Mannitol transport in Streptococcus mutans

Abstract

A hexitol inducible, phosphoenolpyruvate dependent phosphotransferase system was demonstrated in S. mutans. Cell free extracts obtained from mannitol grown cells from a representative strain of each of the five S. mutans serotypes (AHT, BHT, C 67 1, 6715, and LM7) were capable of converting mannitol to mannitol 1 phosphate by a reaction which required phosphoenolpyruvate and Mg2+. Mannitol and sorbitol phosphotransferase activities were found in cell free extracts prepared from cells grown on the respective substrate, but neither hexitol phosphotransferase activity was present in extracts obtained from cells grown on other substrates examined. A heat stable, low molecular weight component was partially purified from glucose grown cells and found to stimulate the mannitol phosphotransferase system. Divalent cations Mn2+ and Ca2+ partially replaced Mg2+, while Zn2+ was found to be highly inhibitory.