Metalloendopeptidase with a Zn-dependent proteolytic activity and substrate cleavage upstream of hydrophobic residues (PubMed:27895226). Positive regulator of senescence, probably by degrading CCD4, thus participating in the controlled removal of carotenoids from the thylakoid membrane during the senescence process (PubMed:27895226, PubMed:28534654). Binds 1 zinc ion per subunit. Interacts with plastoglobule (PG) core proteins ABC1K3, PES1 and CCD4. Mostly expressed in flowers (e.g. sepals, petals and stamen), seeds, leaves and cotyledons. Accumulates during leaf senescence. Delayed senescence. Belongs to the peptidase M48 family. M48D subfamily.