Probable zinc metalloprotease whose natural substrate is unknown. Does not show endo- or exopeptidase activity against resorufin labeled casein, p-nitroanilide (pNA), amidomethylcoumarin (AMC) (one to three amino acids in length), and hippuryl-aminoacid substrates. Binds 2 Zn(2+) ions per subunit. One is catalytic, whereas the other seems to have a structural role. Monomer. Belongs to the peptidase M54 family.