Inhibition of lysis by antibody against phage-associated lysin and requirement of choline residues in the cell wall for progeny phage release inStreptococcus pneumoniae

Abstract

We have prepared an antiserum against a new lytic enzyme (PAL) that has recently been isolated and purified from a mutant ofStreptococcus pneumoniae infected with the bacteriophage Dp-1. This antiserum inhibited the activity of the PALin vitro and was also capable of blocking the lysis of an amidase-deficient transformant of pneumococcus infected with Dp-1. This is a direct illustration of the involvement of the PAL in the liberation of the phage progeney in amidase-deficient strains of pneumococcus. The myeloma protein TEPC-15, an antibody that specifically blocks phosphorylcholine residues, inhibited the degradation of purified choline cell walls by the PAL. Our results also show that the liberation of the phage progeny to the medium requires the presence of choline in the cell wall. These findings demonstrate the basic role of the choline residues for the activity of the PALin vivo andin vitro.