Endolysin with L-alanyl-D-glutamate peptidase activity that degrades host peptidoglycans and participates with the holin in the sequential events which lead to the programmed host cell lysis releasing the mature viral particles. Once the holin has permeabilized the host cell membrane, the endolysin can reach the periplasm and break down the peptidoglycan layer by hydrolyzing the link between L-alanine and D-glutamate residues. Optimum pH is 8.5. Expressed in the early phase of the viral replicative cycle. Belongs to the peptidase M15C family.