Component of the phage ejection machinery which acts as an exolysin. Muralytic protein involved in host peptidoglycan digestion necessary for viral DNA entry into the host cell. Does not display any enzymatic activity. Required for DNA injection in the membrane transformation event. Involved in the formation of the membrane tail tube to connect the virus interior with the host cytosol. Essential for viral infectivity. Exolytic cleavage of the (1->4)-beta-glycosidic linkage between N-acetylmuramic acid (MurNAc) and N-acetylglucosamine (GlcNAc) residues in peptidoglycan, from either the reducing or the non-reducing ends of the peptidoglycan chains, with concomitant formation of a 1,6-anhydrobond in the MurNAc residue. Heteromultimer composed of proteins P7 and P14. Part of the capsid inner membrane. Approximately 20 copies per virion. Approximately 20 copies per virion. Belongs to the transglycosylase Slt family.