Hydrolyzes N-terminal residues in D-amino acid containing peptides. Among the tested substrates, the highest activities are with D-Ala-D-Ala and D-Ala-Gly-Gly. The physiological role is not clear. Binds 2 Zn(2+) ions per subunit. Optimum pH is 9-11. Homodecamer. A 20 Angstroms wide channel runs through the complex, giving access to a central chamber holding the active sites. Expressed early during sporulation. Nutrient deficiency conditions, which also induce sporulation. Belongs to the peptidase M55 family.