MECHANISMS OF SUGAR TRANSPORT IN STREPTOCOCCUS MUTANS

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The sucrose phosphotransferase system (PTS) is one means by which the oral pathogen Streptococcus mutans takes up this disaccharide from the environment. Because sucrose metabolism has been linked to the cariogenicity of S. mutans, our laboratory has been studying the biochemistry of the PTS in this organism. Our long-range goal is to understand the mechanism and regulation of the sucrose PTS in S. mutans to be able to identify important factors influencing the activity of this transport system in vivo. Our work also may lead to the identification of specific inhibitors of sucrose uptake and growth of S. mutans. In continuing this project, we aim to: 1) purify Enzyme I and the sucrose-specific enzyme III of the S. mutans PTS to apparent homogeneity and investigates their properties; 2) purify the sucrose-specific Enzyme II from S. mutans membranes; 3) further investigate sucrose analogs as inhibitors of the sucrose PTS and any other sucrose transport systems of S. mutans; 4) determine the physiological significance of ATP-dependent phosphyorylations of S. mutans proteins; and 5) continue 31p-NMR studies as a complementary approach toward understanding sugar transport systems and their regulation in S. mutans. A combination of well-accepted biochemical and biophysical approaches will be used to accomplish these aims.