Teichoic acid-containing muropeptides from Streptococcus pneumoniae as substrates for the pneumococcal autolysin

Pneumococcal cell walls in which the normal phosphorylcholine component of the wall teichoic acids is replaced with phosphorylethanolamine cannot adsorb the homologous autolytic enzyme and are completely resistant to autolytic degradation (S. Giudicelli and A. Tomasz, J. Bacteriol. 158:1188-1190, 1984). We have now isolated and characterized soluble teichoic acid-containing muropeptides from such cell walls and tested them as substrates for the pneumococcal autolytic enzyme. Both choline- and ethanolamine-containing muropeptides were hydrolyzed to the same extent by the enzyme. Furthermore, free choline concentrations that totally inhibited the digestion of pneumococcal cell walls in vivo and in vitro were without effect when the soluble substrates were used.