Alanyl turnover from lipoteichoic acid to teichoic acid inStaphylococcus aureus

The metabolism of d-alanyl substituents of lipoteichoic acid (LTA) and teichoic acid was studied in Staphylococcus aureus. Double labelling with [3H]glycerol and d-[14C]alanine revealed that during the chase LTA was stable whereas its 14C label rapidly decreased. Half-time comparison indicated an enzyme- rather than a base-catalyzed process. Correlated with the loss of [14C]alanine from LTA was an increase of the radioactivity in wall-linked alanine ester which, after hydrolysis with HF, proved to be linked to teichoic acid. These results suggest that LTA-alanine is the donor for alanine esterification of teichoic acid. In connection with previous data we hypothesize that the loss of alanine from LTA is compensated by de novo incorporation.