a catalytic dyad composed of serine and histidine that are contributed by different transmembrane domains. Inhibited by dichloroisocoumarin (DCI) and N-p-tosyl-L-phenylalanine chloromethyl ketone (TPCK), but not by other serine protease inhibitors such as sulfonyl fluoride PMSF and 4-(2-aminoethyl)benzenesulfonyl fluoride (AEBSF). Is more active at more active at 25 degrees Celsius than at 37 degrees Celsius. Belongs to the peptidase S54 family.